Advice needed... (modifying amas for Triak)

Discussion in 'Fiberglass and Composite Boat Building' started by tpdavis, Aug 3, 2016.

  1. tpdavis
    Joined: Sep 2004
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    tpdavis Junior Member

    I own a trimaran kayak sailboat (Triak brand name). The manufacturer only put 80 pounds of floatation in the amas. That's not enough for the 20 kt winds I routinely see.

    Over the past winter, I sawed spare amas (I have 3 sets) in half lengthwise and added 6" height by putting 1/8" plywood inside. Then I filled with expanding foam, cut the sides of the foam and glassed the two halves together. It worked sortof. The additional floatation is enough to keep me from capsizing.

    I want to do it again, but leave off the foam, on another set of floats. In the set I made, the heat of the day causes the foam to expand further and occasionally bursts the seams. They also leak. And they are heavy.

    The advice I need...I could approach this 2 or 3 ways. I could buy some styrofoam sheets and create a lip inside each float, then glass the middle after gluing together. I could buy a fiberglass sheet and staple it to the inside, build a foam front and rear, then glass the middle. Lastly, I could create the lip inside each half, create a plug and make a spacer with lips on both halves, glue together, then glass.

    I have tried to find someone competent to do this job for me since my glasswork is suspect and my gelcoat skill is nonexistant. I did find one guy who wanted $4000 (boat is worth $3000).

    Advice (please don't tell me to get a better boat, I have another boat - but I like the Triak for single handing simplicity).
     
    Last edited: Aug 3, 2016
  2. Petros
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    Petros Senior Member

    Those Triaks look like a blast. post some pictures.

    There are number of ways to do this but it might be a lot easier to make longer beams, put the ama further outboard from the main hull, to give you more righting moment. likely it would be lighter too.

    Also, rather than cutting the ama, what about adding side "wings" to add volume? all you really need to do is increase the volume, by going out sideways you add volume as the ama is pressed into the water. Take strips of foam and glue them on the sides of the amas, shape them to a nice stream line shape, and than glass them over. I

    If you get cleaver you can even do this with thin foam sheets and leave it hollow. build up the shape by gluing ribs on every foot or so, and than glue the flat sheets over it. once sanded smooth you glass over it. keeping it hollow will not allow it to expand and swell. Though I suspect this may be due to moisture getting into it, so make sure it is seals.

    If it was me I would make skin on frame ama (like the way they make skin on frame kayaks), use light wood stringers with plywood blukheads every 16", screw or lash it together and cover with 9 oz nylon or polyester cloth, seal it with polyurethane floor finish and paint. It would cost only about $40 in materials and take about 15 hours each to make. they also would be very light. I have made some 20 plus hulls using skin on frame, mostly kayaks. and I think that Triaks look like fun so I was considering making one using all skin on frame design, wood frame and nylon skin.
     
  3. tpdavis
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    tpdavis Junior Member

    Thanks for the thoughts, but ... see the boat in action

    https://www.youtube.com/watch?v=OwN18Pxt09Y

    The above link shows the boat and where I sail it and typical sailing conditions.

    The thing that drew me to the Triak in the first place was the single aka "wing" placed behind the driver so you get a dry ride. The boat looks cool on the hard (like a star wars X wing fighter before deploying the X), so I'd rather not mess that up and making the amas taller satisfies my esthetic sense.

    The skin on frame amas would work, but the existing wing has a "key lock" system so that a single screw holds the ama to the aka wing. Granted, the single screw is the weakest link on the boat and causes the amas to fail due to repetitive stress (hobby horses up and down waves).

    As I said before, I have two more sets of floats I could modify and I'm willing to sacrifice one more in the attempt to make it more survivable in big wind.
     
  4. upchurchmr
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    upchurchmr Senior Member

    How much volume do you want?
    clcboats.com has an ama design to add to a kayak or canoe.
    They are 100# displacement at the deckline.
    These are plywood/ epoxy/glass.

    I built a set of hulls (catamaran rowboat) which were also 100# displacement. The shape is simple, they are 11' x 6" width.
    I thought they were pretty easy to build.
    Picture below. These have a semicircular bottom shape. They probably weigh 18# per side and could be lighter.

