Mark,

You are a great straight man. I just answered this over on Boatdesign.net so this is a repeat.

I had to go stage some pictures. Before trying to build the boat I made several "test pieces" to work out the bugs. The pictures are of a flat boat like shape representing the gunwales at the bow of the boat.
I am going to give you links to the pictures in order with a little description, cause I am not very sophisticated at providing the pictures directly.

An illustration of one gunwale with the skins, splines, cap strips and glue. Hope this makes sense.
https://lh4.googleusercontent.com/-JTwMuJQS0VA/UBRPZ-nkACI/AAAAAAAAAqI/HQvw3IOfpN4/s912/Geometry%2520of%2520One%2520Gunwale.jpg

Feel free to skip ahead if I show too many baby steps.

First two pics are just one of the test pieces. You can see the previous install trials. There were grooves on both sides, the other side is completely filled up.
https://lh4.googleusercontent.com/-LejUBbED91s/UBRDK3fUCxI/AAAAAAAAApg/75fQN0fDsdU/s640/IMG_3560.JPG
https://lh3.googleusercontent.com/-AaougSwXvn0/UBRDJU5VgUI/AAAAAAAAApY/hG0DWXinNy8/s640/IMG_3559.JPG
Next is just the nose area I'll use to illustrate. This is the only area not filled up on the test piece, and it is impossible to get the cloth out by pulling. The grooves are 1/8" x 7/16" deep. This is probably not critical but you need some depth.
https://lh6.googleusercontent.com/-x_3BN6wTsWg/UBRCje8g68I/AAAAAAAAAmA/7Zff5GVsdHk/s912/IMG_3531.JPG
https://lh4.googleusercontent.com/-1GcHCCJPbVI/UBRClOYTq7I/AAAAAAAAAmI/p8HgS4cw6FA/s912/IMG_3532.JPG
The tools used to install the skin are shown. A piece of angle to press the cloth and the spline down into the groove, the glue, a trimming shield made from roof flashing (just thin steel with a right angle bend to go into the groove), and a razor blade to trim the skin. Ignore the wooden V, it was the form I used to laminate the curved nose piece to finish out the cap strip.
https://lh4.googleusercontent.com/-zAkpXPBKXRg/UBRCm30IRxI/AAAAAAAAAmY/RBk04nTHW04/s912/IMG_3534.JPG
You can see the test piece thru the cloth. Trim of the cloth is not critical, just leave around 2".
https://lh4.googleusercontent.com/-p9uP48qa9_Q/UBRCq8oEYFI/AAAAAAAAAmw/AdmVSPyqhBg/s640/IMG_3540.JPG
The spline going inside the groove is on the right, on the left is the cap strip before I cut it loose from the beginning strip. The cut would be made on the table saw at and below the pencil line. The spline actually was cut with 5 degree angles on each side, to act as a wedge going in.
https://lh4.googleusercontent.com/-dyEoovWEUMM/UBRCpVty0FI/AAAAAAAAApw/iCfzAGlkWnE/s912/IMG_3538.JPG
First step is to use the angle to press the cloth inside the groove on one side. I then used short pieces of spline with no glue to temporarily hold the first side in place
https://lh6.googleusercontent.com/-xSdVOozHz6M/UBRCuEQ5kiI/AAAAAAAAAnA/iBbmgLY88xY/s912/IMG_3542.JPG
Next I repeated on the opposite side, taking a little care to get the cloth taut but not really tight. Just try to make it smooth so there are no wrinkles you have to really work out. This is still temporary. Nothing really holding it in.
https://lh6.googleusercontent.com/-rChPj6NaK44/UBRCwBRlMBI/AAAAAAAAAnI/nA5AiCSiffg/s912/IMG_3543.JPG
Starting at the middle of the boat on one side, run a 6" line of CA glue. Push a 6" piece of spline to the bottom of the groove with the angle. 30 seconds later it is permanent. Continue down the same side, pulling tension on the cloth as you go to the ends.
https://lh6.googleusercontent.com/-5RkRwWoH45U/UBRCxobbw3I/AAAAAAAAAnQ/oWRq8FP0viM/s912/IMG_3544.JPG
https://lh5.googleusercontent.com/-pmtp1xcc6v8/UBRCzTu_NQI/AAAAAAAAAnY/04kFzV01vX0/s912/IMG_3545.JPG
Move to the opposite side. You may want to reinsert the temporary splines to make the skin smooth. Start at the middle again.
Fill the groove with CA 6". The reason for the short length is to insure you get the spline completely into the groove. If not you might not have room for the second piece of cloth and the cap strip. I was a little slow when using a longer spline and got it stuck at the top. Very difficult to fix that, I just abandoned the try. This is a good reason to get confidence with a test piece.
https://lh6.googleusercontent.com/-lPxsnrAKKG0/UBRC2iwr0MI/AAAAAAAAAno/Lh7X4Z2n3bs/s912/IMG_3547.JPG
Force the spline to the bottom, holding onto the free edge of the skin. It is possible to fold up a big wrinkle below the spline and fill the groove too much. Finish that side.
https://lh6.googleusercontent.com/-oepWzRgoqDc/UBRC4N8dpLI/AAAAAAAAAn4/7x_OduTuPkQ/s912/IMG_3548.JPG
Both splines inserted. These are not forced to the bottom or glued. It will be difficult to see the first spline when you are finished with the deck skin.
https://lh5.googleusercontent.com/-2qAEJ5kpL0Y/UBRC6ES8rvI/AAAAAAAAAoA/EWxeSc_qvso/s912/IMG_3549.JPG
Trim the free edge, cut away from the skin you want to keep. You will be cutting down into the top of the spline. Won't hurt a thing. The cutting shield is there to keep you from cutting the skin you want. I had to use thin CA to bond the cut to the gunwale, and it didn't look very good. Mostly covered by the cap.
https://lh4.googleusercontent.com/-rSQDeBLqeyQ/UBRC7qBpYtI/AAAAAAAAAoI/YPKiGpUYLOU/s912/IMG_3550.JPG
https://lh6.googleusercontent.com/-KNED93GZXlM/UBRC9owzN3I/AAAAAAAAAoQ/TT8RcQjhN74/s912/IMG_3551.JPG
Repeat the whole operation with the "hull" skin. Trimming the free edge is the same problem, you just have two skins to worry about. Not as hard as it might seem. You can just see the installed skin on the outsides of the gunwale with the excess sticking up. This picture has too little excess, that makes it hard to constantly trim the excess.
https://lh5.googleusercontent.com/-rYHXPbS8aTU/UBRDEqzeesI/AAAAAAAAAo8/nS3jT8deH7A/s912/IMG_3556.JPG
This is a picture of the nose without the cap. Ignore the lifting strap in blue.
https://lh6.googleusercontent.com/-TthDyM7ZUY4/UBQa7TNsbnI/AAAAAAAAAdw/4zQVx4WnveM/s912/IMG_3506.JPG
Cap bonded in with thick CA. Please ignore the tip piece, I remade it.
https://lh5.googleusercontent.com/-WyMsJyaSiMk/UBQa_lGKShI/AAAAAAAAAeQ/cRYZhO5Ik0k/s912/IMG_3509.JPG

I know that was over kill. Questions welcomed.

: Marc, very nice job. Could you explain how you get two pieces of
: fabric, two splines and the top cap into the 1/8" wide
: groove. Also how deep is the groove and how "tall" are
: the splines, do they sit below or flush to the top of the
: gunwall.

: Mark