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Old 20-01-2022, 04:21   #1
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I have to have a pedestal made - why not a tabernacle?

I have a mast that is approximately 5ft too short.

There is no way to get a mast section for this extrusion, so I have to add a pedestal at the base of the mast.

While I’m having to get something custom fabricated, why not make that custom thing in such a way as to be able to raise/lower the mast, if needed, for inland/ICW?

Question: is there a mast raising/lowering system that can secure the mast from moderate lateral forces when it’s being lowered other than carrying special shrouds and supports to line up perfectly with the pivot point?

I see this as a fair weather operation. Nothing to be done in a chop or overly windy conditions. Early morning calm is when this would be attempted. Not like the videos you see of people sailing up to a bridge, dipping the mast and raising it again. It would go down to transit the entire ICW. Or to go deep inland through rivers or canals. Or to stay in one anchorage that’s height restricted for a week or two.


Also, how much mast bury do you need below the “Jesus bolt” or pivot point? Some designs have none, others have quite a bit.

Is just a hinged mast step on top of the pedestal good, or do I need a full tabernacle? What’s the difference?

Thanks! This should be the final mast thread
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Old 20-01-2022, 04:31   #2
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Re: I have to have a pedestal made - why not a tabernacle?

Actually a good idea ,to make better job of it make the pivot point above the goose neck ,so the boom stays in place the lower section doesn’t need to match the mast section above ,.⛵️⚓️��
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Old 20-01-2022, 04:44   #3
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Re: I have to have a pedestal made - why not a tabernacle?

Also, this example doesn’t seem to have the stabilizing stays at the exact height of the pivot pin.

Would this still hold the mast from swaying?

Do they not need to be perfectly aligned height wise? Or only in a fore/aft sense?
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Old 20-01-2022, 04:52   #4
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Re: I have to have a pedestal made - why not a tabernacle?

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Actually a good idea ,to make better job of it make the pivot point above the goose neck ,so the boom stays in place the lower section doesn’t need to match the mast section above ,.⛵️⚓️��
Unless I’m misunderstanding your idea, I’m not sure that would work on my boat. Possibly I’m misunderstanding so I’ll post more details.

See the welded tabs facing directly downward in this pic? That’s my gooseneck attachment point.

See the remainder of the mast below the gooseneck? That’s about a meter or 3 feet long. Maximum. And the boom has to clear a coach roof and some items on the coach roof that are about 6ft high from deck level.

Or do you mean to just make the pedestal a bit longer and move the gooseneck to the pedestal so the rest of the mast pivots above it?
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Old 20-01-2022, 05:07   #5
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Re: I have to have a pedestal made - why not a tabernacle?

Disclaimer: in addition to this thread I will probably ask a couple questions to my my racing catamaran designer expert that approved the mast itself for my boat.

That means we can get pretty wild here with ideas. I’ll run them though his consulting service after we come up with something that seems good.
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Old 20-01-2022, 05:43   #6
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Re: I have to have a pedestal made - why not a tabernacle?

The Seawind 1000 mast sits on a tabernacle and from what Iíve heard is easy to lower, even singlehanded. Seawind put out instructions on the process but seems you have to be a member of their ďcommunityĒ to access these.
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Old 20-01-2022, 10:54   #7
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Re: I have to have a pedestal made - why not a tabernacle?

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The Seawind 1000 mast sits on a tabernacle and from what Iíve heard is easy to lower, even singlehanded. Seawind put out instructions on the process but seems you have to be a member of their ďcommunityĒ to access these.
Thanks. Iíll see what I can Google with this.
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Old 20-01-2022, 10:55   #8
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Re: I have to have a pedestal made - why not a tabernacle?

With something this complex, I feel like I may have reached the limits of the cruisers forum. That’s unfortunate. I might have to take this one to Boatdesign.net I guess.
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Old 20-01-2022, 11:11   #9
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Re: I have to have a pedestal made - why not a tabernacle?

That second picture in the first post is the best design I've ever seen!
Because both the tabernacle and the hinge point on the mast are reinforced to prevent twisting (lots of surface area being pivoted on), my mast (the one in the picture), needs no side-to-side guidance. Besides, with the boom or a sheer legs as a crane, the line is pulling from center: the mast doesn't really want to go astray.
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Old 20-01-2022, 11:52   #10
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Re: I have to have a pedestal made - why not a tabernacle?

