Prop advice

[othelloears]

Just installed rebuilt engine and need prop recommendation I have a 1984 well craft elite 200 with mercruiser 260/350 with 1.5 alpha. I was running a 228/305. While I am still working through qjet carb tuning issues, I have WOT of 4500 rpms with an aluminum 19 pitch prop. At 4400 rpms I am only doing 36 mph. At 3000 rpms I am doing 26 mph. It seems I have a ton of prop slip with these numbers. Although it is heavy The boat is completely restored and is not waterlogged.

Do I need 4 prop, more diameter. Why is slip so high?

 

[alldodge]

Re: Prop advice

This needs a bit more info on what boat/size/type is the new engine installed?
We need to know how heavy and what kind of boat your moving.
Also for prop info this should be in the prop section and QC/Bond-o will probably move it to help.

 

[othelloears]

Re: Prop advice

Its a 20ft bowrider. I believe its 2800 lbs

 

[achris]

Re: Prop advice

Yep, something seriously wrong here...

 

[brianspot]

Re: Prop advice

Who knows if this helps you but. I have a (1992 Celebrity Bowrider 200) The boat weighs 2850 dry weight and has just a 4.3LX mecruiser in it. I can get it upto 45mph and at that speed the rpms are running at 4800. The prop is a 19" quicksilvermirage stainless steel.

I too was looking at more speed. But in my search I purchased a apollo 21" stainless steel prop. It was a piece of......well you know.

I lost 5miles an hour, my rpms went from 4800 to 4200. The handling went from responsive to very loose.and my steering went from tight to loose as well.

I am returning my prop tomorrow and looking at the Mirage Thunderbolt. I hope it will be worth the price otherwise ill just keep the original prop and just have it rebalanced. Those are my numbers hope it helps in finding yours.

Just my two cents

 

[othelloears]

Re: Prop advice

The speed is gps. The tach is right. This rebuilt is supposed to be 280hp. Itotherwise runs great and accelerates great. Flattens outin seconds with 10 people in boat. What is a cavitating prop? Can a junk prop make that much difference?

 

[achris]

Re: Prop advice

... Can a junk prop make that much difference?

Absolutely!

 

[othelloears]

Re: Prop advice

Just tried an oversized mirage plus stainless 15.5" x 17 pitch. Wot was 4850 rpm at @41 mph. At 3k doing 27\28 mph. Wot numbers all make sense. And efficiency was better but not great. Recomendations? 4prop?

 

[Radarman68]

Re: Prop advice

"Flattens out in seconds with 10 people in boat."

oh my. 10? Seriously? Are you doing your 36 MPH with all those folks in the boat?

As a point of comparison, I have a 19 foot Century Arabian with a Merc 260 and MC-1 drive swinging a 14.25 x 19 three blade prop and get 51MPH at 4900 RPM with two folks in the boat.

You should be able to get within 5MPH of me. Remember each person weighs on average 180 LBS, so with 10 people, that is 1800 more lbs in your boat. it will be a pig with that much weight!

 

[othelloears]

Re: Prop advice

Tests are done w 1 or 2 people. Based on my rpms I assume I need a stainless oversized 21 or 4 prop 20. Recomendation please