Plank fastening

[Jim Surdyke]

I have been able to replace a portion of a number of frames from the inside while the boat is in the water. Replacement was required due to stress (tensile) cracks on either side of the mast steps.
My question is; Is there any reason why I can't refasten the planks in the area of the repair by screwing from the inside?
My frames are 2 1/4" square white oak and my planks are 1 5/8th" long leaf yellow pine. My plan is to drill through the oak with a drill the same size as the screw shank (# 16 x 3 1/2" silicon bronze). Then use the appropriate tapered drill into the plank. With the head countersunk so as to be flush, I would penetrate the plank 1 1/4". I have marked where the old screws were (3 per plank) and will alternate the new screws opposite the old ones.
It seems to me that from a holding standpoint, the cumulative surface of the thread that penetrates the plank equals or exceed the surface area of the screw head. Am I missing something?
The average number of planks effected by the frame repair is three.
PS: Motivation is to not have to haul out at this time.

[Scott Rosen]

A through hole with a couterbore in the frame could weaken the frame. I don't imagine your boat's scantlings are designed for that. The accepted method for through-frame fastenings is copper nails/rivets, with the counterbore on the plank and the rove on the frame side.

[Bob Cleek]

The idea is bass-ackwards. Always fasten the "little" piece to the "big" piece, not the other way around. The head of the screw will hold the thinner plank to the frame, just like the head of a nail does. You want your screw threads to hold to the larger, stronger member, the frame. As Scott said, putting your biggest hole right through the frame will significantly weaken it. (Rivets are used in such applications because they have a head on both sides.) Frames almost always crack right across a through-hole, ya know. Saving the cost of a haul out to do the job right is false economy.