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Stevens Institute of Technology

Solar Splash 2019

May 6th, 2019

Matthew Colacino Victoria Davis Megan Hand Justin Sitler

Melanie Valentin

Project Advisor: Michael DeLorme

Boat #4

Stevens Institute of Technology 1

Executive Summary Stevens Institute of Technology is competing for the third consecutive year in the Solar Splash Competition. The inaugural 2017 team designed and built the boat and propulsion system and achieved an outstanding finish in 4th place overall. The 2018 team improved the original model, successfully increasing the distance travelled in the endurance race as well as improving speed in the sprint race. The 2019 team has identified three desired areas of improvement: increasing the power available, decreasing the system weight, and implementing an Energy Management System to provide real-time state of charge during the endurance race. The 2019 team consists of five mechanical engineering students who focused on improving the system with the goal of achieving first place in the Solar Splash Competition. The main focus of the team was to design a unique outboard from the ground up, replacing the previous off the shelf outboards to reduce weight, increase power, and eliminate an unnecessary voltage converter. To win the Solar Splash Competition, the team determined that the boat should achieve 28 knots for the sprint race and 6 knots for the endurance race, which is greater than the winning 2018 team for each of these races. To determine the required power of the new outboard at these speeds, model scale testing of the existing hull was done at the expected overall system weight of 450 lb, resulting in a power requirement of 24.5 hp for the sprint race and 2 hp for the endurance race. The DHX Hawk40 motor was selected as it was the lightest motor option to supply this maximum power. The remaining components of the outboard system consist of a hydrodynamic foot, midsection, shaft, belt drive transmission, and housing. The belt drive system was an innovative design since the system is reversible, providing a 1.73:1 gear ratio for the sprint race and 1:1.73 gear ratio for the endurance race. The reversibility allowed the team to keep the belt drive system weight low because, as per competition rule 8.3, all components used must remain secured within the boat for all competitions. The overall weight of the outboard is 85 lb which replaces the 167 lb propulsion system used in the 2018 design. As a result of designing a new outboard motor, the steering and propeller needed a complete redesign. The steering system chosen was a drum steering wheel and pulley system, selected due to its simplicity and reduced weight compared to the 2018 system. The propeller was selected using Wageningen B-series Propeller Charts [3] and optimized to use a single 10” diameter 13” pitch propeller for both the endurance and sprint races. To improve performance in the endurance race, an Energy Management System (EMS) was developed with the capability to display the real-time battery charge while the system is functioning. It also calculates the anticipated state of charge at the end of the race to ensure that the maximum possible power is used, allowing the boat to travel the furthest distance possible. This system uses a human-machine interface so the skipper can easily read values such as battery voltage and current and make adjustments to the boat’s speed on the water as racing conditions change to travel the furthest distance possible. To ensure the system is ready for the Solar Splash event, the team will be conducting various tests to optimize the motor cooling system, ensure the propellers are optimized for the


system, familiarize the skipper with the Energy Management System, and ensure the solar panels are running at the expected efficiency. The team hoped to complete on the water testing earlier in the year, but due to difficulty acquiring funding the schedule was pushed back. The team has had significant support from the Stevens community, a variety of sponsors and donors, and the 2017 and 2018 Stevens Solar Splash teams. This support has been an integral part of the team’s successes. The team is proud of what has been accomplished thus far and is looking forward to demonstrating their hard work at competition. The team has also been working to foster continuity at Stevens between Solar Splash teams and is looking forward to providing the 2020 team with a similar level of support that was given to them this year.


Table of Contents Executive Summary 1

I. Overall Project Objectives 5

II. Hull Design 5 A. Main Hull 5 B. Stern Appendage 6

III. Power Electronics System 7 A. Motor 7 B. Motor Controller 8

IV. Drivetrain and Steering 9 A. Steering System 9 B. Outboard Design 10 C. Propeller Design 13

V. Data Acquisition 15 A. PLC 15 B. HMI 17 C. Motor Controller Data Acquisition 18

VI. Electrical System 18

VII. Solar System Design 19

VIII. Project Management 20 A. Team Members and Leadership Roles 22 B. Effectiveness of Project Planning 21 C. Financial and Fundraising 22 D. Strategy for Team Continuity and Sustainability 22 E. Discussion and Self-Evaluation 22

IX. Conclusion and Recommendations 23

References 24

Acknowledgements 25


Appendices 26 Appendix A: Battery Documentation 26 Appendix B: Flotation Calculations 33 Appendix C: Proof of Insurance 36 Appendix D: Team Roster 37 Appendix E: Center of Gravity Study Estimate 38 Appendix F: Power Electronics System Specifications 40 Appendix G: Sprint and Endurance Required Power Estimates 41 Appendix H: Drivetrain Components 43 Appendix I: Pugh Decision Matrix, Propulsion System 44 Appendix J: Wageningen B-Series Propeller Calculation Tables 45


I. Overall Project Objectives Stevens Institute of Technology has competed in the Solar Splash Competition for the 2017 and 2018 event. The 2017 team designed the entire system from scratch, while the 2018 team made modifications to the existing design, including: reduction in hull weight, increased propeller sizes and modifications to the existing outboard lower units, development of a stern appendage for the endurance event, and development of a system to provide data to the skipper of battery charge during the endurance event. The 2019 team determined that the main areas of improvement needed following the 2018 event were a more powerful and lighter propulsion system and a system to provide real-time data about battery charge during the endurance event. The objective of this team was to utilize the system developed by the previous Stevens Solar Splash teams and make adjustments to bring the team from 5th place overall to 1st place. To achieve this, the team focused on designing a system that would exceed the results of the 2018 winning teams in the sprint and endurance events; see Table 1. To achieve these goals, the team’s main area of focus was reducing the weight and increasing the power of the propulsion system.

Table 1: Design Point Stevens 2017 Stevens 2018 Best Team 2018 Stevens 2019 Design

Endurance Race Longest distance in 4 hours

4.2 knots 4.7 knots 5.7 knots 6.0 knots

Sprint Race Fastest time over 600 meters

12.1 knots 13.1 knots 24.0 knots 28.0 knots

II. Hull Design

A. Main Hull The existing hull design was completed by the 2018 team, which used the existing design of the 2017 team but was remade with different materials to reduce the weight and therefore drag. The 2018 team reduced the freeboard and most importantly reduced the overall hull weight from 326 lb to 55.3 lb by making the hull from four lightweight layers: Duratec coating, an exterior coating of carbon fiber, Nomex Honeycomb, and an interior layer of carbon fiber. The existing hull is well designed for the competition as a planing hull for the sprint race. Because the 2019 team set their design goal for a 450 lb system racing at the speeds in Table 1, a tank test was conducted to determine the power needed to propel the boat as well as to determine the optimal longitudinal center of gravity (LCG) for both low and high speed applications. The tank test was conducted by Joseph Lodge in the Stevens Institute Davidson Laboratory as a Naval Engineering undergraduate research project. For scale model testing, a ⅓ scale model of both the hull and stern appendage was created, and run to model a 450 lb system weight. The scale model testing is shown in Fig. 1.


