Volvo DP 290 Breaking Props

[Riv27]

Hey everyone, I have a Volvo DP290 driven by a AQAD41A. Set up is in a 27 foot Riviera (see photo). I have owned this vessel for two years now and in that time I have dropped a blade from the front prop three times. First two times we were reasonably confident we'd hit something (submerged driftwood, fish, turtle or whatever). However today we were steaming at approximately 14 knots, engine was running at 3,000 rpm and we just lost speed, revs went up and everything started shuddering. It just seems impossible to me that I keep hitting something but that is the obvious conclusion. Each time this has happened we've been in deep water. Can it just be really bad luck or has anyone else had similar issues? Props are not that old and the current prop was only fitted two weeks ago. It had been on the boat previously but was in good condition when refitted. One thing to consider is that we trim the leg right in to assist with planing the hull and as a long shot it occurred to me this may be loading the prop more that normal, but as I say it's a long shot theory and I am really clutching at straws.

 

[Scott Danforth]

First, welcome aboard

If you are buying factory props, you keep hitting things. I have been thru 5 sets of props over the past 11 years and only twice have I spun a hub, the remainder of times it was things like giant rocks, a sunken sailboat, oyster shoals, spoil pile at boat ramp, logs, crab pots, etc

However if you just trim and leave the drive static, you could be sucking air and be cavitation so bad you fatigue the prop. Post a pic of the prop. Is there cavitation burn?

Proper way to use the trim. All the way down for the holeshot, as the boat climbes the hole, trim up until the boat starts to porpoise, then trim back down a bit

 

[Riv27]

First, welcome aboard

If you are buying factory props, you keep hitting things. I have been thru 5 sets of props over the past 11 years and only twice have I spun a hub, the remainder of times it was things like giant rocks, a sunken sailboat, oyster shoals, spoil pile at boat ramp, logs, crab pots, etc

However if you just trim and leave the drive static, you could be sucking air and be cavitation so bad you fatigue the prop. Post a pic of the prop. Is there cavitation burn?

Proper way to use the trim. All the way down for the holeshot, as the boat climbes the hole, trim up until the boat starts to porpoise, then trim back down a bit

Hey Scott, thanks for the response. Yes, props are Volvo factory J3's. I fully understand the role of trimming a leg/outboard etc. However, these hulls are renowned for dragging the stern deep so require a lot of trim to maintain efficiency. Regarding cavitation, is it possible for it to cavitate trimmed all the way in? I have never experienced it in 40+ years of boating, only when trimmed out too far. And note, every time this has occurred we are in deep water on the plane, so not hitting rocks, trees, piles etc.

 

[Scott Danforth]

Find a set of A3s. I'm not sold on the J series yet

 

[Riv27]

Find a set of A3s. I'm not sold on the J series.

I have a set of A3s brand new already. They are a bigger diameter though? But basically the same other than they are bushed?

 

[Scott Danforth]

You're drive came with A series if diesel, and B series if gas/petrol. C series are Stainless B series

J series came out a few years ago as a cheaper variation

 

[Riv27]

Thanks. Have spoken to my mechanic who is a Volvo specialist and he concurred, the A3's would have been what was fitted originally. Will give them a try. Thanks for taking the time to give advice. Really appreciate it.

 

[QBhoy]

Hi. Traditionally, diesels came with A series props…but some cruisers did actually come fitted with b series props and mated to diesels. Most, if not all that I know of that came as that, were associated with the later kad42 engines though.
Anyway. It’s likely you had A4 or maybe A3 original props. One prop being a 4 blade and the other a 3 from memory.
All I can think of is that if the j are larger diameter, and this time of year…you may be more susceptible to a log strike perhaps?

 

[Riv27]

Hi. Traditionally, diesels came with A series props…but some cruisers did actually come fitted with b series props and mated to diesels. Most, if not all that I know of that came as that, were associated with the later kad42 engines though.
Anyway. It’s likely you had A4 or maybe A3 original props. One prop being a 4 blade and the other a 3 from memory.
All I can think of is that if the j are larger diameter, and this time of year…you may be more susceptible to a log strike perhaps?

Hey, cheers for the response. The smashed prop is the front of a set of J3s. A3s are the larger diameter as they are bushed. I have a set of A3s which I am going to fit as a replacement and see how we go with the bushed type. May be more forgiving but I doubt it.

 

[Scott Danforth]

May be more forgiving but I doubt it.

actually, they are.

 

[Riv27]

That would be a good thing for me then! Cheers mate.