Freestanding mast

[KiK]

Hi
I found Nick Charman’s article in PBO from 11/01/2022 titled „Freestanding masts: Why more cruisers should go wireless” and have a question. It’s possible to change my boat , Maxi84 for that? How, who, where? After reading many articles writing by by other sailors and designers of this type of yachts, I became passionate about this solution. I just don't know if I understood your article correctly, that can convert a rigged yacht into a freestanding one?
Kind Regards
Kristof

 

[MisterBaxter]

It can be done but it's expensive and time consuming, needing significant structural work and of course a whole new rig, probably including new sails too.

 

[Black Sheep]

Certainly possible, but as MisterBaxter says, not a trivial task. Would the perceived advantages be enough for the time, effort, money and risk involved?
The usual reason for changing to an unstayed mast is to change the rig. I've done it a couple of times to change from Bermudian to Junk rig. I've enjoyed the task and found it worthwhile.
But the more sensible approach if you fancy a boat with an unstayed mast (or a boat with a Junk rig) is to buy one that's already been converted, or was built that way.
However, if you're interested, there's a couple of threads on the Junk Rig Association forums about converting a Maxi 77 and a Maxi 95 to unstayed mast and junk rig.

 

[KiK]

Mister Baxter and Black Sheep, thanks for messages. I will have a look Junk Rig Association

 

[AntarcticPilot]

The vast majority of modern yachts have masts that are stepped on deck, with supporting structures (bulkheads, compression posts) below the step. My understanding is that a free-standing mast must be keel-stepped, with supporting structures to take horizontal loads at deck level. The engineering is totally different and involves fundamental changes to the structure of the boat. It may be possible on a small, heavily built boat but on most yachts it would involve unacceptable changes. It would also devalue the boat, as few people would be willing to buy a boat so heavily modified.

 

[srm]

Agree totally with @AntarcticPilot above. The other question you need to consider before doing anything is what rig/sail configuration you will use with the unstayed mast as this may well require the mast in a different place to the standard rig.

 

[dunedin]

Can anybody summarise what the supposed benefits are of an unstayed mast?
Having sailed dinghies with stayed and unstayed masts, I can see lots of arguments in favour of a stayed rig. Seems to be lighter, stronger and much better efficiency- hence why 99.999% of yachts have stays, boh cruisers and all out racers.

PS Recently saw a junk rig small hoat, possibly Corribee conversion, at Inverness, and the mast was set in what was originally the forehatch- as well as needing a lot of structural mods to support the rig, it blocked off the emergency exit if have a fire at galley.

 

[Supertramp]

I think in a word "simplicity". I looked at a Freedom 35 when boat hunting and was quite taken with the rig, ease of reefing, adjustability of fore and aft balance and the aerodynamics of a luff sleeve and wishbone boom.

There are some characteristics of unstayed (twin) masts namely they whip about a bit, there can be leakage down the mast (flexing at the deck), no rigging to hold onto on deck plus the foredeck has a mast in the middle of prime anchoring space.

But the Freedom was designed and built for this sort of rig and the structure is engineered to deal with it. A lot less complication than rigging and chainplates.

There are other examples but I think the key point is to design and engineer it rather than retro fit it.

 

[srm]

Seems to be lighter, stronger and much better efficiency- hence why 99.999% of yachts have stays, boh cruisers and all out racers.

The un-stayed mast itself may be heavier if comparing same material, but you also need to account for the weight of all the standing rigging. Efficiency depends on the sail(s), an un-stayed mast allows a double skin sail which may be better on some points of sailing.
Yacht masts have nearly always been stayed, but that does not make it the best solution. Aircraft got rid of spreaders and wires to support wings quite a while back.
I sailed on a Freedom 40 once and was impressed with the ease of handling. In strong winds she sailed to windward under the foresail with no fuss. Obviously not suited to going round and round a pattern of buoys as fast as you can, but made a lot of sense for people who want to go places.

