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 In
Search of the Perfect Sit-on-Top Sailing Kayak - Part III by Robert O. Hess Designing A Removable Leeboard System Part Iooo Part IIooo Part III
Since I wrote Part I and Part II of this article last summer, I had what was at least initially a disappointing realization: My Ocean Kayak Scupper Pro equipped with just a 1.5m Pacific Action (PA) Sail would not reliably get me to the object of my fascination, Catalina Island. To reach this destination, I will have to cross 22+ mi. of open ocean with the Westerly sea breeze on my starboard beam. Being able to paddle only about half the distance, I will have to sail the remaining 10 miles or so.
I certainly wouldn't be able to hit the un-populated middle of the island, the most beautiful stretch of coastline with the best camping possibilities. After experimenting with the PA sail in different wind conditions for about a year's time, I knew it was back to the drawing board. In a way, the problem was quite simple: I needed to be able to sail in a straight line. For that, I knew, I would need a so-called leeboard. II. Removable SOT Leeboard System Like the keel or centerboard of a sailboat, the leeboard of a canoe or kayak offers lateral resistance to the force of the wind, preventing the boat from slipping sideways under sail. Unlike a keel or centerboard, however, a leeboard is attached to either side of the kayak or canoe. As its name suggests, a leeboard is usually mounted on the leeward side, but also works on the windward side, provided it is long enough (otherwise not enough surface area may actually be submerged when the kayak is heeling to leeward). Leeboards vary in size, depending on sail area, i.e., the bigger the sail and the greater the lateral force of the wind, the bigger the leeboard needs to be. Leeboards are traditionally used by canoe sailors, but in principle work just as well on a kayak. The main difference is that due to a wider beam and greater primary stability (usually between 34 and 42 in.), a canoe can carry much more sail than a kayak and therefore requires a much larger leeboard than a kayak. Another difference is that a kayak offers no obvious attachment point for a leeboard. Canoe sailors usually just clamp or bolt the leeboard to the rail of the canoe, an option not available to kayakers.
The real problem turned out to be attachment of the EasyRider leeboard to my Scupper Pro. EasyRider's own sea kayaks have deck grooves and factory-installed mounting points specifically designed to accept the leeboard crossbar and brackets. Needless to say, my Scupper Pro has neither special grooves nor special mounting points built into it. What to do?
Countless more hours on the Internet yielded no real answers. No one, it seemed, had ever attached a leeboard, much less an EasyRider leeboard, to a Scupper Pro. I did run across two posts by other SOT kayak sailors who had managed to bolt home-built leeboards to their SOTs, but the idea of putting permanent, large bolts through the sides of my boat did not appeal to me. I wanted a leeboard system that could be easily and safely installed and un-installed on the water, because a leeboard tends to interfere with paddling (or so I thought at least) and the crossbar takes up valuable deck space. And I didn't want to drill holes anywhere near the waterline. In the end, I realized I would have to design and build my own removable leeboard system. Never having designed or built anything mechanical before in my life, I did not feel particularly confident about my prospects. Owning no tools other than a hammer, a pair of pliers and few screwdrivers also didn't help matters.
Pondering these variables, I soon decided that the area of the compass mount, just aft of the forward hatch, was the most logical place to mount the leeboard on my Scupper Pro. It was far enough forward not to interfere with my feet or legs while sitting in the kayak, and at the same time was far enough aft to produce a reasonably balanced helm. The compass mount as such would provide a solid base for attaching the crossbar (though I had at that point not yet figured out how to do that).
