HERE IS MY WINTER PROJECT.IT A 1978 TROPHY CUSTOM.IT HAS A BBF 460.IT HAS A 12JC-A BERK PUMP.I HOPE TO HAVE THE MOTOR REBUILT,PAINTED, AND INTERIOR DONE FOR NEXT SUMMER.

Bitchen Boat, looks like fun.

Any body know what a 25' citation is worth? Has 455 olds, unknown jet.

Here is some pics of my interior.It's all one piece.Two bucket seats in front and a "u" shape bench in back.I don't have much room,but I think it will work ok.I will try to finish up tonight and I will get more pics.

The wood is seven layer, 3/4 inch ply wood.I will coat the hell out of it with resin.I'm thinking of glassing all the joint areas.Do you guys think that is a good idea?This is my first time doing interior work so any advice would be good.It's not very heavy for being one piece.I'm going to try to make storage areas under the back bench seats.

That is a good idea about cutting the holes under the seats.I will do that.I wish I could of used the marine plywood,but I could barely afford this stuff.This stuff was $27.00 a sheet.Thanks for the help.Do you think I should glass all the joints?

When I did the seats in my last boat from scratch I glassed all the joints and resined the rest , the upholstery shop said they looked like they would stand a beating! And they did. So I would advise doing so. Boat seats tend to receive a lot of abuse.

I second this....a little more re-enforcment wont hurt.

I think the 3" strip deal is a good idea. As for the bonding, I would do a cold batch of resin. What I mean is use the minimum amount of hardener so that the resin can soak into the wood of the seats. This will give you the strongest bond. I honestly think one layer of mat will work fine. Make sure resin extends 2" - 3" past mat.

Step 1

Clean seat joint with acetone
Apply cold batch of resin
Lay in mat, make sure mat is fully saturated with resin

Step 2

Sand bonded joint, removing any sharp edges
Clean with Acetone
Apply second coat of resin

I'm not sure if it was right or not, but we rebuilt all the frames on or 19' Tahiti 15 years ago just like you are doing now.  We were going to resin the entire frames and glass the joints.  A marine upholsterer told us to treat the wood with linseed oil or Thompson's water seal and drill the holes as has already been suggested.  Because the marine grade plywood was over the top even 15 years ago, we used the same size plywood you are using and slathered the hell out of them in linseed oil (5 or 6 coats). We also used stainless wood screws (not cheap either)  The upholsterer said it allowed the wood to breathe and flex while it repelled water.  Given the amount of wear and tear boat seats take, his experience taught him the wood would fracture and break down if glassed. We did use marine grade foam and naugahyde for the remainder We sold the boat a five years after we did this rebuild, so I'm not sure how they have stood the test of time. 

My original '76 Sanger built seats are treated wood frames. They have hung in there pritty well. But I have chose to glass all the frames we do now for the extra protection and durrability.

We did almost the exact same set up in my old boat and the issues ended up being leg room for the rear passengers and a spot for a cooler.

Re phrase that  "the cooler is the most important" . You get way more leg room if you do a two piece and the rear just a stright bench with a little leg room behind each of the front seats.
But in your case it looks really good and I would probably just go with what you have already.
That way you have a excuse if too many people want a ride.

All that really matters is that you have 1 extra seat and a cooler!! Screw the rest!!