Quote:
Originally Posted by Benz View Post
That second picture in the first post is the best design I've ever seen!
Because both the tabernacle and the hinge point on the mast are reinforced to prevent twisting (lots of surface area being pivoted on), my mast (the one in the picture), needs no side-to-side guidance. Besides, with the boom or a sheer legs as a crane, the line is pulling from center: the mast doesn't really want to go astray.
It sure is a good design! (I noticed the name on it when I was googling and was waiting for you to see it. Ha ha)

Really????

No side to side? That tabernacle holds things steady on the way up or down without baby stays?

Exactly what Iím hoping exists.
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Old 20-01-2022, 11:54   #11
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Re: I have to have a pedestal made - why not a tabernacle?

If you are going to have a base five feet high it will need substantial structure to keep the top of the base from moving. Five feet is a lot of leverage. Probably a four legged version of a tripod.

A Seawind 1000 is 33ft. IIRC, yours is 50. The mast weight, length and stresses are far greater.

I agree with you that you need a structural engineer to design something like that.
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Old 20-01-2022, 15:16   #12
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Re: I have to have a pedestal made - why not a tabernacle?

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If you are going to have a base five feet high it will need substantial structure to keep the top of the base from moving. Five feet is a lot of leverage. Probably a four legged version of a tripod.

A Seawind 1000 is 33ft. IIRC, yours is 50. The mast weight, length and stresses are far greater.

I agree with you that you need a structural engineer to design something like that.

This. All the pictures you provided are of small boats and their designs donít apply to what you need.

Forget about a tabernacle and lowering/hoisting the mast on demand. I expect that designing a 6í pedestal will be complex enough, without all the pivoting stuff. Consider that getting a new mast of the proper length may not look too bad in comparison.

If you havenít yet, go sail on a 50+ foot performance cruising cat in a decent breeze and big seas. Experience the loads for yourself, including the pumps and the massive load spikes, so that you really understand the loads involved. The static rig tension alone, assuming your boatís structure can handle it, is massive through the base of the mass. Then imagine a load three times that as you smash off a wave, such that the leeward shroud goes slack. A 1Ē SS bolt ainít gonna be enough.
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Old 20-01-2022, 15:57   #13
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Re: I have to have a pedestal made - why not a tabernacle?

Chotu we have the mast of our 32 foot yacht in a tabernacle. Being a tight wad I decided to make my own with some left over carbon fibre and fibreglass I had laying around. I hot glued a plywood board on the mast base, wrapped the mast and plywood base with masking tape. Then coated it all with mould release wax and started laying up the fiberglass. I stopped laying up cloth once I reached 10mm thick. Once cured I popped my new tabernacle off the mast, trimmed it up with the grinder then glued/fiberglassed the tabernacle to my deck. Five years later it still looks like new.
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Old 20-01-2022, 16:25   #14
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Re: I have to have a pedestal made - why not a tabernacle?

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Originally Posted by Fore and Aft View Post
Chotu we have the mast of our 32 foot yacht in a tabernacle. Being a tight wad I decided to make my own with some left over carbon fibre and fibreglass I had laying around. I hot glued a plywood board on the mast base, wrapped the mast and plywood base with masking tape. Then coated it all with mould release wax and started laying up the fiberglass. I stopped laying up cloth once I reached 10mm thick. Once cured I popped my new tabernacle off the mast, trimmed it up with the grinder then glued/fiberglassed the tabernacle to my deck. Five years later it still looks like new.
Cheers

Wow. That’s a great idea and I love your ingenuity in building it!

I think there is a different detail on my boat that is going to end this thread, unfortunately. I noticed this in real life today looking at the components.

The mast is 59ft without the extension. My deckhouse, which the mast is stepped right at the forward edge of, is 20ft long. Then there is a whole lot of nothing aft of that.

So, I don’t think the mast would be properly supported aft.

It would put all 450lbs on the back edge of my deckhouse and that point would act as a fulcrum too, creating a force pulling the tabernacle out of the deck. Even worse, about 1/3 of the mast would be supported and the rest would be a dangling noodle looking to break.


Looks like I’ll just go to cranes when it’s time to do the ICW or other inland navigation. My boat can’t manage this mast if it’s down and in the tabernacle. It has to be brought down to deck level and moved forward.
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Old 20-01-2022, 16:36   #15
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Re: I have to have a pedestal made - why not a tabernacle?

Chotu ,yes exactly shift the goose neck to the lower fixed section ,so the boom stays in place ,the rest of your too short mast is above ,the lower section can be fabricated th suit.just one solution ,maybe .⛵️⚓️��
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