Did a little more work with Inventor last night.  Haven't figured out how to make the hull yet but I did finish up he bulkheads, including the new one which will make t he companionway opening.

I have worked on the 3D Model somemore over the weekend.  Ideally, I will be able to print full sized templates for the new cabin framing or possibly have them CNC cut.  Still have more work to do, but it is starting to take shape.

Also, I want to mention that I have been talking with Mark Gumprecht, a great small trimaran designer, and he has been giving me some advice on beam construction.  It is always nice to talk with people like Mark who offer advice and help for amatuers like myself.  Thanks Mark!  Check out http://smalltrimarans.com/blog/?p=7027 for his latest project!

I am trying to build a 3D model of the boat so that I can figure things out as I go, but I think I am limited by software.  I am using Autodesk Inventor 2012.  Not the best option but its what I have.
Below you will see an attempt at an initial assembly.

I worked a little bit on the rear beam design...in 3D.

Beam Idea

Below is a sketch of how I intend to build my box beams...I will build a rough prototype this weekend to test my thinking.

Transom Work

Over the weekend I was able to add the transom extension...I need to sand and fair into the existing hull, then lay 1 more layer of fiberglass down.

SO it Begins

This is the beginning of what I hope to be a LONG career of boat building...

The project is to build 22+ ft Trimaran Sailboat.  It all started when I was given hulls from someone else's project!  SO, I am carrying on the legacy, so to speak.  The original use for the hulls were for a 22' home buildable Catamaran called Janus.  It was designed by Woods Design.  When I recieved the hulls, one was mostly complete, while the other was not. 
Now I have been designing RC model sailboats for some time now, but that is another story...Anyway, I have been dabbling with a full sized boat project for some time now and now with the materials provided for me is the perfect chance to build a small trailerable trimaran.

The hulls...

Here I have already cut out for the new beams and additions I plan.  So perhaps we should start with the design first....