[Public-List] Main Sail Track Fasetening

[Don Campbell]

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
>
>
>
>
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