Building a Perfect Kayak: Part Eleven

Woe is I; I made a mistake. I forgot that for displacement, a ton is a long ton and not just 2000 pounds, which is what I’ve been using to convert the numbers in FREE!ship to pounds. With this realization, I’ve had to readjust part 10 for KAPER and the like. It also means that FREE!ship and HULLS calculate displacement so similar that it’s better than good enough for government work. The other good news is that the new KAPER numbers are very very close to the calculations that I did by hand way back at the start of this project. Looks like I still remember geometry and physics. And the even better news is that by the numbers and in my limited test, this is a fast boat. With 3 pounds of resistance predicted at 3.8 knots. The average paddler typically paddles using 3 pounds of force, so the average paddler should be able to drive this baby at 3.8 knots without a problem. I was able to do just that into small waves without a back band and without foot pegs. Sweet!

More Fun Software

Before I get to that last remainder of the project, I’d like to share some new developments about some software I’ve found and used. Since the beginning of this process, I’ve experimented with different software, and now with FREE!ship, I’ve found an ideal program for me. It’s easy to use, and now – get this – comes with KAPER built in. Here is a picture of the KAPER chart that it spits out:

The next exciting news is that FREE!ship now also supports output to Michlet, which is another resistance prediction program that I have yet to completely figure out. But it also outputs a nice graph for resistance:

And it outputs this pretty picture of the waves your hull makes as it travels through the water:

And the waves imported to Free!ship:

Michlet also has a GODZILA mode, which uses evolutionary algorithms to simulate a reproducing population of hulls in order to (Creationists close your ears) evolve into best hull possible. I haven’t even touched this yet. It seems like Darwinism for boat designers. Or maybe it is intelligent design, you know, someone intelligent designed the program. Lots of fun to have here, me thinks.

Anyway, The Final Countdown

The final touches on this kayak seem to have taken forever. It seemed this way in part, because it was getting colder, I was paddling the boat, and I spent a lot of time outdoors enjoying the last part of the year until ski season started. Now, as I post this we have snow, and I’m out on my homemade cross country skis almost every day. This post may seemed jumbled, but it is that way, because the final touches came along in a jumbled-like way.

Melted Nylon Padeyes

Melted nylon padeyes are used to attach the deck lines to the kayak. To make these, I cut a slot into my hatch cutouts and put a folded piece of 1″ webbing through the slot. One side of the webbing forms a loop and the other has the two loose ends. Then with a propane torch, I melted the loose ends until they became a puddle of goo. The goo then hardens flat against the wood, and it becomes hard so you can’t pull the padeye through the hull. It took me a long time to decide to use melted nylon padeyes to attach my deck lines to the kayak. And the main reason why is that they require a large hole to be cut into the hull at each padeye. Or in the case of my deck layout 18 large holes. The nylon padeyes fill most of these holes and then are sealed into place with silicone sealant. Hopefully, they won’t leak. The only reason that I didn’t go with a commercial fitting, like that from KajakSport was cost. At $3.50 a fitting, I would be looking at $63 for enough fittings for my boat, and I just couldn’t stomach that price. I have carbon fiber and considered making my own, but it seemed like an iffy proposition, plus I want to use the carbon fiber to make a canoe paddle, so I didn’t want to waste any. On my next kayak, I will use a style of fittings that I saw on
Bjorn Thomasson’s website. These are made of fiberglass and the lines go into the deck and through a fiberglass tube and then they come back up and out the other side.

Deck Line

The deck line arrangement was decided on because I wanted to be able to store a spare paddle fore or stern. I also felt it necessary to have a perimeter deck line just in case someone ended up in the water and needed to hang on.

Grab Handles

I used KajakSport ergo grab handles for the ends of my kayak. To attach them to the kayak, I drilled a hole through each end of my kayak and then in that hole I fitted a piece of brass tube. The rope for the handle passes through the tube and into the grab handle. There is enough rope so that the handle can easily flip over the stems in case the handles need to be held onto in surf and the boat is spinning. The KajakSport handles are also very comfortable. The brass tube is held into place by some super nice silicone sealant adhesive that the guys at the hardware store recommended for all my deck fitting, etc… It seems that one of them uses the stuff on all his boats. It’s called Lexel.

