Reply With QuoteLooks like corrosion from sitting wet with salt on it.
I have 4 of these spots on the bottom of the boat that are at the back and are a little rough spots, some look like they are pitted a little bit.
Is this corrosion if so is it from the bottom or top that it's happening ? I can see nor access the top/floor behind my back seat due to a stupid shelf that looks from factory to me.
Do I need to get these spots welded if so ?
Pics are not the best sorry.
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Looks like corrosion from sitting wet with salt on it.
Nor sure how though I hose it off after each use, is it coming from the bottom ?
Does it need fixing by welding in New aluminium ?
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That would be pitting corrosion, and its caused by contamination forming an anode, most likely from some salt granules. Possibly also shitty aluminium too, but there is a hundred things that could cause it. Welding is only a temporary solution because that introduces a whole new bunch of issues. If the holes dont go all the way through, I would clean them up so they look like new aluminium and keep a close eye on it. Make sure you clean all salt off it. I remember using an acid mix to create a poor mans anodising of aluminium in my early uni days, but I I cannot for the life of me recall what acid it was, google might help, but something like that could help longevity.
Etch it with an off the shelf aluminium cleaner and then rub a coat of carnauba wax over the area if the pitting isnt close to breaking through hull. If holes are deep just fill with sikaflex. If they go through hull yes weld up. Corrosion is from where you can see judging by larger face is on surface.
Ok I'll have a look, I would like whatever is the best fix as I may sell in the next 6 months want to make sure it's all good for next owner, a bit disappointed it's happened the rest of the boat is in excellent condition.
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Could also be from a sinker or a swivel stuck in there somewhere.
In regards to sinker doing it would the bottom look like it does ? That's why I was wanting to know where the hole is starting from inside or out
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I've been told to get an access hole in the shelf at the back so I can open it and give it a really good clean, then use FlowCoat on the bottom, then If I want Flow Coat all of the floor up to the Flare on the inside, then also I can FlowCoat the bottom side of the boat as well up to the Flare, so i might investigate this rather then fix anything with welds.
Although I see Flowcoat is for fibreglass not sure how it would go on ally, Possibly cleaning everything and painting both sides with a 2 pac might also stop it in its tracks, not sure.
thats electrolosys. check for sinkers and swivels etc inside the hull, under ribs etc. dont ground anything in your boat. Isolate things like flush mounted VHF etc. disconnect batteries after use. Make sure your anode on the engine is ok. If it is maybe just undo and redo the bolt/ clean it up.
Yes i think thats my issue personally, whats under the rear shelf I dont know, I am going to get a 27x37 access port and put in the middle so I can get access, I will clean it up get all the shit out of there, then maybe coat it in something maybe the Flowcoat to just add a barrier on top, I might do the entire inside of it below the flare with that after i gurney it.
Then I might just get the 4 spots welded so they are fixed OR put something over it if welding is not needed at this stage (some are not even a pitting hole just the beginnings of it).
I've been told by my boat mechanic that its a 22 year old hull and it will start to happen at some stage, there is not a lot you can do other then clean it up fix any holes and keep cleaning it after use, he also said this all could have started before I owned the boat (i've had it for about 2-3 years), but the boat should be ok for years to come, just keep fixing it, until I change boats.
As for power the only batter in the boat sits in an old plastic hummingbird GPS case they are 2 x 6 Volt batteries that are connected to my GPS and Nav Lights, I dont disconnect them but its also not earthed anywhere in the boat.
led navlights with a heatsink maybe touching boat?
Back of nav lights are all plastic wires come through hole and that goes through hole in boat.
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Most likely it is salt corrosion if it is in a hard to wash down area.
Electrolysis is a possibility if you have any current passing through the hull.
My boat now has about 30 alloy peen rivets in the bottom after 21 years and 1.6mm aluminium.
My boat has never been applicable to electrolysis because every electrical connection is isolated from the hull, at no point has it ever been earthed.
Jack.
Technically speaking, all corrosion is electrolysis. In this case, its plane old boring corrosion caused by some sort of contaminant, most likely salt. It highly unlikely that its caused by stray current from electrical accessories as its just some isolated pitting..Originally Posted by myusernam
If you want to see what corrosion caused by stray current is like, take a look at the anode on you outboard, or even better the anode on a boat that is always in the water.
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