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.
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
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
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.