Fitting anode whilst boat is in the water.

[colin_dev]

Whilst my Beneteau 311 was out of the water earlier this year I replaced the only anode, this is on the end of the prop shaft. Being a newcomer to sailing I foolishly did not think to use Loctite.

A couple of weeks back I had a diver clean the hull and he noticed that the anode is missing! Fortunately, there does not appear to be any damage to the propeller.

I want to leave the boat in the water during the winter but believe that I need to fit a new anode asap.

Which brings me to a couple of questions for the ‘experts’ out there

1) Is it possible to fit an anode underwater? (The diver would do this for me).The concern I have is that as the securing bolt goes into the threaded hole, the water has nowhere to go and this could prevent the bolt fully seating properly.

2) I doubt if Loctite would be effective when applied under water, is there an alternative product available?

Any suggestions on how to fit the anode underwater would be appreciated.

If the consensus of opinion is that it is not possible, then I will probably use a scrubbing grid.

Colin

 

[sailorman]

fit a shaft anode

 

[Marsupial]

Collin

The prop anodes fitted on French boats don't last very long (yes I have a French boat) fixing them with a plastic screw makes them last longer - if they dont fall off as you go astern.

Shaft anodes are ok but they to have a habit of depleating then rattling around -but they can be fitted without hauling out.

You may end up with an "egg" style anode if you can get continuity from the prop to the anode via the engie or gear box.

Anyone got another suggestion?

cheers


David

 

[sailorman]

the M.G.Duff shaft anodes with the steel inserts dont fall off or come loose

 

[DanTribe]

I beg to differ.
They don't come loose as much, but do start to rattle in time.
I now fit a jubilee clip above them to stop them riding up to the hull.

 

[sailorman]

never had one fail yet.
the steel inserts do stop this happening, are you using the older spherical ones

 

[PuffTheMagicDragon]

[ QUOTE ]
The concern I have is that as the securing bolt goes into the threaded hole, the water has nowhere to go and this could prevent the bolt fully seating properly.



[/ QUOTE ]

If I understand you correctly, the anode is secured by a bolt that goes into a threaded, axial, hole in the end of the shaft.
I doubt very much that the fit would be so exact as to cause hydraulic pressure problems.
I would use a normal anode, similar to what you probably had, but I would include a stainless shake-proof washer (also known as a star washer) or else a split washer. These last are usually rather thick whereas the star ones are flatter and they are more even. Make sure that the diver really tightens things up.

Good luck.

 

[PuffTheMagicDragon]

[ QUOTE ]
never had one fail yet.


[/ QUOTE ]

You have been fortunate! I have seen ends of sterntubes really chewed up badly by loose anodes that rode up the shaft.

The probable reason is that the wrong size is fitted. A 1" anode does not grip well onto a 25mm shaft.
The other way round is even worse. When applied to a 1" shaft, a 25mm anode only seats on the long edges - leaving free space between the anode and the shaft. As soon as these edges are consumed there is nothing left to hold the anode in place.

I might be wrong, but I don't think so /forums/images/graemlins/wink.gif

 

[DavidGrieves]

Hi

You can get an anode that you hang over the side of the boat, you connect it to the boat grounding wiring system. Is your shaft bonded to the gearbox/engine block? You could temporarily attach the hanging annode to the shaft with a large crocodile clip. This would at least get you through the winter. The hanging annode is not a bad option when you consider how much time the boat spends on its mooring!

If you wrap the wire around you throttle lever it will serve as a reminder not to put the boat in gear without removing the anode.

 

[discovery2]

The shaft anode on my Beneteau sometimes falls off - don't know why - it's just sometimes the bolt & anode are missing - other times it is still tight.
However, when lifted out earlier this year, the boatyard advised fitting a through hull (pear shaped) anode, as this would 'protect' the propeller if the shaft anode should go AWOL.
It is possible to fit the shaft anode when the boat is afloat. Just make sure that there is no possibility of anyone starting the engine and the diver does not drop the anode, bolt or allen key!!

 

[sailorman]

this is the type that dont come loose



http://www.mgduff.co.uk/assets/images/image004d.gif

 

[bendyone]

Why dont you just go along side and dry out for a tide, go to be easier and cheaper than using a diver. Also you can see what you are doing.

