Newbie needs help with small DIY sail plan, trimaran setup.

[Todd Bradshaw]

Unfortunately, the common idea of building your sails from oddball materials (including Tyvek and polytarp) until you theoretically "get it right" and then transferring those same parameters to real Dacron sailcloth doesn't really work. Those materials and Dacron sailcloth don't perform the same. When you start learning how to shape a sail, place the draft properly, shape edges for edge stability or for adding specific amounts of draft, the amounts added tend to be pretty small. The amounts you broadseam panel seams will vary with the material chosen, so what works with one material won't likely work the same with something different.

You can make a few Tyvek sails, try them out for flaws, improve as needed and probably eventually get one which works pretty well (while it lasts). The same would be true with polytarp. The ripstop polyester would be a terrible choice with little bias stability. It is also prone to explosive tearing, something which ripstop nylon is generally not - though it would also make a pretty lousy main or jib, being even less stable than the polyester version. Even if you finally perfected your tarp or Tyvek design, transferring the same shaping to real Dacron is very likely to be a big expensive mistake. I had a nice Dacron Genoa for our Farrier trimaran and one day for fun, I decided to duplicate it with some fancy Mylar polyester/Vectran X-ply to make a real sexy one. I just cut it the same as the Dacron one and It came out great - or at least it did after I moved and extended the genoa car tracks because the new fabric was so much more stable than the Dacron had been.

Beware also, that there are some real hack jobs being done with polytarp in particular, and displayed on the web as "how to" videos and articles. These "instructions" aren't really any more simple than real sailmaking and the sails made from them are usually poor at best.

This is a PDF I wrote a few years ago explaining how you can make a real sail out of this sort of temporary material. You might find some helpful information in there which would apply to other sail styles as well.

https://www.dropbox.com/s/uxt5tpentd...LY-LA.PDF?dl=0

[Lee.007]

Thanks Jfitzger and Todd. I actually have that pdf sent to me from upchurchmr some time ago. I have read it extensively and I plan on using it when I make a sail. Your PDF follows along very closely to what "The Sailmaker's Apprentice" says.

In order to get me on the water as fast as possible, I am going to use the sail that jmanflyer sent me with the modifications I made to it. Then when I have time I will experiment with designing and sewing my own sails. Out of curiosity, would there ever be a situation when you would put the max draft points greater than 50% back from the luff? If I think of an airplane wing, it is always very close to the leading edge, or on a sail it would be the luff. And for a light craft like my Kayak trimaran, would I ever want it less than 40% to 45% back from the luff? Just wondering.

[Lee.007]

OH yeah, in other news, I have finished decking the two amas, and should be done fiberglassing them in a week or two. Won't be long before I start on the aka's and then it will be time to rig up and go sailing!! I am about to run out of time... winter is coming...

[Todd Bradshaw]

Out of curiosity, would there ever be a situation when you would put the max draft points greater than 50% back from the luff?

Not really. About the only time we see that is on old sails which have lost their stability, allowing the maximum draft to migrate aft. It tends to be pretty bad for their performance.

And for a light craft like my Kayak trimaran, would I ever want it less than 40% to 45% back from the luff?

There are instances where maximum draft may be as far forward as 35% aft of the luff. Most of those instances are on very fast multihulls. I doubt a sailing kayak is ever going to be nearly fast enough to need that, but you could probably do 45%. Far forward draft would also usually be combined with a more rounded luff entry curve, despite the fact that a flatter entry might be able to yield more speed in perfect conditions. The rounder entry shape is more forgiving of rapid changes in apparent wind angles, where sails may temporarily be over-trimmed or under-trimmed as the boat quickly passes through puffs and lulls and the crew tries to keep up with the sail trimming chores. Moving the draft forward for a fast boat also starts to make a pretty good case for using full battens and pre-cambering them to keep the sail's shape consistent. Light and fast boats like Hobie Cats have pre-cambered, fully-battened sails for a reason.

[Lee.007]

Hmmmm, giving me some ideas Todd. I just might build a few sails, with different draft placement, and see which one works best. Now where can I find some super cheap sailcloth.....

