Radar, Reflectors and Sea Kayaks:A Visibility Study

Introduction In recent years, sea kayaking has beengrowing in popularity throughout NorthAmerica and especially in Maine. Seakayakers are regularly observed along ourcoastal shores; and sea kayak guides andoutfitters are becoming a significant partof the working waterfront, with commer-cial operations spanning from Kittery toCalais. With such popularity, thepotential for kayak collisions with largervessels increases dramatically. Radar reflectors are used by sailboats,motorized recreational craft, and workingboats of all sizes to increase theirpotential appearance on the radar ofother vessels; the more obvious the“return” on a radar screen, the morelikely an attendant boat captain is toavoid collision. On the coast of Maine,sea kayakers are increasingly using radarreflectors to increase their visibility, bothin an effort to avoid collision and tofacilitate search and rescue operations inthe event of trouble. However, concreteinformation is lacking on just howeffective radar reflectors are in helpingkayaks appear on radar. Conventionalwisdom is that the higher a reflector ismounted aloft (such as on a sailboat’smast), the better radar signal it willreturn. The intentional low-profiledesign of sea kayaks that makes themcomparatively sea worthy in the hands ofa capable paddler also makes sea kayaksdifficult to see, both with the naked eyeand on a radar screen. The purpose of this study is to reviewthe effectiveness of a variety of commer-

cial and homemade radar reflectors inincreasing the visibility of sea kayaks onradar. It is intended that the results ofthis study will 1) raise awareness aboutthe efficacy of radar reflectors on seakayaks; 2) provide all users of ourcoastal waters with knowledge to reducethe risk of radar-equipped vesselscolliding with sea kayaks; and 3) begin adialog between motor-/sail- vesseloperators and sea kayakers along thecoast of Maine. This report summarizes the results ofradar reflector tests conducted on thecoast of Maine during the summers of2003 and 2004.

Project History During the spring of 2003, two roundsof preliminary visibility tests wereconducted with the Maine Association ofSea Kayak Guides and Instructors(MASKGI): one with the U.S. CoastGuard, the other with a lobsterman. Twoconflicting sets of results emerged.Using a range of radar settings, the CoastGuard radar was consistently able todetect sea kayaks at various levels ofintensity, depending on the model ofradar reflector. The lobsterman’s radar,similar in caliber to the Coast Guard’s,was NOT able to “see” any of thepaddlers, despite use of the same radarreflectors and similar sea conditions.The conflicting results of these prelimi-

nary tests pointed to a needfor further systematictesting following arepeatable study design. Maine Sea Grant,MASKGI, U.S. CoastGuard, Gulf of MaineExpedition Institute, andCollege of the Atlanticpartnered to developtesting methodologies, runfield tests, and provideresults to sea kayakers andoperators of radar-equipped vessels. For acomplete list of projectparticipants, see back page.

Summer 2003 and 2004

Preparing the first round of radar reflector trials at theCollege of the Atlantic dock, summer 2003.

Top picture: Field tester withDavis #153 radar reflectoron stern deck.

Glossary of radar terms

Blind spot: Any area outside thefield of view of the radar. This isgenerally meant to cover the areabelow the radar’s line-of-sight,generally closer to the radar platform.

Clutter: Term applied to theunwanted returns that appear on theradar screen. These are oftenreturns from waves or precipitation.

Gain: A variable control that adjuststhe radar’s sensitivity; it amplifiessignals received. Typically adjust-able from 0-100%. Tuning gaindown toward zero reduces overallsensitivity; tuning gain up toward100% amplifies noise or clutter,creating false signals or registeringfeatures of little or no concern (suchas lobster buoys or waves).

Noise: Unwanted energy gener-ated internal to the radar that canappear as a false signal on the radarscreen.

Radar Horizon: The line of sightof the radar. Radar arrays mountedhigher can see further than thosemounted lower. In rough seas, thetarget might be obscured by a swellat distances well short of the radarhorizon.

Radar reflector: Any devicespecifically manufactured to reflectradar waves back to a radar platform.The return, or signal, from a radarreflector generally shows up on theradar screen as an amorphous blob.

Radar scope: Another name forradar screen.

Radar screen: The monitor onwhich radar signals are displayed forviewing.

