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Author Topic:   Propeller for 22 Guardian with 140-HP
jettycat posted 01-16-2004 02:55 PM ET (US)   Profile for jettycat   Send Email to jettycat  

I have a 22-foot Boston Whaler GUARDIAN with a 140-HP Evinrude engine. What would be a good prop to run? I operate mostly long distances at high engine RPM, and only for fishing open ocean purposes.

Plotman posted 01-16-2004 03:20 PM ET (US)     Profile for Plotman  Send Email to Plotman     
What is the gear ratio of that engine? --that is the first thing to check.

I have a 22 Outrage with a Mercury 200 and I run a 17-inch prop at a 1.87:1.

Assuming a similar ratio, I would start with a 15" That isn't a lot of engine for that boat.

Sal DiMercurio posted 01-16-2004 08:29 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
First of all, a 140-HP engine on your 22' is just about bare minimum. You are not going to twist much pitch at all.

My guess would be you might just have to swing what is called a square prop. A square prop is as far from a performance prop as you can get without going to a house boat prop. The diameter & pitch are the same numbers on a square prop. I'm going to say either a 13.25 x 15 or a 13.25 x 13.25 for a 140 hp engine on your 22' boat.

If I am not mistaken that engine is rated at 5,500 RPM maximum and it's "VERY, VERY, VERY --I think you get the drift--IMPORTANT" that the engine is able to reach its maximum speed or you will blow the engine for sure. Running your engine with too much pitch in the prop is like driving your pickup with the boat behind you in 5th gear up a big hill. Your foot is to the floorboard but your tach says 2,800 rpms, your speedo says 35 mph, and it is dropping. Your truck engine wouldn't last very long if you ran it that way all the time, same with the boat engine.

Remember this, there is no such thing as going downhill with the boat engine, it's ALWAYS uphill, no exceptions.

jimh posted 01-16-2004 09:30 PM ET (US)     Profile for jimh  Send Email to jimh     
[Edited portions of this thread to improve readability.]

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