Oh yeah everybody, here are some pictures of my cedar strip amas. The starboard ama has the deck glued down, and has been sanded on top to prepare it for fiberglassing. The port ama I just glued down (epoxied) today. You may notice I did the middle sections differently. That's because I didn't want to take the time to do the parallel strips on the starboard ama. It required too much support structure underneath and was a pain. And I also had enough short strips to keep the color pretty much the same across the section. I kept the bows and sterns the same though. While I was sanding I realized my end pour seeped out a lot more epoxy on the stems than I thought. I have got a LOT of sanding to do.:

20201109_180030.jpg 20201109_180012.jpg

[Todd Bradshaw]

I just might build a few sails, with different draft placement, and see which one works best. Now where can I find some super cheap sailcloth.....

I wouldn't be in too big of a hurry. It is not at all unusual for even good sailors to take a full season or better just to learn to reliably tack a new multihull sailboat. We used to have a lot of fun turning over the helm of our trimaran to sailor friends and watching them repeatedly get stuck in irons while trying to figure out the proper particulars - speed, heading, trim and timing to get the boat to tack well. Your design could easily be a real bear to tack efficiently, and you might be well into your second season before you're efficient enough at sailing it to do any serious testing of the fine points.

Most of the sailcloth manufacturers also build a line of budget Dacron sail fabrics, mostly for OEM applications. They tend to get their stability from being heavily resin coated, rather than from the weaving, so they tend to break down and get mushy fairly quickly (like a couple of seasons). Even though they may be half the price of premium sailcloth, most folks probably wouldn't consider them cheap.

[Lee.007]

Fiberglass now complete. Here they are after the epoxy has cured. Spent all day today sanding, I will varnish them tomorrow. I need to get busy on the akas.. and the rudder... and the lee board... winter is coming...

20201111_111415.jpg20201111_111326.jpg20201111_111310.jpg

[Lee.007]

Woo Hoo! Amas are done! I took them outside and snapped some pictures of them with my kayak spaced at 5 feet from kayak centerline:

[Lee.007]

Edited to insert pics. So I figured out that the file size was too big. Let me know what y'all think:

20201115_114558.jpg20201115_114609.jpg
Yak and amas.jpgyakandamas2.jpg 20201115_114632.jpg

[Todd Bradshaw]

Testing, 1, 2, 3.......

sq.jpg

Seems to be working so far. Sometimes it will reject images if I have forgotten to reduce them to a reasonable size for the forum to handle before uploading them.

[Lee.007]

Thanks Todd!! I read the forum FAQ and figured out the right file size.

Ok everybody, I have another design question: What will happen if I don't center the amas around the cockpit like the plans suggest? If I center them, the mast is going to be between my shins in the kayak. I want to move it forward, pretty much put the rear ama kissing the front of my cockpit coaming, and mount the lee board on the rear aka. Thoughts?

[Lee.007]

Here are some more pics of the hatch I installed. Got the set from amazon for $20. Comes with a nifty little "waterproof" bag. I used epoxy thickened with silica to glue them in there, then sprayed with a water hose directly on the hatch after it cured. Didn't leak, so I claim victory. Also installed some drain plugs in the sterns. I used a forstener bit to drill a 1 1/8" hole through the deck and shear clamps, then inserted a wood strip tied to 550 cord, pulled it up and secured it to create a "plug" in the bottom of the hole. Then I put the thickened epoxy in. Once it cured (24 hours) I bored it out with a 3/4" forstener bit and put the drain plugs in that I bought from Academy Sports. This too was put to the test with no leaks.
20201115_114620.jpg20201115_114652.jpg20201115_114717.jpg

[Woxbox]

So on the aft aka location, think about how it will affect paddling the boat. Also, the leeboard has to be located relative to the sail. The aft aka may be too far back. But your progress looks good.

[Lee.007]

Hey guys, I actually sent pics and drawings of my setup to CLC and they gave me advice that I should center the sail center of effort above the lee board center. They said being that it is a long narrow hull, and amas added to the system, I have a lot of directional stability and I can get away with less lead than a heavy monohull with more rocker. Thought I would pass that along for any future kayak trimaran builders. I need to get this thing finished and get it on the water to see how it goes. I am thinking about making my mast position adjustable somehow... But would I even be able to tell a difference in how it handles if I move my mast between a range of 0 to 3 feet? If the answer is no, then I ain't gonna worry about it... but I do like to tinker with stuff...