Rain clutter: Random dots on theradar screen generated from radarwaves hitting raindrops or otherprecipitation. On the radar screen,this can create an effect that lookslike it is “snowing.” Rain clutter doesnot represent “real” returns, andthus, the rain clutter control isgenerally used to filter out thesefeatures.

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How does Radar Work? Radar stands for RAdio DetectionAnd Ranging. In the marine environ-ment, radar refers to a system thatbroadcasts radio waves (electromagneticenergy) toward the horizon. When radarwaves hit an object or target, the wavesbounce or reflect. Some of that reflectedenergy returns toward its point of originwhere it is electronically rendered into aspatial image on a radar screen (areturn). The monitor also shows thelocation of the radar-equipped vessel, orradar platform. With experience andtraining, this image can be readilyinterpreted to represent the surroundinglandscape and seascape. Landforms,navigational aids, and other vessels willbe displayed as returns of varied size andstrength in their correct position. Whenused in conjunction withnautical charts or localknowledge, it is possibleto identify these imagesand avoid collision withobjects on the water. In principle, radaroperation is straightfor-ward. However, vesseloperators should never assume that a lackof returns means that there are no othervessels or objects on the water. A varietyof factors affect the ability of targets to

reflect wave energy back to its source.There are blind spots, areas where anobject is completely out of the path of aradar wave. Objects too close to a radarplatform fall beneath the angle of theradar wave, and therefore would notshow up on the radar screen; objectsoutside the range of the radar also willnot show up. The choppiness of thewater’s surface creates clutter or randompixilated forms on the radar screen. Tothe untrained, this clutter can appear tobe the return of an object. Raindrops canalso reflect radar waves and create a“snow-falling” pattern on the radarscreen. How the radar antenna (some-times referred to as the “radar array”) ismounted on a vessel can affect how theradar signal is sent and whether it will

hit a target at all. Onradar-equipped vessels,the radar array tends tobe mounted either on amast or above thepilothouse. In choppyconditions, radar arraysmounted higher arebetter able to see down

into the troughs of waves; hence, kayaksare more likely to show up if the radarsettings are properly set. Proximity ofother objects on the radar-equipped

“Every radar installationis different.” —Andrew Peterson,Marine Superintendent,

College of the Atlantic

The group gathers for the third set of radar reflector trials, this one at the BoothbayHarbor Coast Guard Station with the help of the Coast Guard Auxiliary. Front row fromleft to right: Rich MacDonald, John Roscoe, Natalie Springuel, Gerry Vaillancourt, DavidLenz and Deb Swanton. Second row: Paul Travis, Gordon Nash, Mark Potter, LT KevinKing, Bob Loney, Jim Powers, Al Johnson and Dave Power. Bob Arledge is in the kayak atfar left.

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Range: The field of view of theradar screen, typically a circle(the center of the screen is thelocation of the radar antenna).For example, if the range is setto one mile, then from the centerof the radar screen to the outeredge of the screen is 1 mile(i.e., this is the radius of theradar screen—typical rangesinclude ¼, ½, 1, and 2 miles).

Return: Any signal that ap-pears on the radar screenindicating an object within therange of the radar platform.

Ring: These are electronicmarkers, in the form ofconcentric circles radiating outfrom the center, placed on theradar screen to aid in judgingdistances. Scale units for thecircle or circles between thecenter of the radar screen andthe outer edge, or range, arefractions of the range (typicalrings include 1/8, ¼, ½, and 1mile).

Scope: Another name for radarscreen.

Sea clutter: Term applied tothe random dots on the radarscreen which appear as a resultof radar waves reflecting off thesea surface; heavier seas createmore clutter on the radar screen.Sea clutter represents real butunwanted returns, and thus, thesea clutter control is generallyused to filter out these features.

Sensitivity: The degree towhich the radar picks up undes-ired returns, whether fromartifacts such as sea or rainclutter and other natural phe-nomena or from lobster buoysand other man-made featuresthat do not pose a significanthazard to navigation.

