SEA-DOO GTI SE

It was a beautiful sunny day at Princes Club. The glassy lake yawned away from the grassy bank, birds chirped in harmony, and fluffy chipmunks joined in a merry a-

cappella. The setting was perfect. Idyllic you might say. Then we came along . . .

Hooning across the lake at full whack on the back of the GTI, throttle wide open, I screamed my lungs out as Matt Crowhurst swung it fast into a corner. “Aaahhhhhh!” I yelled as the G-force wrenched my body towards the clouds. Clutching the passenger strap for dear life with one hand, my camera in the other, we went speeding round the buoy at 45-degrees. Nearly toppling, I gripped harder, forcing the veins in my forehead to pop out like the London Underground map.

I was shooting the video that accompanies this test on jetskier.co.uk and had agreed to let Matt (a pro

wakeboarder sponsored by Sea-Doo) drive the ski. It proved to be a hideous mistake. Belting round the back end of the lake, with my camera shaking all over the place, we looped round the end of an overgrown island, thrashing alongside overhanging trees - so close that leaves were whipping at my face. Racing through the mangroves of Feltham it felt like a scene from Crocodile Dundee, just without Paul Hogan to save us if it did all go tits up.

The GTI is extremely agile, nipping from left to right like an excitable Morris dancer, and with just as many bells and whistles. The GT was Sea-Doo’s primary entry-level craft, originally released in 1990, followed by the launch of a GTI kit in 1991 that could be added to the GT model. It has seen several variations and upgrades over the years, including the transformation to four-stroke in 2006. This year it has been reworked and re-released as the GTI SE (Special Equipment) with swanky add-ons like chrome fairing, a reboarding ladder, a speedo, and two different engine options. This allows buyers the choice to pay a little more to get that extra ounce of oomph.

Back on the bank, knackered and looking like Art Garfunkel having being dragged through a hedge backwards, I give the GTI SE a thorough aesthetic assessment. On first impressions, it looks pretty sophisticated for an entry-level, with smooth curves and lines, smart decals and a deep blue colour with a two-tone silver / blue seat. At 1.17 metres it is roughly the same height as other watercraft in its class but the raised display section with chrome spoiler, gives it the impression that it is taller. It also makes it look like a cross between an eagle’s beak and a clothes iron. But maybe that’s just me. >

View the video of this test on

www.jetskier.co.uk

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Packed with new features and two choices of engine, Spicer takes the Sea-Doo GTI SE for a spin on a lake in Surrey.

SEA-DOO GTI SE

WORDS: SpicerPHOTOS: Jetman / Spicer

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As Archimedes discovered, buoyancy is the upward force that keeps things afloat.

PFD’s (personal floatation devices), life jackets, life preservers or life vests are pretty much one of the same. Whichever name you use they are all designed to keep

you afloat in the event of you parting company with your watercraft.

As a safety device it is very important to understand the differences and establish a PFD most suitable for your requirements. There are five categories and as a general rule the lower the category number the better the performance.

Type IV are throwable devices and type Vs are for special uses, we only really need to look at I to III for personal watercraft use. Unless inflatable all of these will be inherently bouyant. The most common for PW use are Type III Flotation Aids. These are good for conscious users on inland waters where there is a likelihood of a fast rescue. They tend to be the most comfortable but are not intended for extended survival in rough water due to the level of buoyancy and lack of head support.

The type II ‘Near Shore’ vests are ideally suited to calm waters but although some may turn unconscious wearers right side up it’s only the type I or Offshore Life Jackets that can claim a high percentage of success. These are usually very bulky and have a large collar but they are the most suited for open waters where you could be waiting a while should you need to be rescued. They are also a good choice for small children who under normal circumstances don’t have the same strength as an adult.

A good fitting PFD is important. If you can easily slip out of it, it won’t be much use. Choosing one designed for your specific activity is wise; some are designed and tested to help prevent impact injuries, bright coloured ones will help in spotting you and all go some way in helping your body retain heat. Freestylers usually opt for side entry to both avoid scratches and prevent the straps and buckles getting caught up when doing hood tricks. Of course a large percentage match last month’s wetsuits for those of you wishing to remain colour coded.

Whatever you choose it may just save your life but in the wise words of the RNLI it’s Useless Unless Worn.

To enable an object to float, that upward force must be equal to the weight of fluid displaced by the body. This month Jetman has been displace and dat, filling his trolley with the following selection of life saving goodies.

