Repower ?

[Rbmack5]

Hi all I’m new and looking to buy a 32+2 or 35 .I haven’t seen any post’s about repowering .most boats for sale have a LOT of hours .Im wondering if I can repower with a Cummins qsb 5.9 with 480 hp should give a cruise around 22knts .your thoughts ?

[Rbmack5]

I think I made a mistake ,I think the qsb 5.9 will produce 435hp ,or maybe a 6.7 that makes 480hp.

[hulamoon]

Hey, I run a 1989 32 Sportfisher and just repowered from the original 6BTA 250hp to a 6BTA 315hp (I hate computers when cruising). Total gear reduction is 165:1 and I am currently running the original Dyna Jet 22 X 19 3 blade prop which gives me a cruise of 18 kts. and a top end of 21 kts. I do need to re prop as at WOT I am bumping the high idle limiter at 3225rpm (my engine is rated at 2800). I was thinking of going with Michigan DQX 4 blade with a size of 21 X 22. Increased tip clearance and the additional blade should help smooth things out and the additional blade and increased pitch should help eat up those extra 425rpm and turn them into added thrust. I'm hoping for a cruise of 21kts and a top end of 23-24 kts. If I get a bit less, that's OK. The 480 hp your considering is more than enough horsepower but the 32+2 is a semi displacement hull, same as my Sportfisher, and designed hull speed may be difficult to go beyond regardless of horsepower.

[Jhill]

I have a 35 with 6LY2A-STP 440 things get tight to work on with the exhaust blocking the starboard side of the engine. Make sure the engine will fit.

[Rbmack5]

What kind of cruise are you getting ?

[hulamoon]

Hey, I run a 1989 32 Sportfisher and just repowered from the original 6BTA 250hp to a 6BTA 315hp (I hate computers when cruising). Total gear reduction is 165:1 and I am currently running the original Dyna Jet 22 X 19 3 blade prop which gives me a cruise of 18 kts. and a top end of 21 kts. I do need to re prop as at WOT I am bumping the high idle limiter at 3225rpm (my engine is rated at 2800). I was thinking of going with Michigan DQX 4 blade with a size of 21 X 22. Increased tip clearance and the additional blade should help smooth things out and the additional blade and increased pitch should help eat up those extra 425rpm and turn them into added thrust. I'm hoping for a cruise of 21kts and a top end of 23-24 kts. If I get a bit less, that's OK. The 480 hp your considering is more than enough horsepower but the 32+2 is a semi displacement hull, same as my Sportfisher, and designed hull speed may be difficult to go beyond regardless of horsepower.

Just completed successful shake down with the new prop. Cruise is 19.8 kts @ 2400 rpm and top end is 24 kts @ 2800 RPM. The gamble paid off in a big way. I'm very pleased with the performance and also how much less vibration is generated by switching to the 4 blade with increased tip clearance. Smooth as silk now.

[Swede]

Hulamoon,
What was your cruise and max speed with the original 250 HP ?
I'm looking to repower at some point with either the 300 or 370 HP but will make due with what I have now. I bought the boat and it won't go over 2100 rpm and I'm almost certain that over propping is the culprit as I found the original 19x22 on board. Swapping it out this Wednesday, hence my curiosity..
Thanks,

[hulamoon]

Swede,
With the original 250 and 22 X 19, not 19 X 22, I would cruise at about 14 to 15kts and topped out at 18 to 19kts turning 2600rpm. The boat was definitely underpowered with the 250. Much happier with the 315.

[Swede]

Thank you for the response, just got her out of the water.

[hulamoon]

Just curious as to how you made out with the prop change?