So, my 2025 Bayliner VR5 200 hp 4.5L mercruiser STILL barely pulls me up

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,972
Well, turns out the vibration I'm getting is due to cavitation. It's putting cavitation burns on the prop.

Prop guy wonders if the prop sits too low in the water. His theory makes since. This boat you can't hardly even use the trim unless you're going below 10mph.

I was wondering if it was a balance issue, but maybe this motor and drive are installed to low. Looking into this.

Clearly the boat has the power to get me up with 6 people on the boat.
mercruiser has set up drawings on their website of the X dimension that is height off the bottom for the crank center line and thus keyhole. I doubt its off as if it were too low your front motor mounts would be bottomed out on the stringers

If you cant use any trim try a prop with more bite with some cupping. As an example I have a tested Merc Vensura 21" (also called offshore), Enertia 22", and Revolution 4 21". Like you I have 21 ft fairly azz heavy boat. With the Vensura I also couldn't trim much.

On paper I should have highest top speed with the Enertia. I was able to net best top speed with the Rev4 because I cab fully trim out. As you trim more you can see the spray line off the hull walking aft and wake size reduces.

The vensura had best holeshot because the smaller blades allow the engine to spin up in its power band faster, but slip was like 20% at WOT. The Rev4 is almost too much prop for good holeshot, but the vent plugs help on it. I do geta vibration from the cavitation in the mid 2000 rpm range that goes away.

bottom line big diff with these props over the Aluminum ones.

If you can get up slalom with 6 ppl in the boat with 200hp I think you are doing pretty good. Like you I fight bowrise I just dont want to bother with trim tabs.
 

stakultexsun

Seaman Apprentice
Joined
Aug 12, 2009
Messages
42
I'm terrified to try a pitch higher than 19. I have tried a 4 blade 17 pitch as well as a 3 blade 17 pitch (I'm now running the 3 blade 17 pitch, I haven't tried getting up behind it yet though).

The 4 blade 17 pitch seemed about the same holeshot as the 3 blade 17 pitch, but a little slower on the top end.

I will look into the props you mention.

However, I am looking for a good holeshot, the top speed doesn't really matter to me, though I'd like for it to be capable of 40mph (which it is with the 15 and 17 pitch props). Reason I want it to be able to go 40, is I ski around 32mph, and don't want the boat to be running high rpms just to pull me skiing, I think at 32 mph I'm around 3500 to 3700 rpms (but don't quote me).
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,972
I'm terrified to try a pitch higher than 19. I have tried a 4 blade 17 pitch as well as a 3 blade 17 pitch (I'm now running the 3 blade 17 pitch, I haven't tried getting up behind it yet though).

The 4 blade 17 pitch seemed about the same holeshot as the 3 blade 17 pitch, but a little slower on the top end.

I will look into the props you mention.

However, I am looking for a good holeshot, the top speed doesn't really matter to me, though I'd like for it to be capable of 40mph (which it is with the 15 and 17 pitch props). Reason I want it to be able to go 40, is I ski around 32mph, and don't want the boat to be running high rpms just to pull me skiing, I think at 32 mph I'm around 3500 to 3700 rpms (but don't quote me).
Sorry - not higher pitch, I meant the prop design is different than what you are running. You would use a prop with more cupping in similar pitch to what you are running.

Typically if switching from say 15" pitch basic aluminum like a black max prop, I would go down in pitch when switching to a prop with more cupping and or bigger blades
 
Top