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Old 03 August 2014, 06:19   #1
Country: Other
Town: Matosinhos - Portugal
Boat name: Game Club
Make: Valiant PT-520
Length: 5m +
Engine: Suzuki DF90
Join Date: Nov 2013
Posts: 16
Prop size

With my 5.2 m Valiant, fitted with a DF 90 Suzuki and a 13.25*17*3 Rubex prop from Solas, I get a little above 30 kts at around 5700-5800 rpm at WOT.
The rpm at WOT is above the recommended range for the engine (4500-5500).
Would a different prop size (diam or pitch) be recommended?



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Old 03 August 2014, 12:08   #2
Exe treme's Avatar
Country: UK - England
Town: Exeter
Make: Highfield
Length: 5m +
Engine: Honda BF90
Join Date: Mar 2013
Posts: 272
Hi Antonio

I know other factors can influence, but assuming your prop is in good condition, I would try a 19" pitch.

I run a 5.4m rib with Honda 90 outboard and 12.5 x 19 4-blade prop. I top out at about 36kts @ 5,800 which is right in my max rpm range.
My friend runs the same rib and experimented with a few different props, including a 17" pitch. He had the same issue as you with over-revving and low top end. He settled for a 13 x 19 3-blade and gets similar performance to me.

Hope that helps
Happy when wet!
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