Normal WOT rpm's on 2010 4.3 mercruiser bayliner BR 195

[jim casparis]

Just bought this boat and replaced prop. I'm only getting 4500 rpm's at Wide Open Throttle (= 45 mph) and am wondering if I got the prop pitch right (23) when I ordered prop. Was told by previous owner that he'd had it up to 55 mph so just wondering what rpm is right @ WOT. (BTW can't find an owners engine manual for this boat anywhere... bought & downloaded sterndrive SERVICE manual for this year and model, but doesn't include this info)

 

[achris]

4400-4800rpm at WOT. (My preference is to prop to the very top of the range, espeically with the V6.)

 

[jim casparis]

Thank you very much!

 

[Kubaat3lover]

Ive got 19P and barerly reach 4400@ WOT …

 

[achris]

Ive got 19P and barerly reach 4400@ WOT …

I seriously suggest you change to a 17". Not sure of your boat or how it's loaded, but you might also benefit from trying a 4 blade.

Chris......

 

[jim casparis]

Thanks all for input. I guess 4500 with my 23p is acceptable, but am taking her out again today with new fuel & fuel system cleaner, and also will experiment with adjusting trim, to see how she performs. I've got my eye on a 14 3/4" SS prop with a 21p, but should wait till my budget recovers from this latest aluminum prop buy first. Is the diameter that critical in the equation? (I've now got a 14 1/4" ) There's also a 14" SS prop that's a little cheaper but wonder if making it smaller would rob performance?

 

[achris]

Thanks all for input. I guess 4500 with my 23p is acceptable, but am taking her out again today with new fuel & fuel system cleaner, and also will experiment with adjusting trim, to see how she performs. I've got my eye on a 14 3/4" SS prop with a 21p, but should wait till my budget recovers from this latest aluminum prop buy first. Is the diameter that critical in the equation? (I've now got a 14 1/4" ) There's also a 14" SS prop that's a little cheaper but wonder if making it smaller would rob performance?

The pitch is wasn't has the main affect on engine revs. The prop manufacturers then work with the diameter the try to give a consistent rpm change between different pitches, about 200rpm per inch. You choose the pitch and you get the diameter (for that pitch, in the style)..

Chris....

 

[jim casparis]

Thanks all for input. I guess 4500 with my 23p is acceptable, but am taking her out again today with new fuel & fuel system cleaner, and also will experiment with adjusting trim, to see how she performs. I've got my eye on a 14 3/4" SS prop with a 21p, but should wait till my budget recovers from this latest aluminum prop buy first. Is the diameter that critical in the equation? (I've now got a 14 1/4" ) There's also a 14" SS prop that's a little cheaper but wonder if making it smaller would rob performance?

 

[jim casparis]

Just returned from Canyon lake. At WOT with trim all the way down, I achieved 45 mph at approx. 4400 rpm, however upon raising tilt just a tad, the rpm maxed at about 4750, with an increase of speed to 53 mph. I was impressed and will keep this 14 1/4" 23p prop as my default prop. I did notice at that degree of tilt, it seemed to take longer to plane from a dead stop.

 

[achris]

Just returned from Canyon lake. At WOT with trim all the way down, I achieved 45 mph at approx. 4400 rpm, however upon raising tilt just a tad, the rpm maxed at about 4750, with an increase of speed to 53 mph. I was impressed and will keep this 14 1/4" 23p prop as my default prop. I did notice at that degree of tilt, it seemed to take longer to plane from a dead stop.

Assuming a 1.62:1 drive ratio...



I'd call that perfect!

Yes, trimmed up will take longer to plane, because the direction of thrust is slightly down, and that will push the bow up, making it harder to get up on plane. The trim switch is on the throttle handle for a reason, for you to use it. Trim in taking off, as you reach plane, trim out to lighten the load on the engine (and drive) and to give you and your passengers a smoother ride. I'm always on the trim button when I'm driving. I think I trim in and out more than change the throttle setting. Always trimming to find that sweet spot.

Also remember that if you want to start towing toys or skiers around to drop down a size (in your case, to a 21")...

Chris.........

 

[Scott Danforth]

Just returned from Canyon lake. At WOT with trim all the way down, I achieved 45 mph at approx. 4400 rpm, however upon raising tilt just a tad, the rpm maxed at about 4750, with an increase of speed to 53 mph. I was impressed and will keep this 14 1/4" 23p prop as my default prop. I did notice at that degree of tilt, it seemed to take longer to plane from a dead stop.

You should do your holeshot with the drive fully down

Slam the throttle forward, as the boat climbs out od the hole, be trimming up

Trim up until boat starts to porpoise, than tap down just a tad

No trim gauge needed, and if you follow that process it accounts for wind, load, current, etc