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Cast-a-Way Fishing Kayak Build


Bcone1381

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It seems pretty quiet on this forum so I thought I might start sharing with you all a Fishing Kayak I am building. If you are a lurker, thinking about doing this, go for it. The experience has really been fun and rewarding.

I started out building the strong back exactly like Jeff Horton outlined in his book.

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I wish I knew how to rotate a photo. This one is better.

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Frames or Bulkheads were cut with a jig saw, corners rounded with a router, and then sanded.

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I set some key bulkheads onto the strong back, then added stingers and the remaining bulkheads? I have four sons, this is my 17 year old (#3) who helped me assemble the stringers and bulkheads.

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This kayak has around 100 lashing. Each one took me a minimum of 7 minutes, probably averaged 8-9 minutes.

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I guess that means about 14 hours were spent lashing. I like starting the with keel, the working from the center of the boat out towards the bow and stern, trying to keep everything lined up just right, and thinking about the forces being exerted on the structure. Keeping everything as equal as possible makes a straighter boat.

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Here the frame was completed. My obligation is now officially fulfilled! I understand that A FROG-Frame On Grass photo is mandatory. You might see Harley to the left guarding the Kayak Frame. He has been a faithful companion of this build...I think he wants a ride when it's done.

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My wife demonstrates here the lightweight structure of these boats...it was 25 pounds at this point. I also might stress that the Kayak Frame is light in weight, but by no means weak. Jeff Horton has a design that will be legitimate in anyones eyes. I suspect she will really take every reasonable beating a teen age boy could give her.

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I added foot rests, and waited for the original 8oz polyester fabric to arrive, then started sewing.

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The sewing went better and faster than expect. This seam is sewn with the waxed artificial sinew that Jeff sells, and has a piece of parachute cord rolled up on each side. I used one piece of cord with a needle on each end. I really liked this stitch, but in wonder how a baseball stitch would look, at the same time I am afraid to try since this went so fast, easy and came out so straight. By the way, this is my first Kayak I have ever built or owned.

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It's time to go running, c'mon old man-lets Go!

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The combing of the Cast-A-Way is a different build that the typical kayak combing. The instructions called for staples to hold the fabric to the frame. Here I am trying to help the fabric make a compound curve with some heat from an iron. I pulled it and heated it, and tried to shape it.

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I held it in place with tacks, and trimmed it with my "Hillbilly Hot Knife". (An old Kitchen knife heated with propane torch.). This hot knife idea worked out real well...way better than my soldering iron.

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Once everything was in place I glued the fabric to the frame. The glue used Spirit Line, commonly called Cory's Goop from the Skin Boat School. It actually is not designed as glue, but rather coating for SOF fabric. I tested and experimented with several different products, and nothing failed the test. It is a testimony to how good stuff sticks to polyester. Shear loads is what is at stake with my fabric attachment, as opposed to peel loads. Peel loads (forces) are very different from a shearing force. I know some will criticize me here for this decision. This was an improvement over Staples. The biggest draw back I think will be getting the fabric off when it gets reskinned someday.

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I still like the way a standard combing is installed. My next kayak may be another fishing kayak, and I am considering building a very large coming using the typical techniques and fabric attachment methods for SOF kayak.

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Here is the kayak after sewing and shrinking. My iron was only putting out about 200 degrees. I was expecting over 350 degrees F. I bought a new one, and then learned that my federal bureaucrats now limit the temperature on household irons to 180. So, I shrunk my fabric with a 180 degree iron.

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I was happy with it at this point.

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I did not mention that I coated the frame prior to covering with Tung Oil purchased from the Skin Boat School.

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I wanted a translucent mahogany kayak. This is the result of what Cory from the Skin Boat school set me up with. post-3161-0-83499700-1377307607_thumb.jpg

The Spirit Line product is clear, and I added pigment to the resin to give it some color. The other option would be to dye the fabric before coating it, which also looks great.

Today I coated the top of the kayak. I am running low on the Spirit line due to my own fault. I found I mixed too much up a couple times, and it started to set up on my causing waist. I have a 50-50 chance of running out.

So far I have about 90 hours into building it...I have gone slow and taken my time...I am not experienced at all. As far as cost, the Kayak plans, and strongback materials was $118. I bought the best lumber available as far as I know for the frame and spent $197. That included $30 for custom mill work to cut my 18' long stringers to size. My $95 piece of marine grade was BS 1099 compliant and I have enough left over for another boat. $49 for sinew, thread, needles, shipping cost. A rod holder for $13. Footrest, Spirit line Goop, dye, Tung Oil, Bungee Cord, and shipping was $130, the original 8oz fabric was $92. So it looks like in have $600 so far into it, and still need a seat, backrest, and materials for a paddle.

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Very good write-up of you build. One of the better ones I have seen. 

 

Also I am impressed with you straight seams. I have wondered if this might be an easier seam for most and you seem to confirm that possibility.

 

As for the clothes iron, it's all I use and they seem to work just fine. If I find a stubborn spot I grab my cheap Harbor Frieght heat gun. It is not where near as hot as a good heat gun and I suspect a hair dryer would also work. These have a lower risk of melting the fabric but it is possible. I had it happen in the class and had to patch a boat.

 

One last point, polyester cannot be dyed at home from what I read. It takes a special process and I forget the details but it is not a DIY process. Tint in a translucent finish is the probably the best way to get a colored, translucent finish similar to nylon. I am seriously considering building a Short Short, coating in Dura-tuff poly tinted a bright green. 

