Skin-on Frame Kayak Building Jig

I'm getting back to the kayak after an interval of doing other things. The skin is draped and I am now facing the staple or sew question. I have Monel staples. I also have waxed dental floss.

Petros, your familiarity with the skinning process appears pretty well informed.
I can't, in any case, find anything useful on the web to guide me. Every site is extremely limited, often a teaser for an instruction manual you have to buy.
Not to say comments from anyone else aren't welcome. I can use all the help I can get. I am a carpenter, not a nylon technician.

I've painted the framje with two coats of interlux single part urethane, since I happen to have inherited 6 gallons from a friend.
Then I applied extreme waterproof medical tape to each of five stringers to (hopefully) prevent sand abrading the nylon.
The nylon I bought is 9 oz, shipped with a two-part urethane coating system.
I can just wrap the 60" x 18 ft nylon around the middle with a small overlap.
At this point I wonder if it would be easier to staple the skin to the gunwale (first the bottom and then the top) so that the process requires only sewing the ends. also, and importantly, the ridge down the middle of the deck will be eliminated. I would hope to set the staples below the surface enough to fill and simply urethane right over them--- and the overlap of nylon would be glued (what glue is best here?
Spreading the polyurethan two-part skin water-proofing comes next, and here I am again lost, as I haven't used such a system ever before, and I want to ensure I am well armed with the dos and don'ts before I start.
Then I'm essentially done. I've already installed a pair of light aluminum 10" adjustable foot braces (I got these froma buddy, so why not?).
The hoop is figured out. I will drill through every inch or so for sewing the nylon inside of it and lash it to several places including two stanchions attached to the sheer stringers at 3:00 and 9:00.
Then I'm done, except for strap eyes (Harken black plastic) for bungees, painter, and so forth.

 

Rereading, and now letting you know what I did to create the masik. I laminated (30" radius or so) a one inch high bunch of fir strips, then thinned the middle down to 3/4" tall. I didn't add anything to spread the strips (like a tree base looks--- your method) but instead ran two 6" long by 1" (tapering fore and aft to 1/2") shelves, screwed inside each sheer stringer. I positioned these to set the 1" tall masik on, and screwed the masik down into the shelves. I like this because it was the same material bulk but I think stronger and faster to build, with the shelf well glued to the stringers. I'll have to take some pictures if the rain ever stops (boating season here in Maine has been rain every day since Summer started).

 

Finally, I got the skin started. It took, finally, a synthesis of a lot of poor internet how-tos, and some common sense. So far, it's been easy. Dental floss was suggested by a lot of builders, so I got some. Way too weak! I switched to a heavier polyester thread I use normally for whipping rope. It is incredibly strong and allows really tightening the stitches.
The bottom is done. I stretched it on using staples and little cardboard squares at the sheer. One per every two inches. The deck will be stretched independantly.
Time-consuming but gratifying. After all. I am going from frame to finished boat in a short period of time, relatively speaking.
i don't know how others can sew a whole boat in a day. My hands are killing me and I'm half done.
I still have no idea how exactly to apply the two-part polyurethane. Anyone who knows, I'd love to hear how.

 

Lovely job: you are may be making too good a job of it and are suffering from the associated wear and tear! You can shrink the material to get rid of minor wrinkles and sags.

I believe in the value of experiment; in my case I would make up a wood frame and cover it so I could try out my proposed finishing method first before committing it to the boat.

 

Thanks, AK. The deck is going well. I will get back to it in a while.
once I had a feel for it, the calculation of how much gap would pull together was natural.
I slipped a temporary centerline wood backing in, attaching with brads (pulling them out just before covering). i drew two lines on it to indicate the place where the seam would be folded on each of the two sides that would come together. So far it's worked very well to aid in keeping the seam centered.
In a way, the process allows experimentation because stitched are easily taken out.

 

Did you try the "wrapping the loose cloth in a small bit of timber" and tightening, like upholsterers do ?

Dont use two part epoxy paint on the fabric. It will crack and split. You have to use some kind of flexible, rubberised or tarry coating. Some of the rubber compounds dry really smooth, but stretch like .... rubber.

The other option is to use a silicon waterproofing compound like truck tarpaulins use, but most of them are for cotton based cloth.

Have fun.

 

Thanks--- this is a rubbery formula, specifically for ski8n-on-frame boats. It's squeegeed on. I've never used it before either! The outfit I bought it from had videos online for all their products, but the link doesn't work!
As far as tightening goes, I should be okay. I'm on the home "stretch" now(get it?).
It's the polyurethane I'm scared of now. Who's used it?

 

Except for final shrinking and the poly coating, the skinning is done.

 

Alan
A see-through boat.

It is an elegant shape. If looks are any indication of performance it will be a winner.

Looking forward to the finished job and estimate of time with a honed procedure.

Rick W

 

update

The skin on frame rowing boat is working out very well. I've raced her twice and the boat is better than I am right now. I'm rowing at about 5.2 knots over a distance of up to 5 miles. By your kayak standards, she's very heavy, but seems to stand up to the stress of rowing quite well. It is almost a shame to cover up the translucent skin but in my case it was necessary to waterproof things. I'm told that varnish makes cotton canvas brittle and easy to rip. I'm very impressed by the speed of your build. I'm almost a year into mine and still have a few details to finish. Marshfield is on the coast, about 1/2 way between Boston and Plymouth. The local nick name for the area is the "Irish Riviera". Me, being mostly Norweigan, I'm a bit out of place, but it's a great place to live and be right near the water

 

Weight is crucial in a kayak or canoe if it has to be portaged. Not so in a rowing boat. Any human-powered boat may benefit from a bit of weight in a sea.

 

Sounds like a good shape you built. I'm about to waterproof, and finally I found some instructions. Grammatically horrible, but I muddled through and now I'm not too afraid to sling the goo.
I know the area of the Cape and Boston, I grew up near there.
I estimate the speed of the build to be a bit faster than the usual way of eye-balling ribs, but infinitely slower than using plywood frames (which can be built very quickly without much skill required).
I am not convinced the plywood frame method is resiliant enough, but I sure like the build speed.
Now that I'm done, I'd say, addressing Rick's comment, I am pretty sure it would take 10 relaxed days to completely build the boat once refined, and far less time if:
1) I stapled the nylon on and added a guard to the gunwale to cover the staples.
2) Made the cockpit ring out of a single steamed spiral-wound piece of ash or oak (the beginning of the piece would be tapered to a sharp point on a jig).
3) Pre-rounded the stringers prior to assembly
4) pre-painted the parts pior to assembly (linseed oil is very traditional, but two coats of marine enamal will last a long time).

 

I only now spotted this thread and haven't read it all yet. There are some pictures in my gallery of native skin on frame boats built by my niece and others at Corey Friedman's shop in Annacortes, Washington. The gunnels and deck beams and bow and stern pieces are lashed first and then it goes from there, adding the keel and the frames and the battens.

 

Good Idea

This seems like a good idea. I was wondering about putting in ribs inside of stringers ever since I saw that being done on the airolite boats by Mr. Platt (http://groups.yahoo.com/group/Airolite_Boats/)

I have not bent any ribs myself, but always thought it might be easier to put them over something, rather than inside.

Interesting thread though with nice information. The boat also seems to have come out nice.

BTW: I'm building a plywood frame SOF for my wife right now. I guess, I'm used to these kinds of frames from the many Klepper kayaks my family has owned over the years.

 

Nice............

Nice work Alan ! Have only just found this too.....I think I will get some tools out ......