Stainless/alloy corrosion question

[Kelpie]

Hi
I'm fitting some alloy fairleads, but using stainless bolts. Do I need to do something to prevent corrosion? Some kind of gunk/layer between the two metals?

Oh and on a related matter, I'll be laying a mooring this spring: can cast iron sinkers be in direct contact with galvanised steel?

Thanks!

 

[RobBrown]

SS/Al- yes- "gunk" is called "Duralac" paste. Available from most Chandleries.

Others will be along in a minute no doubt re the cast/galvanised query /forums/images/graemlins/smile.gif

 

[matelot]

yes you can put cast iron sinkers in contact with galvanised steel. All it means is that the galv will be eroded away more quickly cos it will try to protect the sinkers as well. But then if you are thinking of galv shackles, the galv coating on the 3rd world shackles that the chandleries sell is usually so thin it erodes away almosr overnight anyway.

 

[alahol2]

Better for moorings is black iron chain and shackles. When the galvanising erodes from the thread of a shackle pin you are left with a loose shackle pin.

 

[vyv_cox]

Shackles are not good news on moorings. Even moused with wire there can be various problems. The professionals I know use welded connectors, 'paper-clip' type designs made of steel rod and welded along the overlapping ends, weld about 2 inches long. Some will also add zinc anodes, if you have the facilities the best way is to cast them onto the chain and connector. Not needed if you intend to lift annually but useful if the mooring will be down for longer.