Validated Opinions On MaxProp Two Blade

[Maine Sail]

I have a very good line on a re-conditioned MaxProp two blade for a "steal" of a deal.

I have never been a big fan of two blade props and have not yet found one that did not exhibit some form of annoying vibration. Our boat now has as close to 0% vibration as I have ever seen on a sailboat using a three blade Campbell Sailor. I REALLY, REALLY like smooth..

The Max has some big "ears" and I have read some decent reports of it as a two blade prop but when there is zero wind, and we are needing to put 50nm under the keel on a given day, I also want a prop that is going to be SMOOTH..

Please do not comment if you have not owned a two blade Maxprop classic. I am only looking for actual experience with the Maxprop. If you owned a three blade fixed and went to a Maxpro two blade those comparisons would be valid.

I also do not want to get into a conversation on drag, I could care less for this particular question. All I care about is forward thrust, the ability to punch into sea or current and how SMOOTH is it..

Sorry to be soo picky but SMOOTH is my #1 criteria. Power is #2..

Worst case scenario is I use it for a season and dump it. Of course I will then have to write an honest review of how bad it was in terms of vibration compared to other props so PLEASE be honest.....

What I am looking for:

Smoothness evaluations compared to other props you've owned.

Fixed three blade to Maxprop two blade / smoothness and thrust comparisons

Fixed two blade to Maxprop two blade / smoothness and thrust comparisons


I have used three blade Maxprops and find them rather impressive so am more concerned with only the two blade design.

Again, sorry to be so picky but I need to make a decision soon and value the input I get here..

 

[dwain6805]

Here's my story. I recently repowered and replaced, trans, coupling, shaft, 2 cutlesses, and the engine. I kept the 2 blade MP Classic. (19" x 20" Rh) After launching & alginment I have not been able to get the vibration out of the drive train (I did about 90% of the work and have a very good idea of what's going on.) However, I have the prop in an aperature and I believe when the blades cross the deadwood they hit an area of calm or "dead" water and then back into the flow. They do this on the top and bottom blade at the same time and I believe that is the majority of my problem. My solution is sitting in my family room, a 19" 3 blade MP. As of this time I haven't got it installed so can't speak to the 3 blades vibration, but I'm hoping that since the blades will cross the deadwood at different times it will lessen the vibrations.
As for power, the 2 blade is fine and my boat is 33,000 #. I easily motor at 7-7.5 knots turning 16-1800 rpm (Engine is a Cummins "slow turner"). Stops fast, considering weight, when reversed, and reverse is good once underway. I have significant propwalk, but I also have a very steep deadrise to the hull above the prop and will have PW with any prop. Plus how else would you spin a large heavy boat around in a fairway?
So I know my results won't help you with the vibration issue, but I think the power question is "Yes". And the vibration issue is "maybe". Your set up is very different, with your shaft running though a strut a 2 blade prop would see "clean water" all of the time.
Dwain
KP44 #279
San Diego

 

[Maine Sail]

Thanks! Good info. I had the same sort of issue a long time ago with a Cape Dory 27. Went to a three blade problem solved. Never had quite the same level of issues with a non-aperture boat but I value your thoughts. Thanks!

 

[Don12364]

I had a 2 blade MaxProp on my last boat for 10 years until I sold the boat.
I too got it secondhand very very cheaply, very worn and the blades were pitted where the PO had it cavitating.
I cleaned it up and put it on without much hope. To my delight it was no more or less unsmooth? than the two blade fixed prop it replaced.
Of course the sailing was much improved and the reversing was better too.
My boat was a race boat with a long exposed shaft to get the exposed shaft allowance. It had a Yanmar 2GM15 two cylinder engine which was not particularly noisy.
We did thousands of miles under engine and all together it was a most successful prop.

I believe that it is the layout of the sterngear which determines whether a prop is smooth or not.
Such things as the tip to hull clearance and the clearance between strut and prop and between rudder and prop make large differences. 3 bladers are often smoother because they can be smaller in diameter with each blade having less area and also with a finer pitch. They produce a 50% higher vibration frequency which is easier to damp out or silence.

Sounds as if the price is so good you could afford to try the one on offer and if you don't like it then pass it on - and make a profit!

 

[Ross]

A comment only on the value of having the prop properly trued. I have a 3 blade of questional parentage that created quite a bit of vibration until I had it repitched and trued. Comparing the change from what has been to a new Maxi Prop will be most valid if the old prop was in good condition.

 

[Hermit Scott]

However, I have the prop in an aperature and I believe when the blades cross the deadwood they hit an...

What is an aperature pertaining to props?

 

[Ross]

What is an aperature pertaining to props?

On full keel boats with attached rudders the prop turns in a cutout in the keel and the rudder.

 

[Bob Mack]

Main:

I had the experience of replacing a 2 bade fixed with a 2 blade max prop on my 1980 Yamaha 33MKII. It was a wonderful boat I sailed for 22 years, but it had an option of a single cyl Yanmar located way forward under the v berth. I replaced the Yanmar with a 2GM about 1987. This boat had approx 12' of about 1" propeller shaft, and included two dampening couplings, 1 of which I replaced with a very satisfactory PYI coupling, and there were two pillow block bearings. The system was very well executed. I was of course very careful about going from forward to reverse.

I did receive a 2 blade racing type folding prop which the prior owner had indicated was unusable due to vibration.

None the less after discussions with PYI I installed a 2 bladed max prop which i used for about 10 years. It is a wonderful product and I never experienced any vibrations. If it worked in this difficult situation, I'd think it would be fine on a more typical boat. In the end I had a fairly loose cutlass bearing, and even then no vibration. all the usual cautions about proper sizing, pitching, and clearance to the hull would of course apply.

My new boat is a 2007 Beneteau 373. After commissioning my first modification was to replace the original 3 blade fixed with a 3 blade max prop. They are terribly expensive, but a great product.

Fred at PYI is a great resource.

PS loved your workup on refinishing.