The question, thus, was how to attach the crossbar to my Scupper Pro without permanently bolting it (or the crossbar and/or other chunky hardware) to the rails. At some point, I considered simply lashing the crossbar to the rails of the kayak, using bungees or ropes of some kind. But this method did not seem to provide sufficient stability. I just couldn't see (perhaps erroneously so) how the round crossbar holding the leeboard could be lashed down onto the kayak's hard plastic rails without rolling or slipping sideways at least to some extent. I had read that to be effective, the leeboard must have a rigid base. In a lucid moment, it finally dawned on me that what I needed was some type of padding to hold the crossbar in place. Once I had had this basic insight, the other pieces of the puzzles came together pretty quickly: there would be three pads, a center pad for the compass mount, and one lateral pad for each rail. The pads would be permanently mounted on (or rather under) some kind of saddle, and the crossbar would then be mounted on the saddle. The whole system would be held down by webbing straps and buckles.
Saddle: First, I had to design and build what I will call the "leeboard saddle." The basic purpose of the leeboard saddle is to hold the crossbar for the leeboard, plus the EasyRider mast base. For that I needed a reasonably stiff, but also durable, waterproof material. While some kind of marine plywood would probably have done the same job, if properly treated, I somehow didn't like the idea of mixing plastic with wood, if only for aesthetic reasons. In the end, I ordered a simple 1' x 3' piece of ½" polyethylene cutting board online for about $50. Another good alternative, also made of polyethylene, would have been so-called "Star Board" marine lumber, though it is said to be even more difficult to glue than cutting board.
One feature I am particularly pleased with is the foot recesses. Until I thought of that solution, the whole idea of a leeboard saddle seemed doomed because it did not leave enough room for my feet. In fact, if I had to use the last footwell of the Scupper Pro for my feet, the leeboard saddle would not work, at least not without major modification (something to keep in mind if you're thinking of building a similar system). Foam pads:
After spending some more time on the Internet, I learned that closed-cell foam actually comes in many different densities and that 2 lbs. minicell foam just happens to be the one most widely used and available. Clearly, what I needed was more density, though I had no idea how much more. Unfortunately, this is where Google could no longer provide answers and I had to resort to more traditional research methods.
On the recommendation of a canoe sailor (you know who you are), I simply called a local foam supplier and, as luck would have it, they carried what turned out to be 4 lbs. closed-cell foam - in white color, which matches the color of my Scupper Pro. This stuff is nothing short of amazing. Though only double the density, it's much, much stronger than 2 lbs. closed-cell foam. At the same time, it can still be easily shaped with just a sharp knife and #36 sandpaper or similar. Without this foam or something equivalent, I truly doubt that my leeboard system would work as well as it does. Next, I cut the sheet of one-inch foam into 8 pieces measuring 8 in. by 3 in. (a stack of 4 layers for each lateral pad), and another 4 pieces measuring 5 in. by 5 in. (one stack of 4 layers for the center pad). Then came what was probably the hardest part the project. I had to cut and sand the two bottom layers of each lateral pad to fit the rails of the Scupper Pro. The problem was that the rails of the Scupper Pro are stepped at an angle of approximately 120° and tapered towards the bow. Despite repeated, careful measuring and using just sandpaper to give the pads their final shape, I still ended up having to glue on an extra strip of 1/4 inch regular 2 lbs. minicell foam at the bottom of each lateral pad to get a snug fit. Fortunately, this turned out to be a good thing in the end because the softer 2 lbs. minicell foam grips the rails even better then its 4 lb. cousin. The final step was to glue the different layers of each pad together using contact cement (H2O glue), and then to attach the pads to the saddle. My original plan was to simply glue the pads to the saddle using some type of plastic adhesive. The problem, as you may already know, is that almost nothing sticks to polyethylene.
