Volvo folding prop question

[Kasanti]

I have inherited two Volvo 3 blade folding props on my new to me FP Mahe catamaran. Volvo D1-30's on 130 SD sail drives.

Whilst cleaning them up for next season I noticed a two digit number stamped on the blades, above the blade timing number (photos). The two digit number is different from the port side set and the starboard side set. Also the blades appear (to me, no expert) that they might be a different pitch (photos below).

I wondered what the two digit number might be. Port side is "10", starboard side is "14". After looking at Volvo's blade kit part number (PDF, below), I thought it might be the last two digits of the blade kit part number.

So that is my main question: Does anyone know what the stamped two digit numbers on the blades are?

If I'm correct then the blades must have been modified, because the part numbers are for two different diameters and the blades do not look (to me) like they are a different diameter. The pitch might be different, if you look at the photo below where the blades are lying flat, the point where they attach to the hub looks like it is at a different angle to the flat of the blade. There is some perspective error in the photo, it's not an orthographic photo, and the difference seems exaggerated in the photo. BUT during the survey test sail I did note that the captain ran the engines at a slightly different RPM (250 rpm difference, about 10%).

Also those part numbers are listed as being for a shaft drive, not sail drive. Not sure what difference that would make, I would think this would be dependent on the hub.

So my secondary question: What would YOU do in this circumstance?

Thanks in advance!

[redneckrob]

Originally Posted by Kasanti

I have inherited two Volvo 3 blade folding props on my new to me FP Mahe catamaran. Volvo D1-30's on 130 SD sail drives.

Whilst cleaning them up for next season I noticed a two digit number stamped on the blades, above the blade timing number (photos). The two digit number is different from the port side set and the starboard side set. Also the blades appear (to me, no expert) that they might be a different pitch (photos below).

I wondered what the two digit number might be. Port side is "10", starboard side is "14". After looking at Volvo's blade kit part number (PDF, below), I thought it might be the last two digits of the blade kit part number.

So that is my main question: Does anyone know what the stamped two digit numbers on the blades are?

If I'm correct then the blades must have been modified, because the part numbers are for two different diameters and the blades do not look (to me) like they are a different diameter. The pitch might be different, if you look at the photo below where the blades are lying flat, the point where they attach to the hub looks like it is at a different angle to the flat of the blade. There is some perspective error in the photo, it's not an orthographic photo, and the difference seems exaggerated in the photo. BUT during the survey test sail I did note that the captain ran the engines at a slightly different RPM (250 rpm difference, about 10%).

Also those part numbers are listed as being for a shaft drive, not sail drive. Not sure what difference that would make, I would think this would be dependent on the hub.

So my secondary question: What would YOU do in this circumstance?

Thanks in advance!

Maybe make a clay or plaster cast of one blade and see if there really is any difference. If not, ignore and put them back on. If you can make rpm with both and there's no unusual vibration then does it really matter if they're different part numbers?
Also, noticed when replacing the hub on my identical Mahe that the hub part number didn't match the other or what I expected when looking it up, but after some more Googling found another source that showed it was correct. So I deduced from that experience that Volvo Penta isn't great with published part numbers at least when it comes to props. Also, turns out you can replace a hub underwater without dive gear, ask me how I know

[Kasanti]

I think you may be right about the numbers. I even reached out to Volvo to find out what they mean and didn't get anything useful. Someone somewhere knows, but the rest of us are in the dark. I won't worry about it for now. Thanks redneckrob.

[DougR]

On all of the three blade folding prop blades that I have ever seen there is a number cast into the blade on the opposite side that you have shown us in the photos. Located in a recess near the pin. This number is the part number for that particular blade, such as an 18x 13 RH. Three of these part numbers makes up a blade set which carries the part number which is shown on the page which you included. If the cast in numbers are different on the various blades which you have, then the blade sizes are different. ( edit....early folding props, maybe 18 or 19 years old, were made of regular bronze. Then they went to Nibral material. At that time the part numbers changed for the same sized prop)

The stamped numbers which you show us probably don't mean anything of consequence....production dates, batches, or something like that.

The reason that some of the blades are listed for sail drives and some for shaft is that VP is not recommending the use of RH props on the saildrive. Has to do with oil flow and lubrication within the drive when used with a RH prop.....

DougR

[Kasanti]

Thanks Doug,

I will check that next time I am there. The only cast number I remember is on the hubs, I didn't take a picture of those but I think they were both the same.

I spent a couple hours cleaning everything, I'd think I'd remember that. But the sun was hot, the mosquitoes were hungry in the yard, and I needed to get everything put back together and get on to other things so maybe I just don't remember.

Brandon

[DougR]

If you make an internet search for " bulletin P-44-7-12" you will find a VP parts bulletin which lists the part number for the individual blades which make up a blade kit, the part number for the blade kit, and the size (diameter & pitch of the prop).

As you will note, the bulletin is from 2008. At that time the blade number was cast into the blade near the mounting pin. As I mentioned earlier that might have changed on later production, I don't know.

Hope this helps.

DougR

[Kasanti]

That does help. A lot. If I'd known all that I would not have speculated on the meaning of the stamped numbers. I have a lot to learn on some things and I don't mind admitting it. It's a big part of the attraction for me. Thanks for the link and thanks for the knowledge Doug!