Does anyone with a similar boat as mine have a preference on a prop that like?

alamantia

Petty Officer 2nd Class
Joined
Dec 16, 2011
Messages
133
1) Performance issue you are trying to correct.
Greater top speed

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Aluminum 3 blade

3) Current prop diameter and pitch (required).
13" diameter with a 19" pitch

4) Wide open throttle RPM and speed with an average load (very helpful)
I never made it up to WOT, the boat planes off around 4000 and I cab back it down to 3200 while still maintaining plane. At 5000 RPM the boat went 39 on the GPS

5) Engine/drive make, model, year, and HP
260/350 mercruiser I/O with a 1.47 (i think) alpha 1

6) Boat make model, year, length and weight
1987 Wellcraft Elite 222 @ 4000 lbs dry, with gas and 2 people in it I suspect around 5000lbs


My first weekend ever driving a boat since I was 10 years old was unbelievable. My 25 year old wellcraft purred like a kitten. She got op on plane and and ran strong and smooth on my maiden voyage. I never placed the throttle in the wide open position because at about 3/4 throttle it would run at about 5000RPM, I did not want to exceed 5000RPM. When I bought the boat from the previous owner I took notice to the fact that he had little kids and water skis and tubes in his garage, he also lived on a small lake. I never did inquire as to what prop he had on the boat and why. I deduced that it was 13" by measuring it, and the number on the side of the prop said 19 so I think the pitch is 19" I am guessing that due to the size of his lake and the fact he towed skiers and I think the prop is a 19" pitch that I could go up to a 14" diameter 21" prop. But since I am new to this I decided to look thru the forum only to find out that propl selection looks to be a heck of an ordeal. I figure I see a lot of 21-24' single engine boats when I am out, perhaps there are people on this forum who can give me their personal experiances and point me in the right direction.

Thanks

2012-05-25_15-01-25_515.jpg


2012-05-25_13-12-55_885.jpg
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Does anyone with a similar boat as mine have a preference on a prop that like?

When I plug in the ratio, speed, rpm and pitch I show slippage of 36% which is way high. When I put in 15% slip that calcs to 50mph+ at 5000 rpm. I think the prop is a problem, perhaps it is the diameter. A 19 pitch should net you 49 or so at 4800 with 15% slip, so the pitch is not really the issue. All of this assumes the 1.47 drive ratio is correct.

http://www.marksmarineinc.com/prop_calc.aspx
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Does anyone with a similar boat as mine have a preference on a prop that like?

The diameter seems really small. Props listed here are all 14" or more some over 15.
May have been selected specifically for water sports.
 

alamantia

Petty Officer 2nd Class
Joined
Dec 16, 2011
Messages
133
Re: Does anyone with a similar boat as mine have a preference on a prop that like?

I removed the 13" diameter 19" pitch prop and replaced it with a quicksilver 14.25" diameter 21" pitch prop. I hope to try it this weekend, I hope I notice a difference.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Does anyone with a similar boat as mine have a preference on a prop that like?

It should behave differently in a positive way I'm sure. Great looking boat by the way :)
 

Robbabob

Senior Chief Petty Officer
Joined
Jun 5, 2009
Messages
678
Re: Does anyone with a similar boat as mine have a preference on a prop that like?

My $.02

Probably a good change and hope it keeps you from the over rpm. A little slower out of the hole, of course, but it may not be too bad.

Happy boating, again!
 
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