Instructables
Picture of Transom Replacement with a plywood core
This tutorial will focus specifically on the most common type of transom job; how to replace/rebuild a plywood cored transom. We will show step by step the entire process using materials and techniques proven over many successful rebuilds. Following this guide will result in a rebuilt transom that is stronger and will last much longer than the original.

The boat featured in this rebuild is a 1984 Grady White. The boats owner is a local customer who purchased all his materials through our store and followed all of our technical advice, making this rebuild a great basis for the tutorial. The entire rebuild was  documented by the owner of e-boat inc. at our message board. (This is a link to the rebuild thread). We provide technical help for all sorts of repair/rebuild projects through our forum. To receive the technical support for your project, please register and read this thread detailing what information we need to be able to help you. All materials in this rebuild were purchased through boatbuildercentral.com

Step 1: Prep Work:

Before beginning demolition: Take measurements of all the parts around the transom; fiberglass thickness of outside skin, plywood thickness, inside transom skin thickness, stringer location, string thickness, etc... You will want these measurements as a reference later. Before removing anything structural you must have the hull well supported. Removing stringers and/or a transom with out properly supporting the hull can result in a deformed or "oil canned" hull. The best support is a bunk trailer with additional blocks under the keel and transom. If you have questions on supporting the hull, please ask them on the forum.

In our example boat, you can see the transom core is soaked and it has lost nearly all of its stiffness.

 
Remove these adsRemove these ads by Signing Up

Hi there

I have a 4.4 meter sea master fibreglass boat. I found after replacing battery the transom was rotten all around the aux motor bracket, the two hooks on rear and rot around where the 70 hp motor bolts on. It was up to the stage of scrapping out mushy ply with a screwdriver. I think it all started because all the penetrations in the transom where directly through the ply, with no source of water proofing around the internal part of the hole. Even around the bungs!!! is this normal boat building???

My big question is' I decided to fix it my self and have so far cut all the rotten ply and more, out of the transom flush to the floor in the boat. All the ply that i can visibly see is in good condition. Can i solidly make a new transom to the shape of my floor, and dowel it into good timber. Then glass it all in from there?

Trying to avoid disruption the floor/stringers to cut out the last little piece of the transom.

Any one got any ideas or advice on this??

no images at this stage

Mark

jerry492 years ago
I did this to my old Fibercraft ob boat 15 years ago. It is thill holding up wery well. In all my pass through points for deck drains, I used Marine tex and pvc pipe to seal any possible points of water intrusion into the core. Before removing the old skin I copied the boat serial number that was molded into the fiberglass. When I was done I used a dremel to engrave the numers into the new skin.
I brushed on colored gel coat to match the original boat color. It wasn't perfect, but close.
l8nite2 years ago
I helped a friend do this once, it's a LOT of work !