Duralac between bronze and aluminium?

[prv]

Going to be mounting some winches on Selden mast pads either tomorrow afternoon or at the weekend. Looking at the shape of them in the catalogue, I assume the pads are cast aluminium. The winch bases are bronze.

KS didn't have any aluminium parts, so I don't really know how this metal behaves around seawater. Should I be putting Duralac between the bronze and aluminium? I have a tube in the shed so it's no bother to do if required.

The bolts will be stainless so I guess I definitely need some on there.

Pete

 

[pvb]

Going to be mounting some winches on Selden mast pads either tomorrow afternoon or at the weekend. Looking at the shape of them in the catalogue, I assume the pads are cast aluminium. The winch bases are bronze.

KS didn't have any aluminium parts, so I don't really know how this metal behaves around seawater. Should I be putting Duralac between the bronze and aluminium? I have a tube in the shed so it's no bother to do if required.

The bolts will be stainless so I guess I definitely need some on there.

Pete

You definitely need some form of separation between bronze and aluminium! Ideally, something more substantial than Duralac. Don't the mast pads come with plastic sheet insulators? If not, suggest you make some.

 

[knuterikt]

You definitely need some form of separation between bronze and aluminium! Ideally, something more substantial than Duralac. Don't the mast pads come with plastic sheet insulators? If not, suggest you make some.

I think they come with plastic sheet insulators, if not make some.

Use Duralac on the bolts.

 

[VicS]

I think they come with plastic sheet insulators, if not make some.

Use Duralac on the bolts.

+1

Aim to fill all gaps between the aluminium and the bolts with the Duralac to leave nowhere for water to accumulate

 

[prv]

Don't the mast pads come with plastic sheet insulators?

They may do. I don't have them yet, I'm picking them up from Aladdin's Cave tomorrow afternoon.

Thanks all for the answers.

Pete

 

[davidwf]

Make sure you are wearing tatty clothes when using Duralac it is neigh on impossible to get out of clothes and I seem to recall a post once where someone had managed to get some on his car seat. Bad news that.

 

[VicS]

Make sure you are wearing tatty clothes when using Duralac it is neigh on impossible to get out of clothes and I seem to recall a post once where someone had managed to get some on his car seat. Bad news that.

Teflon based Tef-Gel is the "clean" alternative but more suited to close fitting joints.

I d think for the job in question Duralac is the better choice around the bolts with an insulator under the base.

 

[prv]

I d think for the job in question Duralac is the better choice around the bolts with an insulator under the base.

Duralac is certainly the better option, because there's a tube of it in my shed

I never work on the boat (or sail the boat, for that matter) wearing "good" clothes.

Pete

 

[pvb]

Meths is pretty good for removing excess Duralac.

 

[prv]

Just been and collected them - the pads don't come with any insulating material. Worth noting they're not the same finish as the mast itself - darker and smoother like cast end fittings in masts, booms and spinnaker poles - so possibly less reactive. Regardless, I'm going to use a barrier sheet as suggested - I think a laminating pouch run through the machine without any paper in it will do the trick for raw material.

Pete

 

[alahol2]

It may well be worthwhile also using a barrier of some sort between the pads and the mast. Certainly dip the rivets in duralac. A mast on a previous boat had signs of corrosion between the mast and pads (both ally).

 

[zambant]

I think a laminating pouch run through the machine without any paper in it will do the trick for raw material.

Sounds good to me

+1 for Duralac - maybe consider a can of ACF-50 for the future as well

 

[Bodach na mara]

For the insulator you could use a bit cut from one of those 2 litre milk bottles. It is easily cut to shape with sissors

 

[prv]

For the insulator you could use a bit cut from one of those 2 litre milk bottles.

1. I don't have any two litre milk bottles. I only buy a pint at a time as I don't use much. And the 1-pint bottle a) doesn't have a surface big enough to fit under a winch, b) has milk in it
2. I've already bolted the winches onto the pads using the laminated sheet. Worked very nicely.

Thanks for trying though

Pete

 

[charles_reed]

I've a sheet of PTFE (Teflon) which I cut to size as a gasket between dissimilar metals. That's quite easily the most inert substance you can find and has the advantage of never, ever, sticking as well killing any galvanic couples.
Whilst Duralac is pretty good on fixings it's almost useless as a gasket material and polyethylene (milk bottles) quickly degenerates with UV action (OK if you re-bed the winches every couple of years).

 

[prv]

Whilst Duralac is pretty good on fixings it's almost useless as a gasket material and polyethylene (milk bottles) quickly degenerates with UV action

I have only applied the Duralac to the fixings.

The laminator plastic ought to be reasonably UV-proof given that laminated notices outside last ok (the ink on the paper may fade if done on a cheap inkjet, but that's not the issue here). In any case, it's under a winch - how is the sun going to get at it anyway?

Pete

 

[rogerthebodger]

When I needed to separate stainless from aluminium I have used plastic shim stock that can be got in various thicknesses. Can be obtained from any engineering/bearing supplier.