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Just a quick question. I worked in the marine leisure industry for 19 years on sea going sailing boats, speed boats and cruisers ect. Most were made of Tupperware some were wooden some were steel and we even had a couple of concrete ones. In 19 years I have changed 100's of anodes but never came across one that was welded to a steel hull.. They were all held on with nuts and bolts. Or two studs welded to the hull.... Why on earth do they weld anodes to narrow boat hulls? it seems. Er... Odd

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10 minutes ago, rbrtcrowther said:

Just a quick question. I worked in the marine leisure industry for 19 years on sea going sailing boats, speed boats and cruisers ect. Most were made of Tupperware some were wooden some were steel and we even had a couple of concrete ones. In 19 years I have changed 100's of anodes but never came across one that was welded to a steel hull.. They were all held on with nuts and bolts. Or two studs welded to the hull.... Why on earth do they weld anodes to narrow boat hulls? it seems. Er... Odd

It makes for a good connection without the need for drilling holes. 

Our grp boat has a through bolted anode to protect stern gear /keels etc. 

Our narrowboat has welded studs for anodes, but was recently advised by surveyor that its not as good as direct welding. 

Edited by rusty69
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31 minutes ago, rusty69 said:

It makes for a good connection without the need for drilling holes. 

Our grp boat has a through bolted anode to protect stern gear /keels etc. 

Our narrowboat has welded studs for anodes, but was recently advised by surveyor that its not as good as direct welding. 

at which point I would ask if I should weld my battery cable to the battery posts..

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Remember all non-metallic boats with hull mounted anodes need the anodes electrically bonded, inside the hull to the items they are supposed to be protecting so you need aat least one through bolt to make the connection to the cable. A metal boat is one great big conductor so the bonding is done automatically.

Nowadays the typical hull side plate is 6mm or in some cases more, not the 3 or 4mm of some steel cruisers. Very har to tear the hull as the many hang ups in ;locks on side anodes have found out when they get the big splash with no damage.

 

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11 hours ago, rbrtcrowther said:

Why on earth do they weld anodes to narrow boat hulls?

Why not? It's quick and easy, no nuts to corrode and gives a reliable connection. It's not like they do an awful lot anyway and usually last for years. 

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9 hours ago, rbrtcrowther said:

I've seen a few boats out of the water that don't have any anodes at all and don't seem to have much hull corrosion...

 

Hmmm, me too, I know what they are supposed to do and how they are supposed to work but sometimes I think we are just sticking lumps of expensive metal all over the place for no reason. I have them on my boat but its a bit like going to church, I don't believe in it but in case I'm wrong its a bit of insurance.

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10 minutes ago, Bee said:

Hmmm, me too, I know what they are supposed to do and how they are supposed to work but sometimes I think we are just sticking lumps of expensive metal all over the place for no reason. I have them on my boat but its a bit like going to church, I don't believe in it but in case I'm wrong its a bit of insurance.

Same here. I'm not convinced they do much but still have them fitted.

I expect man has fitted them to his boats since Jesus was about.... Anode Domini. 

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2 hours ago, Bee said:

Hmmm, me too, I know what they are supposed to do and how they are supposed to work but sometimes I think we are just sticking lumps of expensive metal all over the place for no reason. I have them on my boat but its a bit like going to church, I don't believe in it but in case I'm wrong its a bit of insurance.

It's not really a question of "belief". Anodic/cathodic corrosion is a scientific fact. Anodes will obviously have more of a protective effect in salt or brackish water. Whether they do anything or not in a poor electrolyte such as fresh water will largely depend on the particular impurities and constituents in the water, but as you say, is it really worth not having them?

I know from personal experience that the areas of my hull in proximity to the anodes (at the bow and stern) were better protected than the mid-section areas further away from the anodes. Those areas were starting to show signs of initial pitting until I fitted these.

 

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Edited by blackrose
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Depends on the water the boat is floating in and their size. I get the impression that narrowboat type anodes are massive when compared with those on wooden and plastic boats so would last longer. Typically the answer will be several years or more.

We tend to use Magnesium anodes for fresh water and if you want to see anodes fizzing take a look at the narrowboats in Liverpool docks, or anywhere else with salt water - possiibly including the canals in the salt producing area around the wiches.

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10 minutes ago, rbrtcrowther said:

hmmmm.. How long do they last on narrow boats. We generally changed them every season as they were fizzed away to nothing in the salt water in the marina..

Our NB ones usually last 6 to 8 years. 

Our grp salty boat anode more like 3 years

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20 hours ago, rbrtcrowther said:

at which point I would ask if I should weld my battery cable to the battery posts..

I think that would depend on whether you intend to leave them in the canal for about 1000 days without touching them and have less than half a volt to flow through them

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23 hours ago, Bee said:

Dunno. Seems odd to me too. I welded studs on mine, seems to be ok.

What happens when next time they are replaced the studs don't match the holes? or the nut has rusted on & you have to cut the stud off. Easier just to weld the anode in the first place.

Edited by sharpness
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