24ft donzi need prop info trying to get the boat to 5100rpm at 65mph. wanna keep as much holeshot power as possible.

Question

Answer 1

Answered in 26 minutes by:

6/20/2010

Marine Mechanic: K. Kergan, Marine Mechanic replied 12 years ago

K. Kergan, Marine Mechanic

Category: Boat

Satisfied Customers: 1,031

Experience: 24 yrs exp. Inboard/Outboard mechanic Mercury/ Mercruiser, Volvo Penta and OMC, Johnson/Evin.

Verified

Unfortunately no propeller will give you both more speed and more RPMs, there just is no such animal. To go faster you need more pitch which will rob you of RPMs. To have a good hole shot you need less pitch which will give you more RPMs but your top speed will suffer. The best thing to do is to have two propellers, one that lets the engine turn to the high end of the rated maximum RPM, this will give you a hole shot that is not dangerous to the engine if you open it up. The other would only let the engine RPMs up to the low end of the rated Maximum RPMs, this will give you the best speed without it being dangerous for the engine to open it up. The only way to get it to go faster at higher RPMs is to pull more horsepower from the engine. You would need to change props according to what you were doing that day. I know this isn't what you wanted to hear so sorry for being the bearer of bad news.

Answer 2

Marine Mechanic: K. Kergan, Marine Mechanic replied 12 years ago

That is something I have never tried to nail down because I found that I end up needing to use trial and error to find just the right pitch anyway. The one that gives you 4200 RPMs at 55 mph is likely about as fast as you will get. You might already be out of the max RPM range for the engine, do you know what the rpm range is?

24ft donzi need prop info trying to get the boat to 5100rpm at 65mph. wanna keep as much holeshot power as possible.

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