Propping a 3.0 in a 19'

[smartwork]

I currently have a 3.0LX in a 19' Bayliner. WOT I usually get between 40 and 45 @ 4000 with 2 people. I believe for this engine, I have about 400-600 more RPM at my disposal, so I'm cosidering repropping to get me into this targeted range... while improving my hole shot which we use more than WOT cruising.

Current prop from previous owner is a 3-blade Stiletto M1423 which I believe is a 14 x 23 Stainless and cupped. I love the prop, but it it may just be a little too much for our goals.

I'm considering the same brand prop but going to a 4-blade (for hole shot) which I believe costs me 1+ "jump" in size, so that would start me at a 14x22. Then, if I want to increase the RPMs, I would drop another size or two bringing me to a 14x20 or 14x18.

Any feedback or advice on that? I really like the current prop, so I don't mind staying with that brand. I believe the 4-blade and increase in RPMs will help satisfy our hole shot and bring us in the optimum performance band for that engine. We don't mind losing a bit at WOT for our general use (plus, we'll still have the current prop).

 

[steelespike]

Re: Propping a 3.0 in a 19'

I think your doing amazingly well.Your speed may be a little optimistic.
I'm surprised the prop can provide overall good pertformance.A 23 is really up there for a 3.0 in a 19.A 4 blade in a 18 or 20 chould be amazing.

 

[tawood]

Re: Propping a 3.0 in a 19'

I also have a 3.0L in a 19' bayliner....either you have different gearing then I do, or your tach (or speedo) is way off...I also can see 44mph (gps), but at 5000 rpm w/a 21p. I just picked up a 23p to bring the rpms down a bit.
I also have a 18p 4 blade that has a great hole shot, BUT it is very inefficient and also considerably drops my top speed.
Tim

 

[steelespike]

Re: Propping a 3.0 in a 19'

I'm not surprised that smarts ss23 keeps the 3.0 at about 4000 and 40 may be stretching speed a bit @ 4000.I am a little surprised that a 3.0 can do 5,000 on a 21" prop. in a 19 ft. That must be a pretty fast hull.Typically you see 3.0s doing a "little over 40"Especially in a 19.

 

[smartwork]

Re: Propping a 3.0 in a 19'

All I've got is the dash tach and speedo to go on (no gps or external tach). Usually hitting 40 is no problem. Over 40 depends on water conditions, but with glass water, 40-45 registers on the speedo.

tawood - do you not like your 18 4-blade? I read up on all this last year and then held off because our hole shot was "good enough" for the time being. This year, I would like to yank wakeboarders out a little faster, so I'm revisiting the issue. It sounds like our set-ups are very similar though because if I dropped to a 21 like yours, our speed and RPMs would probably be close. With our prop being cupped, it may be accounting for some of the RPM differences between ours. Do you know what your top speed is with the 4-blade?

Just based on how the engine "feels" in terms of how it sounds, it feels like it could open up a little more to hit its optimum range, but is just slightly being held back which I assume is the 23 pitch. Last year, I was left with the back and forth debate with myself on whether to stick with a 3 blade or go with a 4.

 

[rs1lollie]

Re: Propping a 3.0 in a 19'

I have a 1990 18' maxum with a 3.0L alpha 1 out drive I'm running with a 14x20 4 blade prop, I'm on plain with in about 5 sec top speed is 42mph @ 4800rpm's with 2 adults. GPS confirmed.

 

[tawood]

Re: Propping a 3.0 in a 19'

....
tawood - do you not like your 18 4-blade? I read up on all this last year and then held off because our hole shot was "good enough" for the time being. This year, I would like to yank wakeboarders out a little faster, so I'm revisiting the issue. It sounds like our set-ups are very similar though because if I dropped to a 21 like yours, our speed and RPMs would probably be close. With our prop being cupped, it may be accounting for some of the RPM differences between ours. Do you know what your top speed is with the 4-blade?.....

No, actually, I don't really like it. As I said before, it is really inefficient (top speed is only 36 mph). The reason I keep it (and the one thing I like about it) is that it is somewhat "idiot proof"...in that WOT RPM's are very close to redline even though it has a much lower pitch for hole shot. My wife sometimes takes the boat out without me, and I didn't want to go with a 19p 3 blade because she might toast my motor by ignoring redline. If it was just me driving, I'd get a 3 blade 19p instead.

 

[smartwork]

Re: Propping a 3.0 in a 19'

Thanks for the added info, tawood. It helps knowing what others think of their props. What brand is your 4-blade and what brand 3-blade would you buy if you were going to? And yep, I completely understand your situation about having several drivers and needing to prevent engine damage scenarios.

rs1lollie - what brand/model is your 4-blade?

 

[rs1lollie]

Re: Propping a 3.0 in a 19'

tawood, My prop is a Mercury Alpha4 prop p/n 48-834854A45

 

[tawood]

Re: Propping a 3.0 in a 19'

... What brand is your 4-blade and what brand 3-blade would you buy if you were going to? ...

My 4 blade is a Mercury alpha also.....and as far as 3 blades, I've been using just cheap Michigan props. In fact, my 23p I just got thru craigslist, because I had 2 21p props, so I just put up an add for a trade with 1 of them, and got about 6 responses in the first hour.