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The way I got my seams straight was to roll the port and starboard edges of fabric around the interior cord just enough so that each side made an equal gap along the center stringer. The gap is then closed up by tightening of the sinew. You can really get some leverage yanking on the sinew at this point with a tighter weave fabric.

Once these seams get going straight, they naturally want to stay right on track. If the seam got off track turning it back on course was tougher than undoing and resewing. I focused on a straight seam on every stitch...the two sides were carefully rolled, then pinched with the left hand, then sewn in place, then tightened.

This photo shows the seam when I was sewing a bit loose. I tightened things up a tad after this point due to feedback on this sight from Jeff. The original 8oz fabric can't be tightened too much or its loose weave gives way to holes. Next boat I build I will use a tighter weave fabric and rely much more in skin taughtness with this stitch rather than heat. Future photos will show why. I will show you the good, the bad and the ugly....so far mostly good, nothing bad, but a little ugly mixed in.

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I don't want to come across like my boat is a master piece. It's my first boat, and I've made a few errors. If I show them to you all, maybe you can avoid some of them and come out with a masterpiece first time around.

Our boats have compound curves, and fabric naturally likes straight curves. So, we stretch the fabric, or use darts to make the fabric go around a compound surface. These photos show the area where I had trouble. (I still do not know how to rotate a photo)

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These sharp corners are tough, but the key error was glueing the fabric before visualizing where the shrinkage would best be utilized to remove the extra fabric due to its compound shape. I left too small of a space for heat shrinkage to remove the inch plus of extra fabric. By the time I saw this it was already glued.

Next time I will seriously consider a coaming...a large one...and attach the fabric via the standardized SOF method. I also will consider gussets in corners to transition the area help eliminated he gathering of the material.

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The other problem area I see now is that the fabric has started to relax. I think Jeff says not to rely too much on heat shrinkage of polyester because of this relaxation.

These two photos show some waviness that were not there until the coating process was started. Again, I only heated the fabric up to 180. My advice is to buy an iron that will allow fabric to be shrunk at 250 to 290 degrees. In was in a hurry, and it looked good from the 180 heat shrinking, so I compromised. This is the I iron will get for my next Kayak if I don't find one at a garage sale first.

http://www.aircraftspruce.com/catalog/cspages/sealfabriciron.php

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These errors could have been avoided, and I others hope learn from my errors. Yet, they are pretty minor cosmetics, and the casual observer will not even notice them. Kayaks that build memories will develop some character and this one has some already.

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That is the kind of iron I used back in the days of building RC airplanes to shrink the Monokote.  You may find it cheaper at a hobby store.  The problem with it is it is small and would take a lot longer than an iron.  Be nice to work in tighter areas.  I don't know if you can ever get  it all out.  I have some in my boat.  I think it shows up more in a darker color than lighter colors.  Keep in mind, I could be wrong, I've only built one.

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Experience is a great teacher! There is really no substitute. 

 

As for a hotter iron, I am not sure that would stop the fabric from relaxing. I sometimes use a heat gun on stubborn areas and even though it is a cheap one, I know it is hotter than the iron but it still relaxes some. I am really leaning more and more toward sewing it on tighter and depending less on the heating. The new stitch makes that much more doable.

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Jeff, i wondered if the fabric relaxed in response to receiving a coating. Do all polyesters relax like this, or just the original 8oz? How does the recycled polyester do with relaxation? Well...it does not matter because from now on I too will sew it on tight. It's not that hard. But it will always be a mystery because heat shrinking sure works awesome with aircraft grade fabric.

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The recycled polyester on my FreeB has loosened/stretched slightly with use.  There are slight "ripples" in the skin between the gunwales and chines.  You can only see them in the right light.  There were also a few around the coaming.  I experimented with reshrinking these.  I placed a thin damp cloth over the painted (rustoleum) skin and used an iron set at about 220-230 degrees.  It worked well and they have not reappeared.

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Jeff, i wondered if the fabric relaxed in response to receiving a coating. Do all polyesters relax like this, or just the original 8oz? How does the recycled polyester do with relaxation? Well...it does not matter because from now on I too will sew it on tight. It's not that hard. But it will always be a mystery because...........

 

heat shrinking sure works awesome with aircraft grade fabric.

 

Coating has something to do with it. I don't know why but uncoated fabric seems to stay taught till the paint is applied.  

 

I have noticed with the recycled poly that you can stretch it back out after shrinking and it doesn't return to the shrunk state.

 

Aircraft grade fabric is made specifically for that application. Where the fabrics we use were made for something totally different. No one makes a fabric for skin boats that is designed specific for our application so we are just working with what we can find so it is a compromise. There just isn't enough of a market to get a fabric made for our needs. 

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I have been working on the coaming this weekend. The plans called for 3/8 inch wood attached with SS screws. I changed that to saved a little weight, but cost a lot of time and the jury is out if it was worth the extra effort. Throughout this build I figured if I watched my ounces, the pounds would take care of themselves. The scale will tell.

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I attached strips of 1/8" ply with lashings, put a dado cut into the lumber I used for my stringers for the top rails, then glued in place with tite bond III.

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The floor boards are removable. I figure that I can clean the sand out out the boat a bit easier with the floor boards out.

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I used the 1/8" ply and reinforced it with pine strips. Gaps in the strips allow the floor boards to fit over the kayak frames. They seem real light weight and sturdy. In think they worked out well.

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I still need to install my deck rigging, a seat, and a back strap. We are getting mighty close!

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