Raising a junk mast

[ash2020]

Hello all and Seasons greetings.
I am part way through a design to convert my 20' Hunter Medina to a junk rig. Looking for some ideas to step the mast. It will be approx 8m tall, round in section and weigh approx 30kg. It will go down a hole in the deck 1.2m to the base in the hull. I haven't yet decided whether to have partners at deck level and a separate mast base or whether to slip it in to a fixed in place tube.
My current mast is easy. It has a hinge on the deck and I raise it with an A frame. The new mast has no supports, no rigging, no hinge. It will be smooth, with no spreaders. It will be in three tubular sections, one inside the other, so I was thinking maybe some sort of telescopic arrangement. Or perhaps some sort of hinge and slide arrangement.
I don't have any boaty friends here so I can't do it alongside another boat. There's nowhere high enough and accessible, like a bridge or gantry at the launch site. I really need to do this single handed.
Any ideas would be gratefully received.

 

[Refueler]

Compass24 used to sell a Mast raising system designed for both deck and keel stepped masts .... it was based on telecescopic alloy tubing ... basically telescoped down into a bag ...

But I cannot find it now ... Page 404.

I think you should be able to modify your A frame ? question is how tall is it when stood vertical ? basically it needs to stand more than 50% of mast height so you can pivot into the 'hole' ....
8m less the 1.2m ... so 6.8m .... isn't that a bit tall for a Junk Rig for your 20ft boat ?

My question to you though ... if you have a working standard mast and you handle it well ... why the change to Junk Rig ?

 

[ash2020]

Thanks for that, @Refueler. I have a working standard mast, as far as raising and lowering is concerned but I now have inflexible, creaking body parts and arthritis and don't cope well when single handed, with winches and sheet pulling etc. The Junk rig is so simple to reef and tack.
Years ago I met up with David Tyler and his junk rigged Hunter Duette, Weaverbird, in Scotland. We spent a couple of days with Designer Alan Boswell doing polar diagrams of Weaverbird vs. my bermudan rigged Varne. I remember thinking when sailing on Weaverbird "why aren't all boats like this?".
With modern, cambered, split junk rigs, there's barely any difference in performance.
Also, I get enjoyment from tinkering and messing about with ideas. What could be better than designing and building a mast and sewing your own sails? Can't wait.

 

[LittleSister]

I am part way through a design to convert my 20' Hunter Medina to a junk rig.

. . . the mast. It will be approx 8m tall, round in section and weigh approx 30kg. It will go down a hole in the deck 1.2m to the base in the hull. I haven't yet decided whether to have partners at deck level and a separate mast base or whether to slip it in to a fixed in place tube.

. . . It will be in three tubular sections, one inside the other, so I was thinking maybe some sort of telescopic arrangement. Or perhaps some sort of hinge and slide arrangement.

I have sailed junk rig many miles, but no experience of building them. I certainly don't mean to be negative, but I am a little sceptical that a mast in three sections slotting into one another would be suitable, especially so if they are lightweight (your total works out about 7.5 lbs per metre length).

A junk mast, unlike a conventional mast, is unstayed and has no sideways, nor fore and aft, support save the cabin top pushing one way and the socket at the mast foot pushing the other. The whole of the lateral sail, wind and weight/boat movement forces on the mast have to be carried along its length to those points. I suspect the joints in your mast may tend to work back and forth under those forces, and will in any case tend to be weak points.

I did once inspect a Newbridge Coromandel (junk rigged version of a Corribee, with different cabin top) with a view to purchase it (and would have done so had the vendors shown a little flexibility on the price), and these (or at least some of them?) have a hinged mast. It might well be worth finding out about these to inform your design thoughts. I was unaware of the mast hinge at the time of my viewing and didn't spot it. I do read now that owners often reinforced the hinge and the mast support at the deck

I seem to recall that the Hunter Liberty had unstayed (though not junk rig) tubular aluminium masts, and two of them so the forces on each were smaller (an idea worth thinking about for your conversion, to make mast stepping/unstepping much easier?). I do seem to recall reading long ago (on this very forum, IIRC) that these masts tended to eventually fail through fatigue.

The home-built junk rigged boat I sailed had very heavy solid timber masts of substantial sections. I had no doubts about the strength of the masts, but I couldn't help wonder about the strength of the cabin top, and its ability to handle the enormous sideways loads involved when we were rolling violently in rough conditions!

I know that tubular carbon fibre is sometimes used for unstayed masts, but these are (or were) exceedingly expensive.