Signal: Any signal that appearson the radar screen indicating anobject within the range of theradar platform.

vessel, such as life rafts, can affect theperformance of the radar. Modern radar units have adjustmentsfor sea clutter and rain clutter. Adjust-ing the radar controls for sea clutter orrain clutter affect the sensitivity of theradar signal; thus, it is possible toeliminate the clutter created by choppyseas or rain. Gain is another radaradjustment. This affects overall sensitiv-ity, so adjusting gain can also reduceclutter. Adjusting the sensitivity of a radarunit is a balance between filtering outunwanted clutter or noise and acceptingsome level so that more objects can beobserved. Many radar operators adjustsea clutter, rain clutter, and gain so as tofilter out the maximum amount of clutter.However, this is sometimes done at theexpense of other real targets. The construction material and designof the target object affects how well itshows up on a radar screen. Landmasses,particularly with built-up verticalsurfaces such as cliffs or houses, reflectradar well. In contrast, low-lying,horizontal, or rounded and undevelopedlandmasses (such as rocks, ledges, andbars) tend to disperse energy such thatthey do not show up on radar, or, if theydo show up, not consistently. Similarrules apply to boats. Larger vessels madeout of steel more readily reflect radarwave energy than smaller, lower profilevessels made out of wood, fiberglass, orplastic. Radar reflectors are designed toreflect some of the radar waves back

toward radar platforms, increasing thestrength of the return as a target on theradar screen. An increased radar returnincreases the probability of a boat beingseen by radar-equipped vessels. Sail-boats, typically made of wood orfiberglass, often generate poor radarreturns. To help alleviate this problem,they have long used radar reflectors: tomake the best use of radar reflectors,they are most often affixed to the top ofthe mast. This increased height of theradar reflector is much more likely tointercept radar waves and reflect a signalback to radar-equipped vessels fordefinition on the radar screen. Sea kayakers have a greater challengewhen trying to increase their visibility toradar-equipped vessels. A sea kayak’sstability comes, in part, from its lowprofile. Affixing a mast of any height,even a couple of feet, with a radarreflector at its apex increases windageand thus decreases stability. In the eventof capsize, a mast-mounted radarreflector hampers the ability of a seakayaker to perform an Eskimo roll orattempt other rescue techniques. Thiscreates a potentially significant hazardfor a sea kayaker. Out of necessity, manysea kayakers have experimented withalternative methods of either affixing aradar reflector or developing newstrategies with the intent of increasingvisibility to radar-equipped vessels. Until this study, the effectiveness ofradar reflectors for increasing thevisibility of sea kayaks, traditionallylow-lying vessels, had not been tested.

This radar screen shows oneway that “noise” or “clutter”can appear on screen (patternleft of center). Picture taken onboard U.S. Coast GuardAuxiliary vessel on November 6,2004, Boothbay Harbor, Maine.

Methodology The goal of this study was to assessmethods for increasing sea kayakvisibility on radar. A variety of commer-cial and homemade radar reflectors weretested against different radar settings toassess each variable. Volunteers paddledradar reflector-equipped sea kayaksalong an established course to determinehow well they showed up on the radar.These studies were repeated at threelocations over two paddling seasons:

• 18-19 August 2003. College of theAtlantic, Bar Harbor. The college’sresearch vessel, Indigo, was the radarplatform.• 06 July 2004. U.S. Coast GuardGroup Southwest Harbor. U.S. CoastGuard vessel CG 55120 was the radarplatform.• 06 November 2004. U.S. CoastGuard Station, Boothbay Harbor. U.S.Coast Guard Auxiliary vessel Equinoxwas the radar platform.

The experimental design for eachlocation was the same. Local nauticalcharts were used to establish a course forthe volunteer kayakers to paddle.Courses were generally perpendicular tothe bow of the radar platform. At the

same time, mooring locations for theradar platform were determined. A dataform was created to ensure the sameinformation was collected for each run.Radar settings—tuning, gain, range, andrings—were recorded. Each kayak was paddled, one at atime, along the course without any radarreflector to determine its “baseline” radarsignature. This represented a “run.”Optimal radar settings were used.Aboard the radar platform, a qualitativesliding scale was used to rank thestrength of the radar signal (or return).The captain and one volunteer monitoredthe radar scope and called out “zero,”“one,” or “two” with each sweep of theradar. “Zero” indicated no signal; “one”indicated a weak to moderate signal; and“two” indicated a strong signal. Anothervolunteer recorded this data on thedataform. Initially, up to 100 sweeps ofthe radar were recorded. After reviewingthe first day’s data, it was clear that 30-50 sweeps of the radar would be ad-equate. Each run was at a predetermineddistance from the radar platform:typically 1/8, ¼, and ½ mile. At the ½-mile point, the range and rings were

