Measuring Prop Shaft Height

[Largemouthlou]

This is one way to measure your prop shaft height.. Any one running over 15-20 psi needs to check their height..


Set up is a big key to a smooth running boat, first you must check out the prop shaft to pad measurement. To do this you use the 4' level again place it on the bottom of the pad, dead center of the boat going longways, have some one raise or lower your trailer jack till it reads level, then place a Small level on the motor cavitation plate and trim up or down till this reads level, now take the level and use it as a straight edge on the center of the pad, and run it out to the lower unit, measure from the side of the level that is touching the pad to the point of the lower unit, this will be you prop shaft height, either above or below the pad.. If I didn't word this right and there is some confusion, please ask for clarification Louis

[Rudeman]

Good post Lou. Do ALL outboards have the same water pressure requirements, or should guys check with manufacturer's recommendations before changing motor height?

[Largemouthlou]

All should ck manual That is why I said check motor height not change!! But I don't know of any that are higher then 15 -20.. This is just for a refference to ck engine height Louis

[drfish]

Like Lou said, most engines should be in the 15-20psi range. Some pressure guages are not terribly accurate however. Freezing, dirty tubes, etc can affect the accuracy of the guage. If you have an older boat it would be a good idea to check the water line for obstructions and then watch for changes in pressure when you raise and lower your motor. If in doubt about the condition of your gauge, change it out before raising your engine too high and ruining your engine.

[Largemouthlou]

Very good advise!!

Most stock motors will be around 3" BELOW the pad that is a good starting point!! Always watch water pressure guage after raising motor and double ck you measurements Louis

[Bryan Hester]

HOW DO YOU MEASURE MOTOR HEIGHT WITH A HYDROLIC JACKPLATE. DO YOU NEED TO SINCE YOU CAN PUT IT WHERE YOU WANT IT?

[drfish]

Measure the height or find the best setting for your hydraulic plate and then make a mark on the plate for a reference point. You'll find that you won't move the plate much from this point unless you go way up for shallow water or way down for the rough stuff.

[Largemouthlou]

Mike, are ya sure you are 6" below?? You really need a water pressure guage before ya even think of raiseing the motor.. Sounds like ya might need a 4 or 6" jackplate to be able to raise her.. Louis

[Al from Canada]

Mike........sounds like you need to install a water pressure gauge (fairly simple and not expensive), and then get a jackplate. If you're 6" below the pad you're probably 2.5" to 3" to low.

[Al from Canada]

It wouldn't cause a problem; it would just be back the thickness of the aluminum. You're sure that you're measuring correctly and it's 6" below pad, correct? (Would guess it probably is if it's right down on the transom.)

[kp crane]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drfish &raquo;</TD></TR><TR><TD CLASS="quote">Like Lou said, most engines should be in the 15-20psi range. Some pressure guages are not terribly accurate however. Freezing, dirty tubes, etc can affect the accuracy of the guage. If you have an older boat it would be a good idea to check the water line for obstructions and then watch for changes in pressure when you raise and lower your motor. If in doubt about the condition of your gauge, change it out before raising your engine too high and ruining your engine.</TD></TR></TABLE>i would also like to add, if you have an older boat or especially if you just purchased an older boat, 1st thing, have the water impeller replaced! a worn impeller can also mess with your pressure readings.IMO....