Building a Perfect Kayak: Part Five

Background

Way back in episode two, I explained about station forms and what they are used for, and I mentioned the strong back. If you don’t remember all that dribble then you may want to head back there for review, because in this episode they are the main character.

Attempt One

So, after I had finished milling the strips I went to the local lumber store and picked up a couple sheets of 1/2″ CDX plywood (BTW, including labor after this episode my kayak costs $593.76, so far.) The forms of the kayak are laid out on this CDX plywood and then cut out and aligned on the strong back. Because I had designed my kayak using HULLS, I hadn’t seen what the kayak looked like with curved forms. As I lay out the forms a better image of my boat began to emerge, and it looked way too small. But I continued on until the last of the forms was finished. I quickly cut out the center form just to see how big it was, and it seemed very small. I mean very small. So, I called it quits for the night, and went to bed.

Attempt Two and a Kayak

The next day, I went over to a friend’s house with the center section to compare it to his Romany Explorer kayak. And although the curves where similar (mine has more flare) in the center section under the waterline, above the waterline, the Explorer had much more volume. So much more volume, that I knew it was back to the drawing board … I mean computer. Using HULLS, I added a couple of chines and began to reshape the deck of the kayak to round it and add depth and volume. After about two hours of work, I was satisfied with the look of the kayak. When you turn off auto-spline chines in HULLS, it gives you more flexibility in designing the deck. I drew it out on some white paper I found around the house, and then went to bed.

Kayak, Kayak, Kayak on My Brain

The next morning, I needed to head down to Duluth on a quick trip to pick up some stuff, and while I was down there, I bought a nice Bosch router (I love this thing. By far the best router that I’ve used. Bosch 1617EVSPK 2.25 Horsepower Electronic Variable Speed Plunge and Fixed Base Router Kit) When I got back to Grand Marais, I was back into the garage again with my sheet of white paper with the new forms drawn on them. Over a couple of hours, I used a flexible batten, nails, carbon paper, and brainpower to lie out the forms on plywood. Because HULLS doesn’t output very many points to help with layout for curved forms (yet,) I had to fudge and guess a little bit here and there. In the end, I think I managed to produce fair forms. While doing this, I came up with a few simple suggestions to help you along the way if you decide to loft forms from HULLS.

1. Mark each form with its location.
2. Keep a pencil sharpener nearby.
3. Use the same batten for the whole boat so the curves will remain the same.
4. Try and keep the same curve from section to section if the points don’t give an exact form.
5. Go slow and take your time. It is very important to lay your forms out correctly.
6. Play some good music.

Cutting It Out

Finally, I needed to cut out the forms, so I fired up the old Bosch jigsaw (I’ve had this jigsaw for 3 or 4 years now, and have found it to be extremely powerful, accurate, and adjustable. There is nothing like a good tool. Bosch 1587AVSP Progressor Top-Handle Jig Saw Kit), which made quick and accurate work of the forms. This saw is one of the best and if you go slowly, you won’t have to sand down to the line on your forms. Finally, with all the forms cut out I was able to see what the boat would look like. I leaned the forms against the wall, and in an exciting moment, I felt proud that I designed this kayak from scratch. This is going to be a good kayak.

My Strong Back or Strong back

Before stripping (applying the cedar and pine strips) can begin, you have to make a strong back, which will hold all the forms in alignment while you work. There are two types of strong backs that I know of: internal or external. I’ve never tried an internal before, so I figured it was about time I tried. With an internal strong back, you cut 2×4 holes out of each form, and string the forms onto a 2×4 strong back. It would make a lot of sense if you could just head to the lumber store and buy a 16′ 2×4 and call it good, but if you’ve ever tried to find a straight and true 2×4, then you know that this is harder than it sounds. I decided to make my 2×4 from plywood (mainly, because I had purchased an extra sheet.) Somewhere I measured wrong (go slow and measure twice) and I ended up with a 2.5 x 4 strong back, which is just as well, because it seems pretty flexible. I don’t think that I’d use this type of strong back again. It’s just too flexible. After gluing the strong back together and figuring out how much I needed to cut off of it to make the stems fit, I strung my forms onto the strong back and for the first time, I saw my boat – my boat!!!

A few more hours and the boat was affixed to the strong back. To do this, I first spray painted lines onto the back by running a string between to nails and then spraying the string. The forms are actually aligned on the strong back to these lines. I also ran a line above the forms just to double check the alignment, and made sure everything was level. I figure the more careful you are in setting up the strong back and forms the better chance you’ll have in building a boat that doesn’t turn permanently to the left.

With a great looking kayak, solidish forms and strong back, and a glimmer of excitement in my eye, it was time to put the first strip on…