[Public-List] Main Sail Track Fasetening

[Roger L. Kingsland]

Don,

In the wee hours of the night as I lie awake contemplating "the meaning of
life, the universe and everything else,"  I often wonder why hard neoprene T
washers like these
http://www.acousticalsurfaces.com/mounts_springs/neoprene_isolators_hg.htm?d
=24 aren't used to isolate dissimilar metals.  If used with a rivet I
suppose it wouldn't be good for the "bulge end" of the rivet to seat against
the T washer.  Besides, RE the mast track application, it would be difficult
to get the washers inside the mast.  So aluminum rivets would be appropriate
with the T washer isolating the flange end of the rivet from the SS mast
track.  It would be dependant on the neoprene being rigid enough to prevent
movement at the connection and strong enough to resist crushing from the
compression load created by the rivet fulfilling its destiny forevermore in
tension.     

Roger 148

-----Original Message-----
From: public-list-bounces at lists.alberg30.org
[mailto:public-list-bounces at lists.alberg30.org] On Behalf Of Don Campbell
Sent: Monday, October 19, 2009 9:34 PM
To: Alberg 30 Public List -- open to all
Subject: Re: [Public-List] Main Sail Track Fasetening

Mick:
    So far no one has mentioned galvanic action and if you are in the ocean
with the boat, you might want to add that to the mix. Stainless will also
disappear with what they call crevice corrosion as the alloy ingredients
leak out with electrical current. There is no way without compromise, it is
just where you decide to compromise. I would have thought that round head
machine screws with Roberson heads would have fit the slot in the low part
of the track.
    I do know that if you use something like a Garhauer vang on the existing
track for the gooseneck, you can put enough pressure on the gooseneck to
strip the threads on those bolts holding that track to the mast. And then
you will be into using coil thread fillers there. I have found that any
attempt at backing plates even as low as the gooseneck are a difficult thing
to align, and if one uses anything but aluminum, you are back to the
galvanic capacity again. Steel and aluminum is not a good mix and you can
see the results of that if you look at older highway trailers used in
Canadian winters, hence ones that get road salt on them,  where steel bolts
and aluminum frames are in close proximity. 
The aluminum goes very soft and flaky while the bolts get very rusty. 
Even the titanium coated ones will oxidize with the acid rain we have here
in Ontario.
    My suggestion would be to use what has worked for the first 42 years and
be prepared to replace those sooner the next time.
     Finding the force that is actually pulling on the sail track is not
easy, but if you use the standard sizes for sails, those forces should not
have changed much and if you use a reefed main or a Dragon main with a short
foot, you will not stress the track beyond design. If you are worried, then
doubling the number of sail clips will half the force at the sail clip and
spread the force more evenly and closer to the fasteners.
Don
.

Michael Taylor wrote:
> After painting the mast I am putting the main sail track back onto the
mast.  I see that some have tapped each of the existing holes to replace the
rivets with machine screws.    The track is stainless 7/8" with 3/16th holes
drilled.  The next drill size up will just clean out the existing mast holes
and leave sufficient room to thread either 1/4 inch or 6mm machine screws.
>
> Having got a sample of machine screws with various heads it seems that the
heads are too big for the existing sail track (they don't seat at the base
of the track).  I assume that the only way to use machine screws is to
either change the sail track or drill new holes which I'm not prepared to
do.
>
> If I can't use machine screws it will be back to aluminum rivets with a
steel mandrel as I've found strainless very difficult to remove - and
install.
>
> Have I missed something with machine screw fitting here?
>
> thanks
>
> Mick 
>
> #231
>
>
>
>
>
____________________________________________________________________________
______
> Get more done like never before with Yahoo!7 Mail.
> Learn more: http://au.overview.mail.yahoo.com/
> _______________________________________________
> These businesses support your Association:
> http://www.alberg30.org/store/A30supporters.html
> Please support them.
> _______________________________________________
> Public-List mailing list
> Public-List at lists.alberg30.org
> http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org
>
>
>   
_______________________________________________
These businesses support your Association:
http://www.alberg30.org/store/A30supporters.html
Please support them.
_______________________________________________
Public-List mailing list
Public-List at lists.alberg30.org
http://lists.alberg30.org/listinfo.cgi/public-list-alberg30.org


 1256055255.0