Tabernacle mast - seaworthy?

[Sherpa17]

Is a hinged mast step technically the same thing as a tabernacle? They seem different to me from an engineering standpoint.

[El Pinguino]

Originally Posted by Sherpa17

Is a hinged mast step technically the same thing as a tabernacle? They seem different to me from an engineering standpoint.

Well......
Mine was essentially a hinged mast step... with only about 12 inches of 'shoe' below the pin.
You couldn't just let go the forestay and 'drop it'.... you had to set up the 'wishbone' and a tackle etc etc.... not a big deal but.......

The real deal can be seen here

https://www.youtube.com/watch?v=2WJAEhNCCJQ

where the mast is counter balanced and can in some cases be dropped 'on the run' when shooting bridges etc...

[Chotu]

So for a hinged mast step, on a big boat, how does one keep the mast from swaying side to side as you lower and raise it?

Seems this would be the most difficult part

[Benz]

Originally Posted by Chotu

So for a hinged mast step, on a big boat, how does one keep the mast from swaying side to side as you lower and raise it?

Seems this would be the most difficult part

It is, as I said before, a matter of stiffness: both in the construction of the tabernacle and the reinforcing of the mast. If the pin and the points it bears on are tight enough (mine are machined so the pins just slide in with a smear of Tef-gel), it will be pretty stable side-to side as it comes down. One of the reasons for the big footprint of mine was to spread the load in case of wrenching forces on the way down.
My particular mast is pretty stiff, though, since it's a pole mast for a gaff sail. So it doesn't try to flop around as it goes up and down. Still, I think the tight-tolerance and stiffness principles apply to bendier masts. If there's the luxury of extra hands, it's nice to have someone on each side with a halyard as a guy rope to help steady it, though it's not absolutely necessary for me.

EDIT: Sorry, didn't see the hinged mast step portion of the question until I had written this. I have no experience with hinge steps

[Don C L]

Originally Posted by Benz

It is, as I said before, a matter of stiffness: both in the construction of the tabernacle and the reinforcing of the mast. If the pin and the points it bears on are tight enough (mine are machined so the pins just slide in with a smear of Tef-gel), it will be pretty stable side-to side as it comes down. One of the reasons for the big footprint of mine was to spread the load in case of wrenching forces on the way down.
My particular mast is pretty stiff, though, since it's a pole mast for a gaff sail. So it doesn't try to flop around as it goes up and down. Still, I think the tight-tolerance and stiffness principles apply to bendier masts. If there's the luxury of extra hands, it's nice to have someone on each side with a halyard as a guy rope to help steady it, though it's not absolutely necessary for me.

EDIT: Sorry, didn't see the hinged mast step portion of the question until I had written this. I have no experience with hinge steps

You know, my question about that, and this is not a criticism, is that isn't it really one pin that is taking the strain? I mean for both to take on the strain, one of them is going to have to slip a tiny fraction of an inch, but still, isn't one the main carrier? I have thought about that for chainplates as well and wondered if it isn't better to have chainplates with horizontal bolts rather than vertical. I have seen boats with chainplates like that. With a tabernacle that would mean a second locking pin horizontal through the mast.

[RaymondR]

On my last boat the hinges were built into the mast base so it pivoted about 2" above the deck. It had pins for and aft so you could lower the mast both ways.

If the pivot pin on the mast and the pins on the chain plates are all aligned both horizontally and vertically you do not have to loosen the turnbuckles and the shrouds will prevent most of the sideways swaying as you lower the mast.

[Chotu]

Originally Posted by RaymondR

On my last boat the hinges were built into the mast base so it pivoted about 2" above the deck. It had pins for and aft so you could lower the mast both ways.

If the pivot pin on the mast and the pins on the chain plates are all aligned both horizontally and vertically you do not have to loosen the turnbuckles and the shrouds will prevent most of the sideways swaying as you lower the mast.

That’s what I was thinking of doing. Using a hinged mast base instead of a tabernacle.

I didn’t think in a million years it would be possible to do what you’re describing with the shrouds. Wow!

Do you have any pics or more details on this type of setup?

I’m picturing a generic idea of it, but I can’t envision the pins and alignments.

[CassidyNZ]

Not knocking the idea but I’m having difficulty visualising a situation in which the mast mount and the chain plates can be on a common horizontal plane. After all, 99% of sailing boats have a raised coach roof (mast mount) that is significantly higher than deck level (chainplates).

If that plane can be established then it should indeed be possible to keep a level of lateral support on the mast while dropping it forward or backward. But if I visualise my boat (typical) the deck where the chainplates are is probably 300mm below where the mast interfaces with the coachroof so the cap shrouds would go pretty slack when the mast the mast is being lowered in a longitudinal plane.