End Pours

End pours were standard with some microballons mixed in. I used three squirts of epoxy at each end of the kayak and dumped it in with a cut pop bottle. My end pours didn’t make it all the way to the brass tubes, but I think that the brass tube and sealant is actually a pretty good seal. In the spring, when I can work with epoxy again, I’m going to add a small wooden washer to seal the brass tube in completely.

Foot Pegs

My foot pegs ended up being standard Yakima braces that were pulled out of an old kayak of mine that is no longer in use. The bolts go through the hull, mainly because I wanted them to be as strong as they could. Out of all the parts of a kayak, the foot braces receive a lot of force exerted on them, and I wanted to make sure that the braces would be able to handle that type of abuse, so I drilled two holes on each side making sure they were above the waterline and then mounted the braces. My front bulkhead if pretty close in, so people taller than 6 feet won’t be able to use the kayak with the foot braces, but the front bulkhead position can be adjusted when this kayak gets built again.

Back Band

I made a prototype back band, which actually turned out pretty well. I had some plastic that came out of an old Nike retail display that we trashed a long time ago. The plastic, I use mainly for paddle templates, is 1/8″ thick and flexible. Using two pieces of plastic, I cut out rectangles with round short ends. One of these pieces, I ended up cutting slots into it; these slot allow webbing to pass through and attach to the plastic. Then I used sandpaper to rough up the surfaces on the plastic and used contact cement to join the two plastic piece together, and in addition, I attached a piece of closed cell foam with contact cement to the plastic.

After the contact cement set-up, I used some heat sealable fabric that I had left over from another project to make a quick cover for the back band. If this band works, I’ll sew on a neoprene covering, but I was low on neoprene, so I didn’t do it this time.

To attach the band to my kayak, I drilled two holes in the deck and used round headed bolts to attach the band to the front of the cockpit and to the bulkhead, I used a plastic canoe outfitting padeye bolted through the bulkhead to which I used elastic cord to pull the band back and hold it at the right level. It’s slightly low from Ilena, my significant other, but it seems to work for me. I haven’t had enough time to test this back band for comfort, but it seems to be nice so far.

Seat

In the kayaks that I’ve owned, I’ve had foam seats, plastic seats, and padded seats, but I’ve never really like any of them and the main reason that I don’t like them is that after a full 10 to 12 hour day of paddling, my butt always ends up sweaty and wet. When in a canoe, this doesn’t happen, there is probably a couple reasons for this other than my canoe seats are caned, but I figure the cane can’t hurt, so I used a canoe style seat in this kayak. The main worry that I had was that the center of gravity would be raised too high, but the top of the wooden frame is only one inch off the floor of the kayak, so it’s pretty comparable with fiberglass and plastic seats in commercial boats, and, guess what? It’s very comfortable.

In the spring, or if I get motivated to spend some time in the very cold shop, I’m going to make a more ergonomic seat with a rim or ridge running around it. This will look like a bucket seat with a cane bottom. It will sit 1″ off the floor of the kayak and I expect it will be even more comfortable than my current seat. Overall, I’ve very happy using a canoe seat instead of foam.

Varnish

Although, I haven’t varnished the boat yet, it will be finished the following way. I’ll sand the final coat of epoxy from 80 to 120 to 220, and after 220 I’ll wash the kayak off, let it dry and then use a non-sticky tack cloth to make sure the rest of the epoxy dust is off of the boat. The inside of the cockpit where exposed to sun will also be varnished.

The varnish is applied by using a foam roller and brush. First, I roll out the varnish and as I’m rolling someone comes behind and tips of the varnish by running the brush across the surface. I only use three coats of varnish, but I may use two coats of a two part clear-coat for the bottom, because I expect this kayak will see some rocky beaches along the North Shore of Lake Superior.

And That’s All Folks

Well, that’s almost all. The kayak is finished. The kayak has been tested, and it turned out pretty nicely. I was planning to make some changes to the kayak, but I’ve decided that as built, even though it’s slightly wider at 48″ than I wanted, it’s a great boat. The deck will be slightly redesigned, but overall, I can’t image building a better touring boat than this one. In the next installment (and last), I’ll post my cost and hour spreadsheet.