    [​IMG]
     
  5. upchurchmr
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    upchurchmr Senior Member

    I saw the floats on the Triak web site.
    How long are they and what is the maximum width?

    Another thought is to just glue some foam onto the existing shape and then fiberglass. That would keep the attachment, keep the nice shape, but get some more volume quickly. Perhaps 1/2" of a good foam.
    It would be easy to sand the foam into a smooth shape.

    Can you show a picture of the current modified ama?
     
  6. tpdavis
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    tpdavis Junior Member

    The current modified float is the one seen in the video. The original floats are 8" tall, I added 6" for a total of 14". That increased the floatation to about 150#s per float. That's enough with the 8 foot beam to stabilize the sail plan/boat in 20 kt winds.

    While I could probably build new floats or add foam to the outside of the existing one, making the floats taller is the way I want to go since it keeps the same float surface drag and maintains the boat balance fore and aft thereby making the sailplan still work well.
     
  7. Petros
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    Petros Senior Member

    filling it with foam was probably a bad idea, too much weight and it will soak up moisture when you get leaks. almost all lightweight fiberglass hull structures develope tiny fatigue cracks over time that allows moisture to seep inside.

    I think if you can use sheet foam to add the additional volumn to your cut amas is the best bet. leaving the interior of the ama hollow. when you get seepage you will just have to open the access hatch (I presume it does have one, if not add one), and mop up any accumulated moisture and allow it to dry out between uses.

    another alternative is to perhaps add the additional area by using the same constrution as used on strip built canoes and kayaks, or even stitch and glue. build up the shape, sand and fill until you get a smooth transition, than glass over the assembly. Make sure you rough up the surface of the existing ama skin where you expect the new fiberglass to bond to it.

    putting on flanges seems like a lot of work, and it also adds weight. I am not sure it is any more reliable than doing a lap splice between the old skin and the new sections you are adding.

    If you are willing to sacrifice one set of ama hulls (perhaps the ones you have already cut up, since the results are less than desirable now), is build new lower hulls out of plywood (stitch and glue) or perhaps strip built (much more work), and than just cut the tops off the existing amas and bond them to the new lower hulls. this way you get the same attachment and the smoother round lines on the top. This is a bit more work but will likely results in something much lighter and more suited to your desired results. Stitch and glue marine plywood construction is fairly simple, you can get decent shapes with careful planning and design.

    There may be others that have more fiberglass experiance with better ideas.
     
  8. tpdavis
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    tpdavis Junior Member

    Advice Needed--Modifying (not building) amas for Triak

    I would not have thought of the flange idea except for a local guy who has a long oven and prepreg--but he was talking it over with me on the phone and hadn't seen the floats.
    I think stitch and glue is the most likely avenue for me except I'm having trouble visualizing the entire process since the last seam won't be reachable from the inside. Also, when you stitch and glue for essentially an overlapping strake would you use thickened epoxy by itself or would you use saturated glass tape before tightening the stitches? What guage wire do you use for the stitches?
     
  9. upchurchmr
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    upchurchmr Senior Member

  10. Vantage475T
    Joined: Aug 2016
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    Vantage475T Vantage475T

    I have a CLC Sport Tandem with the outriggers and the mk3 sailrig and it goes really nicely.

    The righting moment in the outriggers is not sufficient when pressing hard if we remain in the main hull, but I added trampolines across the front cockpit so my wife can sit right out and keep us flat. She can't paddle but I can still if needed.

    Now we have also added an RS200 jib on it as well it is a struggle to keep it flat in even reasonably light winds but it really shifts along managing to hit about 20kmh which I am really pleased with.

    I do need to add some fairing to the deck of the outriggers as when getting submerged the water hits the upright aka connector bulkead and slows us down a lot. Adding a simple deflelctor shortly is a priority to imprive things.

    For just kayaking due to neck and back problems (I can't afford to capsize) I also use small outriggers made from thin ply stitch and glued together of a simlar size. Approx 2 ft long and fly just an inch above the water but give huge feeling of safety.
     
