Duralac or grease??

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PetiteFleur

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I'll re reassembling the Rotostay furler after fitting new rigging. The aluminium end of the foil is srewed to the aluminium drum with a very coarse thread. When unscrewed earlier there was only minimal corrosion, which surprised me as I had not touched it for 13 yrs. Should I use Duralac or sticky grease when reassembled?
 
PetiteFleur said:
I'll re reassembling the Rotostay furler after fitting new rigging. The aluminium end of the foil is srewed to the aluminium drum with a very coarse thread. When unscrewed earlier there was only minimal corrosion, which surprised me as I had not touched it for 13 yrs. Should I use Duralac or sticky grease when reassembled?
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Or on a close fitting "joint" like a screw thread Tef-Gel

Description cribbed from Seamark Nunn's website

Ulra Tef-Gel eliminates corrosion between dissimilar metals. Provides a barrier between metals that eliminates interaction.

Tef-Gel is a synthetic based PTFE waterproof lubricant with anti-corrosion and anti-seize properties. Tef-Gel does not break down in salt water or detergents. Tef-Gel is a US Navy specified non-lanolin synthetic formulation. Lanolin, an extract of wool used as the base for the popular anti-seize product can absorb small amounts of moisture which will allow for corrosions and seize your stainless steel to aluminum joint after a few years. The paint will blister in the surrounding area.

Use a dab of Tef-Gel when connecting to aluminum with stainless steel screws. Tef-Gel will eliminate the risk of galvanic corrosion and the paint blistering it causes not to mention that you will be able to unscrew the fastener years from now when you may have to.

Is a waterproof paste that never hardens, runs or stops working. It is also environmentally safe.​
 
MM5AHO said:
Its not clear what metals are involved. Is this an aluminium to aluminium contact? Or is there a stainless threaded component?
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It's aluminium end of the foil to the aluminium drum - no stainless involved. The thread is not the usual vee thread but is a very coarse rounded tips and roots, a bit like the threads you get on plastic screw caps. It's normally 'tightened' when you furl the sail. A little corrosion when unscrewed but not as much as I'd expected. No evidence of grease/duralac or similar.
 
I've mixed Duralac and marine grease together in the past for threaded fixings, that was before I came across Tefgel. Duralac is OK for permanent fixings like rivets but where there's movement or a requirement to unscrew I think Tefgel is better.

Has anyone thought about using PTFE based white greases for bikes? Far cheaper than Tefgel.
 
PetiteFleur said:
It's aluminium end of the foil to the aluminium drum - no stainless involved. The thread is not the usual vee thread but is a very coarse rounded tips and roots, a bit like the threads you get on plastic screw caps. It's normally 'tightened' when you furl the sail. A little corrosion when unscrewed but not as much as I'd expected. No evidence of grease/duralac or similar.
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There is a thread described as "Bottle Closure Thread".
 
Duralac sets hard (and is somewhat messy to apply). It's great for permanent dissimilar metal joints, e.g. monel rivets on spars. Its other advantage is that it will withstand pressure washing and water jets (e.g. waves washing over decks).

A good waterproof grease* will suffice in areas that do not need to withstand water jets and need to be disassembled occasionally, like threaded fittings. All greases (including Tef-Gel**) will capture dirt particles, so excess should be wiped off.

With your alu-on-alu threaded fitting, you don't need much of either, although some grease may ease assembly and prevent any future corrosion. If the fitting is not otherwise secured (split pins, etc.), consider using a threadlocker (Loctite) instead, but don't go crazy with it.

* Good waterproof greases include silicone grease (clear, £10 a 500g tub) and the excellent and slightly thicker Volvo prop shaft grease with molybdenum disulphide (blue, £28 a 500g tub, great for underwater applications). They do not include Lanolin (very low melting point) or Vaseline (attacks some rubbers and plastics).

**Tef-Gel is a overhyped, extremely overpriced product that does nothing that the above mentioned greases don't do at a much lower cost.
 
The reason I asked about metals was that Duralac is for dissimilar metals. If you have the same metal both sides of the thread, then a grease is more suitable, and the answers above cover it.
 
vic008 said:
Anyway to freshen Duralac- going very dry in the tin?
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Not that I know of but others may know better - i think that's like asking how to freshen up dried paint. Duralac usually comes in tubes if you're a tightwad like me at any rate, and after use the top end of the tube sets hard, so that the following time out you have to stab the tube to get any out at all and the tube ain't cheap, and it's even more of a dreadful mess than normal. I wear rubbish clothes and plastic gloves with Duralac. Okay, ESPECIALLY rubbish clothes. And I never wear plastic gloves, usually even when it says wear rubber gloves. Except with Duralac urgh, [shudder]...
 
t21 said:
....and after use the top end of the tube sets hard, so that the following time out you have to stab the tube to get any out at all and the tube ain't cheap, and it's even more of a dreadful mess than normal.
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If you put a dab of lanolin or Teflon-based lubricant onto 'the top end of the tube' and thread, you will not need to stab the tube. The cap will freely rotate...... :rolleyes:
 
zoidberg said:
If you put a dab of lanolin or Teflon-based lubricant onto 'the top end of the tube' and thread, you will not need to stab the tube. The cap will freely rotate...... :rolleyes:
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well, ok, but it still sets hard in hot carib weather when not used it for a year due to aforementioned nightmare. That's my excuse anyway. Rolling eyes ooh what a windup eh first this in the morning! Nearly as bad as the slow despairing head shake. Is there an emoticon for that? No? Good!
 
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