Techno
08-20-2007, 08:53 PM
If your going to change your propshafts height you need to know what this height is. It isn't the top of the clamps or the cavitation plate.
Its where the center of the prop shaft is compared to the lowest point of the hull, the pad. On a Vee hull and modvp this is directly in front of the prop, so its easy :rolleyes: (don't be an ass if you have twins;) )
This measurement is a standard Its not where the water passes the prop. Its where everyone else will be comparing to so can relate. It like any other thing that is measured. It is this point to that point under these conditions.
A: Set the boat hull level, that is the pad is level not the deck or trailer. Put a level on a strake or other flat area near the back of the boat that is flat, no bumps. Again this is the bottom of the boat, the hull.:D
B:Trim the engine down till the prop shaft or cav plate is level.
Put a straight edge on the bottom of the boat and measure the distance to the center of the prop shaft. This is your distance that you can now say you have.
Now a disclaimer. You can be sloppy with the boat level, and the trim level and the measurement. Understand the person saying what they run or suggestion to you is pretty precise. I doubt they are off by 1/16" but if your talking bolt holes it don't matter since each one is 3/4" change.
If you have a jack plate mark it or attach a stickon or ss machinist ruler so you don't have to do this again!!!!
To take the magic out of it.
The purpose of this excercise, moving the engine up- is to move as much of the prop out of the water as possible. Its also moving the draggy parts of the LU out along with your controlling thing called the skeg. This is a measurement and NOT where the water passes the prop. It does mean you might not have water to the intakes:eek: :eek: :eek: :eek: :eek: :eek: Thats an eek for each cylinder.
You MUST have water pressure.
The reason for low water pickups but you can go up without them... which requires a water pressure gauge. Which tells you your up too far if nothing else tells you.
Without a water pressure gauge, even with LWP you have no idea if you have proper water pressure. No water pressure, no coolant, no engine in a very very short time considering the engine is running top RPM-full load.
Its where the center of the prop shaft is compared to the lowest point of the hull, the pad. On a Vee hull and modvp this is directly in front of the prop, so its easy :rolleyes: (don't be an ass if you have twins;) )
This measurement is a standard Its not where the water passes the prop. Its where everyone else will be comparing to so can relate. It like any other thing that is measured. It is this point to that point under these conditions.
A: Set the boat hull level, that is the pad is level not the deck or trailer. Put a level on a strake or other flat area near the back of the boat that is flat, no bumps. Again this is the bottom of the boat, the hull.:D
B:Trim the engine down till the prop shaft or cav plate is level.
Put a straight edge on the bottom of the boat and measure the distance to the center of the prop shaft. This is your distance that you can now say you have.
Now a disclaimer. You can be sloppy with the boat level, and the trim level and the measurement. Understand the person saying what they run or suggestion to you is pretty precise. I doubt they are off by 1/16" but if your talking bolt holes it don't matter since each one is 3/4" change.
If you have a jack plate mark it or attach a stickon or ss machinist ruler so you don't have to do this again!!!!
To take the magic out of it.
The purpose of this excercise, moving the engine up- is to move as much of the prop out of the water as possible. Its also moving the draggy parts of the LU out along with your controlling thing called the skeg. This is a measurement and NOT where the water passes the prop. It does mean you might not have water to the intakes:eek: :eek: :eek: :eek: :eek: :eek: Thats an eek for each cylinder.
You MUST have water pressure.
The reason for low water pickups but you can go up without them... which requires a water pressure gauge. Which tells you your up too far if nothing else tells you.
Without a water pressure gauge, even with LWP you have no idea if you have proper water pressure. No water pressure, no coolant, no engine in a very very short time considering the engine is running top RPM-full load.