aluminum hull OK in salt water?? (looking at buying one)

[old school]

everyone I ask seems divided so is there anyone who has actually owned a aluminum / tin boat and used it regularly in salt water?

wife and I want to buy a 17' sea nymph (rivited not welded) with a 75hp 2 stoke OB - nice boat and good price

boaters say I just need to wash it down with fresh water really good afer use

will it work for us? we will only be in salt water?

thank you

 

[coreng]

Why ?

Why should'nt it work ? There are thousands of aluminium boats in salt water and thousands of entries via google search...

 

[alan_d]

everyone I ask seems divided

Do you really mean that? Perhaps opinion was divided among the people you asked.

I have never owned an aluminium boat, but alloy runabouts (known as tinnies) are used in their thousands in salt water in Australia and New Zealand, so I cannot imagine there are serious problems with them.

 

[Lady Campanula]

will it work for us? we will only be in salt water?

There are real experts around here on galvanic corrosion, and usually three come along at the same time ( weak London joke! )

There are few things in this life that are certain, and one of 'em is that a galvanic cell will be set up and running all the while your intended mistress is immersed in 'electrolytic' salt water. Whether that will incur damage sufficient for you to see, or create weakness/failures in any important parts of the structure, only an specialist and expert inspection would be able to predict.

However, the same experts will be able to tell you how to mitigate such potential and potent problems, quite cheaply. Washing down both structure and engine innards in non-salt water is one of them.

Another is the fitting of suitable sacrificial anodes.

IMHO

 

[PCUK]

There can't be a galvanic cell with only metal, (Stainless steel excepted!) so unless you use brass screws to fix everything you will be OK

 

[Cloven]

Loads of Ovni aluminium boats where we are based in France. I would say however that they all have a multitude of anodes, including hanging anodes at both stem & stern.

 

[Euphonyx]

This aluminium boat was custom built to sail the Northwest Passage..... I think thats proof enough!!!

http://www.northabout.com/

 

[Bajansailor]

Here is another aluminium yacht that was designed for high latitudes cruising - http://www.expeditionsail.com/

Re your Sea Nymph runabout, if it has been built using a 'proper' marine grade aluminium alloy (for the plates and rivits) you will be fine, and the boat will be virtually maintenance free.
The aluminium very rapidly oxidises to form a protective aluminium oxide layer on the surface - a brand new boat will be very shiny, but after a while (as the surface oxidises) it will become a dull matt grey which does not need to be painted, except for cosmetic reasons (or antifouling if kept afloat).
If you do paint the bottom with antifouling, it will need a suitable primer first - and make sure that the paint does not have any copper in it.

If you are storing it ashore on a trailer and just day cruising with it, then you shouldn't really need to antifoul it, or even need to have a zinc anode on the bottom.
Have a look occasionally at the anode on the outboard motor though.

 

[PaulJS]

It might be advisable to consider using magnesium anodes rather than zinc on an aluminium hull.
As mentioned earlier, there are some very clever people who regularly contribute to these fora, and they'll be better placed to give advice.
Enjoy the new boat!

 

[VicS]

It might be advisable to consider using magnesium anodes rather than zinc on an aluminium hull.
As mentioned earlier, there are some very clever people who regularly contribute to these fora, and they'll be better placed to give advice.
Enjoy the new boat!

Generally magnesium anodes are suitable for use in freshwater only, being too reactive for use in saltwater.
also MGDuff say "MAGNESIUM ANODES SHOULD NEVER BE FITTED TO ALUMINIUM HULLED VESSELS."

 

[Euphonyx]

This aluminium boat was custom built to sail the Northwest Passage..... I think thats proof enough!!!

http://www.northabout.com/

oops! northEAST passage!!!

 

[old school]

Thanks everyone! We bought the tin boat!

hope to get much use out of it!

Good winds (or knot) to everyone!

 

[PaulJS]

It might be advisable to consider using magnesium anodes rather than zinc on an aluminium hull.
As mentioned earlier, there are some very clever people who regularly contribute to these fora, and they'll be better placed to give advice.
Enjoy the new boat!

Generally magnesium anodes are suitable for use in freshwater only, being too reactive for use in saltwater.
also MGDuff say "MAGNESIUM ANODES SHOULD NEVER BE FITTED TO ALUMINIUM HULLED VESSELS."

Apologies for posting wrong advice. I did do a quick "Google" before posting the above, but after seeing Vic's post I "Googled" a wee bit more thoroughly and couldn't even find the original site recommending magnesium...