Hull design questions

[TexasZeke]

I was looking at the boat Darrell has started and it brought some questions to mind. My first build was what I consider as standard a pirogue as you will find, flat bottom, splayed out sides. The new boat has a slight v to the bottom, sides splayed out, the max beam shifted lower to the water by use of the tumblehome. Through things I have read here and other places I have, what at best is probably a vague idea of the characteristics of each.

Then we go to Darrells boat, and Striders for that matter, to my eyes they seem similar. Five panel hulls with relatively straight sides. What characteristics are gained, or changed, by going to this setup? I'm just trying to understand the differences between the different shapes and why a person would want one over the other.

thanks
kevin

[gerald]

A boat with straight sides (no flare) has the greatest intitial stability. Two negatives: no secondary stability and it doesn't look good. Thus we flare the sides to give secondary stability. The ratio of intitial to secondary stability is very important. 80 Degrees is about right though may still look too boxy. 70 degrees is a little too much and may make for an initialy tippy boat if you're sticking with a fairly narrow beam. The change from 3 panel to 5 panel is simply for less surface area friction, slightly better slice through the water, and perhaps a bit more seaworthiness that most people can't notice. You can have 10 of the 3 panel boats, all of subtle dimensional differences, and they will generally act, and react, differently in the water. One big positive for me with the odd panel boats is that they are generally flat on the bottom. This means they sit flat when you beach them. I like that. Boats with a slight V or more don't sit flat. Not a biggie but it can be with some boats.

So...it's not the number of panels or strips but the angles at which all these parts go together that determine how your boat is going to perform.

The function of tumblehome is generally considered to be for paddle clearance rather than to bring the max beam closer to the water. This has the same function but also changes your potential heel angle. You see tumblehome in wider boats with higher seating positions like canoes. Some people also like the way tumblehome looks.

A few words about sea worthiness. I consider sea worthiness to be the ability of boat and paddler to handle the water conditions encountered. It would take a 10,000 page book to run through all the ramifications of what I'm fixing to say but while "a" sea kayak is probably the most "seaworthy" small paddled boat, at no time is ANY paddled small craft more than 50% of the equation. A paddler in a sea kayak is much more than 50% of the seaworthy equation. You should never stay out in any boat in conditions where you can become so exhausted that YOU can't act and react quickly enough to handle those conditions. Your boat will do what it can, but if you don't do your part--you're going over. In the example of the sea kayak where the paddler is MORE than 50% of the equation it is even more important not to become totally exhausted. Ultra marathon paddlers in skinny boats have this problem. Near the end of the race they have a hard time staying in the boat. All this means is that you have to have a boat that fits your task AND your abilities. Thus my never ending phrase of "Task specific" boats. Maybe I should also say "task specific" paddlers...

[Light Keeper's Kid]

Gerald,is the boat that Strider paddles a flat or slight V and what about your new hulls

Mike

[gerald]

Gerald,is the boat that Strider paddles a flat or slight V and what about your new hulls

Mike

On my designs--and probably on others--the odd panel S&G designs (3, 5, 7, etc.) will have a flat keel area. Even panel S&G boats will usually have a V keel area.

The current boats under construction are strip built boats with soft chines. They can be either/or but will always have soft, or curved, transitions. These particular two boats are elliptical in shape meaning they have no flat spots.

Strider's boat is a 5 panel with a flat keel area, rising toward the side, then a steeper rise on the side strakes.

[Light Keeper's Kid]

For a layman that would mean something like 5 deg. angle on Striders and do you offer that plan as S&G

Mike

[gerald]

Yes. Strider's boat(s), either in the Conquista 5 panel, or the more stable 5 panel (I can't remember what he calls it--I'm getting senile. Challenger! That's it.), are S&G. Only the decks were done in strips.