Fig. 1a and b: Scale Model Testing (a) Side View and (b) Underwater View

The power needed is shown in Fig. 2, with an assumed propulsive coefficient of 0.5 which was chosen as a realistic but conservative number. The power needed was determined to be 24.5 hp for the sprint race (28 knots) and 2 hp for the endurance race (6 knots). The optimal LCG for 20-30 knots was found to be 66” forward of the transom, while the optimal LCG for 5-7 knots was found to be 62.4” forward of the transom. The LCG was carefully set to these values for each configuration by doing a complete center of gravity study for both the sprint and endurance race, which can be found in Appendix E.

Fig. 2: Scale Model Testing, Graph of Power Needed

B. Stern Appendage The Stevens Institute of Technology 2018 team developed a removable stern appendage

to bridge the gap between planing and displacement hull type. The stern appendage is attached during the endurance races to create a more traditional displacement type stern, which reduces drag compared with the transom stern used for the higher speed races. Fig. 3 shows an image of the stern attached to the hull.


Fig. 3: 2018 Attached Stern Appendage

In efforts to further improve the design, the 2019 team investigated plugging the hole in the stern appendage. Testing the effects of plugging the hole in the 2019 tank test, the team determined that the plug would reduce drag by 2.7 lb at full scale. The hole causes abrupt discontinuities between the transom and stern appendage and creates an inability of the water to flow in a smooth streamline, leading to the presence of eddys and eddy making resistance. The team is using expandable foam in a mold to create two parts to surround the new lower unit mentioned later in this report and fill in the hole.

III. Power Electronics System The power electronics system will be replaced completely from the 2018 configuration which consists of two Elco 9.9 outboard motors. These outboards were donated off the shelf and were not rated for the optimal voltage required by the competition. Due to the voltage issue, voltage converters were utilized to step up the 36V power bank to 48V - the operating voltage of the Elco motors. This system was excessively heavy and limited the power provided to the motors. This year, the focus has been to develop a new power electronics system that not only complies with the competition requirements without additional hardware but also supplies sufficient power to reach higher speeds. A. Motor The first step in redesigning the power electronics system was to determine the necessary power to reach the optimal speed of 28 knots. This was calculated using the tank test data discussed in the hull design section of this report. Upon acquiring this data, the team performed calculations using potential drivetrain systems, propellers, and motors to analyze the performance from the effects of all factors in the propulsion system. Based on the different scenarios that were analyzed, the team opted for the DHX Hawk40 motor, which can be seen in Fig. 4.


Fig. 4: DHX Hawk40 Motor 1) Customized Hawk40 Motor: While the Hawk40 motor had the best power to weight ratio, the total power of this single motor was slightly less than what was necessary based on the tank test data. To make up this power deficiency, the team worked with DHX to develop a customized motor specifically for this application. DHX rewound their Hawk40 motor from 96V to 72V that would result in less of a power reduction when operating the motor using a 36V power bank. Additional specifications for the motor can be seen in Appendix F.

One aspect of the Hawk40 that was beneficial to the team’s application was the torque constant of this particular motor, 0.14 ft-lb/A. Because of this torque constant, the team can travel a further distance during the endurance race because the motor will draw less current. Drawing less current allows for an extended lifespan of the 36V power bank. The calculations for estimated required power for both the sprint and endurance races can be seen in Appendix G. 2) Cooling System: Along with the motor, DHX supplied the team with a closed-loop cooling system specifically designed to be used with their motors. The cooling system is composed of a radiator, pump, and reservoir. During on the water testing, the team will determine how much cooling is needed during the endurance and sprint races to keep the motor running efficiently. By running the cooling system for shorter periods of time, it will be possible to use less battery power for cooling. This is important because as per the competition guidelines, the cooling system will need to be powered by the main 36V battery pack that is powering the motor. B. Motor Controller To control the speed of the motor shaft, the team purchased a programmable motor controller from DHX. The team shared the optimal motor operation settings with DHX based on the tank test so that they would be able to program the motor controller and test the motor in the expected conditions before shipping it to the team. The motor controller was then sent to the team with a wiring harness and diagram of the connections that the team will need to make, including the dashboard controls. 1) InMotion 80L Motor Controller: The motor controller that was provided by DHX was the InMotion 80L motor controller. This controller was chosen because of its capabilities to work with the custom Hawk40 motor at its maximum voltage of 72V. The amperage rating of the motor controller for the 2 minute operation time is appropriate for the amperage requirements for the sprint race of the competition. Specifications for the motor controller can be found in Appendix F.

The motor controller, including its heat sink, can be seen in Fig. 5. The heat sink is necessary to keep the controller within the range of operational temperatures. This is crucial because the motor will be operating at nearly maximum power for the sprint race. The heat sink currently installed was provided by DHX, but the team will attempt to modify or replace the heat sink based on the suggested dimensions provided by InMotion for this specific controller and based on testing of heat generation. The team will acquire a thermocouple to determine the temperature of the motor controller and heat sink. Aside from the current design of a solid piece of aluminum, the team could reduce weight by creating a finned design.


Fig. 5: InMotion 80L with Heat Sink

2) Controlling Components: The wiring harness connected to the motor controller is utilized to make connections not only to the motor but also controlling components on the dashboard. These components include the ignition switch paired with the emergency power stop, the throttle for speed control, and the directional control to specify whether the boat is moving forward or reverse.

IV. Drivetrain and Steering The 2018 propulsion system consists of two ELCO 9.9 outboard motors with a SeaStar

mechanical steering system. For the sprint configuration, the two outboard motors are used with a 9.5” x 12” 3 blade left and right hand propellers. For the endurance race, one motor is secured inside the hull, and only one motor is used for the race.

The main issue with this system is its excessive weight and limited power. The total weight of the system is 167 lb, 65 lb per motor and 37 lb for the voltage converter, while the maximum power available is less than the 24.5 hp needed for the sprint race. To improve this system the team chose to do a complete system redesign, with a goal to double the power available and reduce the propulsion system weight as much as possible. As a part of this redesign, the steering system and propeller design needed to be redesigned from the beginning since the entire system was changing. A. Steering System

The decision to create a new outboard design ultimately resulted in a redesign of the steering system. The new system is composed of a drum steering wheel and a set of pulleys, donated by Portage Bay Systems, to transmit the directional controls from the skipper to the outboard. This type of system was selected because of its low weight and ease of installation and design for a unique outboard unit. A schematic of this design can be seen in Fig. 6. The typical cable that runs this system will be replaced with an Aramid fiber rope to reduce weight and increase flexibility.


Fig. 6: Steering System Schematic

B. Outboard Design As described in the summary above, the team set out to do a full system design. The

design points were derived from scale model testing described in the hull design section of this report. To achieve 28 knots in the sprint race, 24.5 hp is needed, and to achieve 6 knots in the endurance race, 2 hp is needed. After researching different propulsion options, including inboard, outboard, sterndrive, jet propulsion, and podded propulsion systems, the team selected to design an outboard motor with the primary decision factors being efficiency at high and low speed, added drag, and configuration flexibility. A pugh matrix outlining this decision can be found in Appendix I.

