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CliffBeer · 20-07-2019, 00:37

I have a 17 inch max-prop on my C&C 44. The prop came with the boat when I purchased it about six months ago and was installed by the prior owner's mechanic about 2.5 years previously. The prop looked to be in excellent shape when inspected during the pre-purchase haul out.

There's a bit of weed on the bottom which I'm sure if affecting speed, but even at 2,300rpm the boat is still only making 5.5 knots. The engine (turbo Yanmar 4 cylinder) has plenty of power and will turn up to max rpm happily. There's a 2.1:1 reduction in the gearbox.

I'm wondering if perhaps the adjustable pitch is not set properly. Does anyone here have first hand experience with setting the pitch on a max-prop? Not someone's mechanic or friend or brother....rather, first hand experience. If yes, any helpful advice or tips?

Thanks in advance.

HankOnthewater · 20-07-2019, 08:03

Assuming you have an older prop, prior to the newer range of Easy and Whisper.

Here is a video how to disassemble the (older) Maxprop:

https://www.youtube.com/watch?v=umTl6Mk-G3A

The only thing the video does not show is that the 6 allan-head bolts are each secured with a small split-pin.
The video shows briefly the letters and marking for the degrees set. Here is a page for those marking...ooops can't find one on the net, sorry. If you can find that page shown in the video then you can check what degrees pitch your prop is set. If you can't find that, I can scan and post the manual I have on the boat.

By all means try a larger pitch, but my experience with a pitch increase is:
I increased mine by 2 degrees and..... it was over-pitched and the prop walk increased to such a degree that reversing was virtually impossible. I thought I was clever but it costed me another haulout to adjust the pitch to where it was before.

Tsuru · 20-07-2019, 08:29

I called PYI regarding the recommended pitch on a second hand prop. They were very helpful and may be able to offer some suggestions.

Good luck,

lancelot9898 · 20-07-2019, 08:43

I've had 34 years with my max prop so this is what I've done. When the boat was brand new back in 1985 I remove the 17 x 11 inch three blade fixed prop and installed the 17 inch 3 blade max. Never did use the fixed prop, but wanted to match the pitch of the max as close to the 11 inch pitch as possible, but I knew with the flat blades of the max was not as efficient as the fix prop. I was able to achieve the specified rpm (3600) at WOT, but was dissatisfied with having to operate at such a high rpm to achieve hull speed of somewhere above 7 knots so I started increasing the pitch. I was just able to increase in certain steps and finally settled on a WOT of just 3000. So in fact I'm over propped but I cruise at about 80% of the rpm around 2500 and achieve hull speed using about .7 gal/hr. The Perkins is doing fine operating that way for almost the past 34 years and I do like the prop walk in reverse bringing that stern to port when docking. I suppose you have a much newer prop than mine and I had to disassemble each time I hauled out to grease it. Finally I installed some zirk fitting 6 years ago so now the greasing task is so much easier. I think the newer models have adjustment settings so that disassembly is not needed, but not sure about that. Best of luck with it.

Cheechako · 20-07-2019, 09:01

Yes, you should be making a lot more speed. My 44 footer (avatar pic) made 8 knots readily with a 17" max prop. But how fast does your boat go at max rpm? should be a lot faster there.. than 2300 rpm. Isn't that about a 4000 rpm engine?

CliffBeer · 27-07-2019, 09:15

Thanks gents, really good information here. Very helpful.

Just in the last few days a diver friend of mine dove on the prop and gave it brush so that may help. Didn't look like there was a lot of barnacle growth on it.

As suggested, probably first step is to figure out what pitch it's set to now and go from there.

Very helpful video. I did chat with a nice guy from PYI and he was helpful with suggestions too.

Thanks again.

vk4hr · 07-10-2022, 03:46

Quote:

Originally Posted by lancelot9898

I've had 34 years with my max prop so this is what I've done. When the boat was brand new back in 1985 I remove the 17 x 11 inch three blade fixed prop and installed the 17 inch 3 blade max. Never did use the fixed prop, but wanted to match the pitch of the max as close to the 11 inch pitch as possible, but I knew with the flat blades of the max was not as efficient as the fix prop. I was able to achieve the specified rpm (3600) at WOT, but was dissatisfied with having to operate at such a high rpm to achieve hull speed of somewhere above 7 knots so I started increasing the pitch. I was just able to increase in certain steps and finally settled on a WOT of just 3000. So in fact I'm over propped but I cruise at about 80% of the rpm around 2500 and achieve hull speed using about .7 gal/hr. The Perkins is doing fine operating that way for almost the past 34 years and I do like the prop walk in reverse bringing that stern to port when docking. I suppose you have a much newer prop than mine and I had to disassemble each time I hauled out to grease it. Finally I installed some zirk fitting 6 years ago so now the greasing task is so much easier. I think the newer models have adjustment settings so that disassembly is not needed, but not sure about that. Best of luck with it.

hi lancelot...
I have a max prop 3 blade classic.
when I took the prop apart I failed to notice the setting of the "Y" letter.
the "X" setting on the main cone was at "K".

what do I need to set the " X" setting to have it set up right?

what is the relationship between the "X" and the "Y"?
do the have to correspond with the same pitch value?

thanks for your help

regards
Ralph

Cheechako · 07-10-2022, 08:54

Quote:

Originally Posted by vk4hr

hi lancelot...
I have a max prop 3 blade classic.
when I took the prop apart I failed to notice the setting of the "Y" letter.
the "X" setting on the main cone was at "K".

what do I need to set the " X" setting to have it set up right?

what is the relationship between the "X" and the "Y"?
do the have to correspond with the same pitch value?

thanks for your help

regards
Ralph

Though I've had several MaxProps I can't remember this. But contact PYI , they are usually quite helpful. Their support section here has videos and down loads too!
https://www.pyiinc.com/#

ItDepends · 07-10-2022, 15:30

Quote:

Originally Posted by vk4hr

hi lancelot...
I have a max prop 3 blade classic.
when I took the prop apart I failed to notice the setting of the "Y" letter.
the "X" setting on the main cone was at "K".

what do I need to set the " X" setting to have it set up right?

what is the relationship between the "X" and the "Y"?
do the have to correspond with the same pitch value?

thanks for your help

regards
Ralph

Of course the MaxProp manual is available online, so you could look at that. But let's walk through it for you.

The location of these settings control the stops that set the pitch of the blades, and YES they have to match!

To give you a final answer we need to know if your shaft is configured for left hand or a right hand rotation, but we can come most of the way there...

If the "X" setting was "K" then the pitch is 20 degrees. Just by happenstance, this is the only setting where left and right use the same mark for the same pitch. You got lucky.

For a 20 degree pitch, you set the "Y" mark at "E" if it's right hand rotation, and at "C" if it's left hand rotation. If you get the rotation backwards, the prop will work to push the boat, but will not feather, so it is important.

Bill O · 07-10-2022, 15:41

Here is a link to the instructions https://www.pyiinc.com/downloads/max...structions.pdf

Knowing which rotation you have is important to set it properly. Do you know which rotation you have?