Ali boat corosion
Submitted by JohnF on Fri, 2011-05-20 00:03
So, to minimize corrosion of Ali hulls (trailoredboat) is it best to
- have battery switch to isolate battery when not in use (I do this)
- separate the motor from the hull with insulator.....lot of discussion on this. I am not sure? My boat appears to have this, but I think this may be bad as you then don't get the galvanic protection from the anodes on the motor.
- fit separate anodes on hull. My boat does not have this. Seems sensible but method of attachment is impotant I have heard.
- specifically earth the hull?
Comments?
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Boston Whaler 235 Conquest......getting the flogging it was built for.
kane
Posts: 1752
Date Joined: 07/12/08
Anodes on the hull work well
Have seen this method used on Ali commercial vessels and seems to work well.
Gooooone Fishin!
till
Posts: 9358
Date Joined: 21/02/08
Hmm not really sure how
Hmm not really sure how effective isolating the hull from the motor ever really would be? You would need plastic mount plates, then you would need to sleeve the bolt holes I guess?
Anode on the hull itself sounds interesting?
pelagicyachts
Posts: 1322
Date Joined: 23/02/11
Hey JohnI used to have a Ali
Hey John
I used to have a Ali boat that was penned - she had anodes on the hull, legs, rams - eseentially everywhere we could! -it had a tab on the transom (below the waterline) and i used to bolt on hull anodes (disk shape you can buy from whitworths)
Was pretty interesting as they used to get chewed up pretty quick - we also fitted a galvonic isolator - but doubt you would need to do this if your boat is not kept in the water permanently
cheers
Clint
JohnF
Posts: 2839
Date Joined: 07/07/10
Very interesting subject,
Very interesting subject, bimetallic and galvanic corrosion. I have a few bubbles under the paint near screw holes, but on closer inspection appears to be only superficial surface corrosion under the paint. I think a totally unpainted hull would be better.....
If my boat was moored, would definitely put on hull anodes.
Yep, it is hard to isolate the motor from the hull but it appears the motor installer on my boat has tried. It has nylon spacers on the mounting points(maybe this was just for aesthetics) but the bolts through the hull still hit so the motor is still earthed to the hull, which in my opinion in good, as at least the anodes on the motor will help protect the Ali hull as it is electrically connected. I have heard of dramas when the motor is totally isolated, as the Ali hull then brines an aside, especially near any stainless steel scree etc.
Would be interested in others comments on the subject.
Boston Whaler 235 Conquest......getting the flogging it was built for.
pelagicyachts
Posts: 1322
Date Joined: 23/02/11
We got a guy in (forget the
We got a guy in (forget the name -might have been Marina Protection Systems?) as our props were getting chewed out and our anodes were dissapearing fast -turned out to be a boat about 4 boats up who's shore power was not earthed properly -basically putting a light charge into the water!!
The galvanic isolator made our annodes last a lot longer -but specifically i do remember him saying everything should be "linked" ie not isolated -