DIY Simple Catamaran Sailboat Design

Sweet ama. You can add more photos by just uploading one at a time .... yes, it is a pain.

You should be able to cover one end of your JEM like the others have done.

PS, if you need help, you might get some answers from Scott - he already answered a post I put on his blog ....

 

Stability comes at a cost in weight and drag. If you think you can have stability without adding weight and drag it is just a mater of time until the world points out that you sacrificed strength. "Stability is for the old?" This is an odd thing for a 19yr old to say to a 50yr old talking him through an ambitious trip. My case is simple, I think you may be better off with one low drag hull you can push 4 knots by paddle and 6 knots by wind than with two hulls you can paddle less than 3 but will sail to 8 in the right conditions. I should clarify, there is no intrinsic speed difference, there is a difference in the height of the mast and the attention it will take to sail.

Rowing is a stronger way to push a hull through the water -the thrust is balanced, it uses a larger, better distributed bunch of muscles, and takes less skill. The negatives are that it takes more gear and space, you are sitting backward and it is difficult in waves. Double paddle is about as effective as rowing without the sliding seat and it offers a forward view and control in waves -you can surf. But be warned, paddling 40+ miles a day you are going to hurt.

About boxing in 'cubbies', my direction for my own craft is going to be to hard cover only the first 2 or 3 feet from each end, then build in a canvas cover to the cockpit which will have a removable tent enclosure. My reason is versatility to load and carry big things or open up more working space. Note; this is MY preference, you may want something different. If you do plan a large cubbie I would look to do it with some thinner lighter plywood. In any case, plan on installing at least one sheet of foam to the sides of the cockpit for buoyancy in the event you get rolled.

I don't understand your build technique. Earlier on you posted a video about stitch and glue saying that is how you planed to build -did you change your mind?

 

Well my comment about stability was more of a joke, I hope you all know that I appreciated immensely all the help you have all given me... But what I mean is that I don't neccessarily need to be completely stable and comfortable for this trip. In fact, I expect to be somewhat cramped and wet and sore and miserable, I am okay with that. I hope that I can have a good nights sleep aboard, but even that I could work around by sleeping ashore.

As for the paddling, I am okay with a lot of paddling, I think I will get conditioned quickly and if I can make do with a smaller sail set up, that sounds good to me.

I constructed the ama like this for a few reasons... For one, I don't have fiberglass tape yet, or thickener for my epoxy, so I can't really make a good fillet joint. Also, this way I can do simpler steps which will lead me to the final shape of the ama, instead of having to figure out the exact shapes of my plywood before hand. I think this will be good practice in general, and I still have evenings to plan my main hull.

A few construction questions...

1. So these wood shavings are good for use as filler, as long as I sift them to a flour? Would it be worth it for some uses to invest in real thickener?

2. Is 3M 5200 glue adequate to glue all these frame pieces in place? Can I even glue the plywood to the frame with it as well?

3. El_Guero, you asked about the plywood... It is not of great quality, but the surface is entirely free of defects, and it does handle like 1 sheet. However it dos have occasional small "voids" that I read to avoid...

4. Since I do not have a drill, is it okay to pound nails through en lieu of drilling holes for the stitches? If not I have to look into borrowing a drill.

I will hopefully be wrapping this in fiberglass yes. I go tomorrow to the city to get some more supplies and hopefully borrow some power tools.

 

For filler, I would stay with wood filler.

Not sure about 3m, is it WBG - marine type glue? Someone on the board has used Gorilla Glue with good results.

Make due with what you can, you are wrapping this in glass right?

borrow the drill, think ply with nails knocked through? At best they won't look good, at worst, you will break out through the edge of the ply in places.

Keep up the great work.

 

About your questions

1. 'shavings' sound too big. To be right for the job it should be like dust or flour. Most of what you are adding this filler for is to make it handle the right way -a smooth putty that makes a nice smooth fillet with no chunks bubbles or voids. When you sand the plywood, save the dust. I don't think there is a better 'real' filler. Silicon or glass fibers make the joint harder than the wood, tough to sand. Micro bubbles make it weaker but easier to sand. Some add talc powder which is used to fill plastics so it makes sense. I have not used talc so I don't know what it is like.

