Moderated Discussion Areas
ContinuousWave: Whaler Performance
|Author||Topic: Prop advice|
posted 11-28-2002 03:58 PM ET (US)
I have a 1984 OMC v-4 engine on a 17' pre-smirk hull. Currently has the stock alum. prop which is 13 1/4 x 17. Not sure of RPM at WOT, but am satisfied with holeshot and top end speed, also not sure of speed at this time. Was thinking on upgrading to a stainless prop although. Found a deal i think on a Solas 13 x 21 new stainless prop for $100. My question is how will this prop perform to what I,m currently using? Forgot to add this is a 90hp engine. Not very familiar with propping, so any advise and input greatly appreciated.
posted 11-29-2002 01:08 PM ET (US)
Frankly, any advice given here would not be very accurate without at leas knowing what RPM's you are running now.
posted 11-29-2002 01:54 PM ET (US)
I agree with OutrageMan on this one.
There are a couple rules of propping that will kick in without knowing the top RPM and speed though.
1. As you increase pitch you will loose top RPM.
2. As you increase pitch you will probably loose hole shot.
3. As you increase pitch you may pick up top speed.
Don't buy that prop untill you have at least a wide open RPM with the prop you are now running.
posted 12-02-2002 09:17 AM ET (US)
21" no way in hell. 17" for a 90hp, maybe a 19" on a 115.
posted 12-02-2002 11:14 AM ET (US)
17" pitch SS Rapture for a 2001 90hp Johnson on my Montauk maxes out at around 5200 RPM
Don't go any steeper on the pitch.
posted 12-03-2002 01:20 AM ET (US)
Don't even think about it, it's not the prop for your outfit.
Believe me, if your engine has survived 19 years with a 17 pitch prop, the 21 is certainly not for you.
Think of it this way, your driving your stick shift pickup, pulling a 4,000 lb boat, you come to a steep hill, your foot is to the floor on the throttle, your now going 25 mph, but still in 5th gear, thats what will happen to your engine.
Going from a 17 to a 21" pitch prop is going to take 800 rpms right off the top of your engine, & that aint good.
I know your "NOT' running 800 rpms over your recommended max rpms now.
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