: I have built two S&G kayaks by Eric Shade, the Widgeon, that are 14 ft long
: and 24" wide. I am contemplating on building a narrower strip kayak
: for learning to roll. I am 5'8" and 140Lb. Why do most people choose
: such long (17-18ft) kayaks?

Displacement is a factor of both the width of the hull and the length of it. consider the problem of a heavier paddler than you. He has the choice of building a boat which is wider than yours, or longer than yours, to get the displacement they need to keep their body above the waves.

One of the biggest resistance issues is the width of the boat. A wide boat is harder to propel than a narrow one. If the heavier paddler makes a boat which is as wide as your Widgeon (24"), but longer--to suit their weight-- they have to paddle as hard as you to move 24 inches of water around the boat, and then they have to paddle just a little bit harder to account for the added friction of the water on the slightly greater wetted skin area. But suppose they built their boat to be only 20 inches wide. Their boat would be even longer, with again slightly more wetted surface area. But the width of water they would have to push aside would be only 20 inches, not 24.

I can't remember if you square or cube the difference to degtermine the difference in resistance. I just know that a thinner boat is a lot easier to paddle--so for open water I'd opt for the narrowest boat I could handle, and build it to the length which would give me the displacement I'd need.

: I understand the advantages of higher hull
: speeds and higher volumes to carry gears, but don't plan on doing any
: racing or over-night camping, just paddling in local lakes and Long Island
: Sound on calmer days.

Isn't Long Island Sound affected by tides going in and out? How fast do those move? I don't live near there, so I've never bothered to look it up. If I did live there, you could be sure I'd check to make sure that I would be coming home with the tide pushing me in, when I was tired.

I do most of my paddling on the local river, and found that it was always better to start my trips by heading upstream. After I got tired I could get home by mostly floating with the current and just adding enough energy to steer a bit. The first ( and last) time I did the opposite, I decided on a 2 hour trip. One hour downstream and one hour back--forgetting the mild 2 to 3 mph current. After a pleasant hour of paddling at 2 to 3 mph (a bit faster than my "loafing but cruising" speed) I was 4 miles downstream. Heading home I had to dig a bit deeper, but even so, after an hour I was still over a mile from home, and running out of steam. By the time I got back to the put-in point I was wiped out.

Now this was on an urban river. I oculd have gotten out at a dozen points along the way and walked home. The water was quite shallow, and I oculd have even walked in the stream bed faster than I was paddling, and towed my canoe behind me. So I ws never in any danger. I just got a workout because I didn't want to get my shoes wet.

On bigger water (open lakes, LI Sound) and certainly on oceans, there are no places to get out and walk home. On a 3-mile long, 2 mile wide, L-shaped lake in the Boundary Waters Canoe Area our group ran into a head wind which cut our speed in half as we paddled the length of the lake, then we had to paddle at an angle to the wind to make progress on the width of the leg, and to avoind being blown onto the rocky shoreline. The faster a boat can go, the better it is to handle such winds. Even if you never plan to race, you want a boat which will get you home against a headwind, or an outgoing tide.

If you want to get across a lake in a reasonable time you want to go in a straight line. When there is a wind blowing, or a current, or a tide, you need to factor these in, set your course (which may not be a straight line), and be able to hold that course. With a shorter boat you turn the boat side to side a bit more with each paddle stroke than you do with a longer boat. (all other factors being equal)

With a long, narrow boat more of your stroke goes into forward propulsion than with a wider boat. This effect is not usually factored in by hull design programs, but it is noticed by paddlers. This is partly because your paddle is closer to the centerline of the boat, partly because the shape of the boat offers greater resistance to turning, and there are probably some other factors which I don't understand. The combined effect is that your overall paddling efficiency is better in a longer, narrower boat than in a shorter, wider one.

: I had drawn up a few 14x20 kayaks with Ross Leidy's
: Kayakfoundry, with design displacements of around 185Lb with 3.5"
: draft. Before I cut wood, any suggestions or advice?

Would that be a 14 inch by 20 foot boat, or a 14 foot by 20 inch boat?

If you were trying to replace the Widgeon by going with a narrower boat (say 20 inches) then keeping the length at 14 feet means you'll just drop a bit further into the water to make up the displacement, or, you'll have a blunter boat which may not be as streamlined. If you are going for a rowing-shell-like 20 footer, with a 14-inch beam then you may have a learning experience before you achieve comfortable stability in it. but it should be fast!

Just some thoughts

PGJ