gerard

hi all
im running a stock 30 bravo on a merc diesel @3800 rpm getting 52 mph
the boat is 4900lbs
so what i was thinking my max rpm would be the same as your cruise rpm
what prop would you use for max speed at cruise 3800

cheers gerard

mikebrls

have you tried a bigger prop let say a 32 pitch 4 blade and if you did what was the top rpm with that prop ?
if you were 200 or 300 rpm lower then your 3800rpm max you can lab a 32 and pick up the difrence in rpm and have a faster cruise speed

mike

Stormrider

gerard, we need to know what rpm max torque is at, and what is max rpm for the engine?

Griff

Your propslip is about 26% which is way too high. You should be able to get it down to around 16%. I ran about 52mph at 4000rpms with a 26 Bravo prop. Your boat is also about 400# lighter than mine was.

Where is the X dim or propshaft height set at?????
You may want to consider a 5 Blade Maximus or P5X prop.

gerard

hi again thankyou all for your replys

the max torque is 526ft lbs @2400
and the max rpm is 4000
the x was 17.5 and i added a 1" spacer and it made no difference
with the drive tucked under the boat im getting 3600rpm 49mph
and when i trim it out i only gain 3mph
the cabin is gutted so there is little weight up front
i had a 28 b1 before the 30 and it was 50 mph @ 4000