The final design of the outboard propulsion system consists of 6 main parts, which will be discussed below in the following order: lower unit, motor, housing, belt drive, extender, and shaft. The Elco outboards will be completely replaced by this new single outboard design. An exploded view of the SolidWorks design of the complete new outboard unit can be seen in Fig. 7.

Fig. 7: Outboard Exploded View

1) Lower unit and midsection: The lower unit and midsection were the first portion of the outboard that was acquired in the design process. It is a Mercury racing unit from the 80’s, which has been modified for high speed hydroplane racing.

Midsection

Lower

Extender

Shaft Belt

Housing

Motor


The lower unit was the most important part to the team in the selection process. The highly tapered design is hydrodynamic and reduces drag compared to the blunt lower unit of the Elco 9.9 motors used in the 2017 and 2018 teams’ boat. A SolidWorks flow simulation estimated the drag to be 8.18 lbf at 27.5 knots. A variety of blunt lower unit designs were analyzed in SolidWorks which led the team to estimate the drag as approximately ½ of the previous foot drag. It is important to note that the drag is further reduced by using a single lower unit in the sprint race. The lower unit can be seen in Fig. 8, with some approximate dimensions.

Fig. 8: Lower Unit and Midsection, with Extender

2) Motor: The specifications of the motor were outlined in the Power Electronics System section of the report. In terms of mechanical modifications to the Hawk40 motor, DHX was able to customize the shaft to fit the team’s power transmission needs. After selecting this motor, the team needed to design a system to transmit the power from the shaft to the propeller. 3) Housing: The housing was designed to securely mount the motor to the top of the outboard system, and to hold the belt drive system. The housing for the motor consists of a frame and covering to protect the motor. The frame must have the structural integrity to support the motor, motor controller, belt drive under tension, and steering system cables.

The top and bottom of the housing consist of two plates, a plate that mounts to the top of the midsection, and a plate that mounts to the motor. The midsection base plate was machined from ¼” aluminum plate and reinforced with T-slotted aluminum extrusion beams for additional support. The motor also requires a mounting plate that matches the standard mounting pattern for the DHX Hawk40. This plate was machined from 3/16” aluminum plate to reduce weight. The framing was built from T-slotted aluminum extrusion supported by external brackets. The frame connects to the extrusion reinforcement on the base plate to attach to the midsection. There are also two vertical pieces which support the motor controller, which use 3/16” aluminum plates to mount. A mounted bearing is used to align the drive shaft, as well as support the load from the belt tension. To tension the belt, the framing can slide along the T-slot fasteners to adjust the center-to-center distance of the belt and increase tension. A CAD illustration of the drivetrain housing without the covering can be seen in Fig. 9.


Fig. 9: Drivetrain Housing Assembly

4) Belt drive: A transmission system is needed to adjust the motor RPM to the desired propeller RPM for both the sprint and endurance races. The Hawk40 motor supplies a nominal RPM of 2200 when run at 36V, which needs to be adjusted to 2900 RPM at the propeller for the sprint race and approximately 950 RPM for the endurance race. These values will be further explained in the Propeller Design section.

The belt drive was chosen for the transmission over a gearbox due to its lower weight. When considering the gear ratios, the team accounted for the existing 16:21 gear ratio in the lower unit. The gear ratio created by the sprockets was designed to change the overall gear ratio of the drivetrain system to 1.32 for the sprint and 0.44 for the endurance based on the calculations performed in Appendix G. The belt drive that the team will use for the sprint race has a 71:41 ratio, or 1.73:1. The sprockets will then be reversed for the endurance race to yield a ratio of 1:1.73. These ratios were chosen based on the propeller RPM requirements and to simplify the system by making the sprockets reversible. The final configuration consists of the components listed in Appendix H. 5) Extender: As discussed in the Propeller Design section, a 10” propeller is needed for optimal performance. The lower unit-midsection, as acquired, limited the propeller diameter to 7.5” due to the existing distance from the prop shaft centerline to the midsection which is not intended to be submerged. To permit the use of the required propeller, a 2” aluminum extender was designed to mount between the foot and the lower unit. This extender has the same hydrodynamic profile as the lower unit to reduce the drag it induces. The extender and foot assembly can be seen in Fig. 10.


Fig. 10: Foot and Extender

6) Shaft: Due to the extension of the foot, the drive shaft also required extension. A coupling was designed to connect the existing drive shaft and a new shaft, which will extend past the top of the midsection and attach to the bearing and the sprocket. The inner diameter of the midsection is approximately 1 ⅜”, and is the limiting factor on how large the coupling can be. The existing shaft is 9/16” in diameter with a six spline pattern on the end. This means a custom coupling is necessary. The coupling is composed of a 1 ¼” tube which is welded to a 9/16” six spline coupling. The inner diameter of this tube is ⅞”, which allows a ⅞” diameter 6” long shaft to be connected via a pin. The pin must be a 1 ¼” long roll pin to not extend past the diameter of the coupling. The coupling assembly can be seen in Fig. 11.

Fig. 11: Drive Shaft Coupling Assembly

C. Propeller Design To calculate what size propellers are needed, the propeller charts from the Wageningen

B-series propeller tests [3] and Dave Gerr’s Propeller Handbook [1] were used. The calculations were completed for both the sprint and endurance race, to determine the optimal propeller for each application. To determine propeller diameter and RPM relationships, calculations were done using the Propeller Handbook. When detailing Crouch’s Propeller Method of propeller selection, Gerr provides a formula relating diameter, power, and rotation rate, shown below:

𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟,𝐷 = 632.7 × 𝑆ℎ𝑎𝑓𝑡 𝑝𝑜𝑤𝑒𝑟 (ℎ𝑝)0.2

𝑅𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑅𝑎𝑡𝑒 (𝑅𝑃𝑀)0.6

The power needed for each application is known from the scale model testing discussed in the Hull Design section of this report. For the sprint race at 28 knots 24.5 hp is needed, and for the endurance race at 5 knots 1.0 hp (2.0 hp at 6 knots) is needed. For the RPM calculations, 5 knots was used as the design point to ensure a broad range of propeller efficiency, as solar conditions and other unknowns could prevent the system from reaching 6 knots during the endurance race. A variety of propeller diameters were analyzed, but the results for 10” diameter are discussed here as this was the final propeller design selected. For the sprint race 2926 RPM is calculated, and the drivetrain was designed to reach 2900 RPM. For the endurance race 1000 RPM is calculated, and the drivetrain was designed to reach 950 RPM.

