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Old 27-10-2019, 09:49   #76
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Re: Getting Rigging Done on a Budget. Ideas?

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Originally Posted by robertmfranklin View Post
At one point you asked about fastenings. Seems to me, if you think through what is required, everything you need can be assembled inexpensively and fastened without any welding.

Done properly it would look just fine.

Spreaders, mast head fittings, blocks, cleats ... all of that can be fastened and since the forces are almost all sheer the fasteners need not be excessively strong of large.

For example, tangs for shrouds will be pulling almost entirely (although not exclusively) in a direction of sheer load, not a pulling out direction. This seems to be to be the case with everything I can think of.

Even putting 3, 20 foot pieces of aluminum extrusion to create the mast itself
should be relatively easy, if you move away from the idea of welding. I understand that welding aluminum is not an easy task and requires experience and skill.

You can put a mast together as tall as you want by using short pieces of extrusion sized to sleeve into the longer mast sections. Maybe 8 inches into each section, 16 inches total would be enough. A few machine screws would keep the assembly together. All you are doing is keeping the mast sections in alignment with each other.

People make a big deal out of strength in a mast, but as long as the extrusions are lined up, the forces are vertical not sidewards. Masts break when a shroud lets go they do not bend in the middle and snap. Not on a garden variety cruising style mast. The lower end of the inner sleeve can be through bolted and the upper extrusion just slipped over it and secured minimally. In fact you could view the project as being able to transport your mast in 3, 22 foot sections, then assemble on site.

Yes, this takes a little thought, planning and measuring, but as compared to the nightmare of welding aluminum, its basic erector set technology.

You could probably put the whole thing together in your back yard in a couple long weekends for less than $10,000, including all the rigging.

Bob Franklin


Exactly!!!

This is along the lines of what I had been thinking.

Aluminum is so easy to work with. Drilling and bolting. There are some dissimilar metal issues to work with when using stainless for bolting, right?

Also, it seems like anything you bolt through the mast might need a double or backing plate right? Just to be sure nothing pulls out. In the event of a shroud Also, it seems like anything you bought through the mast might need a double or backing plate right? Just to be sure nothing pulls out. In the event of a shroud breaking.
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Old 28-10-2019, 06:15   #77
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Re: Getting Rigging Done on a Budget. Ideas?

I think the mast suppliers use rivets to join the spices together. I was at a boat show last year in Seattle and the new FP 40(?) had a spliced mast. I assumed this was because it was just easier to ship from France with the mast down and in sections.
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Old 28-10-2019, 06:32   #78
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Re: Getting Rigging Done on a Budget. Ideas?

I think the only through bolt you would need to use is for the most significant shroud. Perhaps a lower as well. You would use a stainless bolt smooth on the shank and only threaded at the point is exited the mast on the opposite end of the entrance point. A nut with plastic securing material inside (I forget what they are called) would be plenty to hold it. Besides, your concern is actually the silver lining. In short order, all you stainless fastening with "cold weld" to the aluminum mast. Your standing rigging is what holds the mast up, not the mast as anyone who ever had a shroud break knows very well.

Everything else can be stainless machine screws or stainless sheet metal screws. Someone will have a better opinion on that than I. Backing plates? I can't think of why you would need those. Just keep in mind the different between 0 degrees sheer force and 90 degrees pull out forces.

If you use a light pole as someone suggested, you would need to attach a sail track. This would need to take 90 degrees pull out forces. Track overcome that problem with many very close fastening, but I don't think you are considering this approach. Any extrusion you buy designed for sailing will have a track set up for sail slides.

So concentrate on rigging. The mast is just an excuse for a place to attach the standing rigging and the sails.

As for sleeving it in sections. This must be done routinely in the boat building industry. In fact, I have seen masts bolted up in sections. No big deal I guess. And the idea of transporting the whole thing in small sections may have some appeal depending on your logistics.

Basically you are just building a series of mast steps. As long as the walls are in alignment I can't see any problem with building up your mast height that way.

Overbuilt, as some responders have suggested, doesn't really help, in my opinion (amateur though it is). All you do it create weight aloft and a feeling of psychological well being. Overbuilt when it comes to the mast may actually be contrary to the real objective, safety.

The way I understand the whole business of mast and rigging is as the wind increase and the boat heels (cat or mono) the force downward on the step becomes enormous. The forces operating to break the mast into pieces are much less by comparison and minimal if the rig is set up to prevent the mast from pumping either fore and aft or port to starboard.

Using a smooth through bolt on a mast the size you want, internal halyards won't even notice it.
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Old 28-10-2019, 06:43   #79
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Re: Getting Rigging Done on a Budget. Ideas?

Wow. This thread is really coming together. I just wanted to take a minute to thank everyone for responding. This is an incredible body of knowledge developing here.

I was curious for a moment about the bolting or screwing of aluminum. And I started to think about aircraft frames. These have traditionally been riveted. And in fact, entire aircraft are held together by rivets. At least they were.

Reading an explanation about that online, I saw that the rivet is better than the screw in sheer. Seems to be just what we are talking about here.

https://aviation.stackexchange.com/q...nd-not-screwed
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Old 28-10-2019, 06:45   #80
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Re: Getting Rigging Done on a Budget. Ideas?

I think this is the way I’m going to do the rigging. Truly it makes a lot more sense to get the little pieces together yourself.
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Old 28-10-2019, 06:50   #81
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Re: Getting Rigging Done on a Budget. Ideas?

Oops I said spices when of course I meant splices.
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Old 28-10-2019, 07:40   #82
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Re: Getting Rigging Done on a Budget. Ideas?

Short article on a new spliced mast.
https://www.sailmagazine.com/diy/mast-splicing

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Old 28-10-2019, 18:10   #83
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Re: Getting Rigging Done on a Budget. Ideas?

Quote:
Originally Posted by Sand crab View Post
I think the mast suppliers use rivets to join the spices together. I was at a boat show last year in Seattle and the new FP 40(?) had a spliced mast. I assumed this was because it was just easier to ship from France with the mast down and in sections.
Yep, pretty sure Selden masts come in 12 metre lengths, a rig taller than that has a join in it. They use an insert and a lot of rivets. Probably monel rivets.

Never heard of one of these joins failing.

Lol, just read the above article, says pretty much whay I just did.
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Old 29-10-2019, 00:53   #84
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Re: Getting Rigging Done on a Budget. Ideas?

And finally a major boat project I can do without epoxy. LOL. That’s the stuff that has been slowing me down since I have all of the allergic reactions to it.
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