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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 15883
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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Question I talked with you earlier this morning

Customer Question

Question for Jason I talked with you earlier this morning about my Z7 boat with a mercury 150 4 strike you ask me about what prop was on the boat now I went and checked it has a Tempest Plus 23P. does that help with a prop suggestion for a better hole
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello, Jason here again. I will re-work the math with prop number. But just to confirm, your top RPM is 5500, is that correct?
Also, do you have a speed reading from a GPS of what the boat is doing at that RPM?
Customer: replied 2 years ago.
yes right now top Rpm is 5500 and it should be around 5800 at 5500 rpm the GPS says 56-57 MPH
Expert:  Jason replied 2 years ago.
Okay give me a few to re-run everything.
Customer: replied 2 years ago.
Jason another question for you what height or distance from the center of the prop hub to the bottom of the boat pad be approx.?
Expert:  Jason replied 2 years ago.
Okay it does change a little bit. If you want to go with the High 5 it is going to be 13.25 x 21 this time. - part number 815760A46The Trophy plus is going to be 13.75 x 21 part number 825934A47 The trade off between the 2 props is the High 5 will have the best acceleration and hole shot, but at the trade off of lo0sing a little bit ofof top end speed. The Trophy Plus will have slightly more top end speed than the High 5, but, the holeshot will not be as good as the HIgh 5. (It will still be better than the Tempest however). On the 2nd question. It's really more of a height issue than distance. You want to lift the motor up with the jack plate as high as it will go before the propeller starts drawing in air from the surface and blowing out. Once you get a feel for it you can typically start to hear it before it actually blows out. The quickest way to find the best height is to get yourself at a cruise speed. Say 35 or so. Lift it up until you feel the prop wanting to blow out. And then drop it back down a bit. Then run it up to full speed. And then once at full speed you can usually get the motor up another inch or so, for an extra mile an hour or two. Does that make sense?

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