While the bond is strictly speaking not permanent, I got a very tight bond on the first try, just cleaning and sanding the cutting board and foam. Last but not least - Devcon Plastic Welder was cheap - only about $5 for the whole job. To make absolutely sure that the pads would never come off, I also bolted the top layer of each lateral pad to the saddle using two ¼ inch screws and 1 inch fender washers (before gluing the lower layers to the top layer). Hardware:
All that remained now was to install the deck hardware on my Scupper Pro. This basically involved attaching six heavy-duty pad eyes on the rails and center tunnel, one for each webbing strap. Worried (or paranoid?) about damaging the rails, I used a 1/8 inch stainless steel backing plate for each pad eye. To provide a strong, smooth and flexible turnaround point for the straps, I added a 1.5 inch steel loop to each pad eye. All holes were sealed with silicone to prevent leaks. The end result, I am pleased to report, is exactly what I had envisioned: a rock-solid and removable leeboard mounting system for my Scupper Pro. Thanks to the snug fit of the pads, there is hardly any movement even without the straps. Once the straps are on, I can lift the boat by the ends of the crossbar without any shifting whatsoever. The mounting system, no doubt, could also serve as an attachment point for outriggers, should I ever choose to go that route. As planned, the saddle and crossbar (max. width 30" wide) fits easily inside the forward hatch of my Scupper Pro with plenty of room to spare. The whole leeboard assembly, including saddle, leeboard, crossbar and mast base weighs only about 9 pounds, and the EasyRider spinnaker and mast weigh 1 pound. This makes for a total weight of only 10 pounds, something I deeply appreciate every time I pull the boat up the beach or punch through the surf. III. Hybrid Sail Plan
As I was building my leeboard saddle, I realized that the saddle would also provide a perfect spot for mounting the EasyRider mast base - right above the compass mount. Though I had considered the EasyRider spinnaker before, I had been hesitant to buy one because I was reluctant to install the mast base directly on the compass mount, the only possible location for installation on my Scupper Pro. You see, I regularly use the compass mount as a head rest of sorts to take breaks during long trips. The leeboard saddle provided the perfect solution to this problem and I just couldn't resist the temptation any longer. To install the EasyRider mast base, I simply drilled four more holes in the leeboard saddle, bolting the mast base on the saddle with ¼ inch SS screws and ¾ inch fender washers provided by the EasyRider. Unlike the lateral pads, the center pad is not permanently attached to the leeboard saddle, but is held in place simply by the ends of the four 2 1/2 inch screws fastening the EasyRider mast base to the top of the saddle. I chose this route because it will allow me to un-install the mast base if I ever need to. Otherwise, the nuts for the screws holding the mast base would have been embedded inside the center pad.
Because the two sails are installed about 4 ft. apart (the PA sail sits in front of the forward hatch), they don't interfere with one another. As the sheet for the EasyRider spinnaker runs through a pad eye near the stern and then doubles back to the cockpit, it poses no risk of entanglement with the double sheets of the PA sail (which run through pad eyes on the rails near my knees). Either or both sails can be set and struck in a matter of seconds, and if desired, stowed below deck in a matter of minutes -- on the water.
Leeboard:
When I am done paddling for the day and the afternoon breeze is building, I open the forward hatch, strap on the leeboard saddle, slide the leeboard on the crossbar securing it with the stainless steel pin, insert the 5'6 EasyRider (two-piece) mast into the EasyRider spinnaker mast sleeves, insert the EasyRider mast into the mast base, and connect the sheet line to the clew of the spinnaker. I also switch from my low-back flexible paddling seat to my high-back stiff fishing seat (Surf to Summit GTS Elite). In about 10 minutes, I am ready to sail. If I don't plan on paddling for long or for other reasons don't want to rig the leeboard saddle and sail on the water (e.g., because it's cold and I don't want to stop hanging my feet in the water for 10 minutes), I can also rig on shore.
