Is it ok to use stainless bolts with aluminium?
 

Hi

Thanks for replies to my earlier posting about securing my new fairleads. I
have managed to gain access to underneath the relevant bit of the boat, so I
can hopefully do a proper job viz a vis backing plates. Is it ok to use
stainless nuts and bolt with aluminium - if not, what should I use?

TIA

Stainless bolts and screws is about the only method of securing alum mast
hardware, in my experience. The only exception might be those smaller items
secured with alum rivets.

I have never dealt with an alum. pleasure but but on all US Navy alum. ship
and boats. Stainless bolts are used, however there is always insulators in
the holes and under the fitting.

In outfitting my mast, I used "Lanolin Grease" on the threads of all my
screws and on the faying surface (between the different metals). After 3
years in the water, I haven't noticed any problem with corrosion or siezed
threads.

I might also suggest that when tapping threads in alum., use a oil
especially for this purpose. You can get it at any outfit that speciallizes
in machine shop supplies or from major bolt and screw distributor.


--
My experience and opinion, FWIW
--
Steve
s/v Good Intentions

Adam wrote:
Hi

Thanks for replies to my earlier posting about securing my new fairleads. I
have managed to gain access to underneath the relevant bit of the boat, so I
can hopefully do a proper job viz a vis backing plates. Is it ok to use
stainless nuts and bolt with aluminium - if not, what should I use?

TIA

Yes, if you don't mind a semi-permanent connection :)

Use TEF-GEL (NOT Tuf-Gel) and the bolts won't become one
with the aluminum. If this is an aluminum backing pad and
not a cast aluminum fairlead you're talking about, then just
drill oversize holes.

Evan Gatehouse

I agree with Evan Tef-gel http://www.spursmarine.com/tefgel5.htm is pretty
well the standard marine anti-corrosion/anti seize ointment for stainless
screws in aluminum. A $12 serine is enough to set every screw on your boat.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Adam" wrote in message
...
Hi

Thanks for replies to my earlier posting about securing my new fairleads.
I have managed to gain access to underneath the relevant bit of the boat,
so I can hopefully do a proper job viz a vis backing plates. Is it ok to
use stainless nuts and bolt with aluminium - if not, what should I use?

TIA

Steve writes:

I might also suggest that when tapping threads in alum., use a oil
especially for this purpose. You can get it at any outfit that
speciallizes in machine shop supplies or from major bolt and screw
distributor.

Also use a spiral tap for "stringy" materials, not a standard fluted tap.

On Sun, 01 May 2005 19:52:27 -0700, Evan Gatehouse
wrote:

Adam wrote:
Hi

Thanks for replies to my earlier posting about securing my new fairleads. I
have managed to gain access to underneath the relevant bit of the boat, so I
can hopefully do a proper job viz a vis backing plates. Is it ok to use
stainless nuts and bolt with aluminium - if not, what should I use?

TIA

Yes, if you don't mind a semi-permanent connection :)

Use TEF-GEL (NOT Tuf-Gel) and the bolts won't become one
with the aluminum. If this is an aluminum backing pad and
not a cast aluminum fairlead you're talking about, then just
drill oversize holes.

FWIW:

I've retrofitted almost everything with 1/4" aluminum I've custom cut
myself (replacing original dished fender washers and "acorn nuts") and
that's what I do. Overdrilling the plates by, say, 1/8" allows an
easier fit below deck, too.

I seal the holes through the deck with epoxy, drill through that, coat
the bolts with sealant, coat the piece (say a cheek block) with
sealant on the bottom, pop in the bolts, get my wife to hold the SS
bolts with a screwdriver, and then I put a bead on the plate below,
put the plate on the bolts, and tighten LIGHTLY until I get sealant
ooze.

Then I lead the sealant set up for 24 hours to a week, depending on
what I'm doing. Occasionally this means covering the piece on deck.

I dog down the piece snugly and trim with a razor any excess.

The key parts are sealing the core with epoxy and coating the shaft of
the bolt with a very thin spiral bead. This leaves the head of the
bolt sitting in a little ring of bedding and prevents water getting
down the shaft, never mind into the core.

And the backing plate makes everything a lot stronger due to the
spreading of compression forces.

R.

On Sun, 01 May 2005 20:53:57 +0000, Adam wrote:

Hi

Thanks for replies to my earlier posting about securing my new fairleads. I
have managed to gain access to underneath the relevant bit of the boat, so I
can hopefully do a proper job viz a vis backing plates. Is it ok to use
stainless nuts and bolt with aluminium - if not, what should I use?

TIA

I think it will be fine. If you use enough sealing compound to keep
moisture from getting through the deck or into the core (if applicable)
out, you will inevitably end up with enough compound on the SS hardware to
electrically insulate it from the aluminum.

In this thread, the process outlined by Rhys seems pretty thorough and
sound to me.

When I have done it, I just went ahead and tightened the hardware down
without waiting for the goo to cure. And I didn't use epoxy the way Rhys
does. If I could do it again, I would probably use something very like
Rhys's procedure.

--Mac