Transom repair

I am in the process of repairing an 89 Thompson transom. It looks like the rear is in three pieces. I have cut out the middle and the sides look good. My question is would I be better of cutting out sides and do single piece of wood or just fiberglass in middle piece?
http://www.youtube.com/watch?v=V3e6WmfP3D8&feature=youtube_gdata_player

 

Instead of video with lousy lighting and poor focal range, how about some still pictures with a wide enough angle to see what's there.

 

Here is link to pics sorry about vid could not figure out how to post pics.
Photobucket.com/thompsonrepair

 

As a rule on a flat transom, I recommend a full width transom core. If you piece meal it, you're just bound to have issues. This is less true with a I/O, as the loads are transmitted through the engine mounts and hard coupling between the drive and bell housing, but you still want the transom solid.

 

Thanks I my plan is to do a 1/2 inch plywood fiberglass that in the middle and then do two layers of 1/2 inch ply with fiberglass between the full length across back. The ply that is on the sides is solid.

 

There's no need for 'glass between the plywood core sections, unless using polyester or vinylester resin, in which case mat would be the obvious choice to help improve the bond interface. The most important thing is good, sufficient thickness tabbing to the hull shell.