Tabernacle mast - seaworthy?

[RaymondR]

Tabernacle or deck stepped masts are actually safer for offshore than keel stepped masts as in the event of a rollover the tabernacle mast will generally break off cleanly above the deck whilst the deck stepped mast is much more likely to bend below deck level and take out a large section of deck as it bends and breaks thereby leaving a large hole in the deck through which the vessel could flood.

[Wckoek]

Originally Posted by gbowen

I built a 52 ft LOA, 19 tonne boat in NZ in the 70s. My tabernacle was 3/8 inch thick steel with a 4 x 4 steel box section under it to the ballast. I had a steel mast. It was over-built but allowed me to rig the boat in a tidal creek without needing a crane. The tabernacle was mounted on the coach roof. I have a pic of the tabernacle from the 70s plus the math involved as a JPEG. The lateral stability was by handing the shrouds. The windlass supplied the muscle. Not sure how to upload to this site but will respond if anyone is interested to my e-mail address :"gbowen360@gmail.com We saw plenty of rough weather including 2 hurricanes.

I didn't have a large boat but a reference on building one is nice, send you a mail.

Originally Posted by RaymondR

Tabernacle or deck stepped masts are actually safer for offshore than keel stepped masts as in the event of a rollover the tabernacle mast will generally break off cleanly above the deck whilst the deck stepped mast is much more likely to bend below deck level and take out a large section of deck as it bends and breaks thereby leaving a large hole in the deck through which the vessel could flood.

I see, I just thought it might be less sturdy as there are more moving parts.
A keel stepped mast would have more motion comfort I think.

[double u]

the first singlehanded circumnavigation on a catamaran, Wolfgang Hausner, Austrian, started from Fremantle, where he had built the boat in the mid-sixties.
The boat was a 10m Eric Manners design &, because of the bridge in Fremantle, had a tabernacle.
The boat took him around the world & the trip made him an icon in the German speaking sailing scene. He wrote a book about his adventures that changed many a young man's live, (mine among them).
After losing this cat ("Taboo") on an uncharted reef in PNG in the seventies he designed himself a 60' cat that he built in the Phillipines with local labour. The boat is still going strong, (the guy too, must be 80!), as far as I can see in the book it has a tabernacle too.

[Munoz]

Originally Posted by Wckoek

Probably a dumb question, so far I have only seen tabernacle mast on coastal sailboat, particularly catboats, but is it possible to have a tabernacle mast sailboat that is seaworthy, on the sense that safe to take it offshore?


Is there an example of a sailboat model with easily lowered mast of this kind that can cross ocean?

The Wylo II design: complete with a pullput that doubles as an A-frame for raising and lowering the mast: https://www.whitehouseyachtdesign.co.uk/wylo-ii

https://vimeo.com/284310686

[El Pinguino]

Originally Posted by double u

...not so long ago you could discern boats with homeport Fremantle by their tabernacles & chainplates in axis with the tabernacle's axis...some of them rtw-ed...

My Vertue was built in Fremantle in about 1960. She had tabernacle and chainplates as you say... did plenty offshore miles in and around Bass Strait when I owned her.

Only the cap shroud chain plates need to be aligned... I think you can see the set up in this pic... pivot point is just below the bit of white PVC pipe....... you can also see ... to port and starboard ...parts of the galvanised 'wishbone' used to raise and lower the mast.....

Erith Island, Kent Group, 1985ish..

[RaymondR]

Keel stepping is a lot cheaper and easier to implement than deck stepping with a tabernacle. You just cut a hole in the deck and poke the keel through onto the keel.

[El Pinguino]

Originally Posted by RaymondR

Keel stepping is a lot cheaper and easier to implement than deck stepping with a tabernacle. You just cut a hole in the deck and poke the keel through onto the keel.

Easier to change the bulb in your trilight if in a tabernacle... and you never need a crane to remove your mast....

[double u]

...those chainplates were the giveaway (to the initiated)
Imho most of the tabernacles are more seaworthy (seaworthier?) than most of the maststeps supplied by mastmanufacturers: the throughbolt positively holds the mast whereas standard maststeps rely on the compression to keep the mast coming off a 1/2" lip
https://www.myhanse.com/uploads/2453/Picture_004.jpg

[double u]

Originally Posted by RaymondR

Keel stepping is a lot cheaper and easier to implement than deck stepping with a tabernacle. You just cut a hole in the deck and poke the keel through onto the keel.

keel stepped - deck stepped: had both, deck stepped had more advantages

[Don C L]

The only thing I'd guess to be concerned about is that the tabernacle transmits all the compression force, which can be close to the displacement of the boat, to one pin, so the pin, the upright flanges, and the reinforcement in the mast walls have to be up to the task. The other option, a hinged mast step, requires no extra reinforcement than what is already there for a deck-stepped mast. But sailing close to shore or far from shore, you still, possibly, have the same forces at work on the system. The boat doesn't know how far from the shore it is.

