The Offshore Voyaging Reference Site

Tools and Techniques For Managing Dissimilar Metals on Cruising Boats

Anybody who has ever worked on an aluminum mast knows how hard it can be to disassemble fittings that have been in place for more than ten minutes. No—make that five minutes if they are made of dissimilar metals.

Now build yourself an entire boat in aluminum and imagine the scale of the problem. And it’s certainly true that aluminum has its own set of challenges, just like any other material, mostly to do with avoiding corrosion and achieving a good seal to pipes and tanks.

I got an insight into this early on in my sailing career, when I bought a yacht that had an Aries windvane fitted. Everybody told me just how wonderful it was, and I was really looking forward to using it on the first long passage home. The reality was somewhat less impressive than I’d been lead to believe, though, largely due to all of the bearing surfaces getting ‘sticky’ from salt build up and corrosion—it basically didn’t work.

So I took it off and set about rebuilding it. And then the fun started, as it was an early model that had several different metals employed in the construction, including such wonders as stainless helicoil inserts into aluminum castings, and it was seized absolutely solid. And I’m well aware that many people who look at aluminum boats think that it’s always like that, and it puts them off.

So when I came to rebuild the Aries—yes, I finally did get it apart, though I nearly quit on several occasions—I swore blind that there had to be a better way and I was going to find it!

Happily I’ve been greatly rewarded in searching for that Holy Grail, and now know that there are many simple ways to make life easier, and we now carry all the materials and products that we need to do so. Much of it is applicable to boats built in other materials, too.

Here, then, are some of the materials we carry and techniques to use them that:

  • make maintenance easier,
  • the boat more reliable,
  • are a boon for emergency use and repair on the move;

the result of much hard won experience!


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Matt Marsh

Colin, what are the storage requirements like for Duralac, Tef-Gel, etc.? And are there some of these things for which you’d keep a few small tubes around instead of just one? (Some of us have a hard time keeping any of this stuff usable once the tube’s been opened….)

Re. power tools. I can see a certain appeal to having compressed air on board, if you have the space for a compressor. Air tools are relatively cheap and are often safe to use in wet environments where no one in their right mind would bring an electrically-powered tool.

Colin Speedie

Hi Matt
TefGel, Duralac and Loctite seem to do just fine, although it helps to massage the Duralac tube to make sure that it’s well mixed before use. We have a small, dedicated, sealed locker for paints etc. where we keep all such products. What doesn’t keep well are sealants such as Sikaflex or 5200, so I make sure I buy fresh, in date tubes every year.
I’d love to have air tools, but don’t know how or where I’d put them, or the compressor! One of the good things with aluminium is that it’s almost as easy to work with as wood, and mostly uses the same tools, so emergency repairs with hand tools is straightforward in most of the sizes we’d use.
Best wishes
Colin

Erik de Jong

If you have dive bottles on board, you can make a fitting that fits the bottle regulator, connect that to a hose, put a pressure reducer in that line and use any air tool you want. The amount of energy in a bottle is crazy. In most places it is not difficult or expensive to get a bottle refilled.
I saw this used last year on a friends boat, and I’m going to get myself the proper hose for it so that I can do something similar.

Colin Speedie

Hi Erik
Missed this somehow, when you posted it.

What a great idea – if you’ve got the air tools, why not use them?
Excellent for any expedition boats, that almost always carry dive gear.
Thanks!
Colin

Ferdie Burger

Hi Erik
You can use the normal demand valves that goes onto SCUBA tanks. On the first stage there are various high pressure and low pressure take off ports. The low pressure ports work very well for pneumatic tools. You should be able to buy the hose and connectors from most SCUBA shops.

Regards
Ferdie

Dick Stevenson

Hi Colin,
A really nice addition to the AAC maintenance articles. I especially like that you mention product and product details as too often one is left scratching one’s head when you get to the say: Loctite display with its variety of products.
Some might think that your article is for boats that have been around for a bit, but doing as you suggest to brand new boats is not only easy and informative, but is one of the nicest things you can give yourself with respect to long term ease of maintenance.
My best, Dick Stevenson, Alchemy

Colin Speedie

Hi Dick
far too often we hear a generic name for a type of product without any further information – Loctite being the perfect case in point. And there’s nothing more frustrating than finding that the product in your hand won’t do the job you desperately need it to do – to seal diesel joints for example. As such, boning up on the items to carry is time well spent, and the cost of carrying all I’ve suggested should leave change from $100!
And as far as brand new boats go, I’d be inclined to go through as much as possible to check what’s been done, and if necessary treat it (with say TefGel) to aid easy disassembly at a later date. A stitch in time….
Spar builders are amongst the worst offenders, neglecting to insulate joints with Duralac or use the correct grade of Loctite on load sensitive screws, or use TefGel on screw attached fittings (think masthead lights etc). It saves them seconds and a few dimes and costs us a fortune down the line. I just don’t get it and it makes me mad!
Best wishes
Colin

Dick Stevenson

Hi Matt,
Duralac I have only found in bigger tubes that last a long time. After 6-8 years the last quarter of the tube gets a little drier and using it becomes more difficult to work. TufGel comes in smaller containers and does not seem to dry out. Neither appears to me to deteriorate or have any expiry dates/issues nor do they “separate”. I store all opened tubes of “stuff” in plastic containers (peanut butter jars, etc), partly for air intrusion, but also to contain the “stuff” when it leaks as one invariably does every now and again.
Dick Stevenson, Alchemy

Marc Dacey

Colin, this is an excellent primer and it gladdens me to know that I already follow many of these methods and use these products already. The Duralac is new to me: I have, for instance, merely been coating my steel parts with two-part epoxy and then using a nylon spacer, length or circle to “break” the connection between the aluminum part and the steel part, with Tef-Gel on the threads, of course. So is Duralac available in North America?

By the way, if the job isn’t involving diesel and nitrile isn’t needed, EPDM is also a durable rubber gasketing material in sheet form and is used in things like hatch gaskets.

Colin Speedie

Hi Marc
Hamilton Marine apparently stock Duralac in the USA.
I think the method you outline (epoxy, plastic etc.) to separate materials is fine. But where you want a neat joint between stainless and aluminium such as on a mast, Duralac is very good.
On our hatches we use a variety of mouldings and flat neoprene 1″ wide glued to the hatch lid – whichever is most appropriate. EPDM would equally be good, thanks for the suggestion.
Kind regards
Colin

Marc Dacey

Thanks for the tip. Apparently, the man listed below is the N.A. distributor for Duralac products, and he’s also listed as such on his LinkedIn profie.

ROY SADDINGTON
SADDINGTON CONSULTANTS PLUS
72 JACKSON COURT EAST
WELLAND
ONTARIO
L3C 7G4
CANADA

Tele: +905 735 6372
Fax: +416 850 6697
e-mail: ac.sumirp@pcsyor