The crossbar (or leeboard saddle as such), I was surprised to find out, doesn't interfere with my normal paddle stroke. That's an added plus, because it allows me to switch between sailing and paddling mode without having to remove the leeboard saddle. It is however possible to hit the crossbar with the paddle if I inadvertently modify my normal paddle stroke. As I have carbon blades, that's obviously not a great idea. So, I try not to paddle with the leeboard saddle installed if at all possible. For someone taller and with longer arms than myself, I suspect that the crossbar would be more of a problem, especially for a high-angle paddle stroke. In terms of performance, the leeboard blew me away the first time I used it. In the lightest breeze, I could immediately feel the bite of the leeboard. The boat and leeboard made that unmistakable gurgling sound that only a sailboat makes. Just as designed, the leeboard kept the kayak from slipping sideways on a reach, translating the force of the wind into additional forward momentum (and to some extent also heeling angle). Since then, I have experimented in different wind conditions and found the leeboard to work best in winds between 6-12 mph: I can point the bow at a landmark or buoy across the wind, or even slightly upwind, and hold that course over several miles. In winds higher than that, the leeboard isn't large enough (neither is my current standard Feathercraft rudder blade!) to prevent all side slippage, but still is quite effective. When on the leeside, the leeboard provides so much bite (more submerged area = greater resistance = greater leverage) that I sometimes raise it just a bit to reduce the heeling angle. In short, the leeboard effectively turns my Scupper Pro into a true sailboat. There are limitations, of course, but these have to do less with the leeboard than with my sail plan and lack of outriggers. More on that below. Hybrid sail plan: The main advantage of my hybrid sail plan is its versatility. With both sails and my leeboard installed, I now have three basic sailing modes available to me: I can sail:
Each mode can also be used in combination with paddling (paddle-sailing). And if the wind dies or never comes up, I can strike (and stow) both sails in a jiffy and use just the paddle. As I noted, the leeboard can either be rotated out of the way or can be quickly stowed below deck. Now as before, I love the simplicity of the PA sail. Designed as a downwind sail, it excels downwind and on a broad reach, provided there is enough wind. But, personally, I use the PA sail more for paddle-sailing in light cross winds. Even an early morning breeze of 5-6 mph makes it a pleasure to paddle my Scupper Pro that way over long distances without fatigue. With the new leeboard, I not only avoid leeway, but also gain considerable speed (as compared to sailing without the leeboard). Because the wind is light at this point, the boat hardly heels to windward, which makes for comfortable sitting and paddling. In the mornings especially, I prefer paddle-sailing to pure sailing because I am not warmed up yet and enjoy the workout. I would say that, all things considered, this is my preferred mode of travel. When I get tired of paddling and/or the wind has picked up a bit, I usually add the EasyRider spinnaker to the mix. This gives me a combined sail area of 20 square feet (with 1m PA sail) or 25 square feet (with 1.5m PA sail). In a moderate breeze of 8-10 mph, I can sail that way (without assistance from the paddle) at a cruising speed of about 4 mph (close reach = 75 degrees to the wind) to 5 mph (beam reach = 90 degrees). Things get really interesting when the wind blows 10+ mph. At that point, I reef sail either by striking the 1.5 m PA sail or spinnaker, or switching the 1.5m PA sail for the 1m PA sail, depending on wind force and point of sail. I usually decide on the beach which size PA sail will be appropriate for the day, because switching PA sails on the water, though quite doable, is a bit involved. To sail safely with both sails in winds above 10-12mph, especially over longer distances as I plan to do when I paddle/sail to Catalina Island, I would need to add outriggers. If I were heavier and/or taller than I am (145 lbs., 5'8), and/or if my kayak didn't have such a low center of gravity and narrow cockpit (which prevents me from effectively shifting my weight), I would likely be able to handle a lot more wind without outriggers. So, if you are 200+ pounds and/or 6+ feet and/or paddle something like a Ocean Kayak Prowler or Tarpon 160, you should be able to do quite well without outriggers. But, as things are for me, that won't be an option. My current thinking is to adapt the Hobie Sidekick inflatable outriggers to my EasyRider crossbar. Even with the spinnaker up, I can still paddle without much interference if necessary. The leeboard is no problem because it points downward into the water. The foot of the spinnaker is a bit in the way, but because there is no boom, just the soft edge of rip-stop nylon, I don't mind when my pushing hand or paddle shaft brushes the sail just a bit.
