p-bracket to anode & prop spacing?

[john_morris_uk]

Has anyone got any thoughts as to the preferred spacing between the shaft anode and the p-bracket and the p-bracket and the propeller on the prop shaft? On the one hand it would appear to be better if there was a fairly small gap between the p-bracket and the shaft anode (just f'wd) and the prop (just aft), but I seem to remember that the rubber cutlas bearing needs a free flow of water. Is there an advised gap to allow water flow, or will sufficient water get in anyway? What do people think? I am in the process of fitting a new prop and shaft so I can choose where to put them all! The boat is a fin keel cruiser-racer. One inch shaft, 25 HP motor.

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[dickh]

I would fit it about 2" from the rear of the 'P' bracket - as long as it can 'see' the prop you will be OK. Have also seen them about halfway between the P bracket and the deadwood?.
I would allow about 1½" between the P bracket and the back of the prop - you will then have enough rooom(I think) to fit a Rope Cutter - See
<A target="_blank" HREF=http://www.ropestripper.com>http://www.ropestripper.com</A> - Ambassador marine who should have the info on their website.
It is always possible to shorten a shaft, very difficult to lengthen it!

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I'd rather be sailing... /forums/images/icons/smile.gif

 

[tristan]

About half-way between the p' bracket and the hull is ok, but to be honest i wouldn't bother - they don't work very well anyway unless your boat is sat in a marina most of the season connected to shore power.

Not just ranting - i can back it up!!

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[vyv_cox]

There is another consideration. Putting a heavy weight in the centre of the shaft span can have quite an effect on its rotordynamics. You could cause quite significant vibrations by doing this. I seem to recall that a gap of 10 mm is sufficient for entry of water to the cutless bearing.

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[john_morris_uk]

Thanks for the comments chaps. Regarding whether the anode works or not. Well we are not stuck in the marina all season - Last year we were in Ireland, then the solent, Channel Isles and Brittany, and it was obviously working as it was half eroded away when we hauled out. I was tempted to put it close to the p-bracket as some of the anodes come shaped as if they are supposed to be near something - others are more rounded as if they are designed for more mid shaft.

Happy sailing!

John

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[Seapepper]

If you put your anode foreward of the p bracket, leave a large enough gap to be able to slode the prop shaft aft in order to disconnect the gearbox / shaft coupling in case you need to check / realign the engine. Don't get caught like I did, unable to undo the coupling because the shaft would not slide back far enough.
Cheers
John.

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