  11. tpdavis
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    tpdavis Junior Member

    Thanks, but...

    I came to this forum because I can't seem to find any construction forums on clc...I see builders forums ... their website is hopelessly difficult to find anything useful if you are looking for a specific technique like stitch and glue two flat panels together which is essentially what I'm trying to do with the added issue that the final seam is done without being able to reach both sides of the pieces.

    If you could please give a little more specific direction, I'd be appreciative.
     
  12. upchurchmr
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    upchurchmr Senior Member

    Directly under the picture on the "sail-rig" page I referenced is a button labeled "Construction Gallery".

    For a closed ama there is no way to make the final seam with glass / epoxy on the inside.
    I thicken up the gunwale (another wood strip) to get a bigger gluing surface and use thickened epoxy to make the joint. The glass going over the outside of the joint makes enough strength to survive everything you need.
    This really is similar to the old style ply on frame for this one joint.
    The CLC amas are done the same way.

    If you are concerned, you could cut hand holes in the deck to get access to the close out edge. You would then have to close those holes up by making an exterior closure with an overlapping joint. The overlap should provide enough strength to make good structure.

    You do have a problem that the small size of these amas leaves little room for such access holes. Typical kayak construction does not have this issue.

    Agreed about the poor forum on CLC but that is really the quality of the reports being submitted.

    I suggest you make up a sample of the joint you want to build, and break it. This way you can work from some actual facts and decide if you actually have a problem.
    Talking on a forum leaves so much un-defined about the actual structure. You might compare it to an edge to edge joint where you glass both sides, but don't have additional thickness of wood to beef up the joint.

    I just remembered another frame where one person says that his ply on frame kayak (a double) is lighter and stronger than stitch and glue. He uses 1/8" ply on a frame. Sorry I can't seem to find it.
     
  13. tpdavis
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    tpdavis Junior Member

    Thanks so much, I appreciate the help. The first time I did this over the winter, I rushed through it and didn't have a good idea of how to proceed and the results show it. Unfortunately, I'm not a patient person (hasn't improved since retirement, either) and glass/wood projects tend to become haphazardly done. The first try was just to see if the increased volume would change the sailing characteristics and provide the needed stability. Now that I know that the stability is there and the boat still sails the same, I'm ready for the "final final". Truthfully, I'd still rather find someone to do it for me, but $4000 is too much money. I'd be willing to pay half that, though if someone reading this is interested in taking it on and lives in the SF bay area. :)
     
  14. Petros
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    Petros Senior Member

    your question was well answered, but I would also like to add that you can use heavy fishing line, or even better, polyester lashing cord, to stitch the plywood to the existing edge of the ama skin, and leave it in place. Saves a lot of effort and adds to the strength a little. I used zip ties to build a stich and glue hull and I wish I used finishing line, smaller holes and it stays in place, saving time.

    using one of those curved sewing needles to thread the stitching through the holes along the edge of the new plywood section, and the edge of the ama, would not require that you get access to the back of the joint, even with butt joined edges. Thought it might be eaiser to stitch and glue on a 3" wide plywood strip on the back side of the ama shell, and than lap joint the actual skin plywood. it might make a cleaner and stronger joint. 3 mm or 1/8" plywood is all you should need.

    You will want to fill and carefully sand the joints on the outside so it will be clean and fair for the final glassing over. You will not be able to put a layer on the inside, but you will not need that for strength, the overlapping outside layer will provide all the strength and bond between the "plug" and existing ama structure.

    You should prefinish the inside face of the plywood before you install it (5-6 coats of polyurethane floor finish will work fine, or a layer of epoxy followed by the polyurethane) , just to give it some moisture protection. though it probably will not make much differance in the long run, it will not be exposed to sun or weather.

    you would think the builders of the triak would know better, or perhaps they wanted to limit the speed of it by limiting the ama size? that is a really bad idea, larger amas would also make it safer even if it is not driven hard.

    good luck
     

  15. upchurchmr
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    upchurchmr Senior Member

    Don't ever substitute polyurethane for epoxy to prevent moisture protection.

    You can leave epoxy uncoated on the inside since it will not see sunlight.
     
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