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Discussion Starter · #1 ·
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Had a brand new prop fitted 12 months ago and ws in water 9 month and it is badly corroded to the point there is no tips on the 4 blades and holes right through the blades
Has anode whitch is working as it has corroded to but no shaft annode any Idears(as the boat yard did not advize to put 1 on)
bloody £600 down the drain!!!
Cheers Andy
 

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Had a brand new prop fitted 12 months ago and ws in water 9 month and it is badly corroded to the point there is no tips on the 4 blades and holes right through the blades
Has anode whitch is working as it has corroded to but no shaft annode any Idears(as the boat yard did not advize to put 1 on)
bloody £600 down the drain!!!
Cheers Andy

Andy, go through and list how your electrical circuits are linked together before they connect to the lead to the anode. It sounds as though your engine/prop shaft/prop are not in that circuit for the corrosion to be that bad. Things like rubber dohnut couplings and constant velocity joints in the drive line will interupt the continuity of the set up. I think one would need more information on how your set up is, before an accurate answer can be given.

Afishionado
 

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Andy just adding to the good advice given, if you have r&d couplings or any others that break the continuity of the earth run then you will lose your prop and the your rudder if it is metal, and anything else underwater. Also make sure the bolts that hold the anode to the boat are sound, we found ours were rotted away in the hull even though we could undo the nuts on the outside and the inside, it was by pure chance we found them to Knackered, hold the inside nut and then give the outside one a good tightening see if they give. How long have they been in service? as stated the joints in the line must be bridged. Look up www.clementsmarine.co.uk web site for good info.
 

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Discussion Starter · #4 ·
Andy just adding to the good advice given, if you have r&d couplings or any others that break the continuity of the earth run then you will lose your prop and the your rudder if it is metal, and anything else underwater. Also make sure the bolts that hold the anode to the boat are sound, we found ours were rotted away in the hull even though we could undo the nuts on the outside and the inside, it was by pure chance we found them to Knackered, hold the inside nut and then give the outside one a good tightening see if they give. How long have they been in service? as stated the joints in the line must be bridged. Look up www.clementsmarine.co.uk web site for good info.
cheers for that guys has been ok for first 6 monthswas re antifouled in nov ok then,then they pull up all the outside mooring chains and lay them 20 foot 2 the side of my boat,loads of thick lenghts for the winter:g:
could it have been them?
cheers Andy
 

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NCM, previous is sound advise. Try a continuity test between prop and anode, simple meter set to ohms, this will confirm a break in the circuit. The other problem we had recently in the marina, was two steel boats moored on fingers 1 and 3, and a convetional glass boat on finger 2 between them. The anodes on the glass boat could not cope with the eloctrolosis between the two steel boats!!!!!! I believe there were a few lesser problems with boats in the imediate vacinity as well, that were unresolved, no one adimiting to anything!! Similare problems to those you describe???

Dont solve your imediate problem, but it might help to get the head around it??:unsure:

ET's OPO
 

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Discussion Starter · #7 ·
Are you in a Marina with shore power on the berths?
funny that as the steel barge which lays the chains was moored 6 foot behind my boatas well an d shore power,surly it would not have gone that quick 5 month's fine before the barge and probably 100 tons at least of chain and rotted prop
 

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It is the shore power at a guess, there is an earth fault on the pontoon or on the barge itself. I will bet the pontoons are galv steel and your anodes are trying to protect your boat, the pontoon and the barge. What is happening is a small voltage leak into the water which acts as a potential driving the electrolosys process.

It can help to dangle a big chunk of zinc off a cable attatched to the pontoon to help out your anodes a bit.

I have collected old anodes from the skip at the marina melted them down( slightly higher melting point than lead) and cast them with a length of SS rigging wire to enable them to be hung off the pontoon. The larger the surface area of the zinc the more protection it will afford. it also needs to be in line of sight of your stern gear.

It is up to the marina to sort really but getting proof to force them to act is difficult and expensive as it involves employing a surveyor skilled in the problem.
 