[Woxbox]

Everything makes a difference. Even 3 inches. So make everything as adjustable as possible until you get it sorted out on the water. Good luck, it's going to be a blast to sail.

[Lee.007]

Thanks Dave! I don't know about everything being adjustable. I guess I could do it, so like ratchet strap the akas on so I can move them fore and aft a bit, but as far as a mast goes I don't know if I want to go to the trouble. I have seen adjustable mast steps on the net but most of them only move about 6 inches at the most. For now I think I just want to get the thing together and get on the water. We are starting to dip into the high 30's overnight, so winter aint far off.

I finally got the first aka down on the board. Here is a pic of it after I glued it together. I will probably start working on the rudder and leeboard this weekend while the aka is curing. The manual says to let it cure as long as you can, and a week is not too long they said.

Here is the aka on the board. Seems like no matter how many clamps I buy, I always need at least one or two more...

Edited to add: By the way, Harbor Freight had their six inch trigger clamps on sale for 3 bucks. Get'em while they last. If you are in Augusta GA, forget it. I already bought all they had...

20201118_210538.jpg

[ulav8r]

I bought a few of those trigger clamps a few years ago. Just past snug, they break.

[Lee.007]

I bought a few of those trigger clamps a few years ago. Just past snug, they break.

Hmm... Well, i didn't have any issues and I was able to get good squeeze out and fairly uniform thickness all across the aka. Of course everything is a gamble with Harbor Freight.

[Lee.007]

Soooo.. I have a design dilemma. The rear aka is just about right. It is at a Height where the rear of the ama is going to just kiss the waterline of my kayak. The front however, is about 4 to 6 inches higher. I designed my kayak that way because i wanted a lot of volume up front to keep me from nose diving in waves. Which option do y'all think is best?
1. Make spacers for the front ama and keep the aka as is on the front
2. Make a brand new aka bent to the dimensions I need, putting the front of the ama just kissing the water line like the rear
3. Center the whole thing on the front of my Kayak ( i don't like this one because it points the amas down into the water
4. Center the whole thing on the rear of my kayak and build a separate system for the mast partner, step, and leeboard
20201121_122117[1].jpg

[Woxbox]

It's looking nice, Lee. From what I can see in the photo, I'd split the difference between your suggestions. Move it forward so the rear aka is an inch or two behind the cockpit. This will bring the forward aka lower, but you'll still need spacers to get it right.

Some general principles behind this suggestion:

The amas are always better farther forward than aft to keep the whole boat from nosediving. You want good displacement up forward. As any trimaran heels, if the center of displacement of the ama is ahead of the center of displacement of the main hull, the boat will assume a nose-up attitude. If the center of displacement of the amas are behind that of the main hull, then the ama and the rest of the boat will angle nose down as the boat heels. Not good.

Also, as I mentioned earlier, you will want to be able to paddle the boat too, even if it's for short distances. The further forward the front aka sits, the easier this will be.

Here's a photo of the CLC boat. This geometry works nicely.

CLCtririg.jpg

[Lee.007]

Thanks Dave. I had a feeling making a spacer was the best way to go. I will move it as far forward as I can, and may still need spacers for the rear too. The next kayak I build is going to most likely be a tandem, designed by somebody that knows what they are doing... for example, not me. And I will also build a sailrig for it, so it can be a narrow creek paddler, or an ocean going island hopper.

By the way, what do most people use to keep water out of their hull where that mast partner is? Some kind of rubber gasket? Or do they make a sleeve that is sealed up (PVC pipe?) all the way down to the step? Or does everyone just let the water in, and bail it out when it gets too full?