 

[AntarcticPilot]

The un-stayed mast itself may be heavier if comparing same material, but you also need to account for the weight of all the standing rigging. Efficiency depends on the sail(s), an un-stayed mast allows a double skin sail which may be better on some points of sailing.
Yacht masts have nearly always been stayed, but that does not make it the best solution. Aircraft got rid of spreaders and wires to support wings quite a while back.
I sailed on a Freedom 40 once and was impressed with the ease of handling. In strong winds she sailed to windward under the foresail with no fuss. Obviously not suited to going round and round a pattern of buoys as fast as you can, but made a lot of sense for people who want to go places.

I don't think the analogy with aircraft holds, or if anything it goes the other way. It was increasing speeds and the availability of light materials such as aluminium alloys that did away with aircraft rigging. At the low speeds (which are still a lot higher than yacht speeds!) of early aircraft, the drag wasn't a big factor. I can vouch for that - we hung wire antennae below the wings of a Twin Otter (speeds comparable to pre-1930s aircraft) without any noticeable effect on performance. And the increase in strength of a biplane using cross-braces gave a structure that was capable of aerobatics without being excessively heavy. Early attempts to build all-metal aircraft (e.g. Junkers J 1 - Wikipedia) were too heavy for the power available, and could not match the climbing performance of conventional biplanes.

The availability of Carbon Fibre may have the same effect on yacht rigging as the availability of duralumin did for aircraft, but until we're making speeds like America's Cup machines, I don't think it would have much effect.

 

[MisterBaxter]

I think the popularity of stayed rigs is more to do with the ability to set a foresail, and the ability to throw controlled curves into the mast.
A foresail is an extremely efficient sail as it has no spar on the leading edge to create turbulence, and it lets you carry more sail area on the same height and weight of mast.
And bendy masts let you flatten the main with very good control, to give better power in different wind conditions.
Those two factors together give a rig that's very hard to beat for sailing efficiency, even if it's more work to change sail area than with a junk rig, and a lot more expensive to buy and maintain than a junk rig too.

 

[Supertramp]

I don't think the analogy with aircraft holds, or if anything it goes the other way. It was increasing speeds and the availability of light materials such as aluminium alloys that did away with aircraft rigging. At the low speeds (which are still a lot higher than yacht speeds!) of early aircraft, the drag wasn't a big factor. I can vouch for that - we hung wire antennae below the wings of a Twin Otter (speeds comparable to pre-1930s aircraft) without any noticeable effect on performance. And the increase in strength of a biplane using cross-braces gave a structure that was capable of aerobatics without being excessively heavy. Early attempts to build all-metal aircraft (e.g. Junkers J 1 - Wikipedia) were too heavy for the power available, and could not match the climbing performance of conventional biplanes.

The availability of Carbon Fibre may have the same effect on yacht rigging as the availability of duralumin did for aircraft, but until we're making speeds like America's Cup machines, I don't think it would have much effect.

Freedoms have, or can have, unstayed carbon fibre masts (years before the material was popular). One of the big benefits is the flexing of the mast which greatly reduces the shock loadings intrinsic to a wire stayed metal mast.

Agree that a conventional modern rig will offer more drive, closer pointing etc.

 

[William_H]

I think a typical stayed mast is just the best way to make a strong mast. The geometry makles it obvious the advantages of staying. Forget unstayed mast . ol'will

 

[Laminar Flow]

The early spectacular performance claims made for unstayed rigs were due to a 30% reduction in drag by not having stays, shrouds and all the other accoutrement of a stayed rig.
The problem for unstayed rigs is that the masts are considerably more expensive to build, particularly if they are supposed to be light. It is technically quite possible to build a freestanding spar that is in a similar weight class as a standard stayed one. At a price of course. This is a problem for competitive pricing.
It was/is not uncommon for early alloy rigs to have fatigue failures and carbon which was the material of choice for replacement is still very expensive.
The common practice to place the or a mast in the bows adds considerable pitching moment that can have an adverse effect on a boat's seaworthiness. Notably, Freedom yachts had a problem with one of their models where fine bows and a freestanding mast in the hounds proved to be a poor combination.
I was involved in a project scheduled to have a schooner rig with two free-standing wing spars. When I demonstrated that I could carry as much sail on a single, stayed and cutter-rigged mast, the concept was shelved and the boat was then built as a cutter instead.

