After stripping the bottom planking off (see Remove the Bottom), it’s a good time to take another look at the soundness of the bottom framing. Now you can see it from it’s most vulnerable angle–the joint between the frame and the bottom planking. This is where water is most likely to collect (the bottom of the bilge) and be absorbed into any unsealed wood. Remember, any wood with over 20% moisture content is a great place for rot spore to grow. The factory may or may not have sealed this joint with paint, but that was 60 years ago.
After taking another look at the bottom framing, it’s in pretty good shape for being 60 years old, but still, it is 60 year old wood. It leaks around the transom joint, and is oil-soaked under the engine. We’re going to be putting a newly rebuilt engine in this boat and it is, after all a speedboat. You wouldn’t put a new engine in a 60 year old car without addressing the chassis. It would soon shake apart.
Aside from all that, the original bottom frames are made of Philippine Mahogany–a wood with little to no rot resistance. We’ll replace them with white oak which is a traditional boatbuilding wood because of it’s good fastener-holding and rot resistance properties.
We’ll use the old frames as patterns to cut out new ones. Then we’ll install each new frame, using the old keel and chines to get the lines right, along with battens, and bevel the new frame in place.
Finally, disassemble the whole thing, seal the new frames properly, and permanently install them. This gets the new frames sealed at the joint surfaces–a very important step that keeps them from soaking up moisture where you can’t see it.