The Wageningen B-series propeller charts were used to determine the pitch and diameter of the propellers. This method primarily depends on the advance coefficient and thrust coefficient, which are useful non-dimensional characteristics of propeller performance. The equations for these two coefficients and thrust are:


𝐴𝑑𝑣𝑎𝑛𝑐𝑒 𝐶𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡, 𝐽 =𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑜𝑓 𝐴𝑑𝑣𝑎𝑛𝑐𝑒 �𝑓𝑡𝑠 �

𝑅𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑅𝑎𝑡𝑒 �𝑟𝑒𝑣𝑠 � ×𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟 (𝑓𝑡)

𝑇ℎ𝑟𝑢𝑠𝑡 𝐶𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡,𝐾𝑡 =𝑇ℎ𝑟𝑢𝑠𝑡, 𝑙𝑏𝑓 �𝑠𝑙𝑢𝑔 𝑓𝑡

𝑠2 �

𝑤𝑎𝑡𝑒𝑟 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 �𝑠𝑙𝑢𝑔𝑓𝑡3 � × 𝑅𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑅𝑎𝑡𝑒 �𝑟𝑒𝑣𝑠 �2

× 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟 (𝑓𝑡)4

𝑇ℎ𝑟𝑢𝑠𝑡,𝑇 =𝑃𝑜𝑤𝑒𝑟 �𝑙𝑏𝑓 𝑓𝑡

𝑠 �

𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑜𝑓 𝐴𝑑𝑣𝑎𝑛𝑐𝑒 �𝑓𝑡𝑠 �

To complete these calculations, a known diameter, rotation rate, and velocity of advance are selected. With these provided, the advance coefficient and thrust coefficient needed can be calculated. These lines can then be plotted on a propeller chart, and from that chart the necessary pitch/diameter (P/D) ratio of the propeller can be selected. As seen in Fig. 12 a propeller with 1.3 P/D can be selected for the endurance and sprint races.

Fig. 12: Wageningen B-series Propeller Chart [3]

For the sprint propeller, at the 28 knots design point, the chart demonstrates that more thrust is needed than the 1.3 P/D propeller will provide, however at 25 knots more thrust is provided than needed. This means that the optimal thrust will be provided somewhere between 25 and 28 knots which is satisfactory for the propeller selection. For the endurance propeller, at 6 knots the optimal thrust will be provided. Tables detailing the calculations for these three design points shown above are included in Appendix J.

For this propeller selection, the team was able to acquire a 10” x 12.5” 2 bladed propeller. The propeller selection will be validated using on the water testing, by comparing the performance with several other possible propeller designs, including a 7” x 13” propeller for the sprint race, and a 11” x 15” propeller for the endurance race. The 2018 existing 9.5” x 12”


propellers cannot be compared because the hub design is drastically different than what is needed for the lower unit.

V. Data Acquisition The 2018 team developed an Energy Management System (EMS) to understand the

system performance during testing and at the competition. To achieve data collection capabilities, the team worked with Automation Direct to design a complete PLC system, capable of measuring, logging, and displaying all data in real time. The system is comprised of three voltage transducers, a bidirectional current transducer, single direction current transducer, four signal conditioners, a Do-More PLC unit, an analog expansion module, a C-More Digital Display unit, and a voltage converter. See Fig. 13 below for the electrical schematic of the energy management system, which demonstrates how each module is wired together. The specification sheet for each component of the system was carefully analyzed to ensure that it was compatible not only with the chosen PLC unit, but the actual system loads. For example, the voltage transducers utilized are specified to operate within 0-50V, which falls within the system maximum of 36V.

Fig. 13: Power Management System Schematic

With the hardware in place, the 2019 team reprogrammed the Programmable Logic Controller (PLC) and Human-Machine Interface (HMI) to improve the method of understanding and displaying data to the skipper, since last year’s team was unable to use the EMS effectively during the race. A. PLC The EMS was programmed using a software package called Do-More Designer 2.3. This software is designed by Automation Direct and is built to be compatible with the BX-DM1-10ER-D PLC which was donated by the company to last year’s team. The user interface uses


ladder logic to make programming straightforward and simple. Timers and other functions can be used to make the program more sophisticated by keeping track of the race time. Mathematical expressions can be used to calculate quantities such as State of Charge (SoC) and assign them to variables, which can be referenced in other functions. The program uses current integration to determine SoC and predict how long the batteries will last. Current integration, as the name suggests, integrates the current over time to find the amount of charge consumed, and compares it to the maximum amount of charge in the battery, or capacity. This value is nominally given by the battery manufacturers as 45 A-hrs, but capacity can change over time due to battery health deterioration. The functions programmed into the EMS will emulate the equations of current integration:

𝑄𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑 = �

𝑡𝑐𝑢𝑟𝑟𝑒𝑛𝑡

0𝐼𝑏𝑎𝑡𝑡𝑒𝑟𝑦𝑑𝑡

𝑆𝑜𝐶 =

𝑄𝑚𝑎𝑥−𝑄𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑

𝑄𝑚𝑎𝑥

𝑄𝐸𝑜𝑅 = 𝑄𝑐𝑜𝑛𝑠𝑢𝑚𝑒𝑑 + 𝐼𝑎𝑣𝑔 ∗ 𝑡𝑟𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔

The Do-More Designer 2.3 software which computes these parameters can be seen in Fig. 14 below.

Fig. 14: Energy Management System Implementation in Do-More Designer 2.3


B. HMI Once the key variables are calculated, the EMS must display them through a user interface, so the skipper can make use of the real-time data. The PLC connects to a EA3-T6CL C-More Micro HMI by Automation Direct, which includes a digital display and touch screen for interaction. The HMI can be programmed using C-More Micro Programming Software to display variables and other information collected by the PLC. It can also be used to create new variables, such as the start of a timer, which can will used for calculations to predict state of charge at the end of each 2 hour endurance race. It can be programmed with various windows that can be scrolled through for ease of use, to access all important information at the touch of a button.

The most important window will be used to display key information during the endurance race, which can be seen in Fig. 15. It displays the current state of charge, predicted state of charge at the end of the race, current solar voltage, time remaining (after skipper starts timer at the beginning of race), as well as the rate of energy consumption. The rate of energy consumption is a variable the skipper will become familiar with throughout testing, and will allow the skipper to make informed decisions about how much to slow down or speed up to change the predicted state of charge at end of race to the desired 20% value.

Fig. 15: HMI Endurance Race Window

Additional screens on the HMI can be programmed to show useful information that will help the team troubleshoot during testing. Fig. 16 shows an example screen that will be used during sprint race testing to ensure the system current and voltage are changing as expected.


Fig. 16: HMI Sprint Race Testing Window

C. Motor Controller Data Acquisition The In-Motion motor controller also collects data. Using the Kvaser USB-to-CAN cable to connect to a PC, the team can use data about variables such as temperature, rpm, and torque to make improvements to the system. This will be used to troubleshoot any motor errors as well as to collect data after on the water testing.

