CONTINUOUSWAVE

I have a winter project rehabilitating a 1977 Sport 13. This boat came with only one thwart seat, which may or may not be salvageable. I plan to do all new woodwork myself. I have seen the drawings, and they are not complicated.

On-line I see mahogany wood for the 1-inch x 12-inch boards to construct the seats and console. Generally it says it is African mahogany, although occasionally I see some Honduran mahogany.

Q1: What are the merits of African mahogany?

Q2: What are the merits of Honduran mahogany?

Q3: Is there a reason to no use African mahogany, which seems more available?

The salvageable thwart seat appears to be a true 1-inch thickness. The dimensional lumber I see for sale says "nominal 1-inch and actual 0.75-inch"--like a 2 x 4 is actually 1.5 x 3.5.

Q4: Will a 0.75-inch board be strong enough for the seats?

Q5: Should I add some longitudinal bracing like a couple of 1-inch strips underneath to strengthen a 0.75-inch board?

If you want to duplicate the original thwart seats, they were made from 5/4-board.

In the US, building lumber is sized in rough dimension, prior to finish planing. A 2" x 4" when finish planed is 1-3/4 x 3-3/4 inches in dimension.

For you to purchase a wood board that is a true 1" thick, you would look for a size of 1-1/4" thick, commonly referred to as 5/4 or "five-quarter".

From first hand experience, I recommend against a thwart seat only 3/4 inch thick. My 13-foot Whaler had such, and it flexed in a disconcerting way. Two reinforcing strips (1" by 2") on the under side would separate from the seat, despite being well fastened with glue and screws.

Well, Tom, I wish I had seen your reply before I bought the wood. I found a good local source. The 5/4 they had was a little thicker, 1 and 3/16". So was the 4/4, at 15/16". Rather than have to sand down 3/16 on the thicker piece, I thought I could get away with being 1/16" thin on the 4/4. So, we'll see.

If it doesn't work, getting a new board isn't that big a deal.

For any readers in the Northwest, check with Crosscut Hardwoods. They had a pretty good supply. Stores in Portland, Eugene, and Seattle.