One small fly in the ointment is that the 1.5 m PA sail is to some extent blocked by the EasyRider spinnaker. This noticeably diminishes the power of the 1.5 PA sail on a beam reach, but within acceptable limits. The PA sail still adds considerable speed. The 1 m PA sail is blocked hardly at all, but works best in winds above 10 mph. Interestingly, the best point of sail with both sails set is slightly upwind, as this minimizes blockage. Contrary to what others have said, I have found that the PA sail performs remarkably well upwind to about 75 degrees, provided it is trimmed correctly. In combination with either the paddle or the spinnaker, and of course the channeling effect of the leeboard, the PA sail's upwind performance noticeably improves. If I need to point higher than 75 degrees, I strike the PA sail and continue on with just the reaching spinnaker. It allows me to reach close to 45 degrees, but requires some assistance from the paddle. For good upwind performance, I would clearly need a larger sail and outriggers. Another
benefit of my hybrid sail plan is safety. Both sails have a very
low center of effort, and have either flexible rigging (PA sail)
or a flexible mast (EasyRider spinnaker). V. Conclusion The major design criteria of my removable leeboard system and hybrid sail plan are:
Other sailing kayaks (e.g., the Hobie Island trimaran) are, of course, much faster under sail, offering more excitement and ultimately also greater range of travel. But with a larger sail plan comes a longer, heavier mast, a larger, heavier sail, a larger, heavier leeboard or centerboard, a larger, heavier rudder, bulky outriggers, etc. This level of complexity tends to interfere with loading, rigging, launching and, above all, paddling. It limits the number of safe launching sites, makes hauling the kayak around cumbersome or even painful, turns paddling into a chore to be performed only when absolutely necessary -- effectively converting the kayak into a small sailboat with all of its limitations.
Finally, I want to emphasize that my removable leeboard system should be adaptable to other SOTs. I don't feel that the center pad on the compass mount, a feature unique to the Scupper Pro, is really necessary, though it obviously adds strength. So, if you have a different boat, my basic design may still work. The most significant limiting factor may be leg length: if your feet reach way forward in the cockpit, there may not be enough room for the leeboard saddle, at least not in its present form. But that will depend on your particular physiology, seating position (legs extended or bent), deck layout, and, of course, ingenuity. The sail plan, too, can be adapted to your personal preference. You may opt for one instead of two sails, or you may even prefer a larger sail with outriggers (a great example is the outrigger system Andy Lyne made for his Scupper Pro in the UK) - depending on your sailing objectives. Whatever you do, I strongly recommend that you give the leeboard a try. It will put a big smile on your face, I promise. Robert
is a regular contributor to Topkayaker.net's Forum.
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The
problem with my current setup is that I make way too much leeway
under sail. For every mile traveled towards the island, I drift
downwind for almost half a mile, depending on wind conditions and
swells. Over a 10+ mi. stretch, this means that I might miss Catalina
Island altogether. 
Getting
hold of a leeboard properly dimensioned for a kayak turned out to
be no problem. 
The
first order of business was to decide on placement of the leeboard.
Two main constraints come into play here: 1) The leeboard has to
be aligned, at least roughly, with the sail's center of effort to
balance the helm. Otherwise the kayak will display excessive weather-helm
(the tendency to turn upwind) or lee-helm (the tendency to turn
downwind). 2) The leeboard has to be mounted so that it does not
unduly interfere with sitting in the kayak. Ideally, but not necessarily,
it also should not interfere with paddling.
Attachment
of the leeboard, or rather the crossbar on which the leeboard is
mounted, turned out to be tricky. I had two options: 1) a permanently
installed mounting system with only the leeboard being removable,
and 2) a completely removable leeboard system. An example of the
first option is the "leeboard" system made by KayRak in
Canada. While this system looked functional and solid, it did not
fit the rails of my Scupper Pro nor did I relish the thought of
having chunky metal hardware permanently installed on my boat. As
far as I know, there is no example of the second option, other than
my own system.
