: my questions are

: 1. how did you get to these dimensions ?

Erez,

I had an idea of what I wanted the kayak to be like and checked dimensions of kayaks that performed similarly to what I wanted. I used my other Walrus as a base line then changed most of the attributes to get the design I wanted. I also looked back at the kayak (an Inuit kayak from the 1800's) that the Walrus was modeled after and made it similar to that.

: 2. I mean, how did you know the ratio between narrowing & lengthening it
: ?

No, I basically took a guess on what would be adequate displacement. I looked at other kayaks of a similar width and based my guesses on them.

: 3. did you made any calculations ? (how, which)

I made calculations to scale all width dimensions down at an even ratio. This gave the kayak a greater angle of deadrise, because I did not scale the height of the chines in relation to the keel.

: 4. or did you go by feeling ?

A lot of it was done by feeling.

: I have a thought of doing something similar.

: most of our kayaks are designed for a paddler weighing so & so,
: & gear weighing some more. My thought is to narrow the kayak to get the
: speed
: (& tippiness), but not to lengthen it, so I wont get so much capacity
: that I don't intend to use anyway.

Length essentially equates to speed. Narrowing the kayak generally reduces wetted surface and will make the kayak easier to paddle at a given speed. The volume of mine is more than enough for my 175 pound frame. I wasn't concerned about carrying capacity with this kayak, it was designed as a day-tripper.

If I increased the flare and kept the max beam constant, it would have decreased the wetted surface and the primary stability, but increased the secondary stability and the carved edge turning radius. I think the same can be accomplished by increasing deadrise and keeping everything else constant. We could move this over to the design board, if you want a more in depth discussion

Mike