Unstayed masts or stayed masts?

[Joli]

What are the shortcomings and the benefits? I think I know some of both but lets here from all.

Oh, monos or multi, doesn't really matter.

[Kanani]

At one time, I thought about replacing my wood masts (Ketch) with carbon fiber, un-stayed masts.

The thing that I discovered is that it really is not an option on a boat that was designed for stayed masts. The loads on the mast are tremendous and all of that load is transmitted to a single point on the cabin top as apposed to distributing that load throughout the boat, through the stays.

I even talked to a Naval architect about rebuilding my cabin top to handle the load. Kanani is a very stout built Passport 45 and he said that short of removing the entire deck and rebuilding it, he would not advise going to un-stayed masts.

[Boracay]

I looked at unstayed masts when I first started thinking about getting a cruising yacht.

They do look to have many advantages. Simplicity, efficiency, light weight and automatic depowering to name a few.

However when I looked at the cost it became a different matter. They need professional design and manufacture and all the fittings are going to be non standard. The hull would also need to be reengineered and the position of the mast(s) redesigned.

If the mast comes out substantially overweight then it will need to be rebuilt.

Carbon fibre does not look to be suitable for amateur construction.

I stopped counting when the cost came above $100,000 for a 42' mono.

Just not practical on a budget.

On a totally new design with an experienced company to build the mast it might be OK.

[cburger]

Have a look at "Freedom Yachts" they are one of the leaders with this type of rig.

[44'cruisingcat]

There probably aren't many boats where it would be practical, from a cost point of view, to retrofit an unstayed rig. If you build from scratch with an unstayed rig in mind the costs won't be as high, but from my "shopping around" still more expensive than a "conventional" rig. (I was looking into unstayed twin carbon masts.)

[Steve Rust]

I wonder if they make more sense on a monohull or trimaran as the hulls are for the most part similar and building the support structure would be fairly straightforward. With a cat how do you build this structure on the bridgedeck without compromising the accommadations. Would you have to bring the bridgedeck forward and make it deep enough to support the mast and what would that do to bridgedeck clearance? The unstayed twins may be the best option as then the masts are back in the hulls and supporting them is easier. Keep in mind that the cat will not heel to dump wind pressure so the masts and support system may need to be more robust than a mono or even a tri to some degree.

[Whimsical]

Originally Posted by Boracay

I stopped counting when the cost came above $100,000 for a 42' mono.

Jeeeeesus you must be talking to the wrong people. I need a pair of them for mine. Anybody interested, especially those in Aus, should be talking to Rob Denny of Harry proa.
I'll ask him to visit and pass some comments here.

Mike

[Fard12]

Originally Posted by Whimsical

Jeeeeesus you must be talking to the wrong people. I need a pair of them for mine. Anybody interested, especially those in Aus, should be talking to Rob Denny of Harry proa.
I'll ask him to visit and pass some comments here.

Mike

The mast compression in an Schionning 1230 Wilderness is around 12500kg for a standard 17-mtr mast. The cheapest carbon (professionally built) mast that will fit this boat would cost around $60000.00 all up (rigging furlers etc)
To build 2 of them out of carbon that are un-stayed admittedly no doubt not as tall, will cost an sh.it load.
Unless you build out of cedar and composite. However the weight of the end product will be severely effect the performance of the boat you are building.
Why would you want to turn a pretty good design into a dog of a boat to sail?
Check out the multihull forum comments regarding this type of rig.

[rob denney]

Originally Posted by Fard12

The mast compression in an Schionning 1230 Wilderness is around 12500kg for a standard 17-mtr mast. The cheapest carbon (professionally built) mast that will fit this boat would cost around $60000.00 all up (rigging furlers etc)
To build 2 of them out of carbon that are un-stayed admittedly no doubt not as tall, will cost an sh.it load.
Unless you build out of cedar and composite. However the weight of the end product will be severely effect the performance of the boat you are building.
Why would you want to turn a pretty good design into a dog of a boat to sail?
Check out the multihull forum comments regarding this type of rig.

G'day,
Thanks Mike.

It is not about the compression load. Unstayed rigs do not exert any more compression than the weight of the rig, a couple of hundred kgs. It is about righting moment. In a cat, this is the hull centreline to hull centreline beam multiplied by half the sailing weight. The 1230 Wilderness has rm of 17,500 kg m. The 50' harryproa at

YouTube - Visionarry Sailing

has rm of 18,000 kgm.

The mast for the harryproa cost $AUS25,000 including paint, all fittings for the ballestron boom and jib (which would not be on the Wilderenss) and very light carbon rcb track. The bare tube was about half of this cost. It weighed, when finished about 130 kgs. The Wilderness masts would not be as heavy as 1) they are shorter and 2) with two of them, they do not need to be as stiff. Fard12, what is the cost and weight of a Wilderness alloy mast with all the standing rigging (spreaders, tangs, wires, terminations, turnbuckles, clevis pins, etc, please? Add in the traveller, deck gear, forebeam and seagull striker if you have these handy.

