Best Prop/Pitch for 90 Merc on Pontoon Boat

BigRedJim

Recruit
Joined
Sep 18, 2013
Messages
2
Wondering what best prop pitch would be to maximize speed when pulling a skier or tube. Have a 2003 90 horse 2 stroke on a 21' Misty Harbor pontoon. Gear ratio is 2.33. Current prop is 14 x 13 but damaged. WOT is about 5800 (should be around 5500 or a little less I think but may be due to damaged prop). Top speed is about 24-26 and around 23 with 150lb skier. Have looked at Black Max Extra Cup - wondering if extra cup really solves some cavitation issues. Partial to aluminum versus stainless and 3 blade versus 4 but could be swayed. Have done the calculator and it says 13 or 14 pitch but really would like some feedback on tradeoffs of power versus speed. Thanks for any input.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Best Prop/Pitch for 90 Merc on Pontoon Boat

Is your speed by gps? At 26 your allready faster then similar tests I've seen.
I think a sound 13" prop should do well. Solas Amita and Rubex have good reputations
and I think will resist ventilation(cavitation).
If you try as 14" speed may be a wash but it may fade faster with a skier.
Also could have more ventilation problems.
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Re: Best Prop/Pitch for 90 Merc on Pontoon Boat

My 24 ft Tracker toon with Merc 90 runs a 15 pitch at 5300 rpm.
 

BigRedJim

Recruit
Joined
Sep 18, 2013
Messages
2
Re: Best Prop/Pitch for 90 Merc on Pontoon Boat

Is your speed by gps? At 26 your allready faster then similar tests I've seen.
I think a sound 13" prop should do well. Solas Amita and Rubex have good reputations
and I think will resist ventilation(cavitation).
If you try as 14" speed may be a wash but it may fade faster with a skier.
Also could have more ventilation problems.

Thanks. Speed was measured off of factory installed speedometer so may be a little wishful. Any thoughts on a cupped prop?
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: Best Prop/Pitch for 90 Merc on Pontoon Boat

Generally a cupped prop will resist venting and should have better slip numbers.
Where the cup is placed will also affect the boats reaction.
"Extra" cup may not necessarily be good.
 
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