[RaymondR]

Originally Posted by Don C L

The only thing I'd guess to be concerned about is that the tabernacle transmits all the compression force, which can be close to the displacement of the boat, to one pin, so the pin, the upright flanges, and the reinforcement in the mast walls have to be up to the task. The other option, a hinged mast step, requires no extra reinforcement than what is already there for a deck-stepped mast. But sailing close to shore or far from shore, you still, possibly, have the same forces at work on the system. The boat doesn't know how far from the shore it is.

Not always, I have seen designs where the heel of the mast contacts the floor of the tabernacle and slightly lifts the mast as it hinges to the vertical.

[CassidyNZ]

Is there a difference between “tabernacle” and “deck-stepped”? I guess on smaller boats where the rig may be folded down to facilitate transporting, a swivel pin may be present but on bigger boats the mast will be stepped into a casing above a compression post. In this case, whether it is deck-stepped or keel-stepped makes little difference to the mast, foot pressure is the same.

AFAIK, most French production boats (Beneteau, Jenneau, etc) and many others (Hanse, Bavaria, X-yacht), even the bigger ones, are deck-stepped. I believe it to be the more modern approach.

As far as safer at sea in a dismasting event, yes a deck-stepped rig will leave the boat more cleanly but leaves little opportunity for a jury rig. Mostly, when a keel-stepped rig comes down, a significant or at least usable, portion of the mast remains standing. I reckon the events in which a broken keel-stepped mast tears a hole in the deck are pretty rare. A mast extrusion without the supporting rig (column destroyed) is really quite weak.

Other than having to peer around the mast to talk to someone on the other side of the dinner table, I’m really pleased to have a keel-stepped mast.

[SalingSue]

As long as your fore and aft stays are properly tuned and standing rigging is in good shape, I don’t see how it would be any different from a deck stepped mast.

[Wckoek]

Originally Posted by CassidyNZ

Is there a difference between “tabernacle” and “deck-stepped”? I guess on smaller boats where the rig may be folded down to facilitate transporting, a swivel pin may be present but on bigger boats the mast will be stepped into a casing above a compression post. In this case, whether it is deck-stepped or keel-stepped makes little difference to the mast, foot pressure is the same.

AFAIK, most French production boats (Beneteau, Jenneau, etc) and many others (Hanse, Bavaria, X-yacht), even the bigger ones, are deck-stepped. I believe it to be the more modern approach.

As far as safer at sea in a dismasting event, yes a deck-stepped rig will leave the boat more cleanly but leaves little opportunity for a jury rig. Mostly, when a keel-stepped rig comes down, a significant or at least usable, portion of the mast remains standing. I reckon the events in which a broken keel-stepped mast tears a hole in the deck are pretty rare. A mast extrusion without the supporting rig (column destroyed) is really quite weak.

Other than having to peer around the mast to talk to someone on the other side of the dinner table, I’m really pleased to have a keel-stepped mast.

Most race boats have keel stepped mast, I suspect in terms of performance a keel stepped is better because of the direct weight transfer, but you'll have to deal with leak and other problems in the long term.
There are 7 knockdowns and 5 dismast in 2018 Golden Globe race, Are Wiig's OE32 is keel-stepped, Susie Goodall's Rustler is deckl-stepped converted to keel-stepped, I think the other Biscay 36 and Suihaili are deck-stepped. Neither have significant damage to the deck.
CovariMail - DIY Direct Email Marketing


I am surprised that there are actually a few tabernacle mast that goes offshore, though I never seen one myself, maybe it is just because most offshore cruisers didn't bother to do the custom job or didn't find the need to.

[Benz]

My tabernacle is designed so that when the mast goes upright on the hinge pin, and you slide the locking pin in (which is the same diameter), they share the load. My welder was a really finicky engineer, and it came out beautiful. After the pins are in place, I beat Ipe' wedges under the heel, sliding one from each side and overlapped so that they form a flat surface that further supports the mast.
I think the key to a good tabernacle is stiffness of construction and ample load-spreading. Mine sits on a 12" by 18" (or so) plate with bolts in the corners that engage the deck beams below with 1/2" bolts. The uprights are structural U-channel welded to structural angle, and both welded to the baseplate. Where the pins go through there's welded doublers. It looks big at first, but you soon get used to it. And you never worry about rainwater coming in along the inside, which was a problem before I tabernacled.