transom cap support?
 

how much support does the top cap at the rear actualy give the transom to avoid flex? is it a major factor? were the OE rear hatches and rear inner body work a support as well?

Yes, its all part of the integrity of the transom. The hull vents have pieces that are glassed to the inner hull and the transom, also the corner boxes add a bunch of structure to the corners, even though they are just screwed on. In this picture you can see the 'scoop' that I have glassed to the inner hull, then I smoothed the joints out with putty.

http://i612.photobucket.com/albums/t...b/P4081598.jpg


You can see the white filled seams in this one.

http://i612.photobucket.com/albums/t...b/P5041620.jpg

I popped the whole cap on and laid one layer of glass, to join it in the corners I was amazed how much it kept the 'twist' down while walking around inside it.

Underside of the cap.

http://i612.photobucket.com/albums/t...b/P4091601.jpg

Ground the seams and installed with screws to adjust it

http://i612.photobucket.com/albums/t...b/P5041621.jpg

I can say from trying to moving a boat around with no structure, they flex a TON without anything in them. It was very touchy to get it squared back up once it was in the shop on the concrete floor with just a transom core in it.