DIY Simple Catamaran Sailboat Design

Discussion in 'Boat Design' started by WilliamPrince, Oct 10, 2013.

  1. El_Guero

    El_Guero Previous Member

    Traditional kayak paddles used a smaller blade, and more strokes per minute.

    Less tiring, and most people say they are faster.

    PS, I have a shoulder injury, and what I read about these makes them much easier on the shoulders than larger blades.
     

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  2. Petros
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    Petros Senior Member

    I think the efficiency comes from the high aspect ratio blades, the total area of the traditional blade is actually about the same as the "euro" type blade.

    High aspect ratio is much better for long distance paddling at moderate speeds (it is also much easier to stow in the hull). the low aspect ratio paddles used by surf and white water kayaking are better for high powered sudden bursts of speed because they are stall resistant. hold the high aspect ratio native type paddle wrong when you try and do high powered strokes, like when punching through waves, it will stall and flutter and do all kinds of bad things, so it takes some practice to get good with it.
     
  3. El_Guero

    El_Guero Previous Member

    Thank you! That is good to know.

    One other question for William, you are planing on staying closer to shore? I would think an actual crossing would be much more challenging for a first time sailer.

    Wayne
     
  4. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    Wayne, yea I am planning to cross, but I will spend a few days cruising north along the coast, for a few reasons. Firstly, to reach a more sheltered part of the sea of cortez, where it is a shorter and safer crossing, and to get familiar and confident with my boat. I will stop in La Paz before I cross, to add any final adgustments, but I won't be able to do much.

    Scott, I have a reply in the making for you, but you have given me a damn lot of food for thought and I need to go through it all! Thank you for your detailed and helpul replies though, really, very very much appreciated.

    P.S. my plywood is 4mm
     
  5. El_Guero

    El_Guero Previous Member

  6. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    In fact this will be almost my first time sailing. I had my hands on the ropes for maybe 10 minutes when I was young, in a tiny sailboat on a manmade lake in almost nonexistant winds. But I understand the concepts, and I am a quick learner, I think I will get the hang of it.
     
  7. El_Guero

    El_Guero Previous Member

    Not the sailing, beyond the sight of land .... different experience.

    Until you lose sight of land, you always think you can get home, even if you have to walk on the bottom and push up to get another breath ....

    :)
     
  8. El_Guero

    El_Guero Previous Member

    Now you have me watching the videos, and looking at the plans .... :)
     
  9. scotdomergue
    Joined: Jan 2009
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    scotdomergue Scot

    Concerns

    William,

    I’m VERY glad to learn that you are planning to sail north to La Paz initially. AND I’m very concerned about what you intend now that I understand it after more thoroughly reading the thread. I don’t think you have any idea how easily you could be blown out to sea and never seen or heard from again.

    You are building a canoe that was not designed for sailing, nor for the ocean. You have very little experience and understanding of what it takes to travel the way you intend.

    At the very least, please thoroughly test your craft and yourself in conditions that are relatively benign and then work your way up through more challenging conditions. Make sure that you can sail and/or paddle successfully against the wind and in rough conditions. Learn about the currents there. Currents and/or winds could so easily carry you out to sea faster than you could paddle or sail against them, even when you’re just making your way to La Paz from Cabo! Even just test sailing off Cabo!

    Make sure that your boat will float when fully loaded and completely swamped, that you can bail her out, get back in, and sail or paddle on, making it to shore, even in the roughest conditions. Practice capsizing. See how long it takes to recover in different conditions. Even only a quarter mile off shore, once capsized you could disappear from view in the waves and rescue could become impossible, so you need to be able to recover by yourself. Would you be able to swim to shore if you couldn’t recover? Are sharks a concern there? Get a good PFD and wear it, and think seriously about getting an EPIRB or other type of satellite beacon that will make rescue far more likely if you need it. I think the water is fairly warm down there, but not so warm that you could last in it indefinitely. Think about clothing . . .

    An outrigger might make your craft more resistant to capsize, but much slower and harder to paddle. It may not sail well into wind and waves. If it did capsize it would probably be far harder to recover. In severe conditions it would probably be more likely to break apart. And conditions can become EXTREMELY SEVERE in the Sea of Cortez! You’ll need to pay close attention to weather. When is hurricane season there? A hundred mile crossing could take MANY days.

    I’d feel a lot better if you were going to start at La Paz, sail around the bay there for a few days to get some experience and learn about and test your boat and yourself, and then sail and paddle north along the coast and islands for a few hundred miles until you could make the crossing to Isla San Lorenzo and then San Esteban Island and then Tiburon Island and then Bahia Kino on the mainland, never more than 10 miles from land.

    I’m afraid there is so much that you don’t know and don’t understand about what you want to do.

    With best wishes, but with great concern,
    Scot
     
  10. Skyak
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    Skyak Senior Member

    What you say is true but I am not sure that a greenland style paddle will work well in a canoe due to the wider beam and higher position of the paddler. the increased pace with the longer motion between strokes could be less efficient. The paddling will tend to be low angle which favors a larger area. I would even recommend bringing a single blade paddle for when conditions are pushing you to one side and paddle sailing.
     
  11. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    Okay Scot I have read and absorbed your thoughts and I have a few further questions about a few things you said.

    Firstly about safety; I understand that what I am doing has an inherent risk to it, but I am okay with that. I will take the boat for 1 or 2 test runs around Cabo, and if I feel that I cannot manage her well enough, I will not take her on the journey, at least without modification. I am an extremely strong swimmer; in fact, my original plan was to swim from Cabo to Mazatlan, but I would have no way to transport all my gear and bicycle. I will bring some sort of communication like an EPIRB or radio, so if all goes wrong I can be a huge pain in the *** for the Mexican Navy.

