Feathering Propeller

[Ex-Calif]

A guy at the club gave me this prop and said he had it on his Maxi with the same engine and drive and that it is an "original" Volvo prop. There is no paperwork with it and no identifying marks other than an "alphabetical" legend on the spline shaft you can see in the picture. I have googled and searched but can't identify it.

It is 14 1/2 inches in diameter at the widest part of the chord and 5 1/2 inch chord at the longest part of the chord. There is obviously a great potential for motring speed improvement and handling in reverse with this prop compared to the folding prop I have now.

I have a Volvo-Penta MD2010A (10 hp) and 120s saildrive with a folding prop. I am interested to know if anyone has any ideas on how to rig this prop.

The internal stop and dog does not appear to have any adjustment at all.

The pinion gear that splines into the shaft has an alignment mark and the shaft has a graduated alphabetical scale although all the teeth are uniform and there are no "master" splines. Regardless I have set the spline at "A" and I have set the spline at "V" with no change in the pitch angles.

I have set the blades into the pinion evenly so they both fair together with the dog on the shaft centered between the stop in the case half and it appears that the only adjustment I could make is to rotate the pinion gear so I get a higher pitch in forward than in reverse before the dog hits the stop but it seems if I do this there could be "zero" pitch in reverse or even negative pitch.

Other than trial and error - Any ideas?

PS - It appears that the shaft and nut are wedded to the s-drive shaft and then the removable pinion slides on the shaft, the blades are mated and the halves are put together. The implication is that if there is adjusting to do on this prop the boat will be hauled multiple times or I am diving and assembling underwater - not a happy prospect with 6 allen boalts to install - LOL.

Maybe I know the answer - multiple hauls outs...

[senormechanico]

That's a Maxprop. You should be able to get the formula for what letter combinations go with different pitches if you do some internet searches.

Clean up the poor thing and fill it with EP lube.

We had a 3 blade Maxprop on our cruising boat and loved it.

The blades should turn approximately 180 degrees when you go to reverse, i.e. the leading edge of the blade always is the leading edge during operation.

Steve B.

[Inthewind]

I have a Max prop and I have experimented with repitching it underwater after a repower until I got it right. Mine is a three blade and different than yours. Don't know anything about the two blade you have or if it is adjustible, I'm assuming it is adustible.If it is adjustible then it is doable underwater. I fastend a bucket under mine in case I dropped something. If you can dive and have air suppy, I would suggest learning how your prop works real well and change the pitch underwater, that is the only way I know of to get it pitched it right. If you can't do it, a diver is cheaper than hauling mutiple times. I would do it for you but your on the other side of the world. Good luck.

[Ex-Calif]

Steve,

Perfect! Thanks for the tip. I went to to Max Prop site and downlaoded the installation manual. I "love" the internet.

I figured out that the pinion gear "does" in fact change the pitch through the difference in teeth size between the shaft splines and the pinion gear - Doh! Not very observant of me.

Cleaning up should have been the first thing to do. After celaning the gears on the blades I was able to locate the letters on them as well. Seems a large selection of pitches are available.

Based on the attached table anyone want to take a guess at the initial setting? I'm thinking 22 or 24 degrees right hand rotation.

PS - Anyone have an idea of the value of this thing. I'd like to know how much I am indebted to the member who gave it to me.
.................................................. ................................

And don't forget to add the link to any copyrighted materials
PYI Inc. Max-Prop PSS Shaft Seal Seaview Radar Mounts R&D

[Ex-Calif]

Originally Posted by Inthewind

If you can dive and have air suppy, I would suggest learning how your prop works real well and change the pitch underwater, that is the only way I know of to get it pitched it right. If you can't do it, a diver is cheaper than hauling mutiple times. I would do it for you but your on the other side of the world. Good luck.

Our club is pretty friendly and we are hauling in July for bottom paint around the 18th. I reckon I'll see if they want to haul it up the ramp, let me change the prop, do one test then get a second shot if it's too far out. Technically it's two haul outs but only one high tide ;-)

The manual gives an approximate RPM change per setting so two shots should work unless I don't reach WOT on the first try. i.e if I am throttle limited rather than RPM limited I should be able decrease the pitch a known amount.

If they aren't agreeable I am Scuba certified and have a buddy with gear so will use you bucket method.

[fstbttms]

I have installled many Max Props underwater. If you have any specific questions about about how to do it (2-blade props are the hardest to deal with), lemmee know.

One thing I will say right off the bat is that I don't believe the Max Prop you have will fit on your saildrive.

[fstbttms]

Originally Posted by fstbttms

One thing I will say right off the bat is that I don't believe the Max Prop you have will fit on your saildrive.

Strike that. Upon closer inspection of your photos, I see I am mistaken.

[Ex-Calif]

Thanks to all. I spoke to the club manager and he has agreed to let us haul the boat half up the ramp, change the prop, do a motor test and a second adjustment if required on the day we haul out at no extra charge.

We spent Saturday morning assembling and disassembling the prop and we all agree that doing it underwater will be a non-starter. Our bottom is black mud and our water clarity is not too good.

I plan to do some gps speed tests at various RPMs before and after and I will post the results.

Cheers

[S/V Elusive]

Make DAMN sure that you assemble it correctly (blades in proper position). I didn't when I made a change, and didn't have an agreement with the boatyard, and had to pay for an additional haul and hang. I just put it back to the settings that were on it originally. I think that I could have added an additional 2 degrees, but .. I won't know until next haulout.

Good luck

[fstbttms]

Originally Posted by S/V Elusive

I think that I could have added an additional 2 degrees, but .. I won't know until next haulout.

Call PYI in Lynwood, WA. They can refer you to a diver that can adjust your pitch while the boat is in the water at your slip.

[S/V Elusive]

Originally Posted by fstbttms

Call PYI in Lynwood, WA. They can refer you to a diver that can adjust your pitch while the boat is in the water at your slip.

Thanks - I MAY do that. But, considering I screwed it up ON DRY LAND, and it wasn't an easy job getting all three blades on and in place, I'm a bit hesitant about having a diver do it - I'm screwed if something is lost or damaged.

[fstbttms]

Originally Posted by S/V Elusive

Thanks - I MAY do that. But, considering I screwed it up ON DRY LAND, and it wasn't an easy job getting all three blades on and in place, I'm a bit hesitant about having a diver do it - I'm screwed if something is lost or damaged.

PYI is not going to refer you to someone who doesn't know what they are doing. If your diver is really cool (like me! ) he'll have a "safety net" slung under the prop to catch anything that might be dropped. But even if something is lost, PYI will generally replace it free (at least Hutch tells me they will. I haven't had to test him yet.) Plus, anything small enough to get dropped and lost, the diver will probably have a bag of spares anyway.

[S/V Elusive]

yeah - he had better have at least four hands too!

[fstbttms]

Originally Posted by S/V Elusive

yeah - he had better have at least four hands too!

Seriously, I have installed dozens of Max Props underwater and have never once lost any parts. 'Course, now I've prolly jinxed myself...

[senormechanico]

"PS - Anyone have an idea of the value of this thing. I'd like to know how much I am indebted to the member who gave it to me."


A Maxprop is a very spendy item. I'm glad the cruising boat we had previous to our current boat already had a 3 bladed Maxprop on it when we bought the boat, as it would have cost something like $3,000 USD. A 2 blade obviously isn't as much, but still, you got a great gift giver in your club.

Steve B.