: It may seem crazy but why not a triple? Cut it in half
: in the middle and add maybe 6 ft to it so 3 cockpits can be fitted to it.
: whats the consensus?

Stretching a single to a double involves a lot of compromises. To double the
load you need to double the displacement, but you don't just multiply length
beam and depth by the cube root of two - that would give a boat that was a
horribly sloppy fit. But you don't just double the length, leaving beam and
depth the same, as that would give a boat that would be almost impossible
to turn. The paddlers' arms and paddles don't magically get longer to
apply wider sweep strokes for the longer boat ...

So to stretch a boat you need to lengthen it quite a bit, leave the depth
fairly similar, and broaden the beam so that the boat sides (and chines, if
it has them) still have enough curve for leaned turns to be effective. You
probably add rocker, too. Most designers cave in and put a rudder on a double,
since they go faster and so compromising performance that way is less of an
issue.

Now, to stretch a double to a triple, surely we have exactly the same issue ?
If you just stretch a 20'6" boat without changing beam or depth, you'd need
to add 10'3" if you stretch the design. But if you are just adding an extra
bit in the middle, where the cross section is biggest, you could get away with
adding somewhat less. But just inserting a section in the middle will give
you very straight sides - no curve on the sheer or chine to aid turning, and
probably not a very fair curve. You would get a boat that was seriously
hard to manoeuvre.

To stretch to a triple, you will need to add beam in a fair curve, and add a
bit of depth midships to give you more rocker. The middle paddler will now
be in the widest part of a wider boat, (whereas in a double both paddlers
are off-centre, in a bit of boat where the beam is comparable to a single),
which will make it much harder work for him/her to paddle unless he has
gorilla arms and a 2.5m paddle (and tough knuckles...)

The only triple designs I've seen are essentially designed, like the three-
hole baidarkas, for two fit paddlers to take a passaenger in the middle,
making no contribution to progress. Is that what you are after ?

Andy