bbsb motor board ?

[john a]

hi all been back working on my sneakbox and need to make and install a motor board
I have a nice piece of wood that 1 1/4 thick 20 wide and 36 in long that im going to use
but I need help how high off the transom bottom? how wide ? and how thick should I make it
I could glue 2 pieces together to get a thicker board if need

 

[Dave Diefenderfer]

It all depends..... on the motor, and the hull shape. On my Sam Hunt, displacement hull with a 15hp Yamaha, I made mine 10 1/2" wide, and it now sits almost 19" from the bottom edge of the huill to the top of the motorboard. When I built it originally I had a 15hp Johnson. The Yamaha is longer. I spent a day playing with the height, having taken several pre-cut spacers with me. I tested each pin location for top end, then added a shim and repeated and kept adding until the numbers dropped down. I then permanently added the shims. I bolt my motor on, don't trust the clamp so the narrower motorboard is safe for me. Mine is 2" thick, mahogany.

What is the wood species? Hardwood? If you are going to use the clamps, then go a little wider so there is some safety. I suggest leave it long, and adjust it to your motor and boat trim.

 

[Dwight F.]

I can send you a pic of mine with measurements if you would like.
Boat was made in the 1950's and is 11' long.

 

[Steve Sanford]

Good morning, John~

You're getting good advice re height. Most Owners Manuals (you can download most from on-line sites) will give info about transom height BUT the shape of the hull bottom on sneakboxes can dramarically affect performance. So, experimenting is a good way to go.

I have made several from treated 2x12 lumber (Southern Yellow Pine) coated with 2 coats of marine epoxy and duckboat paint. I bore shallow holes to take the outboard clamps - to keep the motor from twisting right off the boat in a hard turn.

The spacers on this one are needed because of a molded lip on the 'glass hull.

The bottom is rounded to serve as a lifting handle.

All the best,

SJS