? for guys with BBSBs

J

john a

Active member
getting ready to install motor board on my sneak ? is if I put a wedge of 15 deg then my 2in thick motor board what is your measurement from edge of transom to first edge of motor board. and how thick is your wedge at bottom and top of transom
thanks for the help and I hope someone knows what im talking about
 
John, if I understand your question, I don't think we can answer it without knowing the depth of your hull's transom? The length of your motorboard will be dependent on your motor primarily. I would use all the bearing surface of your transom or at least 12" if more is available. Cut your wedges longer than you need, ensure that you either leave a gap for drainage between the motorboard and and transom at the bottom, or plan to fill in the space at the top. But the distance between the top edge of the transom and the motorboard will really depend on the depth of your hull.
 
John,
Check the diagram below to make sure I understand your question. The red triangle shows the 'wedge' that you're asking about. What it comes down to is the top thickness of that wedge, and it is based on the height of the wedge.

It's a trigonometry problem where height x tangent of 15 = thickness at top

thickness = height x 0.27

so, assuming your wedge is the same height as the transom as Dave suggests, height is the existing transom height. You could add a spacer between the transom and this wedge if you like as long as it is the same thickness top to bottom.

View attachment Untitled.png
 
I think Dave and Scott are on the money. Another factor is the height of the motor mount. To get optimum out of the motor, height is important.
I set the cavitation plate is about 1" below the transom. It's been a while, but I'd check with a few of the guy's here...
 
To get optimum out of the motor, height is important.
I set the cavitation plate is about 1" below the transom.
Click to expand...
John, as Rich notes, trimming the motor is critical to performance, though depends on both the hull shape and the motor you are using. The 1" below the transom is a standard rule of thumb.... but really applies mostly to planing hulls. The configuration (shape) of the cavitation plate will have some bearing too. Some motors have a cavitation plate around the lower unit, some only on the sides and back. Best to leave the mount long or install a temporary board for sea trials and testing, then finalize it once you have it determined. If you have a displacement hull, you will likely want the motor a little higher than if you have a planing or semi-planing hull.
 
ok guys so what I think im hearing is their is no true measurement
my transom at center line is 7 .5 inches and going by the diagram above it will be 3in from transom to leading side of motor board
guys thanks for all the help john
 
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