adjusted. The kayaks always ran thesame course; so, to change distances, theradar platform vessel would move and re-anchor. Once baseline data was established,the experimental portion of the studybegan. Each kayak was rigged with aradar reflector (see the picture andcaption below for a list of commercialand homemade radar reflectors used).The procedure was similar to that usedfor gathering baseline data: radarsettings were recorded and kayaks werepaddled one at a time along the course, 1/8 mile from the radar platform. However,the experimental portion varied in thateach kayak ran the course again, but withthe radar platform adjusting gain. Gainwas adjusted to get the best return fromthe kayak while allowing for someminimal amount of clutter deemedacceptable by the captain. The radar platform was moved and thewhole sequence repeated for eachdistance (¼ and ½ mile). As with thebaseline runs, range and rings wereadjusted at ½ mile. Subsequently, alldata were entered into a relationaldatabase to facilitate analyses.

1 RadarFlag 24" x 36" U.S. ensign;2 RadarFlag standard kayak flag;3 10-quart aluminum “chili pot”;4 19" PVC tube filled with crushedaluminum foil (homemade);5 Kayak Watchdog;6 Stalker Radar Super Reflector;7 Hamilton Marine collapsible radarreflector;8 Davis # 151 gold foil radar reflector;9 Davis # 153 aluminum radar reflector;10 space blanket worn as a cape(Academy Broadway Camper’s Emer-gency Blanket (item no. 50330; 84" x 52"aluminum laminated polyethylene).

Radar Reflector ModelsTested

Reflectors tested but not pictured here: A North Water Paddle Sports Equipment 30SK-25R Radar Reflec-tive Paddlefloat; B North Water Paddle Sports Equipment 30SK-51R Radar Reflective Expedition Deck Bag; CHomemade: broad-brimmed hat covered in aluminum foil; D Homemade: PFD with vertical bands of TrimBriteProducts Metal Mend Tape; E Homemade: vest lined with space blanket, vest lined with other reflective mate-rial; F aluminum foil crunched up and worn over a hat.

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Figure 1. Visibility Factor SummaryResults: Visibility factor isan average of the radar return for each radar sweep, on a three pointscale (0, 1 and 2, with 2 being the strongest signal). This graphicrepresents a general average of the visibility factor in all the testingfor all the kayaks. This is to highlight the relationship between kayakvisibility on radar and distance from the radar platforms.

Discussion & ResultsThis study investigated the effective-

ness of a variety of commercial andhomemade radar reflectors for increasingkayak visibility on radar. There are twomajor variables: the kayak and the radarplatform. The following discussionexplores the data collected and thelessons learned during this study.

To illustrate the importance ofproviding a good radar return, considerthat a boat traveling at 15 knots covers ¼nautical mile (nm) in 60 seconds. Whencorrelated with our results—that kayaksare generally only visible at less than ½nm—the window of radar visibility forthe boat operator to detect a kayak is oneto two minutes. Boat operators, espe-cially commercial fishermen, tend to befocused on multiple tasks when inmotion. In reduced visibility, thisprovides little opportunity for the boatoperator to define and discriminateobjects on radar. In addition, in order todetect potential collisions with otherlarge vessels, boat operators tend to settheir radars at longer ranges than thoseused in these field tests. Furthermore,they typically adjust their radar settings toexclude clutter in order to reduce thenumber of objects that need to bedefined. This often eliminates sea kayaksfrom showing up on their radar screen.

For fishermen, adjusting to thedramatic growth in the numbers of seakayakers can be a challenge. However,the fact remains that more and morekayakers are taking to the coasts, andincreasing numbers of guides andoutfitters are joining the ranks of theworking waterfront by making their livingfrom the sea.