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Discussion Starter · #9 ·
It is the shore power at a guess, there is an earth fault on the pontoon or on the barge itself. I will bet the pontoons are galv steel and your anodes are trying to protect your boat, the pontoon and the barge. What is happening is a small voltage leak into the water which acts as a potential driving the electrolosys process.

It can help to dangle a big chunk of zinc off a cable attatched to the pontoon to help out your anodes a bit.

I have collected old anodes from the skip at the marina melted them down( slightly higher melting point than lead) and cast them with a length of SS rigging wire to enable them to be hung off the pontoon. The larger the surface area of the zinc the more protection it will afford. it also needs to be in line of sight of your stern gear.

It is up to the marina to sort really but getting proof to force them to act is difficult and expensive as it involves employing a surveyor skilled in the problem.
cheers seems like a no win game
Thanks everybody for your help
 

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Just been chatting to the Berthing guy at our marina. They have a similar problem with props melting if sufficent anodic material is not present. The reason he says is because of all of the boats permanantly plugged into shore power create massive amounts of Mamps in stray current leakages. The answer it seems is to follow ChrisP's advice and dangle a big lump of anode over the side. But bare in mind it must be connected electricaly to an engine foot or the shaft via a crocodile clip. This will make sure any current leakage goes through your lump of zinc and not your prop.

Afishionado
 

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Discussion Starter · #11 ·
Just been chatting to the Berthing guy at our marina. They have a similar problem with props melting if sufficent anodic material is not present. The reason he says is because of all of the boats permanantly plugged into shore power create massive amounts of Mamps in stray current leakages. The answer it seems is to follow ChrisP's advice and dangle a big lump of anode over the side. But bare in mind it must be connected electricaly to an engine foot or the shaft via a crocodile clip. This will make sure any current leakage goes through your lump of zinc and not your prop.

Afishionado
seems a good idea asked other people near me and they all said strange my prop was badly pitted
to and had problems lucky they never had the steel barge as well as the chains:blink: + electric current.also is a strong tide here that also makes the electorisis worse so i am told:g:
 

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seems a good idea asked other people near me and they all said strange my prop was badly pitted
to and had problems lucky they never had the steel barge as well as the chains:blink: + electric current.also is a strong tide here that also makes the electorisis worse so i am told:g:

There is too the very very slight possibility that your prop when it was new had a poor zinc ratio to copper, tin, and other metals. In other words more Brass than Bronze. If you bought it of a well known reputable company then it would be a good one; but a bargain prop from China or India may well be brass. It is worth having a reasonable 'go' at the prop supplier quoting 'Fitness for purpose' part of Trading Standards. You will need to be able to prove that you had adequate cathodic protection but the prop' still went soft. The seller will have to prove that he made you aware of all the things you needed to do to keep the prop in good condition. Murky waters but still worth having a polite but assertive "I aint 'appy John!" chat. :g:
You may end up with a big chunk of dosh off a replacement:)

Afishionado
 

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Discussion Starter · #13 ·
There is too the very very slight possibility that your prop when it was new had a poor zinc ratio to copper, tin, and other metals. In other words more Brass than Bronze. If you bought it of a well known reputable company then it would be a good one; but a bargain prop from China or India may well be brass. It is worth having a reasonable 'go' at the prop supplier quoting 'Fitness for purpose' part of Trading Standards. You will need to be able to prove that you had adequate cathodic protection but the prop' still went soft. The seller will have to prove that he made you aware of all the things you needed to do to keep the prop in good condition. Murky waters but still worth having a polite but assertive "I aint 'appy John!" chat. :g:
You may end up with a big chunk of dosh off a replacement:)

Afishionado
wel I dought that the poorly mounted heat ex/manifold that broke was hard enough to get my money back in the form of a new 4hp 4 stroke sail drive as they had no money.The alternater now broke for the third time in a year,because as i have found out the thread has gone in the block so just cracks them off dicks
a new rudder mounted 1 inch of square (loverly in a following sea not)
now this!
The prop was only 12 month's old and the mariner had it made.
God I hate boats selling for 6 grand and thats that:schmoll:
cheers guy's
 
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