tabenacle v hinged mast plate

Moderator: GreenLake

tabenacle v hinged mast plate

Postby lbdavis » Fri Jun 25, 2010 8:23 pm

Hi Gang,

I recently bought a 1960 Sailstar Explorer (the same one I posted about earlier). Everything is going great, exept I want to cut the mast so I can step and unstep single handed.

I've been reading around here and it seems as though most everyone uses what I call a hinged mast plate:

Hinged mast plate

And no one uses what I'd call a tabernacle:

Tabernacle

Please correct me if I'm using the wrong terminology.

The simplicity and cost of the latter is appealing, but I'm concerned of it's strength vis a vis the hinged mast plate. Both are only held together with one bolt (assuming the front bolt isn't used on the mast plate - as many do), but I wonder if the bolt in the "tabernacle" will distort the mast under stress?

Are there other disadvantages to the Tabernacle that I'm missing?

Do I make any sense at all?

What is the velocity of an unladen Swallow carrying a coconut?

Lance
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Postby algonquin » Fri Jun 25, 2010 10:58 pm

It seems that you have your terminology reversed. The tabernacle is the most common way to hinge your mast on the DS. It not hard to install and makes stepping your mast much easier. I would suggest that you call Rudy at DR Marine and see if the tabernacle sold for the DS models will fit your Sail Star. Brad


http://www.drmarine.com/proddetail.asp?prod=DS208
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Postby GreenLake » Sat Jun 26, 2010 2:22 am

A tabernacle proper is fitted to the deck and allows the mast to be stepped by rotating it around a pin that's located a short distance above the deck. That's the common use of the term. It derives from the certain religious uses of the word tabernacle where it denotes a particular "box-like vessel".

A true tabernacle has no deck opening, and a compression post underneath the deck (or a frame or bulkhead that can take up the compression loads). Commonly it has side walls containing the pin which gives the whole arrangement a box-like appearance. Sometimes there's a front wall as well against which the mast comes to rest when raised until it is held by the stays.

A hinge is what you use when you cut the mast. For some reason, it's been/become customary in the DS community to also call such a thing a tabernacle, even though it's really nothing more than a hinge with a second pin in front.

The compression loads for a "hinge" are taken up by the fixed, lower portion of the mast, which usually has the same profile.

The effect of a tabernacle or hinge is that the remaining upper portion of the mast can not be bent as easily and that compression loads are higher. The former makes immediate sense, but I can't come up with the rationale for the latter just now, so in that case I'm just repeating what I've heard.

Even if a deck stepped mast is bent, it's radius of curvature is different, as is the location of the midpoint of the curve.
~ green ~ lake ~ ~
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Postby algonquin » Sun Jun 27, 2010 11:50 pm

Hmmm !

Now I see what the confusion is here. Its me ! :wink:

In our DS lingo the term tabernacle has been readily applied to the hinge plate while an actual “tabernacle” is really totally different in design and application. As Ibdavis observed and GreenLake graciously describes the “tabernacle” isn’t really used on the DS models. We commonly use a hinge plate that we have identified as a tabernacle. :roll:

So if you desire to use the hinge plate call DR Marine and order a tabernacle. :? :?

http://www.drmarine.com/proddetail.asp?prod=DS208


My Venture of Newport 23 had an actual tabernacle on the cuddy. Of course I thought it was called a mast step. Well maybe it was a mast step aka. tabernacle. It definitely wasn’t a hinge plate. At this point it really doesn't matter anymore. Brad
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Postby navahoIII » Thu Sep 02, 2010 9:59 pm

Our DSI has the "real" tabernacle, made by Dwyer. It works fine with no problems to speak of. It's a good alternative to the hinged one from D&R.
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Postby lbdavis » Mon Sep 13, 2010 6:58 pm

navahoIII wrote:Our DSI has the "real" tabernacle, made by Dwyer. It works fine with no problems to speak of. It's a good alternative to the hinged one from D&R.


Thanks. I ended up getting a D&R hinged plate. I called Rudy and we figured out the proper casting for my unmarked spars and it all works very slick - as long as I remember to take out the front pin when lowering the mast....

:oops: :oops: :oops:
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