I need help and guidance. I have a 20 ft 1969 flat top and have removed the rotted subfloor. I am down to the long spar that runs the length of the boat. (similar to a 2x4 turned on it's side and it is wet but not rotted. I am trying to dry it and prevent cutting it out since it isn't rotted. There were 2 planks that are wide at the back (transom) and slowly taper as it goes toward the front of the reinforced area. They were rotted and buckled and had to be removed. It looks like a poplar board (yellowish color) but not sure. What kind of wood needs to go back in place of the 2 long tapered planks? There is also a couple of hundred what looks to be like 1 inch thick 1 x 2 squares fiberglassed to the hull on the inside. It looks like a large checkerboard on each side of the planks. What are they made of and does it matter what type of wood I put back in? Can I use pressure treated 3/4 inch plywood or should I go with a plank? Can a get a single width plank or should I go back with 2 pieces like it was before? The wood was obviously a tight fit, and this is the first time I have done this, so is there some recommendations on how to get it a tight fit again? I want to do this repair right one time and have this boat solid. Any help would be greatly appreciated. Thanks.
Welcome to Hydrodyners. Check out this picture: http://www.hydrodyners.com/forum/download/file.php?id=2748&mode=view The spar down the middle is called the keel and is the backbone of the hull. It needs to be completely dry or replaced then glassed in. The tapered pieces of it should be replaced with similar pieces and glassed in. Check the outer hull around the keel for cracks. Since you are going to encase it with glass, I would think pine or any available lumber would be fine. Your hull has no rigidity at present and needs to be well supported and straight. The checkerboard is end grain balsa which is dipped in resin and laid in the hull then glassed over. Check on the internet for pictures of end grain balsa and how to order and deal with it. If it were mine, I would then install stringers over the glassed in balsa core and a flat floor on top of that if there is room. One more thing, I have never done this, but this is how the new boats are constructed. There is a lot of information on the net about this type of construction, it is common. Check your transom for rot. jim
