Propeller Questions

[aznewsh]

I apologise if this is in the wrong forum, seemed the most appropriate from what i could see....

I have a 1977 Sea Ray, 24' Cuddy Cabin with a small block chevvy/volvo 350

I have been having problems with my boat getting up on plane with my aluminum prop which I have recently identidied as 15D X 17P LH rotation, Long hub.

I visited a local prop store and since I wasn't able to provide WOT information, I basically asked what would be the next step down or rather a less aggressive props to make it easier for my boat to get on plane without losing too much on the top end. I would be interested to hear if other people's suggestions match up with what was suggested.

oh, for the record - he suggested 16D x 15P
he felt that would get the boat out of the water easier without losing too much top end.

Was really just looking for other opinions to see if they matched

[marshmat]

So a big, heavy boat with a torquey, low-revving engine. Large diameter square (pitch =~ diameter) wheel sounds good. As you get lighter and faster boats you want higher pitch and lower diameter, given the same power.

Look at a set of trim tabs. They can be good for heavy cuddies like this and can cut planing times dramatically.

Look also into different prop styles. If you're on good terms with your prop dealer he'll want to have you test a few wheels before you buy one. Ask him if more/less rake, a 4- or 5-blade prop, or a different cup style might help. You will need to write down the RPM at a few speeds with your current prop; measuring the time it takes to reach plane will also help.

(For reference- 'rake' refers to the angle that the blades sweep back, or come straight out of, the hub. 'cup' refers to the shape of the trailing edge of the blades, which are curved slightly to grip the water as it slides past the blade.)

[arees]

Can you send me the full details of your boat? please send it to:
"navalarchitectme@netscape.net"