Aluminium mast base/girder

Re: Aluminium mast base/girder

Postby Phillip » Sun Aug 30, 2015 7:11 am

Yep Ian and Woodsy are right but,

The mast shoe should fit tightly into the mast girder without ANY packing!
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Re: Aluminium mast base/girder

Postby Mike » Mon Aug 31, 2015 12:30 pm

All good advice, and I've spoken to the fabricator and he'll be making the box to fit the mast dimensions.

One thing I'm wondering- is there meant to be a shoe of some kind attached to the base of the mast that then sits in the girder?

The mast was just sitting directly on a flat piece of 10 mm alloy in the mast girder, which seemed a bit crude and a good way to introduce point loads, although the base of the mast seemed to be surviving ok in that regard. It had suffered where the steel box had swollen with corrosion and worn away at the sides of the mast. There had been some kind of soft packing down there at one stage, which had taken on the look and water holding capabilities of good garden soil. I imagine a shoe that sleeves into the mast with a base plate cut to exactly the same dimensions as the girder box would be a significant improvement.

I'll be getting some west system microfibre blend (406) to make a solid base for the girder to sit on, and definitely good drainage holes.

Thanks for the comments, it makes the steep learning curve a little less daunting.

Cheers,
Michael.
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Re: Aluminium mast base/girder

Postby SeaLady » Mon Aug 31, 2015 2:05 pm

I think the most important thing is ensuring you put the correct coins under your mast.

Highest coin in the realm? Gold coin?

As I was not sure about either of these two very important points and also not sure if it should be the date of launch or the date of restepping.

I did both :D
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Re: Aluminium mast base/girder

Postby Ianb » Mon Aug 31, 2015 3:06 pm

SeaLady wrote:I think the most important thing is ensuring you put the correct coins under your mast.

Highest coin in the realm? Gold coin?

As I was not sure about either of these two very important points and also not sure if it should be the date of launch or the date of restepping.

I did both :D


Diana, it is good to be reminded of the emotional side of boat ownership, as well as the pure technical.

But back to the technical, it was common to have alloy plugs in the end of the mast at the time, and I am wondering if this was also the case on the Top Hat? Certainly would help with the loading.
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Re: Aluminium mast base/girder

Postby bearmcnally » Mon Aug 31, 2015 6:24 pm

Hi Mike
There should be a plug , if you don't have one just trace the inner dimension of the mast cut it out and weld a plate to it , problem solved ! or use a piece of nylon .(eg a chopping board) and cut it for the mast to bed into.

Now Diana no wonder your having Top Hat problems ? You have the wrong coins under the mast step ! You can only have the highest denomination available at the time the yacht was launched !!

Cheers Bear
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Re: Aluminium mast base/girder

Postby Mike » Sat Oct 03, 2015 4:46 pm

Here's the finished piece!

Came in at $340.

Cheers,
Michael.
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Re: Aluminium mast base/girder

Postby Phillip » Sat Oct 03, 2015 6:46 pm

Looks great Mike, BUT

You need 4 drain holes; one each in the corners of the central square in which the mast sits.
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Re: Aluminium mast base/girder

Postby woodsy » Sat Oct 03, 2015 9:44 pm

Thanks for the photo Mike!
No offence intended but the holes need to drain out fore & aft and/or port & starboard.
Don't drill through the base
Yes I know its obvious but we've all done something similar & then had to correct it.
Cheers.
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Re: Aluminium mast base/girder

Postby Ianb » Mon Oct 05, 2015 12:30 pm

Sorry to be an engineer, but the welds should be continuous to seal the gap. They do not have to be big structural ones, just seal welds. Gaps lead to crevice corrosion.
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