1998 Props on 405

[Serendipity]

I was wondering what seems to be consensus on the MW 22/21 standard props regarding pitch.
I am looking for more speed. My engines are maxing out at 3600 rpms and I was just wondering if changing the pitch as suggested by my mechanic will make that much of a difference. Boat will be in fresh water.
Any suggestions very much appreciated

[g36]

on my 405 i have oem 4 blade 22x20 's and crusader xli ho engines i can reach 4600 rpm wot. and i am by no means running lightweight. dont know what engines you have but i wonder if you dont have something else going on such as fuel or timing advance etc. not right.

[Serendipity]

Thank you very much G36
I will check it out

[bud37]

Is the bottom and running gear clean ? Boat is on the gulf now, correct ?

[Midnightsun]

Assuming you have gas engines you should be around the mid 4000 rpm mark @ WOT otherwise there is definately something not quite right.

[Serendipity]

So the boat has averaged 18 hours per year since new. I have completely updated everything engine wise known possible to this old sevice manager right down to the fuel regulator which I am told rarely goes bad. I mean pretty much everything.
So my first trip out for the survey the boat would only do 3200 on the port side and 2900 on the starboard side.

Yesterday I was able to get 3600 rpms out of both engines after 5k worth of maintenance was done. Mainly everything fuel related and pretty much anything you can think of and this included a new carb for the gen.

I will send pics of the props and I probably would have replaced them but the prop veteran says he has saved a lot worse. So I am going with him refinishing them in the hopes this will take some of the vibration felt out. Not sure it is going to do much for the rpms though. I am beginning to wonder if the engines just dont need a good blowing out and being run for a few hours with compression in the 160 to 165 range on all cylinders. Probably do need to check the timing as mentioned after 20 years. No one really used the boat especially in the last 5 years sadly.
Pics are of one of the props as the other prop looks fine.

[Serendipity]

It has a few blisters in the bottom but I was told they will dry up with the 95 degree weather and my 30 year veteran survey retired coast guard guy said nohing to worry about. He said they were cosmetic and none were a structural issue. I am listening to people wiser than I and going from there. I moved it to the hard yesterday for a week or so while the props are off and the rudder glands are packed.

[bud37]

Sounds good to me actually, I had pictured all kinds of gunk hanging from the bottom....a good prop shop will sort that out for you.....a good gage would be what speed you were at , say 1500-1600 rpm then the speed at wide open.......pretty sure the prop guys will ask.

It is possible you are already over propped a bit not allowing the engines to spin up. Be careful what you wish for here, sometimes they are propped like that for fuel economy a hull speed, and for me the idea of running 20 year old engines flat out is a bit unsettling, but to each his own as they say.....good luck man.

[Serendipity]

Bud37
I am in a lake/reservoir that is 16 miles wide by 7 miles long. I wish I could sretch them out but I simply am not going to have the room.

Most these engines will see is the trip from Galveston back to Mississippi.
So I was actually wondering if they simply did not need blowing out.

Fuel MPG is not really going to be my concern once I get it to the Reservoir as I will be land locked. Simply get on plane for 5 to 10 minutes and I am in the middle of the lake to drop anchor and use the Waverunners with my daughter.

I really appreciate your vast knowledge and yes I expected the bottom to look awful but it didnt??

I feel like once I get the props done, painted and the rudders painted i will pick up what I would perceive to be normal rpms of 4000.

Thanks again for everyone's thoughts.

[mjk1040]

I do not think your RPM issue is a prop or bottom issue, more a power plant and tranny one. I sounds like the hours on this boat are low, thus one must assume it did not get run a lot, not to mention run at WOT maybe at all. Not to say bottom attention will not help some, but my guess is the more you run her the better she'll get. Carver was know for changing the prop pitches from OEM specs to keep the WOT rpms from exceeding 4500 on some engine configurations! Good luck with ur issue, but I strongly suggest running it more and use a good fuel additive to help clean up interior engine parts and sensors.