2. 3M 5200 is not glue, it is high quality sealant. If you want good cheap glue use PL premium construction glue
http://www.architecturaldepot.com/1390595.html?gclid=CMGtnvy0sLoCFe5cMgodGmAA7A

Gorilla glue is strong but it does not fill joints (it doesn't sound like you making good large area matching surfaces) and nothing sticks to it once hard.

Voids are bad. avoid the void.

get a drill

 

Okay I have almost finished the ama, besides putting plywood on. I will upload pics tomorrow, I only finished gluing everything today after dark so I couldn´t get any good pictures. Well okay Sky, as you pointed out, 5200 is not actually glue, but that is what I used in this case, so I guess we will have to see. I did in fact read somewhere that it is a powerful marine glue, so I have some limited amount of faith that it will work. Well it either works or it fails, and I reglue with real glue.

I came away from today with a distinct feeling that this project is going to be a huge amount of work. Especially with no power tools, a small relatively simple cut can take me 15 minutes of heavy sawing with my hand saw. Also there are so many nuances in the construction that I just never imagined of until I actually started working... All the notches which must be made to fit this wood to that, all the measurements, all the sanding... my god.

Tomorrow I will go to town to look at the prices for fiberglass 6" tape, and the 4´ rolls, look for a real marine glue, as well as try to find a drill to borrow. When I come back, I will finish up the frame of the ama, if the glue has come out okay. If not I will reglue it. Honestly, I am not sure if I should even waste 2 more sheets of plywood on this thing... The only reason I am inclined to do that is to practice putting the plywood on, but since I will be stitch and gluing the main hull, it is hard to justify.

As for the main hull, I think I will go with the Jem canoe design. I don´t really have any plans of the same detail and readability as this thing... I like the looks of the KIR 8A but honestly as a novice it is very hard for me to read and understand... The Jem seems like a nice canoe, if a little wide for my liking. Honestly, the more I think about it, the more I like the idea of rowing/paddling! I am very physically strong and fit, with great stamina, and I love a physical challenge like that... So although I would like a sail as well of course, I want to pay close attention to making a craft that I can control easily with the use of paddles/oars.

As a side note, sometimes I get very discouraged when I try and think of every element that I have to go through and conquer one by one. It can be a scary thought, and I frequently doubt myself, but this challenge is exactly what I want in my life right now, and I don´t plan to let the challenge beat me. So I would like to say thanks to everybody who posts and continues to post, and follow my progress. Whether I succeed or fail, this has been an incredible time for me.

Will update when I have the prices for/have bought fiberglass, and will post pictures of the ama in it's current state. Hoping the glue (sealant) has held together decently. Will determine next steps tomorrow.

 

Success follows failures ....

 

Okay I have learned the prices for fiberglass, it is actually affordable. Strangely enough the 6" roll costs more per length than the 4 foot roll... Well anyways, I can get them both in sufficient length, so that is a good sign. I have a question about the large rolls though: there are 2 kinds, one seems to be of small fibers seemingly randomly woven, just looks like a big mess of fibers, and the other one is larger fibers but woven in a checkerboard pattern... Which do I want?

Going back to the workshop to check on my gluing and hopefully lay the keel!! Will post pics in a bit.

 

Day 1 -Enthusiasm!
Day 2 -Discouragement! When you throw yourself into a project be prepared to bounce off. You are learning something very important to small boat cruising -patience! Stitch and glue are termed "instant boats". There is a book by that name by Dynamite Payson and Phill Bolger. Traditional boat builders sneered at them because they were so simple. A carefully built canoe should take 40 hours or less to build. Consider that jig saw or at least a bow saw. Without the right tools it takes 10 times the work.