VI. Electrical System The 2017 and 2018 Stevens team’s electrical system utilized three batteries, a voltage

converter, a charge controller, a motor controller, and fuses for overcurrent protection. Three 12V batteries are connected in series to create a 36V battery bank with a capacity of 45 A-hrs. These batteries are mounted to a flat surface with a strap and ratchet, and connected with 2/0 gauge wire to a waterproof housing. Refer to Appendix A for the battery documentation. With the new custom 72V DHX motor that will be ran at 36V, the voltage converter was no longer needed. The team removed this component from the system and remade the connections between the batteries, On/Off Switch, and motor controller. The removal of the voltage converter provided a 37 lb weight reduction to the overall system. The new DHX motor requires 425 amperes (A) for maximum power output during the sprint race. Therefore, the 2/0 wire is undersized for the application. From voltage drop calculations, the team expects the undersized wire to experience a voltage drop of 2.76%. The team decided that the voltage drop was the worth being able reuse wire from last year, that is lighter in weight than that of a heavier duty wire. The team also had to create the electrical connections between the In-Motion motor controller, the DHX motor, and the components on the dashboard (dead man’s switch, key switch, forward/reverse toggle switch, and throttle). With assistance from the team’s contacts at DHX, In-Motion, Kvaser, and the Davidson Laboratory Machine Shop, the team created the wire connections seen in the electrical schematic in Fig. 17.


Fig. 17: Inmotion 80L Electrical Schematic

VII. Solar System Design The Stevens Institute of Technology 2017 team created a simple and effective solar

system, which utilized solar modules by KingSolar. The system includes four solar modules and a solar optimizer that connect to the battery bank. The solar optimizers ensure that each module is providing maximum power, even if another module is shaded. These modules are all 120 watts (W), 18 volts (V) KingSolar Solar Panels, which are mounted to the top of the freeboard with two wooden frames. Two sets of two solar panels are connected in parallel, while each set is connected in series. This provides 13.33 A at a nominal 36V, meeting the requirements for charging the battery bank. The total power available from the panels is 480 W. The panels are thin film monocrystalline solar modules, which are lightweight and flexible. Fig. 18 depicts a photo of the module and some of its components in detail.

Fig. 18: KingSolar Panel with MC4 Connectors and Grommets


VIII. Project Management A. Team Members and Leadership Roles The team developed 5 different stages of this project. During these stages, more work was required in different areas which resulted in transitions of team member roles. These stages are outlined in this section. 1) Stage 1: During the initial research stages of this project, the team split into three groups to best manage the work:

● Propulsion System - Matthew Colacino & Megan Hand ● Electric Motors - Victoria Davis & Justin Sitler ● Previous Competitors & Stevens Inventory - Melanie Valentin

Matthew and Megan focused on researching all the options the team could use for the propulsion system to determine which is most feasible for a boat that is required to run efficiently at both high and low speeds. Victoria and Justin researched the electric motors that are on the market to find one that can supply the appropriate amount of torque for the propulsion systems. Melanie dug into the inventory of the past two years’ teams and took the initiative of studying what the previous competitors utilized for their EMS and other aspects of the boat so that the team can use this information to improve their boat design. 2) Stage 2: After the initial research phase, the team realized they needed to divide up the work in a different fashion. This breakdown was the structure for the remainder of the project and can be seen below:

● Propulsion System & Steering - Matthew Colacino, Victoria Davis, & Megan Hand ● EMS (Assembly & Coding) - Justin Sitler & Melanie Valentin

Victoria was absorbed into the propulsion system team while Justin joined Melanie in developing the EMS system. The propulsion team will be working towards integrating all of the parts of the propulsion system including:

● Motors ● Propeller

● Drive Train ● Steering System

The EMS team created a flow diagram with how they intend to work with their inputs and outputs to utilize the batteries in the most efficient way. This stage of the project encompassed writing the actual code and determining which sensors to purchase for the construction of the system. The members of each team assisted other teams upon discovering issues that needed more support to complete. 3) Stage 3: After determining how the propulsion system and EMS would be integrated into the design of the boat, the next step was to begin ordering the parts. Each member is responsible for deciding what needs to be ordered. Melanie has taken point on ordering these materials and worked to see what parts can be acquired by donation from supporters. 4) Stage 4: Once all the material has been acquired, the team began assembling the new systems into the boat. The team breakdown took on a heavier focus on the propulsion system due to the amount of integrated parts. 5) Stage 5: The final stage of this project is testing all the systems of the boat. All members of the team will contribute to troubleshooting each system. By including everyone in the process, issues were quickly resolved, and new solutions were brought to the table. Following this stage of the project is the competition where the team hopes to take home first place.


B. Effectiveness of Project Planning Outlining the different tasks that were related to each other helped the team prioritize work. Having the appropriate number of members associated with each system allowed for efficient distribution of work. The team anticipated problems that would halt or delay progress of certain systems, which allowed for team members to be flexible in their time commitments to different systems. Due to issues acquiring funding, the team saw sufficient delays in progress of the propulsion system, but they worked to improve other systems and took proactive approaches to their work to ensure that when all of the components were acquired, integration was as simple as possible. C. Financial and Fundraising

At Stevens Institute of Technology this project is a senior design project and is given a limited budget. An initial budget was put together based on the 2019 teams goals, but this budget was larger than the allotted finances. The team used a combination of fundraising and company outreach to obtain the necessary components.

Alan van Weele, a co-owner of the company Aeroliner Race Boats was a large contributor who donated the shaft and the lower unit for the outboard system. He also supported the team with a coupler to connect the outboard shaft and the motor shaft and propellers to test. Craig Dewald from Dewald Propellers helped the team scope out propellers specifications needed and Gabe Capobianchi from Procision Propellers enlarged and repitched the final the propeller to those specifications.

DHX was able to provide us with a student discount for the motor, motor controller, and cooling system. The company provided the team with support with calculations and customized the motor to meet horsepower requirements. Kvaser donated the cable used to program the motor controller. Jamestown Distributors gave us credit to the team’s account to help us order hardware and other supplies to the boat. Odyssey Battery donated a set of batteries to the team. Portage Bay Systems donated the steering components to the team. The team also utilized crowdfunding to gain additional funding for components that were not donated to the team. D. Strategy for Team Continuity and Sustainability

Not only was it a goal of the team’s to build a successful boat and improve as many of the issues initially identified, but the team wanted to document as much as possible to make learning about the system easier for next year’s team. Similar to last year, most components of the system were donated and will be passed onto future teams. The team this year has been documenting set-up of the components, especially for water testing, to help future teams to understand the system and how to integrate all components, rather than trying to base the set-up off of pictures that were passed down to them. Just like this year, next year’s team is in a great place to continue improving the system. The team this year has identified other issues that were not initially recognized and documented them to be passed onto next year’s team to start them off with potential areas of improvement.

Like in the previous years, Stevens Solar Splash is senior design project at the university. The 2019 team made efforts to recruit underclassmen onto the team and show them the progress made. One of these students, Samuel Murphy, is helping the team create a Solar Splash club on campus to continue to engage underclassmen in the project.


