How heavy is a mast, stepping by hand - how hard can it be..

[pandos]

I have done this on smaller boats with a tabernacle and it can be tricky, but doable.

I often wonder has anyone considered a temporary track both sides of the mast base so that the mast is captive but can move forward and back, using horizontal control lines (this would require a pair of bearings bolted through the mast near the base and two pieces of channel iron) then an "A" frame fixed in the cockpit with a pulley attached to the front of the mast, as high up as possible but below the spreaders...

As the mast base is allowed to slide forward, its weight will be taken up on the A frame and eventually will come to rest at the bow and on a crutch at the stern...

This method would get over the really scary point where the entire mast is trying to act as a 12m lever to lift the base up off the deck or to crush the human like a nut cracker....

 

[William_H]

Well done, first person to actually focus on where all the opposing forces meet.
And which might well scupper the whole idea, looks like it could be a bit complex to sort.

Just pivoting on the base would very likely go bang as it broke with all the force concentrated at the leading edge but doesn't matter as the mast heel plug looks like it just sits in the base anyway. Looks like it could be a show stopper, which is a pity - a lot of the idea was to be completely self sufficient in the future when somewhere without a crane.

Interesting shape of the existing mast base. I presume that the lug (at the back?) is to take vang etc. It is remarkably similar to mine on a much lighter mast. The mast itself has a slot in the base and 2 lugs on the aft side of the mast that match the lug in the base. So the whole mast when pivoting sits on this lug. In my case made of stainless steel. It has the huge advantage that with lots of slop it can handle the mast swing sideways to a fair degree. It does tend to spread the lugs on the mast a bit. The point is that geometry means that a large swing of the mast sideways results in small movement at the base due to narrow "wheel " base. Those bases sold for the purpose with 2 lugs spread slightly wider than the mast width are very susceptible to snap off with any mast side swing. Of course measures should be taken to avert side swing but then things do go wrong.
On this subject Mc Greggor 26 come with a fractional rig with cap shrouds chain plate aft of abeam the mast. They fit extra intermediate wire side stays from spreader base to chain plates on the cabin top in line with mast pivot. Just to keep mast central when being raised or lowered.
The idea of a track from mast base location down to foredeck has been mooted for trailer sailors. Would have to work with a roller on the stern support. As said this second stage of mast right down and forward till the base is at the pulpit can be very fraught. I suspect people with big masts while they may lower them for a bridge would not do this last stage without a crane. Anyway if you do decide to try to do it your self just be very careful and good luck ol'will

 

[Daydream believer]

When cruising in the Netherlands I met a chap with a 35ft boat ( Bavaria I seem to recall, certainly an AWB) who could raise & lower his mast from the cockpit whilst under way.
He had small "A" shaped frames built on the deck where the shrouds normally connected such that the top of the "A" came level with the centre of the mast base. He had a main A frame with the base of the legs permanently fastened to the deck at the same point as the small "A" frames. The top of the A frame came just under the jib furler & had an attachment to take the furler & to fasten to the deck with a quick release pin.
To this point was a wire led through a block in the anchor well back to the anchor winch suitable adapted to take the wire.
As he approached some of the non lifting bridges (or at least those that only opened at awkward hours) he would pass under the same spot that barges would pass. Just as he approached he would release the pin, let the anchor winch off (sails furled of course as he was motoring in the canals) from the cockpit & the mast would drop back to an angle of 30 degrees to horizontal. This allowed him to go under the bridge & the boom etc could still be attached to the mast & lay between mast & cabin top.

The shrouds maintained tension as the small "A" structures at the side were at the pivot point of the mast base. This stopped the mast moving sideways.

Once through he set the anchor winch to pull in & the mast went up. He then walked forward &put the retaining pin back into the main A frame in case the anchor winch let the wire out.

He had refined it so that the small "A" frames were in the line of the guardrail & the main A frame had curved legs so when lowered they sat just inside the guardrail & did not foul the deck in the way straight leg would have done. He altered the deck cleats as well but I forget how he did those.

