New prop hunting for 4.3 MPI Mercruiser on Crestliner

[Kravchenko]

Hey there,

My boat:

2007 Crestliner 1800 Sportfish
4.3 Mercruiser with MPI
Alpha one outdrive with 1.62 gear ratio

Boat came with a 19 pitch by 14" quicksilver Silverado stainless steel prop. My boat runs pretty well on it except for the follow issues I am looking to address:

1) My wife, who slalom skis says the holeshot is not as good as our old 16 foot starcraft with a 75 HP etec.

2) With a full load (2 adults, 3 children - 7 years and 2x four years), bow mount trolling motor, cooler, fishing gear, 3 batteries and all the what-not, my boat will still hit 80 km/h (gps clocked) when it is fairly calm and I can trim out nice. Problem is, is that it also hits 5000 RPM according to my tach. With a lesser load, it appears to hit 5200. Boat should only go up to 4800 RPM. Tach might not be accurate, for certain though.

I want more hole shot, yet i do not want to gain any more RPM, so simply dropping pitch is not my preferred solution. I am willing to lose about 5-7 km/h. I am thinking of getting a 4 blade prop that is also 19p. I am in Canada, so I do not want to experiment with incredibly expensive stainless props unless I have to. No one lets you test out a prop and then exchange it around here.

I am thinking of getting a Turning Point Hustler 4 blade prop. They are "squeeze cast" which supposedly makes them almost as ridged as stainless. The part number is 21501930. They are reasonable priced and locally available here in Winnipeg. I also looked at stainless props like quicksilver Typhoon, Merc Rev4 and High Five. Just too much money.

Any other suggestions? I do not want to drill into the transom and any tabs will likely interfere with the location of my fish sonar.

Thanks for reading and your thoughts.

 

[porscheguy]

You can drop weight, drop pitch, or do a bit of both.

Keep in mind, you’ve got an MPI engine which means it has a rev limiter.

The absolute best watersports prop is going to be a mercury high5. That’s stainless and I’ve read your comments on stainless. I’m just putting it out there.

Any prop that reduces rpm is going to slow acceleration.

The only way to improve acceleration enough to placate a slalom skier is to drop pitch. Go with a 17p turning point. If 18p is available, try that.

A lot of people balk at the prospect of swapping props according to how the boat will be used. It only takes a few minutes.

 

[Kravchenko]

Well, I just picked up a 4 blade turning point. It will be my spare unless I try it and really like it. If I hate it, I will sell it and other unsuitable props I have and see about a High Five or a turning point 4 blade stainless. Maybe Michigan Wheel.

 

[jimmbo]

It doesn't surprise me that the I/O has poorer Hole Shot, even when underpropped, than a much smaller O/B. That especially holds true with the higher HP versions of a given Displacement, as HP goes up the torque in the lower rpms drops.

High 5 is marketed under the Mercury brand, there is an almost identical prop under the Quicksilver brand(so non dealers can sell mercury parts/accessories), It is called the QST5 and is usually a couple of Hundred bucks less than the High 5

 

[Kravchenko]

There is local used High 5. Still wants $500 for it.

 

[QBhoy]

Hi

your inboard isn’t going to be as good usually at hole shot compared to an outboard within reason. Especially a 2 stroke on a light boat.
Other thing is that your tachometer is defo wrong of you can see 5200 rpm. Your 4.3 mpi will limit itself and beep on the dash a good bit before then.