Prop for a Ocean 42

[rbrtmccorkle]

Thought I ask is anyone else has run into this.  In the initial survey for the my 1998/99 Ocean 42 the prop had major corrosion issues and on the test drive the engine could be over-speeded meaning that without hitting the stop, the Volvo/Penta MD22L hit 4500 RPM. The theory at the time was that the corroded prop was cavitating.  At that point I replaced the 17 X 12 fixed pitch prop ( this what the BV manual calls for) with a three bladed 17 x 12 folding prop purchased from Volvo/Penta.  This prop also over-speeds.  The boat is currently on the hard and I asked the local prop shop to come out to see if we could be increase the pitch on the flukes.   I'm now being advised to buy the next size larger flukes which I will probably do - but thought I would ask if anyone else has run into this issue as these things are pricey.

I'm certain that 4500 RPM is outside the engines operating range and something should be done.  Any thoughts

Bob
SV Chaos

[geoff]

Until I replaced it with a Kiwiprop my ocean 40 had a 3 blade 17x14 and it seemed about right. Your 17x12 seems well underpropped  particularly as you can get to 4500rpm . My max revs have always been about 2800 . Geoff

[Yngmar]

Sounds like too flat a pitch to begin with. Our 40 Ocean has a 17 x 15 L 3-blade propeller, Volvo part 21381279, and I believe that is the original one. The first number is the diameter in inch, the second the pitch (in inches forward travel per revolution).

Our MD22L-B does not revolve anywhere near that high when under load. I think it's doing about 3k at full throttle, but I might remember it wrong. Anyways, never over 4k!

Would try the above prop, it's likely the same for your 42 Ocean with the same engine, unless maybe your saildrive has a very different ratio (ours is a 120S-E).

[Symphony]

You have been sold the wrong propelle. If the supplier recommended that size given the information on the boat then it is their mistake and they should recalculate and supply the correct blades. As suggested you need at least 2 more inches of pitch. That will bring down the RPM by between 5-600rpm. My suggestion would be to get 15" pitch blades which will still allow you to achieve maximum hull speed but at much lower rpm. Or better still get a refund and fit a FlexoFold 3 blade folding prop which is (in my opinion) a much better propeller.

[rbrtmccorkle]

thanks to all - did speak with Volvo Penta through the prop shop that sold me the original prop and was sold new blades at a discount - based on the part numbers the old prop that was supposed to be a 17X12 (as indicated in my owners manual)  turned out to be a 16X11 - am now trying a 18X12 - we'll see. Boat gets splashed on Friday.

[tckearney]

Hi pity youve already splashed it I have three of the original spare props for a B42