DIY Simple Catamaran Sailboat Design

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

  1. scotdomergue
    Joined: Jan 2009
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    Location: Twisp, WA USA

    scotdomergue Scot

    Hi William,

    Your rudder will take care of directional stability and allow you to adjust for wind/wave pushing you off course (combined with lee-board(s)). You'll need to have a way to keep the rudder in one place and to occasionally adjust it while paddling. Many sailing canoes (including my Marsh Duck) use a yoke on top of the rudder with long rods coming up either side for steering. I use small bungees to hold them tight enough that the rudder tends to stay where I set it.

    I hope it's not too late for this . . . I would epoxy your bulkheads in before doing any fiberglass and epoxy. For your needs, a single layer of fiberglass cloth over the entire outside of the hull should be all that's needed (no need for separate strip down the chines nor for bottom reinforcement, though you could add another layer of cloth on the bottom if you want it really tough, which I would add while the initial layer is green enough to chemically bond if you don't need to sand first anyway - or you could just add a narrow strip down the keel which is what I have on the Marsh Duck, though for your plans I don't really think it's necessary).

    I use a very small anchor with the Marsh Duck (1 kg/2.2 lbs). Rode is 4 to 6 feet of chain and 150 feet of 1/4 inch line (smaller would be strong enough). The rode goes in a small bucket (maybe 7 inch diameter and 7 inches high) and both it and the anchor sit in the bottom-back of the forward storage compartment, easily accessed for use. I toss the anchor & chain over, let out as much line as needed, tie it to my bow rope, let more line out, and cleat it so that she rides to anchor from the bow, but I can easily pull the anchor in with the cleated end of the rode, returning rode to bucket as I go.

    Don't forget lee-board(s)

    From what I understand of your plan, I imagine plywood tops for storage compartments. After those are completed a coated nylon (or other light weight tarp material) cockpit cover/tent would provide weather protection while sleeping. A cover could be supported by wood slats that fit into notches in the gunnels to provided an arched support for the cover. I doubt you'll experience much rain, so I wouldn't bother with a more complicated tent/frame to allow sitting up and moving around inside.

    If you have a raised floor with storage below for water and other heavy stuff, you may only need a pad on that for a seat.

    Scot
     
  2. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    Scot, I think I understand what you are saying about the rudder. Well, maybe not exactly, but I understand the theory... I will see how I am able to implement it.

    Okay, now I am come to the fiberglass. Stupidly and without thinking I dove in and laid cloth along the two upper chines. I do not have enough 6oz cloth left to cloth the rest of the chines, inside and out. I would need 31 more meters, and I only have 27. So, what are my options with this?

    1. I could buy 4 more meters of 6oz tape. In fact, if I was to do this, I might as well go ahead and buy more than 4 meters, so that I can accout for my other fiberglass needs (bulkheads, etc.) Depending on how much more I need, this may be affordable, or may be too much for me to buy.

    2. I could only lay cloth on some of the remaining chines. With help, I would decide where the cloth will be the most useful, and lay it only on those. For example, I could finish the upper chines by laying cloth along the inside of them, and lay cloth along the inside of the bottom chines, leaving the outside of the bottom chines naked. However, the large mat of glass that I lay over the entire bottom will cover them, as you mentioned Scot, so maybe that is okay.

    Okay, this decision will determine my next course of action on the hull. Tomorrow I will buy fiberglass mat, hopefully 1.5m wide. I have calculated that 1 length of 1.5m fiberglass, as long as the hull, will cover the hull sufficiently in all places... I think. The longest stretch, across the middle of the hull, will need 55 inches of material. 1.5m is 56 inches unless I am mistaken, and if there is a tiny bit of unglassed plywood at the tips, that is okay, that is where my gunnels are going anyways.

    Tomorrow I will also spend as much time as possible looking for a mast. Is there any input you have to share on the mast? I am looking for about 120 square feet of sail area, although that is a very vague and uninformed estimate. That being said, I can of course do with a little more or a little less. What would you guys reccomend I search for in a mast? I think an attachable boom is of course important, but what size am I looking for? Well, any help is appreciated.

    I am thinking a raised floor for my sleeping and living platform, about 6 inches off the bottom of the boat. I am thinking of installing some sort of inner framework under that, to organize my storage as well as provide structural support for my boat. At the very least that will be 2 vertical plywood rectangles, running lengthwise between the inside frame, for me to mount my main platform on.

    I am thinking that I will cover the fore and aft compartments with plywood. That will come near the end though I think, as the mast will complicate the foredeck and the rudder will complicate the aft deck. (I feel certain there is a name for the aft deck). Anyways, the attachment the ama will complicate both of those, unless I decide to put the cross beams on the inside of the frames.

