Testing Prop SIzes Need Advice

[badjo]

I have an 18ft Champion with a 175hp Mariner.

I was having trouble getting this boat to rev over 1800rpms and tried all sorts of fixes only to try some different prop sizes and like magic she ran.
oh well dumb me.

I am trying some different sizes but this is the prop thats on the boat now.
3 blade J 15 x 17P

From a dead stop if I give it full throttle it is slow to gain its revs to take the boat up on plane. WHen it does get on plane it runs well and limits at 5k rpms.

What prop could I try that would not take so much time to get going?

I am kind of new to this so if more info is needed let me know and I will get it.

 

[12vMan]

Re: Testing Prop SIzes Need Advice

Dropping the pitch will get you more power out of the hole. Are you running at altitude? That usually requires a lower pitch prop to get the same results that a higher pitch prop would get at sea level.

Props are gauged diameter X pitch. Your diameter may be a little wide. Usually a 14-1/4 X 17 gives adequate power out of the hole. Are you having to buy these props or borrow them?

 

[codertimt]

Re: Testing Prop SIzes Need Advice

I hate to be the bearer of bad news, but I think you still have motor problems...

I read through some of you're posts in the engine section, but didn't get a good idea of what you have actually done... Have you ran a compression check? Because it sounds like you're really down on power big time. An 18' bass boat with 175 on it should be able to turn a prop in the 23-25" range and reach speeds in the 60mph range. If you can only turn a 17" prop to 5000rpm(probably upper 30s in mph) and it's slow to plane, then there is something going on with that 175 still...

 

[Bondo]

Re: Testing Prop SIzes Need Advice

I was having trouble getting this boat to rev over 1800rpms and tried all sorts of fixes only to try some different prop sizes and like magic she ran.
oh well dumb me.

Ayuh,.... I Agree with codertimt,.....

Either you're Seriously down on Power,....
Or,...
Your Outdrive is geared for a V8......

I believe the former.....