Eric, I confess that I'm too lazy to drop the boat out of the ceiling and measure for you. Sorry about that.

Keep in mind that this section serves the purpose of a Masik, or Aajaq Seeqqortarfik. That is to say, rather than thigh braces, this member is supposed to be tight to your thighs just behind the kneecap, to give you attitude control of the kayak.

I weigh about 185 pounds at 5'9", and I find that my station 4 is a bit high at times. If I plan to paddle where I may need a lot of control (for example rough conditions or surfing) I wedge a piece of 1/2" foam between my knees and station 4. It's still not tight (as some kayaks I've wiggled in to) but it does take up some space.

I don't like the shape of the top of my station 4 either. I find that the semi-circular curve does not provide good contact for rolling - in fact, it allows my knees to move closer together, which will necessarily be at a higher point of the curve, and thus have even more room to have to brace up to. Therefore, next boat would be build about an inch lower, and fairly flat across the top, with curved radius at the sides.

It is hard to decide how high to make this section. After my frame was complete, I sat in it, and found it was quite easy to get into. But that was because there was no skin on it.

You should consider building up the top of that station, if you plan to use it as intended for a masik or aajaq seeqqortarfik. You want something at least 2" thicker. Make sure that you bevel the heck out of the edges - a sander is not good enough. With a very good radius on the aft side of this member, it will provide maybe 1/4" more room to get your kneecaps underneath, while trying to get in. I wish I had done this on mine, and I'm still trying to figure out a good tool to do this considering I have to work inside the boat and with the skin on. It will certainly be changed when I have to re-skin.

Brian

: I've been laying out the sea rider forms on poster board and I'm
: wondering if something isn't right with my frame 4
: which is the frame on the forward side of the cockpit.

: http://yostwerks.com/SeaRider1.html

: The offsets are given in fractional feet so I converted them all to
: centimeters by multiplying * 12 (in/ft) * 2.54 (cm/in).
: This gives the deck ridge HAB at: .833 * 12 * 2.54 = 25.39 cm. The
: keel HAB for frame 4 is 0.

: My first try just blindly working my way back from frame 1, I cut a
: squarish frame 4:

:
: http://www.antibozo.net/cgi-bin/eric/imglib/prod/image.pl/eric/pictures/Archive/2009_sea_rider/1-resized/IMG_1898.jpg

: I end up with a pretty small opening to squeeze my legs through.
: Only about 6-3/4 inches high at the centerline. Checked
: all the HABs and I think they are right. It is approximately 25.4
: cm from the keel to the top of the form at the deck ridge.
: Looking at the pics of wooden sea rider frames I see that they show
: a form 4 with a rounded masik-like upper span for
: frame 4 so I drew one like that which opens up a little more leg
: room:

:
: http://www.antibozo.net/cgi-bin/eric/imglib/prod/image.pl/eric/pictures/Archive/2009_sea_rider/1-resized/IMG_1900.jpg

: This still has an opening height of about 6-3/4 inch at the
: centerline but a little more roomy. Not much.

: Is frame 4 really supposed to be this tight? Are my measurements
: completely off somehow?

: --
: Ogata, eric