I looked at that KIR-8A -wow that is a bunch of detail. Interesting construction, dense, lots of wood, very heavy. It also is not very rigid. I can see the value of the construction if I was making a seagoing craft from materials in the jungle. 23 footer would take a lot to build, and power.

The JEM is a great one chine 3 sheet canoe -it is not the only design. The 35inch beam does not add much drag and will help stand up to sail. If you were to make narrower flat bottom hull it might still have as much drag. If you weren't carrying a bike you could go narrower and lower like rob-roy or a kayak.

For fiberglass you want the woven stuff. The other you describe sounds like roving.

 

I just want to repeat that if you flip this thing, next stop is the Marquesas. Does not matter if you are only a mile offshore if the wind is blowing offshore. Stability has less to do with comfort than it does with staying alive.

 

Whats important is the ability to get the boat righted and bailed out quickly, the ability to set the sea anchor and hunker down safely, and the weather reports and good sense not to push your luck.

 

Okay, so I have quit working on the ama for the time being, reasons being that I don't even know if I will use it for sure, and it is not super well constructed in the first place. I don't know what makes me think the main hull will be be very well constructed either... But I will work on that for now.

I am starting by building the stitch and glue frame of the canoe, as dictated by the PDF instructions. I think modifying it afterwords won't be too difficult, although I can make a few adjustments on the fly. I have bought the lumber, and started drawing the cuts I need to make. I have decided to quicken the pace, to finish in 2 weeks, and to help stay on target, I have made myself a schedule.

Sunday, Oct 27 - Finish drawing shapes, start cutting
Monday, Oct 28 - Restoring ship/get supplies in the morning, cutting in evening
Tuesday, Oct 29 - Move out of apartment, Finish cutting, epoxy wood
Wednesday, Oct 30 - Connect pieces with epoxy + fiberglass (or butt blocks?)
Thursday, Oct 31 - Begin stitching pieces together
Friday, Nov 1 - Stitching
Saturday, Nov 2 - Stitching
Sunday, Nov 3 - Finish stitching
Monday, Nov 4 - Interior work/details (storage, handholds, seat, flooring, etc)
Tuesday, Nov 5 - Interior work/details
Wednesday, Nov 6 - Get a mast
Thursday, Nov 7 - Rigging, get a sail
Friday, Nov 8 - Get a paddle, test launch
Saturday, Nov 9 - Troubleshooting, painting
Sunday, Nov 10 - Finish painting, carve masthead
Monday, Nov 11 - Finalize gear, buy food, water, radio or something
Tuesday, Nov 12 - Set sail to eternal glory

Will do my best to keep to this schedule, of course some things might come up here and there, and some may take longer than expected, but I hope to be gone as soon as possible. I am looking to rent a jigsaw or a drill, whatever I can't borrow from the guys on the boat I am helping to restore, to expedite the process.

One question... Butt blocks or fiberglass splicings? What are the pros and cons of each, and which should I use?

Edit - I think I will start posting more specific questions in a thread of their own, but will still update this with general progress for those who are interested/have input. For the time being I have my general questions answered.

 

Butt blocks will be faster, I think .... especially with a power drill.

Rent a jigsaw and a drill .... cordless are always easier to work with, until juice runs down.

 

I still recommend stitch and glue for the chined canoe. I don't know how you will cut long narrow angled chine logs without proper power tools (table saw or at least a saber saw) and or skill -filled epoxy forms these in place. I also don't know how you will glue the chine logs in place without lots of clamps -stitch and glue uses wire for clamps. I fear major quality problems if you try build with chine logs and don't have the skill and tools.

It is good that you have a schedule, but I don't understand it. Stitching comes before glue and it shouldn't take more than an hour to do a chine. You can drill stitch and tack in one day. I suspect the mast and sail will take longer than you think. I would also plan a shakdown cruise -load it with water bags and sail it for a day, capsize it and recover as if you were in deep water.
Sleep in it for a night -is there anything you want to improve while you have a shop handy?

 

I didn't understand the question. Be careful the blocks don't get in the way of some later feature which you will then have to notch or move.