E. Discussion and Self-Evaluation One of the difficulties the team had was that unlike other teams, the team is not a college club, but a senior design project. This means that every year, the entire roster is replaced with new people who have no experience with the boat. Team members must spend a significant amount of time relearning the basics of what is needed and how the boat works. In addition, the team is small, with only five people as official members. The team is trying to make a Solar Splash club next year, which would alleviate this problem by having recurring members with experience as well as letting in ambitious students who are eager to participate. The team has had some trouble with staying on schedule as well. For example, the team did not get to test on the water until May, when the goal was to be able to test in late March. Part of the delay was due to a team member becoming sick for an extended period of time. The team is already small, so being understaffed set the team back. Another important setback was the team did not have funding to purchase the DHX motor until late. This meant the team had to wait until the motor arrived in mid-April to do preliminary testing. These setbacks were out of the team’s control, but it is something future teams should keep in mind to prepare for.


IX. Conclusion and Recommendations The team’s design has multiple competitive advantages that will let us perform well in the competition. The combination of an incredibly lightweight hull and the state-of-the-art, lightweight yet powerful motor will allow the team to reach the high speeds required to be a top competitor. However, the design does have some weaknesses as well. Being a custom-built outboard, there is considerable additional troubleshooting and uncertainty with the design compared to off-the-shelf outboards which are more reliable. This provides an additional challenge in making the design successful, but if this challenge is overcome, the design will achieve the overall goal of reducing weight while increasing power due to the customized outboard. The team is proud of the accomplishments achieved thus far, and optimistic to see continued improvements before the competition. The original plan of redesigning the outboard was upheld, but the predicted timeline and schedule were delayed. The process could have been smoother if the team followed the schedule more closely to avoid last minute complications. Ideally this will be alleviated when the team becomes a club in subsequent years, because the difficulty in relearning all of the requirements and skills will be lessened. Subsequent teams still have much to improve on the boat. Reducing weight is always a concern, and there could definitely be improvements to not just the outboard but the cooling system, electronics, batteries, solar panels, and other areas. The outboard designed this year achieved the team’s goals, but construction from T-slotted aluminum extrusion is perhaps not the most efficient design. The next year’s teams might also want to improve the transmission, perhaps experimenting with different ratios. The weights of the sprockets could be cut down as well, as they are made from steel; lighter material and smaller sprockets could be used to decrease the transmission weight.

The team learned many different engineering skills through hands-on work on the boat, including but not limited to electrical systems design, naval engineering principles, mechanical design, project planning, budgeting, and teamwork. The team also realized the importance of setting realistic yet ambitious goals - the objective to reduce weight and increase power was ambitious, but the team managed to accomplish it through setting realistic expectations and a careful plan of how to achieve it. Simple designs are usually more successful than elaborate and overly ambitious ones.


References [1] D. Gerr, Propeller Handbook: The Complete Reference for Choosing, Installing, and Understanding Boat Propellers. Camden: International Marine, 2016. [2] Gates Poly Chain GT Carbon Belt Drive Design Manual, Gates Corporation. Denver, CO, 2009. [3] W. Van Lammeren et al, “The Wageningen B-screw series,” Transactions of the Society of Naval Architects and Marine Engineers, vol. 77, pp. 269-317, 1969.


Acknowledgements The team would like to acknowledge the following people and organizations for their major

contributions to the success of the project: ● Uihoon Chung ● Joseph Lodge ● Robert Weiss ● Bruce Fraser ● Alan van Weele ● Henry Colie ● Craig Dewald ● Benjamin Sorkin

● Steve Greaves ● Howie Goheen ● Samuel Murphy ● Gabe Capobianchi ● Sara and Frank Poor ● Members of 2017 and 2018

Stevens Teams

The team would also like to thank the following sponsors:


Appendices Appendix A: Battery Documentation

The team uses two sets of three 12V Odyssey marine grade sealed lead acid batteries (PC1100).


Appendix B: Flotation Calculations The 2019 Stevens Solar Splash competition race boat will weight 300 lb in its heaviest

configuration without the skipper. Rules require 20% factor of safety to be included in the buoyancy calculations (Rule 7.14.2 - Buoyancy of Craft). Therefore, the boat must include an extra 60 lb of buoyancy, for a total of 360 lb of buoyant force.

Total Weight 20% Reserve Total Needed

Buoyancy

(lb) (lb) (lb)

315 63 378 1) Hull & Internal Structures Buoyancy: To calculate the total buoyant force of the hull and internal structures, if they were to be submerged, the team used their Rhino3D model to measure their area. The transom was divided into two portions, because a portion was thickened with a penske board during the 2018 hull build. Additionally, the first 3.5 inches under the Freeboard have a different thickness of 0.0625 in. The area of this section is noted in the Reduction column and its volume is accounted for in the Reductions Sum row. The model’s thicknesses were confirmed through measuring the boat.

Part Area Reduction Thickness Volume

(in^2) (in^2) (in) (in^3)

Nomex Honeycomb Transom

395.68 48.08 0.375 130.35

Penske Board Transom 292.96 0 0.25 73.24

Starboard Bottom Surface 1495.76 0 0.375 564.59

Port Bottom Surface 1495.76 0 0.375 560.91

Starboard Side Surface 3567.39 372.00 0.375 1198.27

Port Side Surface 3567.39 372.00 0.375 1198.27

Longitudinal Structures 1363.97 0 0.375 511.49

Transverse Structures 487.62 0 0.375 182.86

Reductions Sum 792.08 0 0.0625 49.51

Sum 13458.61 4469.48 The Buoyant Force was calculated through Archimedes Principle and using the properties of water at 65 degrees Fahrenheit.


Hull & Internal Structure Volume

Hull & Internal

Structure Volume

ρ, Density of Water at 65

degrees Fahrenheit

g, Acceleratio

n Due to Gravity

γ=ρg, Specific Weight of

Water at 65 degrees

Fahrenheit

Buoyant Force

(in^3) (ft^3) (sl/ft^3) (ft/s^2) (lb/ft^3) (lb)

4469.48 2.59 1.94 32.17 62.28 161.09

2) Stern Appendage: Next, the total buoyant force of the stern was calculated through the same method of using the model to conduct the calculations. The total area of the stern (AStern) is 10.93 ft2 plus a 1.0 ft2 middle section which divides the stern in half. This is a result of manufacturing the stern by assembling two half sections. The thickness of the stern is 0.5 in (0.042 ft). The middle section is 1 in (0.083ft) thick, as it is the meeting of two 0.5in walls. The volume of the stern (VStern) is therefore 0.542 ft3. By multiplying the specific weight of water with VStern, the total buoyant force of the stern was calculated to be 33.76 lb.

Stern Appendage Volume γ Buoyant Force

(ft^3) (lb/ft^3) (lb)

0.542 62.28 33.76

3) Batteries: Since the batteries are watertight and remain attached to the boat, they were included in the total buoyancy. Each battery volume was measured to be 280.4 in3 (0.162 ft3). By multiplying the specific weight of water with VBattery, the total buoyant force of each battery was calculated to be 10.1 lb. Since 3 batteries are used, the total buoyant force for all of the batteries is 30.3 lb.

Battery Use Volume Quantity γ Buoyant Force

(ft^3) (lb/ft^3) (lb)

Propulsion 0.162 3 62.28 30.32

4) Additional Buoyancy: The remaining buoyancy will be accounted for by using two 43L buoyancy bags.