 

[john_morris_uk]

[ QUOTE ]
Shaft anodes are ok but they to have a habit of depleating then rattling around -but they can be fitted without hauling out

[/ QUOTE ] Mine sometimes used to come loose until a boat yard mechanic showned me how to tighten them up!

Tighten as normal, then use a pair of hammers to simultaneously hit the anode and 'tighten' it onto the shaft. After a few hits tighten the screws a bit more. Repeat the process several times. You will be surprised at how much more you can 'tighten' the allen screws that fix the two halves together.

I have never lost an anode since!

 

[dulcibella]

Cone anodes made for Brunton autoprops seem to come off very quickly. Oddly, the nylon screws remain in place. I suspect that the slightly flexible screws let the anode wobble slightly on a fast-turning shaft, wearing away the zinc around the screw holes until they are big enough to pass over the screw heads. Whatever the cause, wrapping the part of each screw nearest the head in plastic tape seems to make them stay on for a season.

 

[duncan]

surely (2) the loctite should be allowed to dry on the thread before being used so, as long as this is done, it should work fine.

the bolts supplied with my anodes are 'pre loctited' and I have installed them underwater many times

 

[harvey]

As Dantribe says, fit a jubilee clip above and below. That has always kept mine where it should be on the shaft even if it's come loose.
John

 

[vyv_cox]

I almost wrote the same thing earlier up the thread but scrolled down and saw your contribution. I have used this method for about 15 years and never had an anode come loose. Conversely, replacing old ones at the end of the season is somtimes quite difficult as they are so tightly attached to the shaft. Before I was told this method I did once have an anode come loose.

 

[colin_dev]

Thank you to everyone for their postings.

A number of you have suggested fitting a Shaft Anode, this created a sub thread. Unfortunately on my boat this is not possible; when the prop shaft comes out of the skeg it runs in a stern tube, once it exits that, there is nowhere on it to fit a shaft anode.

The type of anode I have, or rather had, fits on the end of the shaft. http://www.mailspeedmarine.com/ProductDe...e4-5b1a0874525c

There were a number of suggestions:-
1)Refit an anode whilst afloat using a star or split washer. Good suggestion.
2)Get an anode with a screw that already has Locktite applied. I will look for one of these, the one I fitted earlier in the year did not even have a screw with it and I foolishly used the old screw! Duncan, you suggest that Locktite should be allowed to dry before use, this is not what it says on the instructions.
3)Go alongside a quay and wait for the tide to go out. Being in Portsmouth Harbour does anyone have any suggestion of a suitable quay? I only know the scrubbing grid at Hardway Sailing Club.
4)Hang an anode over the side when the boat is in the marina. I would have to ensure that there is an electrical path to the prop shaft. This of course is feasible, and will be a temporary solution until the boat next gets lifted.
5)Fit an anode on the outside of the hull. This would be ‘belt and braces’ in case the one on the end of the shaft goes missing again. Great idea, I may do this, but again it will have to wait until the next lift.

Considering everything, in the short term, I will get the diver to fit a new anode, using a star washer, and Loctite on the bolt, and then use a hanging anode just in case.

Why are hanging anodes so expensive?. http://www.mailspeedmarine.com/ProductDe...e4-5b1a0874525c
It would be far cheaper to make one with a standard anode and a piece of earth wire.

Thanks again for your help.

Colin

 

[Keiron]

As a commercially qualified diver fitting anodes underwater is usually a really simple job. To be honest if you have a friend who is a competent UK sports diver they should be easily be capable of doing this for you rather than paying a commercial diver. Just make sure you don't pay them more than their actual expenses as that would be illegal uder HSE legistlation. The key thing on a prop shaft job such as this is the engine MUST not be operated with the diver in the water, several fatalities have occured for this reason. Isolate the engine so it cannot be operated by accident.

Keiron

 

[Sea Devil]

admittedly not in UK waters, I have fitted a new anode using only a mask and snorkel and more easily with scuba gear. It is not a very shallow dive and you can hold your breath long enough to do it, in only a few dives.... No reason why it should be any less secure than one fitted on shore... Bit cold this time of year to do it... without a wet suit.

Michael