Next,
I designed the layout of the leeboard saddle on paper. This process
was quite difficult, as none of the measurements were predetermined
- everything was wide open and left to my "best" judgment.
As a result, my first saddle was a failure (I like to think of it
as a prototype), and ended up having to order and wait for a new
piece of cutting board. The second time around I was more careful
and, after re-measuring everything for the umpteenth time, finally
felt that the leeboard saddle would do what it was supposed to do.
The
basic purpose of the foam pads is to fit the saddle snugly to the
rails and compass mount of my Scupper Pro. For that, I needed a
material that was lightweight and flexible enough to hug the rails,
but also stiff enough to resist compression and deformation. My
first idea, regular closed-cell outfitting foam (minicell foam),
didn't work. After experimenting with this material for awhile,
I realized that due to its low density (2 lbs. per cubic foot),
regular minicell foam was just not strong enough for the job.
So,
I searched for, and after many hours finally found - not on the
Internet, but rather at my local hardware store! - a glue that produced
a surprisingly strong bond between polyethylene cutting board and
closed-cell foam - Devcon Plastic Welder, a 2-part plastic epoxy.
So much for the theory that nothing sticks to polyethylene! 
Next,
I attached 6 stainless steel 
Before
I tell you how my new leeboard system performs on the water, I want
to say a few words about my new hybrid sail plan. I still use my
1.5 m PA sail, but I have now added the 
With
the EasyRider mast base installed on my leeboard saddle, I now have
the option of sailing with a) just my 1.5m (or 1m PA sail), b) just
the EasyRider spinnaker, or c) both my 1.5m (or 1m PA sail) and
the EasyRider spinnaker, depending on wind conditions (more on that
below). 
One
beauty of my removable leeboard saddle is that I don't have to install
it until needed. I generally launch through the Southern California
surf with just my furled PA sail installed and propped up at a 45
degree angle, and the rest of my sailing gear stowed in the forward
hatch. 
In
that case, I rig the mast and sail, but stash the sail in a small
The
additional sail, of course, also heels the boat over more, but within
acceptable limits. At only 145 lbs., I have to shift my weight to
windward just a bit, but nothing dramatic. I regularly eat a snack
while sailing in this manner. For a heavier sailor, I would think
that even less leaning/shifting would be needed. To add counterweight
in higher wind, I sometimes prop up my paddle between my thighs,
with one blade held between my legs and the other extending to windward.
It's looks a bit unorthodox, but is surprisingly effective, as it
allows me to rest my windward arm on the paddle shaft and lean more
comfortably to windward. I may try wrapping a 2-3 pound weight to
the end of the paddle to make it even more effective.
There
are two -- admittedly unintended -- benefits to my hybrid sail plan
that go beyond just being able to carry more sail area. First, I
have noticed that both sail together balance the helm (i.e., prevent
the boat from having a tendency to turn upwind or downwind) better
than either sail does by itself. While the PA sail creates just
a bit of lee-helm (tendency to turn downwind) because it is mounted
near the bow, the EasyRider spinnaker creates some weather-helm
because it is mounted in the cockpit with its center of effort is
aft of the leeboard. When used in combination, the forces exerted
by the two sails on the helm seem to cancel each other out. There
is still some residual weather-helm, but that appears to be attributable
to the size of my rudder blade - it is too small to prevent the
stern from swinging to leeward. I plan to switch to a larger blade
soon. Another unintended, but welcome synergy between the two sails
is that they have complementary strengths and weaknesses. The PA
sail, by itself, doesn't move upwind very well, but together with
the reaching spinnaker claws upwind quite willingly, without assistance
from the paddle. Conversely, the reaching spinnaker, by itself,
is not great on a broad reach or even a beam reach, but together
with the PA sail does very well on both points of sail.
