Repair or replace props

[Captain Ralph]

That’s the same as twenty grand off a set of Sharrow/Veem props that may be significantly more efficient, it’s free to find out, just sign up for their evaluation.

My estimate came from the largest Veem dealer on the FL east coast.
We have been discussing these Sharrow wheels for a long time now.
" It will be a very long time before they are a marketable item for our boats,,,,, If ever".
His words are sacred to me.

 

[Phasma2128]

Random thought/concern….

I am slowly moving forward with new props. Acme prop’s estimated time frame is 6 weeks as the props needed are not in stock. Their engineer advised that the 3666 props that were on it are under propped for the size of the boat, engines and transmission step down. They advise a 40” blade will give me better performance, fuel mileage and handling. What I’m curious about is if the added prop size will put undo strain on the transmissions?

48 cpmy
6V92
4.35:1 step down

 

[Captain Ralph]

What I’m curious about is if the added prop size will put undo strain on the transmissions?

48 cpmy

What clutch do you have?

Clutch selection is usually sized (new) by horse power rating of the engine.
Reduction is determined by lots of other variables.

If your clutches are in good shape and you have not souped up the HP of your engine greatly, I don't see any issues.

Under propped uh?
So your making RPM pretty quick and WOT is easy??

6V92
4.35:1 step down

I'm assuming when you type step down your typing reduction.
I do question 4.35:1 reduction ratio. IMO, that is near double (or more) than any 48 would usually have.

 

[Phasma2128]

The 4.35:1 is stamped on the plate of the transmissions. A lot about this boat is unique from what I’ve discovered. I’ve also been told that a 2.5 “ prop shaft should be more like 3” for this size of boat.

As for clutches I have no idea. I will try and look it up. I’ve never had any trouble with the clutches. I am no mechanic so I learn as I go. Each breakdown is a new adventure in boat mechanics

 

[Captain Ralph]

The 4.35:1 is stamped on the plate of the transmissions. A lot about this boat is unique from what I’ve discovered. I’ve also been told that a 2.5 “ prop shaft should be more like 3” for this size of boat.

As for clutches I have no idea. I will try and look it up. I’ve never had any trouble with the clutches. I am no mechanic so I learn as I go. Each breakdown is a new adventure in boat mechanics

Please humor me and find the stamp on the other clutch.
If it really has that much reduction, your close to tug boat operation.

For comparison on my dock now;
With 650SHP, TD514, 2;1 reduction & 2.5 inch shafts pushes our old 58 Bertram.
With 875SHP, ZF9(?), 2.5:1 reduction & 3 inch shafts pushes our friends 75 Hatt.

Send us a picture of your clutch and we can I D it.
Some older surveys may have a reduction written.
Maybe your ships manual may document the reduction.

Is that your boat in your ID picture?
<-----

 

[cww]

Please humor me and find the stamp on the other clutch.
If it really has that much reduction, your close to tug boat operation.

For comparison on my dock now;
With 650SHP, TD514, 2;1 reduction & 2.5 inch shafts pushes our old 58 Bertram.
With 875SHP, ZF9(?), 2.5:1 reduction & 3 inch shafts pushes our friends 75 Hatt.

Send us a picture of your clutch and we can I D it.
Some older surveys may have a reduction written.
Maybe your ships manual may document the reduction.

Is that your boat in your ID picture?
<-----

I think he's not wrong, have you ever seen one of those CPMY's from the 90's/2000's out of the water? They have enormous wheels on them, probably close to 40" and way more blades than usual. Not sure why they did it that way, but that's normal for this boat.

 

[rsmith]

I think he's not wrong, have you ever seen one of those CPMY's from the 90's/2000's out of the water? They have enormous wheels on them, probably close to 40" and way more blades than usual. Not sure why they did it that way, but that's normal for this boat.

They have tunnels in that hull

 

[Phasma2128]

Yes that is my boat in the profile

 

[Phasma2128]

 

[Phasma2128]

uploaded photos but the uploader squashes them. It clearly says on the trans tags 4.43:1 ratio

 

[Phasma2128]

old props

 

[cww]

View attachment 75067

old props

I don't think those are the right props for that boat. My dock neighbor in Halifax Harbor had a 48 CPMY with the deep reduction gearing same as yours, and his props were 7 blades and much larger. I think the prop shop that's telling you you're underpropped is probably right. What is your top speed?

 

[Captain Ralph]

I can't read the tag but I see the props.
Looks like a Twin Disk (or DDC/TD) plate.

Not in a tunnel but still monster pitch and blade sized.
WOW

Not a lot on the internet for me to research. Are these DDEC engines?
Still; WOW

 

[Phasma2128]

Not DDEC. 1995 was when ddec was started. One year newer than mine.

it is a twin disk

I guess I am hopeful all will be well with 40” props. The handling should be hugely noticeable. My current top speed was 15-16 knots at 2400 rpm. The Acme engineer said he believes I may see a top speed of as much as 5-6 knots above 16. He also said I may even realize a 10% improvement in fuel consumption.

 

[Captain Ralph]

Monster reduction. Any idea what the original prop sizes were?

 

[Phasma2128]

The props that were on it were Radici 3666. I’m not sure what the new props pitch will be. I do know they are 40” props from Acme

 

[cww]

Here, these are the props that originally came on that boat with the 4:1 reduction gears. This is your same model boat out of the water. Most likely somebody damaged them and cheaped out at some point. I can't even imagine what these cost to replace. Just to be clear: Zero judgment from me if you cheap out again and get something that will work but doesn't cost you your left nut and firstborn child. I wouldn't be happy about spending $20k apiece on props either.

That said, hatteras was pretty good about testing a bunch of different prop combinations before shipping a new model, I'm not sure you'll get the advertised performance out of the boat if you deviate too far off the mark. Or whether an extra knot or two even matters to you, with today's fuel prices most of us just putt around at 9 knots anyway.

Whatever your decisions, I wanted to provide it as a frame of reference. The 30-something inch normal props in your pic are not what your boat is supposed to have, the 4:1 boats came with a pretty exotic setup.

 

[Captain Ralph]

The tops of these props are not hidden in the tunnels.
Are they missing a lot of diameter also?

 

[Phasma2128]

I suppose that is why the engineer at Acme Props recommended 40” props. $21k each….ugh. They are ordered and hopefully be here before our summer ends

 

[madhatter1]

My new wheels are $4k each. Cheap by comparison.