[Lee.007]

Well..... Dang it. I just don't like the look of the front spacer. After leveling everything up today for a dry fit and getting the alignments as close to "perfectly square" as I could, it looks like I need to fill in 6" of space between the front bulkhead and the aka's. That works out to a piece of plywood that is 9" square (shown in the pics below). I emailed my pics to CLC to see what they think. I really think I should just make some custom akas. I am good at AutoCAD so I could draw up a new bending design for a new laminated beam/aka. I will probably do that while I am waiting to see what CLC advises. They are really good at getting back to me by the way. I have been working with Terry, and he had his design guy help with centering the sail balance. Anyway, what do you guys think?? I do plan on building another sailing tri-yak in the future, so the akas I just made won't be wasted if I made new ones.
Here's what my numbers are right now: Kayak draft is 4.3" ( or 4 and 3/8") and I have the ama's raised up 4" so that they just kiss the Kayak waterline with their keel.
The front bulkhead is 6" below the front aka when it is leveled on the kayak. This is going to require a 9" x 9" mending plate, shown below.
The rear bulkhead is 3" below the rear aka when the rear aka is leveled on the kayak. This one isn't so bad, I can lay the aka right on top of the bulkhead, and use a 9" by 3" mending plate made out of plywood.

My biggest worry is, Will the 9x9 mending plate flex too much under the forces of waves and heavy winds? I say heavy, but I don't think I want to be out in anything more than a 15mph wind until I get some experience in this thing on the water. But there is always that freak storm that comes out of no where.
Here's the pics:
20201122_170324.jpg20201122_170313.jpg20201122_170250.jpg

[Woxbox]

Well that is off a bit too much. So where will the mast go? If it's going to be just ahead of the forward aka, you could cut the aka in half at the centerline, and then make up a unit that would both support the mast and reconnect the two aka halves at the best angle to meet the amas, lower down where you want them.

[Lee.007]

Unless clc responds and tells me to do something different, I am going to just make new custom akas. I put the numbers from the clc plans into Autocad last night and was able to change the geometry midway from the center of the aka to the end so that the angle of the end still matches the ama bulkhead, and the curve in the center still mates with the kayak. I will save these akas for a new future tandem kayak sail rig I an to build.

[Lee.007]

Hey all, I called Terry at CLC. He said the main reason for the curvature in the aka's is to provide clearance for paddling, and a fringe benefit is a little bit of geometric strength. So, with that said, I am going to build my own custom aka's cause paddling is not a primary concern. I do intend to paddle, but I will curve the aka's just enough to clear and still make it smooth enough to not break the strips during the assembly.
It might be a while before I can get to it though. Thanksgiving weekend family trips are going to destroy my boat building time.

[Lee.007]

Now Thanksgiving is over, I had some time this week to build my new akas in the evening after work. Hopefully this weekend will be nice weather and I can put most of this whole thing together and maybe even take it for a float! Oh yeah, the winter has beaten me. dipped down in the 30's two nights in a row now. Yeah, I know, you Yankee boys are laughing at me. I can't help it if most of my Army time has been spent in the south and my body has acclimated to it. I bet if y'all came down here in the summer you would melt!
Anyhow, here are the two akas on my work bench. The one with the high curves is the fore aka, the one with the low curves is the aft aka. I drew up the numbers from the CLC plans in AutoCAD and moved them until I got what I wanted fitted around my kayak's contours. I also have a pic below of my cad drawing.

20201202_210920.jpg

[Lee.007]

Sorry bout the bad cad pic, this one is better:
Attachment 74416

[Lee.007]

Well, looks like the pic I posted yesterday got smashed or something. Anyway, this evening I clamped the new Akas to the Amas and laid it over the kayak for a dry fit. I gotta say I am quite ecstatic at the way it turned out. Even after just eyeballing it I got within 1/4" of being square corner to corner diagonally on the ama's bow tip and stern tip. I am going to mark the center's and get it nailed perfect according to the CLC plans. But as far as the aka's go, I think I nailed it! I allowed a little bit of space for making the mounting base between the kayak and the ama's, so it should be close enough to perfect when I am done as far as distance from the kayak water line. Sure does help having AutoCAD and some design experience. I guess I have to give credit to the engineers that trained me up, and also pay tribute to my geometry teacher in high school!

