Need help with Mercury High Five replacement

[Maclin]

I have a 4.3MPI with a Mercury 19p high 5 prop in the 19 foot bowrider in my sig. It can hit the rev beeper too easily, even for a light load. My thinking would be a 3 blade stainless of some ilk with a 21p. However when I went thru a Prop Wizard with the boat model and year and engine it came up with 17p for watersports and 19p for cruising. Did it a couple of times, same thing. That threw me off balance. Does that make sense? I want the boat for cruising mainly, with some tubing. I really do not want to have to think about hitting the over-rev alarm.

It (the high 5) also seems to need a lot of rpm's to begin moving in reverse. Is this a characteristic of the high 5? Blew out once on a turn also, was trimmed up maybe 50%. All of these are conditions I want to remedy if possible.

Thanks in advance...

 

[floater212]

the high five has thin a (width) blades and smaller diameter than most props, I had one and it was ok but not great for skiing, tubing and kneeboarding which needs a slower tow with the boat wanting to raise up, checked out Ron Hill pleasure 5 blade....wow couldn't be any happier. great hole shots for skiing and wakeboarding, nice pulling for tubing and a top speed that was never reached with the high five. the pleasure prop is a full 14 1/2" and the blades are a thick (width) as a normal 3 blade prop, you'll even get better reverse with it too. the high five I had was a 21" so when I was looking at the Ron Hill I got the 19" for better skiing and was amazed at how it reacted to all water sport and cruising. check them out....ps. the ron hill was just shy of half the high five price.

 

[89retta]

I was having the same issues as you . Went with 19" Turning Point 4 blade perfect prop for me. With the high 5 I could still hit the limiter with a 21" and real easy with a 19"

 

[Maclin]

Thanks floater and 89. That was some of the same negative review info I got out on the net about the high five. It came with the boat and I am pretty sure the high five would not have been my choice for sure. I am thinking that this boat is a little too heavy for the high five's diameter and small blade area.

Still a little confused about the pitch for the new prop, 19p or 21p. Just seems like, on paper anyway, that this 220hp engine should be able to turn a 21. I may try an alum 21p and see how that goes. Not feeling too much like funding an SS prop chase for the next month or two Maybe I can get lucky and find a prop swapping dealer close by.

Wonder who I can pay to take this high five off my hands

 

[Maclin]

Additional info, the prop is ported but all the plugs are in.

 

[89retta]

I have the same engine as you but mine is a Volvo 4.3 GXI 225HP. My boat weighs around 2700 lbs with it loaded I would say 3200 give or take. Came with a 17 and 19 pitch Volvo 3 blade stainless props. Could always hit the limiter. Tried the High 5 and returned it after first trip 21 pitch and still hit the limiter. Next prop was a SS 4 blade Apollo xhs 20 pitch. Pretty good prop but was lacking. Next was a 4 blade Turning point 21" great prop for a light load. Bought the same prop in a 17" for water sports or heavy load. Final best all around prop is 19" Turning point 4 blade. All Turning point props are aluminium and cost less then the SS Apollo.

 

[Maclin]

Thanks 89. I had Caravelle on my list of mfg's to look for in my recent boat quest. Your 187 seems to be very similar to my boat. I had begun to settle in on a Solas iPop 3 Blade 14.5 X 20P aluminum propeller. I will look at the Turning points too, both seem fairly economical, close in price.

The boat handled kind of squirrely when trimmed up. Trimming up slowly the rpms would go up a little, but when you hit a certain trim position the revs climbed noticeably by engine sound and tach reading but speed would not climb. Just did not feel right.

 

[89retta]

The fourth blade really helps with the holeshot. And I can still get around 45 mph at around 4500 rpm

 

[Maclin]

Yes, I bet.

My previous boat was 22 footer with 1991 Volvo 570 DuoProp with 275HP, so I may have to modify my expectations somewhat for this combo. It had superb holeshot with B5 propset (about 21p) and could push almost to 50. With the B7 propset (23p) holeshot was ok and pushed well past 50.

I was getting used to the new boat, trimming up waiting for it to porpoise a little, it never did, just RPM's went up with no speed gain, tried it more than once. This boat has fuel tank up front but would still expect that the prop could hold enough to get it to porpoise.

Thanks!

 

[Maclin]

I was able to get out on the lake and run the new Michigan Wheel Vortex 21p aluminum prop. When I was backing out I could tell a difference immediately, the boat moved much "sooner" with much less throttle.

Prop has good bite at holeshot, not stellar but as expected for the basic design. I had a good hour's run in, playing with trim at top rpm's quite a bit at first. I could only hit the rev beep when I trimmed up just a tad too much and the revs climbed with no speed increase, obvious it was close to blowing out. Boat still would not porpoise as I would expect, but that's ok, accepting this as "by design" from Bryant. Speed by the speedometer in the boat (I think someone besides me ended up with my handheld GPS, grrr) was much higher this time, was approaching 50 bouncing a little from 48 or so.

Running the numbers in a prop calculator it seems I am getting about 18% slip using 4800 rpm at 48mph. Not too bad for aluminum but I think I can do better with props that are put there. This prop is now my baseline.

Another problem showed up though after a while. At first all was great, throttle response was good, no surging, could cruise at 4600 - 4800rpm for minutes at a time. Then it began to cut out and surge at anything above 4600, then 4400 then 4000. I am going to post these symptoms in a different subject area.

 

[QBhoy]

Funnily enough, I was wondering the effect going the other way.
What ratio are you running ? Perhaps the wrong details have been put into the prop calculator ?
I'd imagine you would need at least a 21"p ?
Thinking behind this is that I have a similar boat with 5.0 mpi and a 1.47 ratio. Running 19" laser 2 with really good results and right on with rpm range.
I'm presuming your ratio will be lower than 1.47, therefore a 19" would be under propped ?
Can totally recommend a laser 2....but as always, we chase prop perfection ! Haha.

 

[Maclin]

This 21p is just right regarding RPM's, gets to top of range but does not overrev.. It is the standard Mercruiser 4.3l ratio of 1.62. The only 19p I tried was underpropped.