I rather like junk rig (though like all types, it has its downsides), and I would certainly consider it if I found myself with a sailing boat that was missing a rig, but personally wouldn't go to the trouble of replacing a perfectly serviceable mast and rig of another type to get it. (Also, a conversion to junk rig often doesn't fit well with the existing layout below decks, with the mast position usually needing to be further forward.) Perhaps a compromise in a situation like yours would be to make various changes to the existing rig to make it less demanding to handle - perhaps a self-tacking jib, etc?

 

[ash2020]

Hey thanks for the input. I've been having many discussions on the Jug Rig Association and it seems that a hybrid mast of 6", 5" and 4" tubes, overlapped by 450mm (my calcs) would be strong enough. Tapered lamp posts used to be a thing but they are very difficult to get now. It looks like Norsk Hydro, the main supplier, are about to go bust. Also a tapered 8m pole is around £800.
Solid timber would be too heavy, my boat has a displacement of only 860kg. I'm thinking the best support would be a length of 7" tube in the cabin, glassed into sole and cabin roof, that the mast will sit down into. The position in the cabin isn't a problem. It already has a substantial pole to support the current deck-stepped mast.
I have 100mm space to move the mast position forward before interfering with the hatch. This should be enough for a split junk rig with 30% mast balance. It's all looking do-able, apart from my original question of how to get the mast in place single handedly.
With the greatest respect, the question wasn't whether a junk rig is advisable but how to step the mast.
Thanks.

 

[William_H]

On the basis that OP has a solid round mast of 8m which must be drfopped in to a hole in the deck Lakesailor of this forum long ago advocated for very long A frame Which extends well up beyond mid point of mast with mast mast above the cabin top. So mast is bodily lifted on A frame (which is stayed fore and aft) the base is guided in to the hole and the mast lowered on a tackle. This could work for OP if cumbersome to do on water under way for bridges etc.
However around here, with bridges to traverse under) we have some larger boats with fractional rig keel stepped mast where the mast is cut about 60 cms above the deck level at a 45 degree angle
Plates are welded onto the two surfaces such that when bolted together the mast returns to rigid one piece. (in terms of bending strength) Back edge of the plates form a hinge that then facilitates lowering in the usual way. Front edge bolted together once mast is up. Might be an answer to OP. ol'will

 

[AntarcticPilot]

As @Refueler says, you only need a derrick or A-frame that is higher than half the length of the mast. If you made an A-frame by securing two spars to the chainplates, with lines fore and aft to control the movement, then run a tackle from the head of the A-frame to a point somewhat above the point of balance of the mast, that should work. You'd need:

• Two spars more than half the length of the mast. These could be rough timber. They should only take compressive forces, so they don't need to be enormous - maybe 4"x4?" That may be too heavy; 2"x2" might do. Or scaffolding poles.
• Two or three long lines to use as stays for the A-frame
• Block and tackle (I suggest 4-1; i.e. two double blocks with the fall from the upper block)
• Assorted cordage

The procedure I'd suggest would be:

1. Erect an A-frame with its foot at the chainplates and the head a little forward of the mast step. Use stays fore and aft to hold it steady. Two backstays will give better clearance for the mast.
2. Place the mast on deck with the point of balance beneath the head of the A-frame and the top of the mast towards the stern. The foot should be on the foredeck.
3. Attach tackle ( probably 4-1 or thereabouts) to a point on the mast just above the balance point. A rolling hitch is probably the right knot, but ensure the connection between tackle and mast can't slip.
4. Use the tackle to lift the mast while guiding the foot to the step
5. Once the foot is at the step, guide it into the hole, and then lower away on the tackle.
6. All done!

 

[PabloPicasso]

Could you hire a hiab? One of those builders delivery trucks with a crane.

But you'd still need some help.

Even stepping a mast with a proper crane I need help. Preferably one bloke on each stay, and someone at the mast foot. I realise you don't have stays. But nothing like a few beer tokens to motivate some help.

One benefit of joining a club is potential of available help. What we give we are likely to receive.

Stepping a tall heavy mast single handed may be difficult, and dangerous! Even more so with creaky arthritic ol' bod.

Where are you based? Maybe there is a club near by or marina with facilities. If a club is lifting in with mobile crane they could fit you in at the end.

Whatever you decide, stay safe.

 

[Refueler]

Funny you say Hiab 'Pablo' ..... I have one on my flat bed mini truck. But the limiting factor is that you need to be close to bank and the flat bed itself ... of course if you get hold of a truck with greater capacity HIAB .. then OK .. but most HIAB's are in the lower lift range and as the arm extends it reduces lift limit drastically.
My HIAB lifts 1 tonne at full retracted short arm ... but then lift point is close to truck ... when fully extended at about 3.5m - I can only lift 300kg. Even then if its a hot day - that will drop to just over 200kg.