Our first radar reflector field test (inBar Harbor) was designed to generatebaseline data. As defined by the boatoperator, “optimal” radar settings wereused so as to filter out unwanted clutter.The area where we conducted this firststudy contained numerous obstacles—islands, floats, moorings, and othermarine traffic, including a large locally-guided group of kayakers—that ob-

structed or confused returns, exemplify-ing the challenges a radar operator has formaintaining orientation to all potentialobstacles. Regardless of which commer-cial or homemade radar reflector wasused, the kayaks generally did not showup on the radar except at the closestdistance (1/8 nautical mile).

We identified the need to vary radarsettings, particularly gain. Gain adjuststhe sensitivity of the radar; it may be themost important adjustment for increasingdetectability of sea kayaks. Varying gainadjusts the amount of unwanted signalsshowing up on the radar screen. Tuninggain down reduces the number of falsesignals or signals from small objects, suchas lobster buoys…or kayaks. When gainis turned up, the number of returns isgreatly increased. This can pose achallenge to the radar operator indeciphering what is just “clutter” andwhat is a target of interest.

During our second field tests inSouthwest Harbor with the U.S. CoastGuard, we assessed the effectiveness ofradar reflectors to return hits at variousradar settings. In addition to gain, weexperimented withrange. Range is thescaled distance fromthe center point ofthe radar screen(which is thelocation of the radarplatform) to theedge of the screen.Increasing rangeincreases the areadisplayed on the

radar screen. One additional experimen-tal design introduced in SouthwestHarbor was having all kayaks paddletogether in a tight pod: the radar returnwas significant.

Our third round of field tests inBoothbay Harbor had several goals: 1)Given a different radar platform andoperator, could we repeat our SouthwestHarbor results? 2) Which, if any,combination of radar reflector and radarsettings are most effective at generating areturn from a sea kayak? 3) Does theconstruction material of a sea kayak affectradar visibility?

Upon completion of the BoothbayHarbor tests, data from all three sets offield tests were entered into a relationaldatabase. To facilitate comparison amongfield tests, we developed a “visibilityfactor.” During testing, as described inthe methodology section, each radarreturn was ranked on a three-point scale.The visibility factor for each individualkayak/reflector combination, is an averageof these scores and can range from 0 to 2;the higher the number, the more visiblethat particular radar reflector was onradar.

Kayaks traveling in a tight pod, like this group during our Southwest Harbortrials, are more likely to be seen on radar than kayaks spread apart.

Figure 3. Gain Settings [1/2 mile distance]: This graphicshows the impact the radar unit GAIN setting has on visibility.

Based on the three sets of field tests,we made the following findings con-cerning the effectiveness of commercialand homemade radar reflectors forincreasing kayak visibility on radar.

1. Choose and mount your reflectorwisely. Commercial and homemaderadar reflectors provide increasinglybetter visibility as height above waterlineis maximized (e.g., a radar-reflective hatprovides better visibility on radar than adeck bag made of radar reflectivematerials).

2. The greater the “angularity” of aradar reflector, the greater its visibil-ity factor (e.g., the Davis 153 and thehomemade tin foil hat, both with sharpangles, generated stronger radar returnsthan smooth radar-reflective surfacessuch as deck bags, flags, or vests).

3. The larger the kayak, the greaterits visibility factor. The tandem seakayak turned up much better than thesolo sea kayaks, regardless of radarreflector. The material a sea kayak ismade of had little effect on visibility

Switching out reflectors during the third radar reflector visibility trials.Boothbay Harbor, Maine.

factor: Kevlar sea kayaks were equallyvisible as those made of polyethylene(figure 5).

4. Kayaks paddling closely together ina pod formation produce a much moresignificant radar return than a kayakpaddling singly with a radar reflector.

5. At both 1/8 and ¼ nautical milefrom the radar platform, kayaksconsistently showed up on radar,regardless of whether there was areflector in use or not. Beginning at ½nautical mile, kayaks produced anobvious radar signal less than 10% ofthe time (fig. 2).

6. The angle of the sea kayak to theradar platform affects visibility: a seakayak perpendicular to the radarplatform has a greater visibility factorthan one whose bow or stern is facingthe radar platform.

7. Changing gain and sea clutter onthe radar screen will increase theability to detect kayaks (figure 3).However, this comes at the cost ofadditional background clutter or noise.

It is important to allow radar threesweeps to help identify questionablereturns.