 

[Quandary]

When we had the Sigma 33 we tried to raise the mast by placing the boat in the travel hoist dock at low tide (after hours when the driver had gone home) and dragging it up with ropes to the elevated platforms at each side, the step was similar to that shown above and we had a screwdriver as a temporary pivot pin, halfway up it would go no further but with more effort from our crew of six it suddenly went bang, the screwdriver sheared and the mast skidded along the deck. On close examination the step and the mast base geometry was such that pivoting on the lug did not work. We were lucky that the screwdriver sheared, breaking off the lugs on the step or the mast would have been much more expensive to fix.

 

[GHA]

2Kg/M sounds incredibly light for the extrusion (more like a dinghy). Without knowing the section the weight is hard to lookup on that Selden extrusion data document. But assuming something near the middle of the range, the weight is more like 6Kg/m (range is 3.7Kg/m to 15.5Kg/m across all their sections). I'd say your mast is more like 100Kg for the extrusion and then the spreaders on top.

I'm not an engineer, but would the whisker pole/endcaps (and mast section if the pole were attached to the mast itself) be strong enough?

Probably right about the mass/metre, but the mast isn't very heavy really, very similar mast in the yard can't be more than 100Kg, not much in the real world.With the shrouds slackened off you can tell by the resonance when shaking it that it's not crazy, been lifting stuff for decades in the day job so eventually you get a bit of a feel for loads.

And the pole was getting some considerable attention yesterday, made a pivot bracket to sit on the deck so the force can only go dead centre of the plus plus at the other end the dyneema geometry will be easy to rig to keep the force dead centre.
With the force along the extrusion centroid pretty sure there will be masses of spare capacity before any buckling occurs. I should look at the force sketch again but looks like couple hundred Kg going down the pole, that's just 2 1/2 blokes sitting on top, nothing major.

Would dearly love a calibrated load cell!!

 

[GHA]

When we had the Sigma 33 we tried to raise the mast by placing the boat in the travel hoist dock at low tide (after hours when the driver had gone home) and dragging it up with ropes to the elevated platforms at each side, the step was similar to that shown above and we had a screwdriver as a temporary pivot pin, halfway up it would go no further but with more effort from our crew of six it suddenly went bang, the screwdriver sheared and the mast skidded along the deck. On close examination the step and the mast base geometry was such that pivoting on the lug did not work. We were lucky that the screwdriver sheared, breaking off the lugs on the step or the mast would have been much more expensive to fix.

Dyneema is really strong.

Screwdrivers aren't.

 

[GHA]

So I assume you are using your genoa halyard in place of the forestay.

There is one on there but doesn't need it. Even with the inner forestay off the lowers are plenty to keep it up there. The rigging is designed to transfer BIG loads on the mast down to the boat, enough to push it on it's side with a decent factor of safety on top. Stick on it's own needs little to keep it upright.

 

[AntarcticPilot]

When I was knee high to a grashopper, my Dad bought a converted lifeboat - 27', with a gaff rig. The mast was stepped in a tabernacle, and although heavy for its height, it was short, and probably wasnt that much heavier than the mast the OP is considering.

My Dad decided to lower it (I forget why - perhaps for winter), and got everything ready, including a trestle to take it when it was down. He lowered away on the forestay, and everyone who can picture it will know exatly what happened - he got to the point where he lost the mechanical advantage, and the mast slammed down. Fortunately the tabernacle kept it straight, and it landed in the support. Even more fortunately, my Mum (who was waiting to take the weight as it came down) managed to jump quickly enough to avoid being brained; I recall that she got a rope-burn from one of the shrouds! For future events, my Dad designed an A-frame that doubled as a pulpit.

That was with a mast short enough to be lowered so that the centre of gravity remained inside the boat, with a tabernacle to keep it straight. The same thing with the mast on a modern mast-head rig would end with the mast being destroyed, the step badly damaged and a high likelihood of someone being killed.

As far as I'm concerned, lowering the mast on a modern yacht is a job for a crane and a crew of people who know what they're doing. I simply wouldn't take the risk of lowering it any other way.

