NEW FLOORS, CARRIAGE BOLT PHOTOS FOR YOUR ANALYSIS, FIRST BOTTOM FRAME SCARPH CUT

[bob mitchell]

    Yesterday I spent the day making floors (the bottom cross pieces of the frames that rest on and are bolted through the apron) out of white oak. I did not expect to have to replace so many ( 8 out of eleven pieces), but it is area of the boat where the main mast step is seated, and these are the frames that transfer all that torque to the rest of the boat. It is the area where a collision might be felt. And finally, it is the area where the stove pipe, the mast, and the chainplate can let water into the boat to do damage. The floors with the notches are where the mast step sits.

Old ones were rejected for various reasons, even though they initially looked ok. Number 8 was brittle, ie the piece of wood had some original strange grain patterns that were stressing badly. Another looked ok until you poked around in the bolt holes and found a lot of pithy wood. And some were just shot - like the rotted number 10 and 12.

 One point I would really emphasize. SAVE the old frames, because when you go to install the new ones the subtleties and questions that pop up can only be solved by lining up the bolt holes of the original floors. Drilling the new holes is a thoughtful back and forth dance between what stays and what leaves when. Think it through ahead of time.

      I have included a photo of almost all the bolts I took out - certainly a representative data collection. Overall I was impressed with the amount of metal left. Once again, it was not really the galvanized metal that was the problem, it was the degradation of the wood surrounding the metal, which I  believe was a combination of crushing the wood fiber in the first place and then 43 years of electrolytic corrosion between the bronze keel bolts and the galvanized floor bolts. Still, even the boat nails in the apron holding the sheathing on had significant holding power.  I plan to reduce the electrolytic action by dipping all my new galvanized floor bolts in epoxy ahead of time and letting them dry, giving somewhat of a tough insulating coat.

And finally, I had my first discernable motion when I took the iron strap off around floor 9. The strap shifted 1/8" to port, indicating some imbalence in the bracing.

       I also made my first bottom frame member scarf cut today. I have tested cuts in both dimensions, and not only is this the easiest cut to make, but from my tests it is the consistently the strongest scarph.  The boatnails that connected the sheathing to the frame I am scarfing were rusted but substantial, and the heads pulled through the damaged sheathing when I pryed the frame part up. Photo is underside of bottom frame in water damaged area, along with the four boat nails I pulled out of the frame with CONSIDERABLE effort.