Volvo Outdrive

[regal25]

I have a dual prop volvo outdrive. The propeller is slipping when I trim up just a little bit. Any ideas why the propeller would be slipping?

 

[Don S]

Re: Volvo Outdrive

Volvo has a lot of different duo prop outddrives. How about some detail as to which one, what year, what engine, what do you mean by slipping when you trim up and any other minor details you may have omitted that may help us help you.

 

[regal25]

Re: Volvo Outdrive

I have a volvo DPS-A stern drive. When I trim up just a small amount I can feel the propellars losing their bite. It it like I have trimmed up much higher.

 

[Maclin]

Re: Volvo Outdrive

Is the installation all stock for that boat? Is this a new condition? Are the props a matched set (both B5's, not a B5 and a B3, etc)? Are they in good condition? Are they Alum or SS? Are you sure the unit is trimmed all the way down for sure when you start?

They could be not clocked or timed correctly, that could make some difference. Basically you do not want both prop blades going under the anti-cav plate at the same time. On some boats this can make a difference and hurt performance. The props turn at the same rpm, just different directions. You can check them easily, turn them until the big forward prop has one blade straight up. The smaller rear prop should have one blade straight down. If both are straight straight up then this can cause cavitation and burn the prop edges, and I suppose the trim angle could exacerbate it until you feel the slippage.

 

[Don S]

Re: Volvo Outdrive

They could be not clocked or timed correctly, that could make some difference. Basically you do not want both prop blades going under the anti-cav plate at the same time.

That might have some effect in racing and high speeds, but it is not a subject even mentioned by Volvo on any of their outdrives. And is not the cause of his problem.
Cavitation plate height yes, trim angle yes but not prop clocking.

You aren't makeing all your trim adjustments up and down by the gauge only are you?

 

[nimrod69]

Re: Volvo Outdrive

This prop clocking (timing) has come up before. I have spoken to a Volvo tech and that is a myth. The "timing" of the duo prop doesnt matter- the blades can be installed in any pattern you want.

 

[Maclin]

Re: Volvo Outdrive

I think regal25's problem is from excess trimming at speed, and like Don I am wondering if they are actually trimmed down as far as they think they are before trimming up. Prop burn on the edges is a symptom of cavitation and if it is occurring is definitely exacerbated by any excess trimming. I am not saying that the prop clocking is the root of the problem they are experiencing now, but if the edges of their props are getting the paint bubbled off and wearing away then cavititation is being induced somehow, most likely by running at higher speeds with excess trimming. Regal25 can provide more clues by reporting on the condition of their props and the speeds and rpm's they are running at when the slippage happens.

Just some justification for the clocking point....The DuoProps can get that type of prop wear from the clocking issue, this has been experienced and written about. I was experiencing the edge wear and found a lot of info about it, especially from the Albemarle boat owners site. That was the only issue I had, no wierd vibration or other symptom or issue. I had the props redone one more time and clocked them and the paint stayed on and no edge wear. Excess trim angle is usually the culprit but the clocking did make a difference for me and others. I did not notice any particular performance gain, the duoprops are a great performer all by themselves.

 

[regal25]

Re: Volvo Outdrive

I am making adjustments only by the trim guage.

 

[Maclin]

Re: Volvo Outdrive

You are using the trim switch at the top of the throttle, right?

My trim indicator does not work so I have to go by the sound of the unit. At rest and preferably with engine off or moving very slowly I get it all the way down with the tilt lever switch first, I can hear the pump change tone. Then when I take off I trim up some as the speed comes up, then once on plane I trim up until I can tell that the engine rpms are at the max for the throttle setting. With a constant hit on the tim switch usually a count of 5 is way too far up. Sometimes I lose my place and have to go down a little at a time until I know the bow is about to plow, then go up a little at a time until the engine "frees up" and it is planing and cruising well. In rough conditions I do not trim up as much. My boat will usually start porpoising rather than blow out the props when I go past the sweet spot.