Aluminium boats and dissimilar metals

[NaClH2OK9]

I've recently become aware of the problem with dissimilar metals on aluminium hulls.

Does this issue affect different grades of aluminium?

I. E. Can I pick up a piece of ally section from a diy store and rivet to my boat with an ally rivet with no worries?

Thanks guys.

Edited September 3, 2014 by NaClH2OK9

[chocolate]

Interesting, Yes I think there is but I have done this on all my boats, But what I will say is the alloy was always prepared ,Painted ,and propyl sealed. If you were to put the alloys together with no sealer or paint and straight rivets yes , Corrosion ETC will occur and so on. Another way to look at the difference is the boats with paint jobs straight out alloy, Try not to use rivets were you can stainless bolts , Rivets tend to loosen up. Hope this helps.

[fragmeister]

I've recently become aware of the problem with dissimilar metals on aluminium hulls.

Does this issue affect different grades of aluminium?

I. E. Can I pick up a piece of ally section from a diy store and rivet to my boat with an ally rivet with no worries?

Thanks guys.

Thats an excellent question.

I believe this wouldn't be a problem but its worth further research. Alloys are not all the same and they can have a range of different metals in them.

if you do attach alloy to alloy and use stainless you will need to use something like TefGel to separate these two dissimilar metals otherwise you will get serious corrosion.

Many boat builders use alloy rivets and fix alloy rod holders etc and I believe that is considered the best combination you can use if it is practical.

Edited September 5, 2014 by fragmeister

[NaClH2OK9]

Hi. Yes I understand using stainless fasteners requires the use of duralac or something similar ( I will be rectifying my errors over the next couple of weekends).

I'm unsure if boat builders source rivets of the same grade as the plate they are using.

[Geoff]

Keep copper , brass & lead away from aluminium boats. There is a reaction between these metals which , in the case of lead will actually eat through the aluminium & create a hole. EG , sinkers under the floor

Only use 316 stainless screw / fittings or aluminium.

Needless to say any mild steel should never be used.

Geoff

[oz_brett]

make sure you use rivets with aluminium mandrel .

[fragmeister]

make sure you use rivets with aluminium mandrel .

Very good point

[Paikea]

Steve, we just got back from the NT, give me a call and I will show you what I did to my Trailcraft to attach some ally fittings, also I have got some bits that you can use and can point you in the right direction for Ally.

Cheers

Paikea

[NaClH2OK9]

Cheers Paikea. I'll give you a shout over the weekend.

[NaClH2OK9]

Thanks everyone. So I'm going on the idea that different ally grades is ok.

I've had a look for the ally mandrel rivets but not turned much up. I'll keep looking

[brickman]

i think the grade off ally is very important for example

i had a 10mm thick section lazer cut for stewy to fit an electric to his polly craft

i asked the lazer cutter to use marine grade ally as it would cop salt water spray every time stewy went fishing,with in 2 years the plate looked like puff pastry now this was strange being ally on plastic it was clearly electrolicis[sorry for the spelling lol] now the only way this can happen is two ways or a combination off both,1;;;crapp aluminium 2;;; earth leakage we did use stainless bolts the plate was acting like an anode on a plastic boat wtf

anyway we replaced the ally plate with 316 stainless plate in 10mm that should sort out the problem in stewys case o yer sorry stewy for dropping the ratchet in your hull glad you got it out cheers gary

[NaClH2OK9]

Thanks for the detail brickman.