8. The visibility factor decreases withdistance away from the radar platform(figure 1). Generally, sea kayaks 1 milefrom the radar platform are not visible onradar, whether or not they have reflectors.

9. The higher a radar antenna ismounted on a vessel, the less effect seastate has on kayak visibility (figure 4).It is important that the radar antenna bemounted with no obstructions, such aslife rafts, impeding line of sight to thehorizon.

10. Motion of the radar platform canreduce its effectiveness at picking uptargets. One Coast Guardsman said thatthe bows of typical Maine lobster boatstend to point upward when traveling atcruising speeds. Therefore, radar wavesmay completely miss an object low to thewaterline, such as a kayak.

11. The strength of the return is thedominant factor. Even with radarreflectors, the strength of the return ismore of a driving factor than the radarhorizon. In other words, the strength ofthe return may fall short of the radarhorizon.

12. Radar is only effective when it isbeing watched; if the radar is not beingattended, then the quality of the radarsignal produced by a sea kayak isirrelevant.

Figure 2. Kayak Radar Visibility Results: This graphic is acomparison of 10 types of reflectors at two of the test distances.This highlights the performance of various reflectors duringtesting. We can also correlate reflector height above the waterlinewith performance. The higher reflectors, Foil Hat and Flag,demonstrated less performance degradation at the increaseddistance.

Figure 4. Kayak Radar Visibility -- Effect of Sea StateThis graphic compares the SW Harbor data (calm seas) with theBB Harbor data (3 ft. chop). Differences based on sea state werenot as large as expected.

It is increasingly important for seakayakers and boat operators to minimizevariables that increase the potential ofcollision or reduce the effectiveness ofradar reflectors and radar platforms.Some variables should be addressed bysea kayakers, some by boat operators,and some require further research anddevelopment. Applied collectively, thelikelihood of kayaker/boater conflictshould decrease and all boaters can plythe seas with greater peace of mind.

Recommendations for paddlers Based on our field tests, we foundthat some form of radar reflector, be itcommercially manufactured or home-made, is better than none and biggerradar reflectors produce better returns. Radar reflector design needs to befunctional for paddling. While our fieldtests and common sense dictate that asolo kayak equipped with a radarreflector atop a four-foot mast may beoptimal for visibility, it is neitherpractical nor safe to do so. Such areflector increases windage, thusdecreasing kayak stability. A mast-mounted reflector can also impairrescues. Mount radar reflectors so that theywill generate the greatest return. Octahe-dral reflectors (those made of threeintersecting, right-angle planes forming

eight trihedral shapes; e.g.,Davis 153) are best mountedin the “catch-rain” positionwith one trihedral facing up,one facing down, and theremaining six optimallypositioned to reflect radarwaves. Radar reflectors are onecomponent of any paddler’ssafety preparations. Al-though they do not guaranteevisibility, used in combina-tion with other safe seakayaking practices, they can enhancesafety. When traveling with one reflectorfor a group—as is often the case onguided tours—paddlers should travel in atight pod. Tight pods increase the size ofthe return and thus increase the chancesof being identified by radar operators.Plan crossings for narrow channels andknown navigation references (i.e.,navigation buoys). Make securité callson VHF channel 16 to advise otherboating traffic that a crossing is under-way, and specify exact points of cross-ing. This provides a reference point tothe boat operator to slow speed andchange radar settings in order to find thegroup on the radar screen.

Conclusions andRecommendations

Due to a combination of height and angles,this homemade “hat reflector” generated

among the clearest returns.

Recommendations for radar operators Radar is only as effective as itsinstallation. Obstructions, such as liferafts, placed in front of the radar antennaimpede proper radar operations. Settingsneed to be optimized for a combinationof clear returns without filtering out toomany real targets. For radar to work atall, it must be monitored, especially infog. And, not surprisingly, higher endradar systems mounted at the highestelevation above the waterline produce thebest results.

