P-bracket bent

[jfkal]

Additional to my prior post.
Lifted the boat and found the p-bracket ok but slightly bent so that the shaft is no longer fully centered in the stern tube. Any reason wshy I should'nt use the old shaft on its way out to bend it back a little ?? Braqcket is made out of bronze.

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by jfkal on 13/05/2003 08:51 (server time).</FONT></P>

 

[Birdseye]

interesting question. if the bracket is very slightly bent i would be inclined to see if i could get away with simply re-aligning the engine to the new shaft alignment. if this is possible, it is less risky than what you propose.

the correct solution is to replace the p bracket, at the same time strengthening the p bracket housing which will have suffered to some degree. not that difficult to do on most boats.

doesnt the p bracket housing leak now?

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[jfkal]

P bracket base does not leak and the bend is slight only. Will follow your suggestion.

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[PeterGibbs]

You have a potentially damaging situation, I'm afraid. Any variation from true will eventually catch up with you in terms of accelerated wear and potentially the failure of the gearbox. So it depends on the level of integrity you desire in the vessel that is carrying you and presumably, your nearest and dearest out to sea!

Having the shaft rebalanced is a specialist job but not a huge expense. But doing this without fixing the P bracket makes little sense. This can usually be removed without deconstructing the rear of the vessel. The leak test is not helpful in regard to the damage done to this piece of gear. A competent yard should have it out in an hour or so, assuming you have prepared the site etc.

You can then sleep for ever amber, knowing when you eventually sell the boat the surveyor will not knock it out - at least not for this reason!

If the boat is out of the water now's the time to do it - otherwise, you can take a chance and wait for the end of the season!

PWG

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[philip_stevens]

"JFKAL" has a 12 month sailing season - in Singapore. Envy.

<hr width=100% size=1>regards,
Philip

 

[Birdseye]

From Peter Gibbs comments, I can see that I did not make it clear that you must change or have straightened a bent shaft (not balancing by the way). As he said, not difficult to do. When mine was supplied bent, one of my toolmakers straightened it on a lathe by leaning on it at the right point. But he knew what he was doing.

The point that I was making was that if the p bracket was only slightly bent it might well be possible to compensate by re-aligning (after installing the new shaft) without the shaft fouling the stern tube in use. depends on the degree of bend, the geometry of the stern tube etc. certainly, very few if any shafts will be absolutely concentric with the stern tube - its a matter of how far out they are, not whether. and even if they are, they wont stay concenrtic when the engine is in use unless there is a uj and an intermediate bearing in the system.

However, a small degree of bend at the p bracket can require a large lateral or vertical movement at the engine to compensate. so you might have to go the pukka route and to remove / replace the p bracket, including laminating in some strengthening of the p bracket mount which might have been damaged. this may or may not be necessary - only you can tell, and you should take on the spot advice if you are doubtful. but being a bit "careful" i would no more do this automatically on my boat than i would have the keels dropped and re-bedded every time i go aground.

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