    My boat is double chined, you are right (Flat bottom and 2 panels vertically on each side.) I feel reassured that you think the shape will not be too unweildy in the water; as mentioned, it doesn't have to be a perfect optomized shape, as long as it gets the job done. As for the ama... You may have seen earlier in the thread, I have an ama partially constructed, which I could finish and implement into my final craft if neccessary, but I will test run the canoe without it first. I think it is probable that I will want to use it, though you are right that it will slow me down significantly.

    The Pygmy construction videos are fantastic- thanks for pointing me to them! I will be making my first half of the fiberglass splices today. I have encountered an annoying limitation, among many, that is that I have no flat ground. All the ground around me is significantly tilted in one way or other. I have a woodworking table about 10 feet in length, which is the flattest thing I have access to, but it means I can only splice a few pieces at a time. How long does epoxy take to cure, to a point where I can remove the weights and work on the other side? Also, what easily accessible paper can I use that will not stick to Epoxy? I have heard Saran wrap and Wax paper mentioned...

    As for taping the seams vs fiberglassing the entire hull.. Whatever I do is not determined by the fact that I already have the 6 inch tape. I am thinking I will buy 14 meters of fiberglass (~100$) and do the inside and out in fiberglass... Or maybe just the outside, I don't know if I have enough epoxy for all that!

    A few last questions...

    How to begin making a leeboard or daggerboard? What setup does your boat use?

    Are there some study plans or something available in PDF that I could buy from you? Or some subset of the plans? Just as a frame of reference - had I found your boat 4 days ago, I suspect I would have purchased the plans, and made that instead. Well, too late.

    Thanks for all the input everybody!

    -william

    P.S. here is the wood shavings I have... Is this sufficient? If I sifted it into a smaller powder would it be okay ?
     

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  12. Petros
    Joined: Oct 2007
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    Petros Senior Member

    those chips are much too course, you need fine dust, like wheat flour. either sift out the fine material and use it, or see if you can grind it up finer and than sift it.

    I do not really see a problem with your proposed trip, it can be done. However I think the concern is that you do not get in over your head, which can happen on long open water crossings. Usually not, but it can happen. Take these precausions: make your boat hull and rigging very strong, what ever the forces you think it will see, will be much higher in heavy chop and high winds; take lots of one and two day practice trips along the coast not too far out in as many different conditions as you can get before the big trip. You will find there are lots of things you will want to change before you go out to sea. Plan the crossing carefully, go to the local marinas and talk to experience local fisherman or sailors about currents, weather, conditions, etc (most will be willing to help you), make sure you have a good weather window before you leave (weather info and forecasts are readily available, USE THEM). take extra supplies in case you are delayed or have a gear malfunction that slows you down. But mostly, be prepared to delay your trip if you are not comfortable with your preparation or conditions are not good. Better to delay the trip, even a whole year, than to not survive the ordeal.

    there is no reason to think you could not do this trip, just prepare thoughtfully and plan ahead. there are people that have done it in sea kayaks, no reason you could not with a sturdy home made sailboat.
     
  13. scotdomergue
    Joined: Jan 2009
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    scotdomergue Scot

    William,
    All sounds good.

    If you’ll send me your direct e-mail address I’ll send you a PDF. If it’s too big to easily download where you are, let me know and maybe I can break it up and just send the most relevant pieces.

    I agree with Petros; you may have quite a wonderful sail and adventure, especially if conditions are very favorable: relatively calm conditions with following winds. But also realize that a good sea kayak is probably significantly more seaworthy than your boat will be, and that the kayakers who have crossed the Sea of Cortez are probably very experienced.

    By the time you get to La Paz, you should have a good idea of how your boat performs, at least in the conditions you’ve experienced. You may also have a much better idea of the length of time you’ll need to get across. Weather will be very important! Make sure you have an adequate window.

    The time for curing is very temperature dependent, and with the West System epoxy also dependent on which hardener. Sunlight also speeds the process. It takes a good while to reach full strength, but if it’s relatively warm for the particular hardener, you may be able to CAREFULLY flip your butt joints within a couple of hours to do the other side. The key is to keep it all fully and carefully supported as you flip or move it until it reaches good handling strength which is often a number of hours, maybe overnight.

    I used clear plastic, the type used for making winter storm windows where I live. The opaque construction plastic would also work, even plastic bags, though best if it’s thick enough to stay flat easily.

    The finer your filler material the better. I mostly used the West System colloidial filler, but used sawdust when I ran out – and it was coarse enough to make for very rough cove joints that took a lot of hard sanding.

    The Marsh Duck has a dagger-board, but that requires building a trunk and cutting a hole in the bottom of the boat. Much better to use one or 2 lee boards for you boat, I think. The key will be making a good way to attach it/them to the boat. Look on-line.

    That's all I have time for right now. I'll check in again in an hour or two.

    Scot
     
  14. scotdomergue
    Joined: Jan 2009
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    scotdomergue Scot


  15. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    Okay, I am joining the panels, and I have encountered a small problem, well perhaps a large problem.

    I cut my top middle panel too short (although I followed the directions precisely, and the check dimensions are correct) but only by a tiny bit. There is a gap of about .5cm on each side, where I need to connect it to the top end panels. Here is my question... Should I push them together, and take a ~1cm reduction on the total length of the board, or should I fill that with thickened epoxy, and put the fiberglass on as normal? Picture is the gap in question
     

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