Buoyancy Bag Volume Quantity γ Buoyant Force

(ft^3) (lb/ft^3) (lb)

1.51853 2 62.28 189.1514983


5) Final Buoyancy:

Item Volume Buoyant Force

(ft^3) (lb)

Hull & Internal Structures 2.59 161.09

Stern Appendage 0.54 33.76

Batteries (3 Propulsion) 0.49 30.32

Buoyancy Bags (2) 3.04 189.15

Sum 6.65 414.32

Buoyancy/Total Weight 131.53%


Appendix C: Proof of Insurance Proof of general liability insurance is provided.


Appendix D: Team Roster As a senior design project, all members of the team are graduating in May 2019 with a

BE in their respective fields. Undergraduate Joseph Lodge also assisted the team with the tank testing.

Team Member Degree Program Year Role

Matthew Colacino BE in Mechanical Engineering Senior (4/4) Auxiliary Team Member

Victoria Davis BE in Mechanical Engineering Senior (5/5) Electrical System Purchasing Steering Project Management

Megan Hand BE in Mechanical Engineering Senior (5/5) Propeller Design Cooling System HMI Design

Joseph Lodge BE in Engineering, with a concentration in Naval Engineering

Junior (3/4) Scale Model Tank Test

Justin Sitler BE in Mechanical Engineering Senior (5/5) Drivetrain Data Acquisition

Melanie Valentin BE in Mechanical Engineering Senior (5/5) Electrical System Data Acquisition Social Media Outreach Project Management


Appendix E: Center of Gravity Study Estimate

As determined in the 2019 tank test, the optimal LCG for 20-30 knots was found to be 66”, while the optimal LCG for 5-7 knots was found to be 62.4”. A Center of Gravity study was conducted for the Sprint/Slalom and Endurance races to determine the optimal placement of components in the boat. The team also calculated Vertical and Transverse Center of Gravity to ensure safety of the skipper. Component weights were obtained from previous year measurements, 2019 measurements, and listed weights on their websites. ENDURANCE SPRINT / SLALOM

Item Weight

(lb)

LCG (in) (measured fwd

transom)

LCG Moment (lb-in)

LCG (in) (measured

fwd transom)

LCG Moment (lb-

in) Hull & Internal Structure 55.3 81.60 4512.48 81.60 4512.48 Stern Appendage 10.0 -12.75 -127.50 106.00 1060.00 Etc.

Skipper 150.0 65.00 9750.00 67.00 9045.00 Ballast 5.0 165.00 825.00 155.00 3100.00

Forward Solar Array Solar Panels FWD 9.7 135.00 1312.20 N/A N/A Solar Mount FWD 1.3 135.00 172.80 N/A N/A

Power Bank Batteries 82.5 110.00 9075.00 100.00 8250.00

Battery Boxes 7.4 110.00 808.50 100.00 478.40 Electronics Container

Container (19 qt. Weathertight Tote Clear) 2.5 98.00 243.04 92.00 8250.00 Electronics 5.2 98.00 509.60 92.00 735.00

Dashboard Throttle 0.6 86.16 51.70 86.16 51.70

Steering Wheel 4.5 86.16 387.72 86.16 387.72 Display 1.3 86.16 112.01 86.16 112.01

Dashboard Material and mounting hardware 1.5 86.16 131.39 86.16 131.39

Dashboard 8020 1.5 86.16 129.24 86.16 129.24 Seat 5.0 65.00 325.00 67.00 335.00 Rear Solar Array

Solar Panels AFT 9.7 35.00 340.20 N/A N/A Solar Mount AFT 1.3 35.00 44.80 N/A N/A

Buoyancy


Buoyancy Bag #1 0.6 24.00 14.40 24.00 14.40 Buoyancy Bag #2 0.6 24.00 14.40 24.00 14.40

Cooling System Pump 1.4 8.00 11.44 8.00 11.44

Radiator 8.5 8.00 67.76 8.00 67.76 Reservoir 1.0 8.00 7.60 8.00 7.60

Outboard System Motor 20.9 -11.05 -230.95 -11.05 -230.95

Tower unit, foot extender, shaft extender, keyed shaft, lower unit 25.9 -1.96 -50.67 -1.96 -50.67

Motor Controller 11.5 -17.11 -195.91 -17.11 -195.91 Sprocket (Big) 9.7 -11.01 -106.25 -11.01 -106.25

Sprocket (Small) 2.9 -4.26 -12.14 -4.26 -12.14 Propeller 0.8 -9.07 -6.80 -9.07 -6.80

Tiller Bar 1.0 6.00 6.00 6.00 6.00 Mounting 10.0 -11.83 -117.71 -11.83 -117.71

Belt 0.1 -7.00 -0.70 -7.00 -0.70 Bearing 1.4 -4.24 -5.72 -4.24 -5.72 Casing -11.00 0.00 -11.00 0.00

Steering Cables 2.0 0.00 0.00 Pulleys 0.2 0.00 0.00

Wiring Control Wires 0.5 50.00 25.00 50.00 25.00

Motor to Motor Controller Wires 0.5 -9.00 -4.50 -9.00 -4.50 Power Wires (Between batteries

and back to motor) 12.0 67.00 804.00 67.00 804.00

Total Weight 465.305 LCG fwd transom 61.94

LCG fwd transom 64.91

Goal 62.4 Goal 62.4


Appendix F: Power Electronics System Specifications Tables 1 and 2 provide the specifications of the Hawk40 DHX motor rewound to 72V

and the InMotion 80L motor controller.

Table 1: Customized Hawk40 72V Motor Specifications Run at 36V Nominal Speed 2,200 RPM

Max Speed 3,600 RPM Continuous Torque 36.9 ft-lb

Max Torque 59 ft-lb Continuous Power 15.4 hp

Max Power 24.5 hp

Nominal Voltage 36 V

Rated Current 250 A

Peak Current 425 A

Table 2: InMotion 80L Specifications Nominal Voltage 80 V Rated Current (2 min) 440 A Rated Current (1 hr) 200 A

Product information for the motor and motor controller can be found in Table 3.

Table 3: Power Electronics System Product Information

Component Name Part Number Price Manufacturer Information

Customized Hawk40 72V N/A $2,750.00 DHX Electric Machines, Inc. 1101 HWY 124, Building 5 Hoschton, GA 30548 (678) 900-1074

InMotion Motor Controller ACS80L $900.00 InMotion US, LLC 3157 State St. Blacksburg, VA 24060 (540) 605-9622


Appendix G: Sprint and Endurance Required Power Estimates The following relates the specifications of the Hawk40 rewound to 72V DHX Motor,

36V Battery Bank, gearing ratio conversion of the belt drive, and predicted solar conditions/solar panel specification to estimate the required power for the sprint and endurance race.