 

[dunedin]

Yes I think all of the suggested theoretical benefits of a Freedom style unstayed mast rig were either wishful thinking or now made obsolete by improvements in conventional rigs. “Reducing sail area” might have been easier than with hanked on jibs and old sails, but with electric furling main and jib typically available now that is long gone.
And whilst a flexible top mast can help with gust feathering on some rigs (eg 49ers and similar fast dinghies and fast racer yachts) a flexible mast overall doesn’t tend to help efficiency - as can’t keep jib luff tight and whole rig leans to leeward - whereas ideally want rig to lean to windward, as some exotics allow.
And the claimed theoretical efficiency benefit of a sleeve luff is probably never noticed in most cruising rigs, and for real efficiency (if permitted by rules) a rotating mast that can be angled is even better - as used on many multihulls and open mono racers.

There are good reasons why 99.999% of yachts don’t have unstayed rigs. Even in dinghies, few if any modern fast boats have followed the old Laser / ICLA with its simple but quite heavy and difficult to control rig.

 

[MisterBaxter]

I think if I was going to sail long distances single handed I'd go for a junk rig if I could find the right boat. The incredibly easy reefing and unreefing would be the obvious advantage, but also the way that the full sail area is working at full efficiency when sailing downwind. There was a PBO test years ago with two Van de Stadt Sprinters, one junk and one conventional. The junk was faster on a run if the conventional one didn't fly a spinnaker.

 

[DownWest]

I think if I was going to sail long distances single handed I'd go for a junk rig if I could find the right boat. The incredibly easy reefing and unreefing would be the obvious advantage, but also the way that the full sail area is working at full efficiency when sailing downwind. There was a PBO test years ago with two Van de Stadt Sprinters, one junk and one conventional. The junk was faster on a run if the conventional one didn't fly a spinnaker.

Just read Taylor's MingMing exploits and have Annie Hill's book. Certainly easy to operate and low stresses compared to a stayed rig. As long as the mast stays intact, breakages do not stop you, where as a single point failure in a stayed rig can bring it down.
Currently finishing off (slowly..) little cat yawl. Both wooden sticks are unstayed with sprit booms, so the sails still run in tracks, but a very simple rig. This is not a conversion, designed that way.
Less rope too. Halyard, sprit control and single part sheet

 

[DownWest]

I think in a word "simplicity". I looked at a Freedom 35 when boat hunting and was quite taken with the rig, ease of reefing, adjustability of fore and aft balance and the aerodynamics of a luff sleeve and wishbone boom.

There are some characteristics of unstayed (twin) masts namely they whip about a bit, there can be leakage down the mast (flexing at the deck), no rigging to hold onto on deck plus the foredeck has a mast in the middle of prime anchoring space.

But the Freedom was designed and built for this sort of rig and the structure is engineered to deal with it. A lot less complication than rigging and chainplates.

There are other examples but I think the key point is to design and engineer it rather than retro fit it.

On the Freedoms, I knew the guy that bought the first UK built F 40, though that had alloy masts. Also, I was asked to act as the purchaser of a F 65/70 to replace the yacht owned by a company I helped out. That fizzled when an early one had problems with the foremast support during a Transat race.

 

[MisterBaxter]

Currently finishing off (slowly..) little cat yawl. Both wooden sticks are unstayed with sprit booms, so the sails still run in tracks, but a very simple rig. This is not a conversion, designed that way.
Less rope too. Halyard, sprit control and single part sheet

That sounds interesting, what's the design?

 

[DownWest]

Looks like this, but the hull is longer and not so 'square', rig is the same. Both developed from Bolger's Micro design. I wanted something for local trailer sailing, but comfy for a few nights and stable compared to my Oughtred faering (getting creaky). Will right dry from masts in the water. Carries 200kg of lead keel. Roughly 45% of weight.

Mine, 'Colette', is still in my cramped boat shed, so can't get a good picture.