???Prop type

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Bill Krause

I have a 98 H240 with a Honda 8hp outboard. Over the years it seems have more than enough power and have no complaints about the motor. However it came with a two bladed prop and I assume the correct size. Sometimes especially if I am turning sharply or apply a lot of power the prop will cavitate and of course lose the bite to help turn/stop the boat. Has anybody else had this problem?? Is the answer a tree bladed prop or a larger size two bladed prop??
 
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Gus Elia

Which Way are you turning?

Bill, It might be caused by the direction you are turning the boat. With my engine mounted on the starboard side, if I try and make a hard turn to starboard the engine will start lifting out of the water, causing cavitation. If I am turning to port - no problem the prop is pushed further into the water and there is no cavitation. If I need to make a hard turn around, and their are no obstacles around, I will alway turn to port.
 
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Michael Bell

Interesting note from Chapman Piloting

I had always thought that cavitation meant the prop coming out of the water (or air being sucked down to the prop that’s near the surface), but… According to Chapman’s 63rd edition (p33) – “If the propeller tips spin to fast, the propeller will begin to cavitate.” (it goes on to explain what happens). “Ventilation is a different condition that is often confused with cavitation. It results from the propeller running to close to the surface of the water.” The solution to cavitation is reducing the propeller speed. The solution to ventilation is keeping the propeller in the water. ie a longer shaft on the outboard. You would most likely experience the same problem in four or five foot waves, as the wave will lift the aft of the boat out of the water. Personally, I wouldn’t do anything about it until replacement of the outboard is necessary. Just be aware of it, and be careful you don’t blow up your motor over-revving it.
 
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Dave Renouf

I have the same boat/engine

And I dont seem to have that problem, even when the engine cavitate (not ventilate) I still get pretty good thrust. I have the same Honda 8HP but I have the extra long shaft version, which version do you have ??? In big swell I do have the ventilation problem, but reducing speed seems to help a lot. daver Fate
 
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Bill Krause

Shaft length

I think I have the long shafted engine, but nowI'm going to check it and make sure
 
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