Re: 68 duo restoration
I am not familiar with the specific model you mentioned. Generally stringers and decks are made using plywood as a replacement. Dimensional lumber could be used but it is more expensive for custom lengths. Also plywood can be built stronger than dimensional wood at a lighter weight.
If the deck is to be finished rather than coated, (stained) then I would go for a veneer or a high quality marine ply rather than dimensional depending on the value of the boat. Older wooden boats that are finish stained or oiled are pieces of art, I would certainly go back with what was original in one of those boats.
The size would be dictated by what was there originally. If they are not there to go by, then I would build the stringers and deck according to the original deck elevation in the hull. The thickness of the wood would be dictated by the finished height of the deck. I would use the thinnest material that will maintain the integrity of the deck to save weight.
Some pictures of what you are working on would be a big help.
To get answeres about your Mercury post in the Mercury engine forum or in one of the engine forums.
