1958 Alumacraft 12' boat with 1973 Merc 7.5 outboard.
Transom length: 15"
Shaft length: approx 17" (top of transom clamp to bottom of cav. plate)
The best I could measure the bottom of the a/v plate is approx. 1-3/4" below the bottom of the hull. The attached Pix will illustrate that the top of the 2x4 resting on top of the a/v plate is even with the bottom of the hull.
The 2x4 is 1-1/2" thick plus approx. 1/4" to the bottom of the a/v plate = approx. 1-3/4" below the hull bottom.
Reading other posts, the bottom of the a/v plate should be even with the bottom of the hull. That said, I have read that on older motors since the water pump is not self priming and located above the a/v plate, that the motor should be low enough that the water pump is below the hull bottom.
The top of the water pump is nearly flush with the rib above the a/v plate where the lower unit attaches to the upper unit.
I am confused which is correct. Do I need to raise the motor on the transom?
Another pix illustrates the motor raised 1-1/4" which would raise the bottom of the a/v plate to approx. 1/2" below the hull bottom.
I would place a reinforced spacer to accomplish the raising of the motor and also bolt the motor to the transom.
I have read many threads concerning these issues, but have only come away with more questions and confusion.
I have recently replaced the water pump and had a broken skeg repaired. The motor runs great in a barrel with plenty of flow through the pee hole and I would like to resolve the motor depth issue before I take it to the lake or river.
All advice will be appreciated.
Chief Bob
Transom length: 15"
Shaft length: approx 17" (top of transom clamp to bottom of cav. plate)
The best I could measure the bottom of the a/v plate is approx. 1-3/4" below the bottom of the hull. The attached Pix will illustrate that the top of the 2x4 resting on top of the a/v plate is even with the bottom of the hull.
The 2x4 is 1-1/2" thick plus approx. 1/4" to the bottom of the a/v plate = approx. 1-3/4" below the hull bottom.
Reading other posts, the bottom of the a/v plate should be even with the bottom of the hull. That said, I have read that on older motors since the water pump is not self priming and located above the a/v plate, that the motor should be low enough that the water pump is below the hull bottom.
The top of the water pump is nearly flush with the rib above the a/v plate where the lower unit attaches to the upper unit.
I am confused which is correct. Do I need to raise the motor on the transom?
Another pix illustrates the motor raised 1-1/4" which would raise the bottom of the a/v plate to approx. 1/2" below the hull bottom.
I would place a reinforced spacer to accomplish the raising of the motor and also bolt the motor to the transom.
I have read many threads concerning these issues, but have only come away with more questions and confusion.
I have recently replaced the water pump and had a broken skeg repaired. The motor runs great in a barrel with plenty of flow through the pee hole and I would like to resolve the motor depth issue before I take it to the lake or river.
All advice will be appreciated.
Chief Bob