: you are correct in stating that most of the kayaking i have done
: was in wider (27 to 30") wide kayaks that were in the 10 to
: 12 foot range. I just want something i can throw gear in a dry
: bag and fit inside the kayak. I love backpacking and would love
: to combine the two and hit some of the island chains in northern
: michigan or something. I also enjoy fishing quite a bit as well.
: I'm starting to lean towards the 22 - 24" beam in the 14 to
: 15 foot length. I really like the single chine yost style kayaks
: that fit in that range. they seem like a solid beginner build as
: they seem simplest as well as they use less of the stringer
: wood. Thats why i wish there was still plans for the sea bee
: single chine...

What you neglect to figure for is the depth the boat sits in the water. On the shorter and wider boats the capacity is frequently calculated with the boat having 6 (or more) inches under water. That gives a lower center of gravity, which is reassuring to many beginning paddlers. Most boat designs you'll see are designed with a displacement of just 3" to 4", with the latter point being probably the most common.

If the sidewalls of the boat are high enough you can sink a boat pretty deeply into the water by just adding more weight. Add too much weight and the water gets over the sides and fills the boat. For many boat designs in 16' to 18' lengths, adding about 100 pounds of weight (paddler, cargo, or both) into the boat makes it sink another inch into the water. With a shorter boat you'll probably sink an inch for every 65 to 80 pounds. So, a 12' boat designed for a 150 pound paddler at a displacement depth of 4 inches would hold a 300 pound paddler but the displacement depth (the amount of the boat which is under water) would be about 6 inches.

Check the overall height of some of those plastic boats and you'll find they are 13"- 14" or so tall. With 6 inches under water they have 8 inches of freeboard, or the amount of boat above the water. Six inches of freeboard is good, but some paddlers like it to be a lot less so the boat is not affected by winds, or the boat can have low decks for rolling the kayak, or they want to reduce weight. And some want the freeboard to be a lot more because they want to carry a lot of camping gear, or expect to catch heavy fish, or they have size 12 feet and need the deck to be a bit higher so their feet can fit in!

If you are taking one of Yost's shorter designs and modifying it for your (greater-than-design) weight, just draw the shape of the frame according to his offsets. You can do this on a computer or on paper. Then extend the sidewall lines an inch or two (make it the same on all the frames), to get higher sides. Add the same amount to the center measurements, to increase the center height of the frames. Measure the new points and use those for your CAD/CAM inputs. Sure, the width will get slightly greater, too, but that is not a big deal.

If you are fishing in lakes the added inch or so of draft will not bother you. If you are going in shallow streams, you want a longer boat with less draft so you don't get hung up on the bottom.

Good luck with your project.

PGJ