[Ed]

Gents-

The problem with doing an outside transom job versus an inside transom job is that an outside transom job is more structurally invasive and MAY affect the geometry of the hull. However, inside transom jobs are more work and sometimes require working in confined areas.

Definitely lay up one (or two- depends on how much room you have to work with and what the shape is of the inner transom) layers of mat first against the inside of the transom and temporarily bolt, screw, etc. it in place. I also like to make fillets around the entire perimeter of teh core material. It helps adhere the core edges to the hull, keeps water out and also gives you a rounded surface to roll out the glass on versus a hard edge if you did not use them. Fillet materials can be made out of any type of resin, by adding cabosil, Q-cell or microballons.

As far as layup schedule is concerned, that was just my recommendation based on the transoms that I did when I used to work at a restoration facility. Yes, that's a lot of glass on the inside (bilge side) of the core, but with today's motors weighing what they do, why take the chance and skimp on materials? The important thing is to make sure that each layer has enough resin (but not too much resin)on it and is rolled out tightly to promote good adhesion and eliminate any air bubble. Also, if you are using biaxial in between layers of mat, it is a good idea to use alternating layers of different orientation (45 degrees, 90 degrees, etc).

As far as what resin to use (polyester, epoxy, vinylester) there are pro's and con's to each. It all depends on the project at hand and what your budget is.

The important thing to remember is that each job is different and to take your time and do things right. As EBEACH said, DEFINITELY dry fit everything (glass, core material) before you start rolling on resin.

Hopefully this helps.

Ed