    Speaking of the amas... I have recently been introduced to the idea of 2 amas (thanks Tom!) So, there are pros and cons to this of course. Incredible stability, unsinkability, balanced in terms of which side I can put to the wind, increased sailing ability... But of course it will take more raw material, more time to build, and difficult the matter of attaching them (maybe, or maybe this will not be as hard as I think). All thoughts and input appreciated!

    As always, thanks for everythig, Scot thank you for an interesting in depth reply!
     
  3. scotdomergue
    Joined: Jan 2009
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    scotdomergue Scot

    William,

    At the bottom of pg 28 of the PFD I sent you there's a picture of my rudder with steering rods. At the very forward end of the cabin you can see a small black cleat. When out on the water, a small bungee is tied around each rod and its cleat, keeping the rods in place and tight enough that it takes some force on the rods to move them forward and back, keeping the rudder where I set it. I also have tennis balls slid over the ends of the rods to hold them off the side decks.

    Re fiberglass: first, I'm a little confused, I think because of terminology, so to clarify:
    - You speak of 6 oz cloth, 6 oz tape, and matt. I THINK that you are using both cloth and tape to refer to a 6 oz woven fiberglass that is not very wide, perhaps around 4 inches? maybe 6 inches? If so, I would call that tape. How wide is it? When I use the term cloth, I'm referring to a woven fiberglass that is wider, often 38 inches or 60 inches. Matt is a thicker fiberglass that is not woven, usually taking a lot more epoxy, and I think not as strong. I would be reluctant to use that for anything on your project due to weight (particularly of epoxy).
    - I understand your boat to have 2 chines; bottom is flat (no keel), and the top edge I would call the rail or gunnel. So, I think you are saying that you have laid fiberglass tape on the upper chines on both sides of the boat (port and starboard or left and right). Yes? Both inside and out? or only outside?

    Probably the most important place to have some fiberglass is on the outsides of the chines, especially the lower chine (and the outside of bow and stern). Next priority would be the inside of the chines. Third priority would be the outside of the bottom, and next after that outside of the bilge panels (between the chines), and after that the top panels. As I explained in a previous message, I would just use fiberglass cloth (not bothering with tape at all) on the outside of the hull, hopefully a single piece wide enough to cover the entire hull, including the chines. I think it's too late for that, and it's not clear whether you even have access to cloth that would be wide enough.

    Assuming that you have taped the outside of the upper chines, IF you can get fiberglass CLOTH that is wide enough to cover the flat bottom and the lower chines, up to a couple of inches above the chine, that would be ideal. Then you could also slightly cove and then tape the inside of the chines, and that should be enough in my mind for what you want to do. Of course better and stronger to use fiberglass cloth inside and out over the entire surfaces, but really not necessary.

    If you can't get cloth, but only matt, then I would advise taping both the inside and outside of the chines, which I think you've started, but don't have quite enough cloth to finish (I'd also tape the outside of bow and stern, of course).

    I'm sorry that I haven't been on-line earlier, and fear that you've already gone beyond the things in this message, but I'll send it immediately, just in case, and then respond more . . .
     
  4. scotdomergue
    Joined: Jan 2009
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    Location: Twisp, WA USA

    scotdomergue Scot

    Hello again,

    On more careful reading I see that you had already answered one of my questions. At the point of writing your message you had fiberglass taped only the outside of the upper chine.

    A little more on the fiberglass issue: what is the weight of the matt? 8 oz? 10 oz? and how thick is it compared to the 6 oz cloth tape? The thickness will indicate the amount of epoxy you'll need to use with it, and therefore give some indication of weight.

    If you are going to use matt, particularly with good epoxy like West System, maybe it will be OK to not tape the outside of the lower chine . . .

    I don't know that you need any fiberglass on your bulkheads. I'd cove the bulkhead to hull joints with thickened epoxy.

    Regarding mast and boom: I'd look for used windsurfer masts if you can find them. They're very light weight and strong. I can easily imagine that people wind surf at Cabo. If so, it's very possible that you'll be able to find some old carbon fiber windsurfer masts at reasonable cost. Again, there are pictures and explanation in the PDF file I sent you, pgs 30 to 33. Of course, you'd have to put it all together, creating the mast-boom connection (gooseneck) and other things, which could be challenging.

    Another possibility would be finding a used sail rig including mast(s), boom(s), sail(s), etc. and adapting it to your boat. It might be hard to find one that's light weight and suitable. Something from an old racing dinghy or perhaps other sailing dinghy could work.

    It sounds as though you've decided to use at least 1 ama; 2 is far better in my opinion. Realize that, while amas make for MUCH greater stability as long as everything holds together, they do NOT make a boat unsinkable. They create their own challenges. Still, for an inexperienced sailor, they're probably a good idea.

