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S&S Swan Maintenance - Vibrating propeller |
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Join Date: 28 July 2008
Posts: 79 |
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Vibrating propeller Dear All, We have a three bladed Maxprop, that has a very annoying vibration. It starts vibrating at just over 5knots; just before cruising speed. Oddly, and very annoyingly, it does not go away if you increase the revs and try and power through it. Which one might expect it to do. The vibration is sufficient for it to be clearly felt and heard on deck; to the point that I think it would damage the gearbox and engine. It’s always vibrated to a certain extent since new about 5 years ago, but would come and go and could generally be powered through. About two years ago we had some electrolysis problems which lead to two of the blades needing to be re-built due to corrosion. It was rebalanced, statically, at the time but continues to vibrate. We have tried new cutlass bearings, but that make no difference. We have also considered cavitation due to incorrect pitch, but checked the pitch settings with the distributor and have no signs of erosion on the blade tips, or of the anti-fouling on the hull above the prop. Several people far more experienced than I am have sailed on Tiderace and are all at a bit of a lose to explain what is going on. My next course is to see if I can get the prop dynamically balanced, but nobody I have spoken to knows of anybody that could do this on a feathering prop. Has anybody experienced anything similar or can offer an explanation? Your thoughts would be much appreciated. Many thanks in anticipation (TIDERACE II) |
Join Date: 06 August 2010
Posts: 24 |
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Hi Adrian,
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Join Date: 28 July 2008
Posts: 79 |
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Thanks Brian. I will double check the shaft length this winter but think it is OK. We dropped a new engine in last winter and the engine fitter had to shorten the shaft as it pushed it too far aft. Would certainly cause/contribute to the problem though. Cheers Adrian |
Join Date: 02 January 2008
Posts: 1547 |
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Adrian |
Join Date: 28 July 2008
Posts: 79 |
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Lars, Thank you for those suggestions. We will go through those this winter and report back. A couple I have not thought off and also some I had assumed would be OK, but should be checked out as you suggest. The engine is a Beta 50. New last winter, and a marked difference over the Perkins which was original to the boat. We have done about 250 hours this year with it (two long delivery trips) and its been very good; much reduced fuel consumption and quieter. (If anybody is interested I'll post a thread on it, with some pics.) Cheers Adrian |
Join Date: 27 January 2011
Posts: 140 |
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We also have a problem with engine vibrations, starting at higher speeds, and being exacerbated by higher seas. Today we found out that two silentblocks were broken, which was not visible from the outside. Replacing them seems to have fixed the problem as far as we can tell, but sea trials tomorrow will show for sure. Before we had already fixed a bent shaft, changed strut bearings, shaft log and coupling, and were astonished about continued vibrations after the reparations. The theory now is that the bent shaft led to vibrations which in turn destroyed the silent blocks. Christain 411/28 IF |
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