Sprint Variable: Units Supplied Voltage: 36 V Supplied Current: 425 A Motor Specs: Rated Voltage: 72 V Nominal RPM: 4400 RPM Continuous Power: 30.8 hp Peak Power: 49 hp Continuous Current: 250 A Peak Current: 425 A Continuous Torque: 36.9 ft-lb Peak Torque: 59 ft-lb Torque Constant: 0.14769 ft-lb/A Power Calculations: Maximum Power: 24.714 hp Supplied RPM 2200 RPM Supplied Torque: 359 ft-lb Supplied Power: 24.714 hp Battery Calculations: Maximum Capacity: 45 A-hrs Feasible Capacity: 36 A-hrs Duration w/out Solar: 5.1 minutes Gearing Calculations: Lower Unit Gear Ratio: 0.762 Sprocket Belt Drive Gear Ratio: 1.73 Drive Shaft RPM: 3810.4 RPM Propeller Shaft RPM: 2903 RPM Net Ratio: 1.320 Mechanical Efficiency: 0.9 Output Torque: 40.239 ft-lb Output Power: 22.243 hp Propeller Efficiency: 0.7 Propeller Power: 15.570 hp


Endurance Variable: Supplied Voltage: 36 V Supplied Current: 23.5 A Power Calculations: Maximum Power: 24.714 hp Supplied RPM 2200 RPM Supplied Torque: 3.262 ft-lb Supplied Power: 1.367 hp Battery Calculations: Maximum Capacity: 45 A-hrs Feasible Capacity: 36 A-hrs Duration w/out Solar: 91.9 minutes Solar Calculations: Solar Power: 200 W Solar Voltage: 36 V Current Provided: 5.556 A Duration of Race: 2 hrs Added Capacity: 11.1 A-hrs Total Capacity: 47.1 A-hrs Duration: 120.3 minutes Gearing Calculations: Lower Unit Gear Ratio: 0.762 Sprocket Belt Drive Gear Ratio: 0.577 Drive Shaft RPM: 1270.2 RPM Propeller Shaft RPM: 968 RPM Net Ratio: 0.440 Mechanical Efficiency: 0.9 Output Torque: 6.675 ft-lb Output Power: 1.230 hp Propeller Efficiency: 0.7 Propeller Power: 0.861 hp


Appendix H: Drivetrain Components The components purchased for the drivetrain are identified below. The sprockets and belt used were chosen from Gates Poly Chain GT Carbon Belt Drive Design Manual [2] for synchronous belt design. According to this catalog, there is a recommended pitch and minimum sprocket size for the horsepower and RPM the motor will be operating at. For a top speed of 2200 RPM and peak horsepower of 24.5 hp, the pitch should be 8 mm and the minimum sprocket diameter is 4.0”. Then, the desired belt and sprockets can be picked from the drive selection tables. The goal was to find the belt that would give us the desired ratio with the shortest center-to-center distance. This yielded the 8MPC-41S-12 sprocket, 8MPC-71S-12 sprocket, and 8MPCC-800-12 belt which each use TL-2012 taper lock bushings for a ⅞” shaft. The belt drive uses a 800 mm x 12 mm wide (31.5” x 0.47” wide) belt and a 4.11” and 7.11” sprocket to give a total center-to-center distance of 6.76”.

Component Name Part Number Price Manufacturer Information

Small Sprocket 8MPC-41S-12 $61.71 Clark Transmission Co. 20 Fairfield Rd. Fairfield, NJ 07004 (973) 227-4422

Large Sprocket 8MPC-71S-12 $106.00 Clark Transmission Co. 20 Fairfield Rd. Fairfield, NJ 07004 (973) 227-4422

Belt 8MPCC-800-12 $22.19 Clark Transmission Co. 20 Fairfield Rd. Fairfield, NJ 07004 (973) 227-4422

Bushing x 2 TL2012 $27.72 Clark Transmission Co. 20 Fairfield Rd. Fairfield, NJ 07004 (973) 227-4422


Appendix I: Pugh Decision Matrix, Propulsion System Pugh Decision Matrix used when determining what type of propulsion system the team

would design. Each type of propulsion system, listed at the top of the chart, was researched by the group to determine the pros and cons of this system type. The result of the research and decision matrix was to design an outboard motor.

Criteria Weight Water Jet Podded

Propulsion Inboard Outboard Sterndrive

Efficiency at high speed (~28 knots) 5 5 -5 -5 -5 -5

Efficiency at low speed (~8 knots) 5 -5 0 5 5 5

Complexity 3 -5 -5 0 0 0

Adjustments to hull 2 -2 -2 -2 2 0

Configuration flexibility 4 -4 0 0 0 0

Damage susceptibility 2 -2 -2 0 0 0

Maneuverability (steerability) 4

Added drag 5 5 -5 0 5 0

Totals -8 -19 -2 7 0


Appendix J: Wageningen B-Series Propeller Calculation Tables In the Drivetrain and Steering portion of the report, under Propellers, calculations for the

Wageningen B-series Propeller Charts are shown graphically. Below is a table for each of the propeller calculation lines included in Fig. 12 of that section. Table 1 details the calculations for the sprint propeller at 28 knots, Table 2 details the sprint propeller at 25 knots, and Table 3 details the endurance propeller at 6 knots. Note that each of these propeller designs is for a 2 bladed 10 in. diameter, 13 in. pitch propeller.

Table 1: Sprint Propeller at 28 knots

Sprint Propeller 2-bladed (10 in. Diameter, 13 in. Pitch)

Selected and Calculated Values Diameter (D) 10 in 0.83 ft Rotation Rate (N) 2900 rpm 78.3 rps Velocity of Advance (Va) 27.2 knots 45.9 ft/sec Thrust Needed (T) 311 lbf Thrust Coefficient Needed 0.14 Advance Coefficient (J) 1.14

Values from Chart Thrust Coefficient 0.12 Thrust Generated (T) 260 lbf Propeller Pitch Ratio 1.3 Propeller Efficiency 79%

Table 2: Sprint Propeller at 25 knots


Selected and Calculated Values Diameter (D) 10 in 0.83 ft Rotation Rate (N) 2900 rpm 78.3 rps Velocity of Advance (Va) 24.2 knots 40.8 ft/sec Thrust Needed (T) 242 lbf Thrust Coefficient Needed 0.11 Advance Coefficient (J) 1.01

Values from Chart Thrust Coefficient 0.12 Thrust Generated (T) 262 lbf Propeller Pitch Ratio 1.3 Propeller Efficiency 75%



Selected and Calculated Values Diameter (D) 10 in 0.83 ft Rotation Rate (N) 910 rpm 15.8 rps Velocity of Advance (Va) 5.7 knots 9.58 ft/sec Thrust Needed (T) 57.3 lbf Thrust Coefficient Needed 0.24 Advance Coefficient (J) 0.73

Values from Chart Thrust Coefficient 0.24 Thrust Generated (T) 57.3 lbf Propeller Pitch Ratio 1.3 Propeller Efficiency 58%

Table 3: Endurance Propeller at 6 knots

boat #4solarsplash.com/wp-content/uploads/2014/10/2019... · was selected using wageningen b-series...

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