Hello everyone, I see there is mention of tabernacles made out of wood or metal, but i just wonder, is it feasible to make a tabernacle out of fibreglass. I am only asking as i have a home built boat ( in fibreglass ), which i hope to change from bermudan cutter rig, to junk rig. building a fibreglass tabernacle means i can glass it at deck level for strength and water tightness, and at the heel again, i could glass the tabernacle on top of the keel and laminate up the sides of the hull. I would appreciate any advice. Best regards, Asim.

Rope Hinge

Hi Andrew. In my humble opinion the pin should never go through the mast, and I can see no reason at all why rope could not be used as the hinge.

It seems to me that the axis of rotation (as the mast raises and lowers) could just as well be directly behind the mast, rather than through it. A stainless steel pin could go through the top of the tabernacle  at its rear, and be stout enough to extend each side by about 10 or15 cm, in the manner of a bollard.  The pin could be left there permanently, or it could be a loose enough fit to be removeable. The reason for the extended pin is to allow the mast to be firmly lashed to it with a simple “boy scout” square lashing, which would be able to rotate around the centreline of the pin, providing the hinge.  When raising the mast, it will also be wise to have a short strop (removeable) between the heel of the mast and the pin, to prevent any chance of the mast perhaps slipping down through the lashing and dropping slightly when it is in the near vertical position.

The question of strength and durability is irrelevant here, because the rope hinge (or any type of hinge, for that matter) should serve no other purpose than to assist in the raising and lowering of the mast. Once the mast is up, it should be locked in place with a bolted-on plate making up the 4^th side of the tabernacle, and the rope (and pin, too, if you like) would be removed. The 4-sided box tabernacle would be a much stronger assembly than a conventional 2 or 3-sided tabernacle, especially one with a pin going through the mast.

This was my plan some years ago. I had a “top hat” section folded from a sheet of 6mm aluminium plate, and got a length of tube welded across the top of it, to carry a 12mm stainless steel pin. (See images below). This was to be the tabernacle, very quick and economical if you can find someone with a folder who can handle that thickness, although lighter plate could be used for a smaller boat. When the mast is in the raised position, the 4^th side of the tabernacle would bolt to the flange so-formed. I made the tabernacle, and the 12m mast, but the project stalled and the conversion did not get beyond the stage of a “thought experiment” (though I have since used the aluminium top hat section idea successfully on a smaller boat).  I think there are a number of ways of applying the same principle, including steel U-section (which I also considered, with mounting bolts welded on for the locking plate),  or wood (which would  be very nice but would cost more and involve more work).

I think you are on the right track by considering a rope hinge.

Key points: Wood, steel or aluminium, the tabernacle of itself should be of sufficient strength to be seaworthy, regardless of the hinge. The scantlings of the mast can determine the scantlings of the tabernacle. The hinge itself need merely be strong enough to enable raising and lowering the mast, the rest of the time it being out of consideration. The pin should be part of the tabernacle, not part of the the mast. Dissimilar metals should not be permanently in direct contact.

Purely for bouncing further ideas (as it was never actually used) here is what I did, some years ago :

A 12mm ss pin, sliding fit in the tube above, extended each side of the tabernacle to form the cross for the square lashing, and the axis of the temporary rope hinge.

The mast had a solid block of wood at the heel, fitting perfectly in the tabernacle.

At the top of the tabernacle, I cast, in two parts, a solid rubber fitting to encapsulate the mast at that very important point, using the tabernacle itself as a mold, as shown below. (David T might recall providing advice at the time, on how to do this).

I think you could do just as well with galvanised steel U-section and mounting bolts welded on the sides for the (4^th side) locking plate, and encapsulate the mast at the heel and at the top of the tabernacle with wood and fibreglass, possibly using the tabernacle as a mold to get a perfect fit (using a couple of layers of baking paper as a parting agent!!)   

I am sure a similar principle could be used with wood, of sufficient scantling, which would be slightly more problematic, though more aesthetically pleasing than aluminium or galvanised steel..

If you run with this idea, or similar, please take photos and let's know how it goes.

Mast heel extension [As an aside: Jonny K in his earlier post at the commencement of this thread, is concerned about "blue water strength", but does not refer to the raising and lowering of his mast. He seems to be looking purely for a mast heel extension. In that case all that would be needed is a galvanised steel tube, square or round section, of sufficient wall thickness -  and judicious use made of castable rubber and/or wood-fibreglass packing at the heel of the mast and where it exits the tube].

Anonymous wrote:

Anonymous wrote:

Hi all,

Just doing some research on masts and tabernacles. I have been looking around for an affordable ie: IN A SCRAP YARD! mast for my possible Traveller 32 conversion, and I've found a few galvanized poles that are approximately 9-10 ft too short. I would prefer Aluminum , but am not writing off steel. 

I was looking online , especially at Shirley's Speedwell Of Hong Kong and thought "What about building with a tabernacle? I shorter , cheaper and easier to source pole , and steel box tabernacle seems like it would be fairly simple to construct.

Thoughts and opinions?

The most important thought to me is Bluewater strength?

thanks

Jonny

I don't have any thoughts that might be useful here, beyond suggesting a wood tabernacle might be just as easy to construct, as strong as steel, more pleasant to live with and easier to maintain. Pete Hill built Shirley's douglas fir tabernacle as well as those aboard Oryx and China Moon, in which he sailed non-stop from N E Brazil to Tasmania. How's that for blue water strength?

By the way, I've made several blue water voyages and the only times I've seriously feared for my rig have been on coastal passages, for example, on departing from a river on an ebb tide running out against an incoming sea. On those occasions, I wondered why the ship didn't fling her sticks out. The chief difference between blue water passages and grey water ones is that blue water voyagers put themselves beyond any hope of rescue and must be utterly self-reliant.

Thanks Asmat! 

That is some great food for thought. And I agree. Boats LIKE water . the do not like LAND.

A well found boat should be fine out at sea. 

I just got my old dog eared copy of PJR out of storage and will read up on tabernacles this evening.

HJ

Hi all,

Just doing some research on masts and tabernacles. I have been looking around for an affordable ie: IN A SCRAP YARD! mast for my possible Traveller 32 conversion, and I've found a few galvanized poles that are approximately 9-10 ft too short. I would prefer Aluminum , but am not writing off steel. 

I was looking online , especially at Shirley's Speedwell Of Hong Kong and thought "What about building with a tabernacle? I shorter , cheaper and easier to source pole , and steel box tabernacle seems like it would be fairly simple to construct.

Thoughts and opinions?

The most important thought to me is Bluewater strength?

thanks

Jonny