The other HIAB factor - is that lifting is done by the arm raising up and as it does - the distance out from the truck reduces. I am lucky that I have a 1 tonne winch bolted to my HIAB as well ... so I can clip a block out at the head and leave head as is - while using the cable winch to lift item. But still only within the HIAB limits as the power to the winch is via the HIAB safety systems.

I use mine to raise / lower my deck-stepped mast on my 25ft boat - saves rigging the A frame. But means I have to put boat bow to bank so I get a direct longitudinal line for the winch ...

 

[LittleSister]

With the greatest respect, the question wasn't whether a junk rig is advisable but how to step the mast.
Thanks.

With the greatest respect, this is a discussion forum. People can say what they like, and their comments might engage readers and contributors other than the OP, or be of use to someone coming to the thread later to explore related issues.

No one is telling you what to do. If you don't like a comment, then ignore it.

Good luck with your project.

 

[PabloPicasso]

Funny you say Hiab 'Pablo' ..... I have one on my flat bed mini truck. But the limiting factor is that you need to be close to bank and the flat bed itself ... of course if you get hold of a truck with greater capacity HIAB .. then OK .. but most HIAB's are in the lower lift range and as the arm extends it reduces lift limit drastically.
My HIAB lifts 1 tonne at full retracted short arm ... but then lift point is close to truck ... when fully extended at about 3.5m - I can only lift 300kg. Even then if its a hot day - that will drop to just over 200kg.

The other HIAB factor - is that lifting is done by the arm raising up and as it does - the distance out from the truck reduces. I am lucky that I have a 1 tonne winch bolted to my HIAB as well ... so I can clip a block out at the head and leave head as is - while using the cable winch to lift item. But still only within the HIAB limits as the power to the winch is via the HIAB safety systems.

I use mine to raise / lower my deck-stepped mast on my 25ft boat - saves rigging the A frame. But means I have to put boat bow to bank so I get a direct longitudinal line for the winch ...

That is all very interesting.

I've never had the privilege of owning or using one.

Hire a crane? Expensive.

Build a scaffold tower maybe?

Tall overhanging tree? Lamp post?

You'll need height somehow.

A trick I've seen charter companies use is to lift between the masts of two other boats. But this needs willing able team mates and good control.

Even with a crane or bridge ideally located, doing it single handed will be difficult, I'd have thought.

 

[oz-1]

Hi ash2020, I have seen your discussions on the junk rig forum with some interest, as I too am in the very early stages of converting my home built 22 foot cutter rigged boat to junk rig. I originally contacted a company in Wales that supplied aluminium street lighting columns, but alas wasn't able to purchase one. I just wanted to say god luck with your project. Best regards, Oz.

 

[ash2020]

On the basis that OP has a solid round mast of 8m which must be drfopped in to a hole in the deck Lakesailor of this forum long ago advocated for very long A frame Which extends well up beyond mid point of mast with mast mast above the cabin top. So mast is bodily lifted on A frame (which is stayed fore and aft) the base is guided in to the hole and the mast lowered on a tackle. This could work for OP if cumbersome to do on water under way for bridges etc.
However around here, with bridges to traverse under) we have some larger boats with fractional rig keel stepped mast where the mast is cut about 60 cms above the deck level at a 45 degree angle
Plates are welded onto the two surfaces such that when bolted together the mast returns to rigid one piece. (in terms of bending strength) Back edge of the plates form a hinge that then facilitates lowering in the usual way. Front edge bolted together once mast is up. Might be an answer to OP. ol'will

That sounds like a sensible idea, the A frame, if a little cumbersome. I like the idea of a hinge but I don't know enough about the strength of plates welded on an aluminium tube. The mast will be unstayed so there will be a lot of force on the lower section.

 

[ash2020]

As @Refueler says, you only need a derrick or A-frame that is higher than half the length of the mast. If you made an A-frame by securing two spars to the chainplates, with lines fore and aft to control the movement, then run a tackle from the head of the A-frame to a point somewhat above the point of balance of the mast, that should work. You'd need:

I think that's do-able. I can get 4.8 metre lengths of timber, maybe 3"x2".

 

[AntarcticPilot]

I think that's do-able. I can get 4.8 metre lengths of timber, maybe 3"x2".

I think it would be easier with two people, as hoisting and lowering the mast and guiding the foot would probably need more hands than you've got! I can see ways to do it using jamming cleats, but the key is going to be keeping control of the foot of the mast.