Drag, wave length, stability, volume.
My shorter kayak is easier to maintain a cruising pace then my 5 m kayaks and it is roomier. I love it heaps yet my friend that gave it to me and I were chatting the other day. I mentioned the boat and prompted the question to him, ' look, I love the boat heaps, I still have the other boat we swapped with (10 footer) and the boat you gave me is heaps better plus although the paddle is ship loads better than the expensive one I bought, it still yours plus the skirt is top shelf. My new one's being built soon. '
He replied, ' full of holes, '
We both laughed,' yeah, I lost count at 8 but I'll see ya Sunday. There is epoxy and 3 inch glass ready on desk, she's in shed, dry and hard as rock. '
In terms of speed, wave length of displacement and frictional drag will greatly influence effort required to get speeds. If you can try one out. I'm glad I used the holy boat because it surprised me as to how fast a 55 year old boat is. I hope I get to keep it
Best of luck brother