Stay afloatthe PfD and lifejacket guide

1 O’Neill 4-Belt Nylon VestColour: Black/GreySizes: XS - 2XLFeatures: USCG approvedULC approvedCE approvedClosed Cell PVC Marine FoamCoated Nylon ShellSoft and ComfortableQuick-Release Delrin Buckles

RRP £40.00www.oneill.com

2 Jet Pilot Black Hawk VestColour: Black, RedSizes: Contact for availabilityFeatures:4 Buckle Closure DesignHeavy Duty CoatedLanyard Clip

RRP £39.95www.ncjetski.co.uk

3 Yamaha Adventure Front Entry VestColour: Black/Red/GreySizes: S-XXXLFeatures: CE-approved neoprene vestIntegrated webbingMesh panels for water drainageIntegrated back protectorD-ring for PWC emergency cord attachmentTwo wide, adjustable strapsApplied soft foam for maximum comfort

RRP £76.99www.yamaha-motor.co.uk

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JS&PW PfD GUIDE

4 Jobe Viper VestColour: Black, GreenSizes: S, M, L, XL, XXL, XXLFeatures: CE-approved neoprene vestGood freedom of movementFoam side panels for extra protection, high side cut for more manoeuvrabilityLeather skin panels, webbed straps, D-ring for lanyard,Mesh panels for drainage.

RRP £69.95www.justwatersports.com

5 Gill Compressor VestColour: Black/GreySizes: S, M, L Features: Neoprene and foam construction. 3mm neoprene with a Lycra lining. Concealed waist belt. Snap-shut buckle. Approved as a 50Newton buoyancy aid. Tested to EN ISO 12402-7 safety standardGill has created a buoyancy aid that is comfortable for jetskiing and most watersports.

RRP £65.00www.gillmarine.com

6 Sea-Doo Navigator VestColour: Autumn Red, Red, Navy, BlackSizes: XS, S/M, L/XL, 2XL/3XLFeatures:Super-duty nylon outer shellPolyethylene foam inserts4 woven straps with quick release bucklesArmholes cut large for riding comfortD-ring for floating lanyard

RRP £33.92 + VATwww.brp.com

7 Palm River Tec Whitewater PFDColour: Cadet/Ice, Red/BlackSizes: XS-S (65N), M-L (70N), XL-XXL (75N)Features: A whitewater PFD with large front cargo pocket with water resistant document pocket, 3D anti ride-up waistbelt, shoulder straps tested to 500kg, removable chest harness, O-ring, reflective detail on shoulders, front and rear. As worn by Thumper.

RRP £119.95palmequipmenteurope.com

8 Yamaha Adventure Side Entry VestColour: Black/Red/GreySizes: S-XXXLFeatures:CE-approved neoprene vestExtra padded side panels for more protectionD-ring for PWC emergency cord attachmentApplied soft foam for maximum comfortPull over vest with side zipper

RRP £92.99www.yamaha-motor.co.uk

9 Jet Pilot Flight Race VestColour: Black/GreySizes: Contact for availabilityFeatures:Side Entry3 Buckle Closure DesignHighest Quality PVC FoamHeavy Duty Coated NylonLanyard Clip

RRP £51.95www.ncjetski.co.uk

10 Jobe Outburst VestColour: Red, Blue, YellowSizes: S/M, L/XL, XXL/XXXL, 4XL/5XLFeatures:CE-approved floatation deviceNylon side panels for adjustabilityFully adjustable straps for a better fit

RRP £29.95www.justwatersports.com

11 Yamaha Escape VestColour: Black/Red/WhiteSizes: XS-XXXLFeatures:CE-approved boating vest2 wide adjustable strapsD-ring for PWC emergency cord attachmentThick front panel for safety. Mesh panels for water drainage

RRP £72.99www.yamaha-motor.co.uk

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need a girdle as it does not have an aftermarket exhaust system.

We will need the use of two CNC machines for this - one CNC VMC (vertical machining centre), which will be used for the head shell and O-ring groove on the domes, and one CNC Production Turning Centre, which will be used to produce the domes.

As this is the first time we’ve been asked for a head to fit with a stock exhaust system a new design was needed. Using our CAD/CAM drawing program we created the design, which is the program that will be fed into the machine. We need to tell the machine what to do using tool paths. This means programming which milling cutters to use and where, at what spindle speed, what depth and speed of cut to take and where to finish.