 

[C08]

I would agree with everythiing said about the dangers and risks in raising and lowering masts. I made a large strong A frame frome 2x4 timber to drop a 30ft mast on a catamaran. In conjunction with a scaffold pole we lowered the mast ok but getting it back up became very hard going and rather than break something or someone we lowered it back and got a crane lift.

 

[GHA]

Forces coming out easily handled, so just the fulcrum to sort out & might actually be a goer
Think those vectors are right, feels about right. Based on a 100Kg mast.
To get something viewable a scale of 1N to 1mm was used, so divide by 10 for Kgf.

 

[Graham376]

You're contemplating a dangerous game there, can just imagine Bruce's face when the mast lands on adjacent boat. Why not cadge some steel plate from him and weld a temporary tabernacle to the deck? Should be able to bolt a band around the mast part way up as fulcrum.

 

[capnsensible]

Let the crane take the strain........:encouragement:

 

[Kukri]

Dutch steel boats up to 10 metres or so LOA often have an A frame which forms the foredeck guard rail and pulpit, pivoted on substantial triangulated steel constructions which bring the pivot point precisely into line with the tabernacle. Neat and reliable, but heavy, system.

For the record, 20 metre two spreader keel stepped mast - 800 kg without the rigging.

 

[lw395]

These Bermudan rigs will never catch on!

 

[SteveGorst]

I have experience of doing this with my old Etap 26. The mast length was about 10m and we used the same arrangement as you have drawn. We did put the shrouds on incase it went sideways but it never did. It was always an emotional experience and although my son and I are big and strong ex rugby players it was on the limit of what we could do. I would not contemplate it with a 12m mast.

 

[Boathook]

My mast is around 11 metres length and in a tabernacle. I have lowered it once many years ago with 4 of us and it nearly went wrong swaying all over the place in the wind. Lifting off / lowering is now done by a crane. The mast is a fairly heavy section but the weight is greatly increased by all the rigging. If you really want to carry on use a tabernacle, have the shroud fixing points the same height as the bolt in the tabernacle. This does allow some 'tension' to be maintained in the shrouds.

 

[GHA]

Let the crane take the strain........:encouragement:

Many places a crane or hiab just isn't an option, which is a lot of the reason for having a play. Actually going quite well, whisker pole now pivots nicely on it's own plate & rigging half done to guy the top. Cunning plan slowly revealing itself for the mast base to pivot which should work but needs a some time on CAD to get the dims bang on, moving the mast forward when it's down will be mostly with lifting equipment so no struggling on deck, centre of mast will be very close to radar arch so nearly in balance, need some nylon or low friction plate or something for it to slide on, radar arch is well man enough, new braces been put in already. And there's always to option to back off if it starts looking a bit iffy for any reason.
All the horror stories so far would have been avoided with plenty of guys (stays, not blokes ) and plenty mechanical advantage so no need for any huffing and puffing.
Every doom and gloom post is just more motivation to do a number on it and do it properly with no drama

 

[steveeasy]

Many places a crane or hiab just isn't an option, which is a lot of the reason for having a play. Actually going quite well, whisker pole now pivots nicely on it's own plate & rigging half done to guy the top. Cunning plan slowly revealing itself for the mast base to pivot which should work but needs a some time on CAD to get the dims bang on, moving the mast forward when it's down will be mostly with lifting equipment so no struggling on deck, centre of mast will be very close to radar arch so nearly in balance, need some nylon or low friction plate or something for it to slide on, radar arch is well man enough, new braces been put in already. And there's always to option to back off if it starts looking a bit iffy for any reason.
All the horror stories so far would have been avoided with plenty of guys (stays, not blokes ) and plenty mechanical advantage so no need for any huffing and puffing.
Every doom and gloom post is just more motivation to do a number on it and do it properly with no drama

Clearly a clever chap but you would not think so. Just remember not to put others in danger to satisfy your own ego.

Steveeasy

 

[Billows]

 

[prv]

The OP may or may not screw it up, but I don't think he's ****ing stupid enough to try raising the mast without any stays attached like those idiots

Pete