    Assuming you're using amas and therefore sailing a tri, 120 square feet of sail should be fine as long as you can reduce sail when winds get stronger. For a mono-hull approach you'd want less sail. As a tri, your boat could probably handle over 120 square feet in gentle winds.

    And then you need to decide how that sail area will be arranged. And that is a big subject. And complicated by your inexperience with sailing. To me, a two masted rig with one jib would be ideal. That way you have 3 sails and some self-steering potential. You could probably created that from 3 or 4 windsurfer masts, a lot of work, etc. And then there's the question of where/how you'll get or make your sail(s)? That could have a big impact on the rig you choose!

    Easiest if you can simply find an entire rig.

    Enough for now.

    I'll be off-line for an hour or so, but after that will be fairly available, and will review you message and maybe respond further.

    Scot
     
  5. scotdomergue
    Joined: Jan 2009
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    scotdomergue Scot

    William, I just saw on the Noah's Marine website that epoxy is not recommended for use with fiberglass mat due to incompatibility with the binders used to hold the mat together!!!
     
  6. kerosene
    Joined: Jul 2006
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    kerosene Senior Member

    I think he means fabric when he says mat.
    Generally you do not want to use mat ever. Not exactly true for ALL cases but pretty much.

    with epoxy never - mat is for cheapo stuff where epoxy would be overkill anyway. Use woven fabric.
     
  7. ricardoribeiro
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    ricardoribeiro Junior member

  8. WilliamPrince
    Joined: Oct 2013
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    WilliamPrince Junior Member

    Sorry for abandoning this thread, but I thought I should at least post a closer for those who are interested. Here is me and my boat, not a trimaran or outrigger canoe, just a canoe. I failed in this project, really. I could have made something incredible had I been able to focus and think critically and apply myself. ****, feels like high school all over again, dropped out in my last grade. Well, I do have a pretty cool canoe. Check it out. I leave in 2 hours! So long, thanks for the help everybody!
     

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  9. P Flados
    Joined: Oct 2010
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    P Flados Senior Member


    Do not be discouraged.

    You completed at least a canoe that you can use. This is much better than many projects that never get to the "useable" stage.

    Use it and have fun.

    After you have enough fun with it "as is", you also have a great start for an "upgrade" to an outrigger. A 10' section of 6" thinwall PVC and two cross beams can be very easy and pretty cheap. Glass on foam, glass on plywood, glass on wood strips and a purchased inflatable are some other common choices.
     
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  10. Skyak
    Joined: Jul 2012
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    Skyak Senior Member

    "failed project"? On this I strongly disagree. You came here with no experience and some pretty bad ideas of how to coastal cruise and you are leaving today with a very capable craft you built yourself on a greater adventure than most of us will attempt. For all the time I spend on these boards I feel we are launching too few adventurers -and discouraging too many. Lots of people come to this board with the desire to sail great distances in a cheap boat they build themselves and few achieve the success you have. Lots of good advice along the way inspired by your action. The board will serve as good reference.

    Keep track of your travels it will make great reading. "This is what I was doing while most of my generation was staring at their phone telling the world what they had for breakfast of commenting about celebrities they have never met".

    Godspeed William!
     
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  11. scotdomergue
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    scotdomergue Scot

    Yes, a very successful project! Congratulations! Have fun with her! I hope you will return here with at least a short post about your experiences once you've been using her for a while.
     
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  12. kerosene
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    kerosene Senior Member

    I echo the others. You have achieved a lot. You made a boat and finished it - you learned about project scope and sizing it for the future. You had a bit high bar for the time allotted for a total newbie but you walked a way with a craft you can have adventures with.

    Sooo many walk away from projects with nothing usable. You can have a blast with yours and be proud of it. Take the actual adventures bit by bit - you will see that day trips can be tremendous fun and very fulfilling - the grand crossings and big stories are cool but bragging rights and all that is over rated.

    Enjoy. and yes please - post back here.
     
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  13. scotdomergue
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    scotdomergue Scot

    I wonder how it went! Has anyone heard from William? Would love to have an update!
     
  14. Skyak
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    Skyak Senior Member

    Nothing. Not that anything was expected, but you can't help but wonder about such an epic journey on such humble budget -most refugees pay more to do less.

    I wonder because I feel I talked him into the 2 sheet canoe design he built. Now I know how parents feel when kids don't call (like me).

    I recommended your marsh duck this past month. Did you finish that new smaller design?
     

  15. Fanie
    Joined: Oct 2007
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    Fanie Fanie

    Don't worry, he'll be back (one day). Boat building is addictive, a young bloke like that has many things to distract him for some time, like girls, ambition... LOL.

    I'm glad he finished it.
     
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