Figure 5. Radar Visibility - Drop Off Distance. As paddlersmoved away from the radar platform, the distance in miles wherethe radar return was lost is called the “drop off.” This graphicshows the radar “drop off” point for various boats. In this testthe paddlers were moving directly away from the radar vessel.SINGLE[K] - single person kayak, Kevlar constructionSINGLE[P] - single person kayak, Plastic constructionTANDEM[G] - tandem kayak, Fiberglass construction

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Principal Project Collaborators:

Study and report authors and designers: Natalie Springuel, Paul Travis, Richard MacDonald.Data compilation services: Norumbega Technologies Inc., Bangor, MaineProject supporters and volunteers: U.S. Coast Guard (First Coast Guard District Recreational Boating Safety Specialist Al Johnsonand LT Kevin King, Office of Search and Rescue); U.S. Coast Guard Group Southwest Harbor (LTJG Tom Gorgol, Chief Ken Hill and theAids to Navigation team); U.S. Coast Guard Station Boothbay Harbor (Chief Don Holcomb, Officer-in-Charge); U.S. Coast GuardAuxiliary (Bob Loney, Gordon Nash, Mark Potter, Jim Powers, Dave Power); College of the Atlantic (Captains Andrew Peterson andHillary Hudson, deck hand Cory Whitney); Kayak guides (Chuck Herrick of National Park Kayak Tours, John Roscoe of Salt & StoneKayaking, Jessica Herbert and Paige Rutherford of Coastal Kayaking Tours); Mount Desert Island Paddlers Club (George Mitchell, SueTurner); Southern Maine Sea Kayak Network (Bob Arledge, David Lenz, Jonathan Pershouse, Deb Swanton, Gerry Vaillancourt; Advisors(U.S. Coast Guard Research & Development Center, Groton, CT; Tom Teller, Aviation Professor, Daniel Webster College).

Recommendations for future researchand development As more and more sea kayakers—whether on guided tours or on theirown—take to the seas, there is a need forinnovations in safety equipment designedspecifically for kayaks. Of all thecommercial reflectors included in thesefield tests, only one was designed withkayakers in mind (the Kayak Watchdog)and even it needed modifications formounting on a kayak. Mounting theother reflectors, which were intended forlarger vessels, was awkward at best. A radar reflector designed specifi-cally for kayaks would need to maintainthe kayak’s low profile to limit windageand instability. It would need to bemounted such that it does not interfere

paddling jackets could be outfitted withreflective material as well. There is alsoa need to research the potential forincorporating reflective material withinthe kayak’s hull design. More research is needed on each ofthese possible designs. Radar-reflectivecloth materials currently on the markethave some limitations, not least of whichare that they eliminate the angularfeatures typical of highly visible reflec-tors. Alternatively, investigating activeradar reflectors—reflectors that transmit asignal on the radar frequencies typicallyused by boats—could lead to a new,portable, affordable device. Overall,there is a tremendous opportunity formanufacturers to develop a new marketby designing radar reflectors specificallywith kayakers in mind.

Even on a clear day, kayaks are hard to see from the cabin of this CoastGuard Auxiliary vessel. Radar reflectors can help increase visibility.

Effectively setting and reading radartakes proper instruction, practice, andtime. Our field tests demonstrated that ittakes practice to differentiate betweennoise and an actual target. There is a fineline to setting the radar to minimizenoise without filtering out small butlegitimate targets. Before altering settings, watch thescreen through multiple radar revolu-tions: false returns do not repeatindefinitely the way a true echo would.If a target looks suspicious, it is a goodidea to let the radar make at least threesweeps to differentiate between legiti-mate targets and false returns. Navigating cautiously in knownkayak territory, such as island-studdedregions, harbors, and inshore waters, is agreat step in decreasing chances ofcollision.

with self- or assisted-rescues or Eskimorolls. And it would need to be light, easyto carry and affix to the kayak, and notinterfere with other deck rigging systems.Although conventional models currentlydo not meet these needs, the limitationsare not insurmountable, as has beenproven by several of the homemadereflectors included in this study. Some options manufacturers mightconsider include incorporating radarreflective materials and designs withinexisting sea kayaking equipment andclothing. The paddle blade could beutilized to take advantage of the height itachieves. Our field tests demonstratedthat crushed aluminum in a paddler’s hatyielded decent results; a manufacturercould design a new hat with built-inreflective material. Life jackets and

For more information: Maine Sea Grant ExtensionCollege of the Atlantic, 105 Eden St., Bar Harbor, ME04609, 207-288-5015x298. nspringuel@coa.edu.www.seagrant.umaine.edu.