Question about engine rpm's

[freeheel4life]

Little late to the thread, but sounds like you are right in there. Just out of curiosity, what is your usual lake? NorCal is big, and Almanor and Shasta are two different lakes. From the sound of it you are regularly boating in same place just new boat. Mike I'm sure would know better, but ratio on your old PCM 351 DD may be playing into RPM difference as well. May be worth checking fuel pressure while under load. Have had a Merc 350 mag MPI "hunt" for sweet spot as fuel pump was experiencing problems. Outside chance, just a thought.
Also, I know it's not cheap but have you considered PP?? I know we all think we are supreme operators, but I've never met anyone better than stargazer when it comes to consistency IMO.

[Techna22v]

Little late to the thread, but sounds like you are right in there. Just out of curiosity, what is your usual lake? NorCal is big, and Almanor and Shasta are two different lakes. From the sound of it you are regularly boating in same place just new boat. Mike I'm sure would know better, but ratio on your old PCM 351 DD may be playing into RPM difference as well. May be worth checking fuel pressure while under load. Have had a Merc 350 mag MPI "hunt" for sweet spot as fuel pump was experiencing problems. Outside chance, just a thought.
Also, I know it's not cheap but have you considered PP?? I know we all think we are supreme operators, but I've never met anyone better than stargazer when it comes to consistency IMO.

Little more south, Folsom would be my home lake, Sac river for a quick ride after work or just want to get out as its close to my storage and nothing like docking up and having some food at Crawdad's or Chevy's. But since both of those options are full of debris, Folsom being the worst. I've been hitting up Camp Far West, small but clear of hazards when compared to Folsom. But take a few trips to Bullard's a year for weekend camping, been to others but we love Bullard's

As far as PP goes that is in the near future, and on the short list. FAE, PP and Stereo upgrade. I just want to make sure the boat is mechanically sound and that's were all my $$$ and attention is going right now.

[TigeFamily]

You can get that prop repaired too that was "nicked" by trailer....Nettles Prop in Austin TX will repair it for reasonable amount and there are many other places that can also repair. Cheaper than a new prop if the old one did a better job for what you are looking for.

[Bakes5]

3800 RPMs to go 22-23 MPH with a 537 (13.5 x 16 pitch prop) sounds a little high. I wonder if your relatively small diameter prop combined with a high pitch is causing XS prop slip when weighted. Seems like a read somewhere that the prop is most efficient when the diameter and the pitch are the same.

For reference, my Z3 (1.5 gear ratio) with a 15" x 14 pitch prop hits 28mph at 3650 and 30MPH at about 3875 RPM. It hit 30 MPH at 4200 RPMs with my 15"x12 pitch 2219 prop before I swapped it out.

I actually have a 13.5 x 16" prop that I was going to experiment with but my wife hit a 3" branch with it 30 seconds into the test run so that data will have to wait. From the 30 seconds of testing, I expect that it will suck with any weight and be marginal with a regular sized crew and no ballast at altitude. I think it might be fine at sea level, unweighted with 2-3 people in the boat. Your 22V will be about 1000lbs lighter though but 500lbs lead, 6 adults and 5 kids = ~2000 lbs heavier = kinda loaded even without ballast.

When you do you testing, try to do it with an empty boat first then load it up for a usual day then add the ballast. Try to record several speeds 15,20, 22,25,28,30 and WOT and what the RPMs are.

Anyway, do some weighted and unweighted testing and let us know the results. I'd be looking at some of the 14x14 props....assuming they clear trailer and hull.

[Techna22v]

You can get that prop repaired too that was "nicked" by trailer....Nettles Prop in Austin TX will repair it for reasonable amount and there are many other places that can also repair. Cheaper than a new prop if the old one did a better job for what you are looking for.

The "nicked" one is already at the shop being repaired. The original owner had 2 (two) ACME 537's one spare one on the shaft. He never needed the spare at all and it just sat in the storage. That's before he hit the trailer with it, something he did last year with the low water at the lake, or that's the story he gave me. I just pulled that one off and put the spare on.

[TigeFamily]

While they are repairing....they can re-pitch it, perhaps that would help and give you another option and perhaps better low end power

[Techna22v]

We got out this weekend, and I was able to spend a few mins to test

2 people (400ish/lbs) 500lbs lead, 200lbs of misc stuff, full tank of gas......

GPS and speedo were spot on...the boat seemed to plain out around 16-17mph..

20mph=3000rpm
25mph=3200rpm
30mph=3500rpm
35mph=4000rpm
WOT 41mph=5k rpm