I only have one question for the group: Should the stern be higher than the bow on the amas?? As you can see in my pics below, the stern keel looks to be at least 4" higher than the bow keel. But, the midships area is perfectly level according to my cheap old kobalt level. Is that the way it is supposed to be? Or should I raise the bow up a little higher when I make the mounting base that sits on the kayak? I think I will also hit CLC up about it. Thoughts?


20201203_182446.jpg20201203_182421.jpg

[Woxbox]

That is common tri geometry, and matches the photo of the CLC boat I posted earlier. As the boat goes faster and heels more, you get more length submerged and working. But when not needed, most of the hull is out of the water, saving drag. High sterns also improve maneuverability, important when tacking.

[Lee.007]

Thanks Dave!

So I have another question for the group. Now that I have the amas and akas mostly finished, I am thinking ahead again to my mast and boom. The Laser sail I have looks like it could be boomless, and I was planning on running it loose footed anyway. Most of the pictures and videos I see on youtube show the clc sail rig running boomless with the lightweight aluminum mast. I built a 2.5" diameter birdsmouth mast, so surely it can handle the 60 square foot of the laser sail. I think a boom will help hold the sail shape better. But do they(sailors in the videos) go boomless so they can keep the sail lower and not get smacked in the head by the boom when they tack? Or is it just personal preference? I know it is best to keep the sail as low as possible for hydro/aero-dynamics and all, and if that is the case then I think I want to go without a boom, and also for fear of losing my gray matter while out at sea. Your advice gentlemen(and ladies there are any)?

[boatman1975]

Wow! Nice boat!

[Lee.007]

Hey guys, sorry to not post in a while. I have been working a lot recently. I also snooped and found my Christmas present from my wife, a Yamaha FG420-12A, thats a 12 string acoustic guitar. So since I found it, she went ahead and let me have it. I have been playing the hell out of it for the last 4 days, and my fingers are about to bleed so I guess its time to get back to working on my boat!

So, since last time I put up the pictures, I heard back from CLC on the question about the stern vs bow height that I was worried about. They said it looks great, and they said as long as the water strikes the bow about 2 to 3 inches back from where the keel meets the bow (I am calling it the bow corner), you should be good. He made a very strong point to not let the bows dig. If anything should be too high, it should be the bow. So, I will be making my kayak to aka spacer/mounting base for the front aka to ensure the bow's are high enough. Hopefully I can get that done during our Holiday Block Leave period that starts next week. Then Maybe I can catch a warm day in Jan/Feb to get this sucker on the water!

[Lee.007]

Soo, holiday commitments are mostly finished. Now time to focus on a rudder. I am thinking about just buying a decent mount with foot steering system off Amazon for $100 or less. Anybody got any suggestions? I was looking for about 2 hours and I don't like any of the rudder blades. I want at least 1 square foot of surface area, so I am thinking I will have to make my own blade, but was wanting to save time on the mount and rigging of the foot pedals. Does anybody have a good system they would recommend?

[Woxbox]

I recently put a commercial rudder kit on a kayak. It works exactly as designed to control a kayak being paddled, but there's no way I could see it working under sail. The blade isn't big enough, and the range of travel isn't great enough, either. I also suspect the loads from sailing would be too great for the hardware, which is designed to be as light and efficient as possible for the very low loads experienced while paddling a kayak.

I can't point you to a specific plan, but I think to work, the rudder system will need to be designed to work on a sailboat. Your question got me wondering what others who built the CLC conversion used. A couple of shots appear to show stock kayak rudders, but the others show homemade systems with bigger blades.

I like the look of this one -- made simple with a push-pull tiller instead of running cables to the foot braces.

Tri-rudder.jpg

[Lee.007]

Thanks Dave. I am debating push-pull tiller vs foot pedals. I don't like the idea of drilling holes and running cables in my kayak, and those systems are pretty pricy. Maybe you can advise me which is best for sailing. Since I have never done any real sailing, how much juggling is there between manning the sheet and tiller? Do I need my hands free at all times for the sheet? Or can I just set it, wrap it in a cleat, and then just worry about the tiller until its time to tack or turn upwind/downwind?