MANUFACTURING THE

HEADNext we need to place the block of

6082 T6 aluminium into the machine and clamp down in the vice. This is

aircraft grade aluminium and of a slightly higher grade than most commonly used by aftermarket companies. The next job is to reference the machine with height gauges. Referencing is required so the machine knows where the block is in relation to the machine bed and spindle. The tolerances we work to are usually 0.01 mm. But the referencing must be perfect otherwise there is nothing stopping three tons of spindle smashing through the machine bed.

As the program has already been sent over to the machine via the network, we are ready to close the doors and press start. The machine will begin cutting, following the program code given, the milling cutters will go to work then automatically retract and change over to the next tool required. The ATC (automatic tool change) is a huge time saver in manufacturing.

Now the machine has finished the topside of the head we now need to turn this over for the underside to be done. Again this will require re-referencing and the second part of the program will need to be sent over via the network.

FINISHING

The new head is now finished on the machine along with the special exhaust bracket mounting. The head now requires finishing, so we clean it off to remove the machine coolant before it can be finished. This head is going to be anodized black satin/matt finish.

First, we polish it. This is done in a small sealed room as polishing aluminium is a really dirty job that creates a black greasy deposit during the process. We

PROJECT SUPERJET STAGE IV PROJECT SUPERJET STAGE IV

. . . being fed into machine

Code from computer . . .

The billet used to make the cylinder heads

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PROJECT SUPERJET STAGE IV PROJECT SUPERJET STAGE IV

use a floor mounted polishing spindle with various polishing mops and grades of compound to achieve the required finish e.g brushed, mirror etc. Most ATP parts are mirror finished before they are anodised.

The next stage is the satin finish. Again, before we can do this we need to thoroughly clean off the greasy polishing compound. This can be a lengthy process using various chemicals and good old household detergent. It has to be perfectly clean in between each stage. Now you may wonder why we would mirror finish something to then put it through a process that will dull it down. The polishing helps remove/lessen the machining lines and marks it also gives an even finish, making it easier to apply the satin finish. The head is then cleaned off again.

ANODISING

For protection against corrosion the head is going to be anodised. Anodising is a process in which the normal thin layer of oxide on the surface of aluminium is artificially thickened to give it added protection from corrosion; the part is then dyed and finally sealed. It is done by making aluminium the anode in an electrolysis cell in which dilute sulphuric is electrolysed.

Many people are under the wrong impression that anodising is a separate coating i.e a spray or something similar. As it’s actually the aluminium’s natural coating, just “enhanced”, it is the best protection for it. All ATP Parts are heat-sealed rather than the traditional cold seal as the heat ensures the dye is retained for a non fade colour.

ENGRAVING

Engraving is now the last finishing stage. We place secure this back in the CNC VMC. Again we need to reference this, the best way now is with a centre finder. This tool is placed in the spindle, the machine bed is moved to place the head directly underneath the spindle. This needs to be done otherwise the engraving will be off centre or even off the head.

The combustion chambers are made on the CNC turning centre. We are unable to take photos of this process as the machine does not have a very good “viewing” window. All you get to see is the coolant and swarf propelling itself at every surface and a blurred view of the part being machined.

The domes are “turned on this machine then moved to the CNC VMC to have the O-ring grooves machined. CAD drawings are created for every single part we make on these machines, as the machines wouldn’t work without them. This offers massive flexibility for producing custom one offs, altering or modifying any of our new or existing parts. It also offers the reassurance of tight tolerances.

It can appear that most of the aluminium is machined away on some parts, and it can appear wasteful but simply isn’t the case, as aluminium is the only metal which is 100 per cent recyclable time and time again.

------------------------------------So there we have it, our very own High

Performance Head made in front of our very own eyes. So if any of you out there have got a Yamaha Superjet and were put off by thinking that you had to fork out £800 for a Factory Pipe Exhaust Pipe, think again, you can now put a non-girdled high performance head with a standard exhaust pipe for £260.

In part V of Project Superjet we get to find out what goes on behind the scenes at Preban Engineering where we see our crankshaft being re-built and the cylinder re-bored.

Yet another program is written for the engraving this is verified on the machine before pressing “Start”

Engraving in process

The finished head with bracket and domes.

If we were making a Snake G2 Head then we would also need to make the girdle kit. The studs and dome nuts are made on the CNC Turning Centre.

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Plenty of legroom on the Yamaha FXHO Cruiser