For example, when hauling my boat, I have to remove the forestay to fit into the travel-lift - I would never risk doing that without a halyard keeping the mast forward - I’m pretty sure it will fall if left unsupported.

[Chotu]

Originally Posted by CassidyNZ

Not knocking the idea but I’m having difficulty visualising a situation in which the mast mount and the chain plates can be on a common horizontal plane. After all, 99% of sailing boats have a raised coach roof (mast mount) that is significantly higher than deck level (chainplates).

If that plane can be established then it should indeed be possible to keep a level of lateral support on the mast while dropping it forward or backward. But if I visualise my boat (typical) the deck where the chainplates are is probably 300mm below where the mast interfaces with the coachroof so the cap shrouds would go pretty slack when the mast the mast is being lowered in a longitudinal plane.

For example, when hauling my boat, I have to remove the forestay to fit into the travel-lift - I would never risk doing that without a halyard keeping the mast forward - I’m pretty sure it will fall if left unsupported.

This is where I’m struggling to imagine it too.

I have 3 stays. A forestay and 2 back stays.

Back stays are at deck level and so is the mast step point. A good start. But Chainplates are aft of the mast by a good 2-3 meters (6-9ft)

I had always envisioned a sort of “running back stay” setup to drop the mast forward, while using the boom or another gin pole to get the right angle on the mast for the final lowering degrees to deck level.

I’d use a hinged mast base, NOT a tabernacle (weight issues).

But how to keep the mast from swinging side to side when lowering it has eluded me

[El Pinguino]

Originally Posted by CassidyNZ

Not knocking the idea but I’m having difficulty visualising a situation in which the mast mount and the chain plates can be on a common horizontal plane. After all, 99% of sailing boats have a raised coach roof (mast mount) that is significantly higher than deck level (chainplates).

If that plane can be established then it should indeed be possible to keep a level of lateral support on the mast while dropping it forward or backward. But if I visualise my boat (typical) the deck where the chainplates are is probably 300mm below where the mast interfaces with the coachroof so the cap shrouds would go pretty slack when the mast the mast is being lowered in a longitudinal plane.

For example, when hauling my boat, I have to remove the forestay to fit into the travel-lift - I would never risk doing that without a halyard keeping the mast forward - I’m pretty sure it will fall if left unsupported.

As stated earlier by 'Double U' and as shown in my photo posted at #20....

The connection point of the cap shrouds must be in line with the pin at the tabernacle.

If you look again at my photo.... the port cap shroud is attached ( just below the bit of white PVC tube) to a pair of chain plates which extend above the deck and form an inverted 'V'. This attachment point is in line with the mast pin which by memory was about 8 or 10 inches above the coachroof.
( If you look closely the metal mast shoe is green... the 'tabernacle' is galvanised....)

This meant that as the mast is lowered the cap shrouds stayed in tension.

Not having a 'Broads Style' counterweight as shown in the Youtube vid above an 'A frame' or 'Wishbone' has to be employed to keep a good 'angle of attack' between forestay and mast as it is lowered. This stayed in place on my boat and was handy for lashing stuff to.

To lower the mast..... Remove boom....place a couple of fenders on coachroof to make a bed for mast... tension jib halyard.... undo forestay ... attach forestay to wish bone.... set up block and tackle between wishbone peak and stemhead fitting.
Let go inner forestay and forward lowers...give mast a bit of a shove to start it.... and lower away on the tackle...

Boat was 25 foot long.... don't see this system working above ... say ... 30 foot.

As built she lived on the Swan River and it was neccesary to drop the mast to get down to Fremantle Harbour and the sea.

I used to do it once a year when taking the mast ashore to varnish it.

[RaymondR]

If the pins all align then everything is rotating around the same centre and nine of the relative distances from pins to attachments up the mast change.

The previous boat had wide and extended chain plates which bought the pins up to tthe same level as the pins on the mast base.

On Travel Lifting.

I found that it was much less work to back the boat into the travel lift slot. I would put a wire clamp on each of the twin back stays and use the genoa sheets with the deck blocks all the way aft and the main halyard to keep back tension on the mast.

[Wckoek]

Hinged mast step, of these type in the pictures?
It would be difficult to visualize from descriptions alone.

[Don C L]

Originally Posted by Wckoek

Hinged mast step, of these type in the pictures?
It would be difficult to visualize from descriptions alone.

Yes, those are all hinged mast steps.

[Wckoek]

Originally Posted by Don C L

Yes, those are all hinged mast steps.

I see it is possible to have a few horizontal bolts to secure and maybe stiffer than a pin, but I tend to see tabernacle more than hinged of these types.
Maybe a tabernacle is easier, or drilling through deck is undesirable?

[NevilleCat]

another big boat tabernacle from Perth; this is a 47 foot Bowman (Holman and Pye)