Hello Toni

: kayaks Kaper should do pretty good, but if you make some strange shapes
: the results might not be so right.

The 2 kayaks I built so far were meant to have a Greenlandish look. The last one was a bit boxy looking but did have a razor sharp bow and stern, the new design too. Maybe that caused the problame that Kaper had with it.

I know there is a wide variety of shapes of traditional kayaks. I was at TAKS 2007 where about half of the traditional SOF kayaks had the kind of typical Grenland shape that I refer to - narrow, long and sharp edged bow and stern, low waterline - a few Baidarkas and some other other odd shapes. Harvey Golden gave a nice presentation about traditional kayaks. It was a great event.

: I think slowish performance of some kayaks does not come from CP, but from
: waterline lenght mostly. And that comes from the fact that these kayaks
: were done for real world paddling in real waves. You won't be happy to
: paddle 6 metre hull without rocker in short waves.

My current boat is 19' x 20", has a narrow bow and stern (low CP), zero rocker but is not as fast as I would have liked. I think my 15' SOT is almost equally fast which is slightly disappointing. I may be wrong, usually I am way ahead of the pack but I was in my SOT, too. It made me suspicious about the shape though. Low CP implies more wetted area than neceassary so it is expected to be slower. These boats perform great cutting through waves and surf though.

: So there's a need for kayak for some typical (or maybe worse) conditions and
: the kayak must work in those situtations. Sprint racing kayak will do fine
: in high speed and flat water. It sucks in slower speed and in small waves.

Yep that's why I mentioned that I need to decide what it is I am looking for. I definitely like the low volume in waves and surf. Speed is nice too but it requires a different hull shape. I am curious about your KOG77, it looks very nice. I will check it out.

: waterline quite close to hull lenght. I've had couple Baidarka models in
: Freeship/Michlet and considering the waterline lenght they aren't so
: different from Greenland kayaks in speed side.

But their bow is fuller and the hull is more rounded which should be more efficient. I also think that a narrow chine splits the water too gradually which makes the wave length that fits effectively around the hull, shorter. Thus the speed is lower, too. Speed daemons usually have a boxy look, zero rocker, rounded hull with full bow and stern profile.

: Here's couple images to see that Greenland kayaks do have some differencies -
: not all have fine and pinched ends:
: http://personal.inet.fi/koti/tonivee/kog77.jpg
: http://personal.inet.fi/koti/tonivee/kog103.jpg

Thanks for the links, nice kayaks. It is good to hear that their performance can be good. Personally I have never seen the traditional SOF kayake that I alluded to go fast, they are mostly used for surf and rolling practice. Maybe this has to do with the people that paddle them.

: Btw. Your kayak looks quite interesting. The chine form especially. I guess
: you are looking for high initial stability, ease of paddling and low
: secondary stability. Interesting look in any case.

Thanks. I like the shape too, maybe I will build it as is. The Kaper profile was not that different from my current kayak (below) which is OK. And thanks for your advice regarding using Kaper directly, too. For now it is a bit too much to take on but others did it, like KayakFoundry.

Henk

+-------+---------+
| Speed | Spilman |
| [kn] | [lbs] |
+-------+---------+
| 2.00 | 1.003 |
| 3.00 | 2.175 |
| 4.00 | 3.818 |
| 4.50 | 5.071 |
| 5.00 | 6.950 |
| 5.90 | 13.188 |
+-------+---------+