'92 270 DA prop opinions

[akwalker]

Greetings,

Thinking of a new prop for next season. Currently running a 17.5X23 aluminum 3 blade. Engine is a 454, 2 year old repower. Bravo II outdrive, 2.00 gear ratio.

My top speed is 32 kts, GPS @ 4100 RPM WOT.

Thinking I may be slightly overpropped. Was thinking of trying a 17.75X21.

Opinions/info, please?

 

[wakeup 19]

That will increase rpm and get it closer to range. What does sea ray recommend?
Older engine? Or heavier now than when new can cause loss in RPM. was it always on lower end of scale

 

[akwalker]

That will increase rpm and get it closer to range. What does sea ray recommend?
Older engine? Or heavier now than when new can cause loss in RPM. was it always on lower end of scale

Boat was repowered 2 seasons ago, maybe 120 hrs on the engine. We picked it up this past spring, so no history before this season.

The 17.5X23 is what Sea Ray recommends, as what was installed when the boat was new. According to Mercruiser calculator, the smaller 17.7X21 should bring the engine closer to WOT specs. Just seems like dropping 2" of pitch is a big change, but there's nothing I've found between those 2 sizes.

 

[wakeup 19]

Check with Hill Marine if you have all your rpm ranges and speeds. They are excellent at measuring prop slip and give recommendations