For various reasons, the company that made this mast is not doing so anymore, but I am negotiating with another builder to build them using an improved technique which should reduce the price. Plan to be up and running in a month or so. Once we achieve a bit of economy of scale, carbon masts will be the cheapest option, and alloy will go the way of wood. Sooner or later, conservative sailors will figure out that stays are as out of place on modern boats as they are on modern aeroplanes, and stays will follow aluminium.

The multihull forum may not like unstayed rigs, but the following is hard to dispute:

1) They work on multihulls, as the boat in the video, Team Phillips (2nd highest righting moment of any performance cat, ever), Jimmy (60' Irens cat) and others have shown
2) There is almost nothing (total standing and running rigging is one halyard, 2 reefs, one mainsheet) to go wrong, particularly on a jibless rig.
3) There is no maintenance. Fard 12, how often do you advise alloy mast owners to check their rigging? How often to replace it and their masts? A properly built unstayed carbon mast will outlive the boat.
4) They are safer. The knowledge that releasing the mainsheet, on any point of sail, in any breeze will stop the boat is extremely reassuring.
5) They are less effort to sail. The first reef is automatic. The mast flexes, the sail depowers. The next generation of masts will do the same for the second reef. The sail can be easily raised and lowered on any point of sail, in any wind. The savings on ball bearing cars and tracks and on your nerves, are appreciable. There are no flogging headsails, winches or deck tracks and gybes are safe as the boom does not hit the shrouds.
6) The boom can be self vanging, so no traveller is required. This is a cost and safety consideration.
7) The loads on the deck and heel bearings are high, but the load on the rest of the boat from the rig is non existent. Much lighter scantlings, no forebeam, no massive main beam, no traveller beam, no chainplates or bulkheads to attach them to. The 50'ter in the video weighs 3 and a bit tonnes.
8) They can be wing section, which uses less carbon, and has much less drag, and more lift than a stayed rig.

On the downside, there is no jib to back if the boat won't tack. This is a fault of the boat, not the rig. There are no stays to hold onto on the pitching deck, but there are far fewer reasons to venture onto the pitching deck.

Steve Rust. We built an unstayed ballestron rig for a 37' non bridgedeck cat. harryproa / masts / Taywun Sorry, there are no sailing pictures. The main beam is 750mm high and we used this to support the mast. Works a treat. On a bridge deck cat it is even easier. You wrap uni around the mast bearing and across the cabin top and the saloon floor. It requires surprisingly little as the uni is so strong in tension, and this is the load it sees. You do need to be careful routing the loads around windows and hatches.

Regards,

Rob

[Joli]

Interesting so far.

Rob, congrats on this months write up in Sail Magazine.

[GordMay]

Staying put - How do masts do it?
Masts

The Fallacy of Freestanding Masts
The Fallacy of Freestanding Mast


Yacht Design Explained: A Sailor's Guide to the Principles and Practice of Design
by Steve Killing
Chapter 5 - Rigs begins on page 127
Yacht Design Explained: A Sailor's ... - Google Book Search

[David M]

It sounds as if it would be more economical to sell the boat you have and purchase a boat that was built with an unstayed mast from the beginning.

[rob denney]

The Fallacy of Freestanding Masts
The Fallacy of Freestanding Mast

G'day,

These guys should read my post above and check out the video. We can compare their weight and cost claims if Fard comes back with some numbers.

Re windage, if we look at the Wilderness 1230, there are 3 x 15m of 10mm wire holding the mast up, and 3 x 12m holding it in column, plus one (two?) sets of spreaders, a seagull striker and forward beam. Total frontal area is more than 2 square metres, a little less than a sheet of 8 x 4 (2.88 sq m) ply. A significant percentage of overall air drag.

There is no reason why an unstayed rig cannot carry extras. There is a Wylie 30 (a much better example of an unstayed rig than the Freedom 38) with a chute on San Fransisco bay. Cleans up everything of similar size, upwind and down.

Joli, Thanks. It is a big week when an establishment magazine like Sail _and_ a long time lead mine sailor acknowledge harryproas. :-) We have also had a few pages in English and European main stream magazines. Nothing yet from the Australian and New Zealand mainstream non multi magazines.

regards,

Rob

[Robertcateran]

Rob,
Any idea on the cost of a Ballestrom rig on a Jarcat 5. There is plenty of bury and it would mean being able to carry more sail more safely, though I am unsure how to raise and lower easily for trailing, and I would miss the back winding of the jib in the tacks in sloppy conditions with a bit of a swell. Possibly for the lowering is to make a hole in the main crossbeam at the back of the cabin, hinge it on the main crossbeam, drop it down the hole and then have a clamp at the top of the cabin. For getting in irons in the tacks, I may just have to shunt(:<)
Robert

[rob denney]

G'day,
The first ballestron we built was for a Jarcat 5. Worked extremely well. No idea of a price until we get the shop running, but it won't be much as it is only 10 kgs or so of material. We built a ply boom and the mast was light enough for me to pick it up and drop it in the hole. A better bet would be a tripod with a block and tackle attached to the mast above the boom. Pull the rope, then rotate the mast and lower into the hole.

regards,

Rob