Best rig for small catamaran circumnavigator?

G'day,

I should think Randy would be very happy. He has received the conventional wisdom from possibly the most popular small multi designer in the world (Richard) and a couple of other options. Why would he be disappointed?

Your 2c worth is on the right track, but I don't think it goes go far enough. A rig so simple that there is nothing to break is much better than one that is easy to repair. A single unstayed mast, with a fixed boom and single main sail is as uncomplicated and unbreakable as it is possible to get. The fact that on a cruising boat it is also the most efficient and easiest to use is a bonus.

regards,

Rob

 

One could use a spoon to dig the Panama Canal. Just because the sppon is simpler and less expensive than a shovel does not make it a superior choice.

The "best" solution is the one that works with the least complexity for a given performance. A single unstayed mast has not been the choice for many boats bigger than a dinghy when performance is one of the design goals. Unless the boat is fast enough to sail with the wind forward of the beam at all times (not the case with a small catamaran circumnavigator), extra sail area will be needed when off the wind. Good light air performance requires either high lift or large area, the split rig (jib and main) has proved itself to be a very easy to handle sail plan than provides decent light air performance without the added area that a single sail would need to give equal force. A single sail that can drive a relatively heavy boat well in light air and less than ideal sea state would be much too large much of the time and would be reefed much of the time. In contrast, the high lift mode of a split rig can be trimmed to a low lift / high L/D mode. Splitting the needed area into 2 (or more) smaller sails makes those sails easier to handle. Add to all this the structure needed to support an unstayed rig in the middle of a catamaran cross-beam and the cost/complexity of hull/beam design replaces and offsets the cost/complexity of the stayed rig.

 

Sorry for not replying sooner, but as you know I was away sailing. Yesterday we were in a crowded anchorage in quite a strong wind. We decided to sail off the anchor rather than motor. We pulled the anchor up short, unrolled part of the genoa, backed it, lifted the anchor and were away. Simple, quick and in full control.

You cannot sensibly "back" a una rig except on a dinghy when it is easy to push the boom into the wind. Furthermore, I wouldn't have liked to have had the mainsail (or any other sail) hoisted (even with reefs in to keep the speed down as we sailed out) while hauling the anchor up short.

In my experience most rot in masts occurs under the sail track, which I assume you'd use even on an unstayed mast? Ocean cruisers must assume they will be hit by lightning at some stage. Most carbon masts don't survive a lightning strike so for that reason alone I'd steer clear of one. Also, although you want to show off your black mast, if it is unpainted (and the paint maintained) you will eventually have a failure from UV degrading the epoxy. Electrolysis also causes major problems.

To be honest I'd have thought that even in the Philippines it would be easier/cheaper to ship in a mast along with the deck gear, interior fittings, engines etc.

I think Rob misunderstood my comments on the Americas Cup rigs. Obviously racing boats have different requirements to cruising boats. They just need efficient rigs. Cost, complexity, handling problems when shorthanded and durability are irrelevant. That is why I said it will be interesting to see what the America Cup designers think is the most efficient racing rig (as opposed to the "best" rig for a cruiser)

I write a bit about the Aerorig style balestrom rigs on my FAQ's page. In short, getting the balance right when reefed seemed to be a problem, and don't try motorsailing unless the jib is furled!

I made the temporay wood mast comment to make people think of different options. I did look into having a boat built in the Phillipines myself, but didn't. Partly because I thought I should be there to supervise, partly because it seemed a difficult place to sail away from.

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

R Hough

All the expensive earth moving equipment in the world would not have dug the canal any quicker than a spoon if there was no maintenance facility available, or the operators could not afford it. This is the case with the low cost world cruiser, exacerbated by the fact that a rigging failure on a stayed mast is usually terminal, causing the mast to fall down. This simply does not happen with unstayed masts.

Unstayed masts have been expensive, sailors are very conservative people. Which is why they have not been used. At least with the expense, this is no longer the case.

Tall masts and long booms are one way of getting a lot of sail area on a single mast, and as the top mast is light and small section, the weight and windage when reefed is not as big a problem as a stayed rig. The cog of the unstayed rig will be lower as well. In light air, it will have more area up high where there is more breeze. See Bethwaite for the comparative advantage of high area vs low area. Also, the rest of the boat can be built much lighter, so a smaller, cheaper rig is possible. Take this to it's logical conclusion and you have a 15m/50' harryproa weighing 2,000 kgs/4,500 lbs; less than half the weight of a comparable cat.

If rig height/sail area is a problem, another option is temporary runners for light air sails, or a ballestron rig, see below. Both are better than a conventional stayed rig.

The rig does not have to go in the middle of the beam, but even if it does, the beefing up is far less than that required to support a stayed rig. We put a 14m high rig on an overweight 11m cat with 600mm/24" high beam Added maybe 15 kgs/33 lbs of structure to hold it up. It works well. http://www.harryproa.com/MASTS/Taywun/Taywun.htm

Richard,

Unstayed rigs sail on and off anchors by hoisting the main and letting it weathercock. Take the anchor warp to the stern, pull it up and trim just enough main to give you steerage. A lot easier than having to raise the main once you have left the anchorage, especially if it has lazy jacks fitted in which case you probably have to start the motor anyway. It also does not involve jib sheets flailing round the anchor lifter, nor does it need the single hander to be running from one end of the boat to the other while the boat is drifting backwards. On boats big enough to need anchor winches, it is easier to sail backwards with the main up than it is to back the jib.

Of course, the ultimate backing rig is a proa, but that is another subject.

Most wood rot happens round highly stressed fitttings, such as the hounds. Regardless, we bond sail tracks to carbon masts, would do the same to a wooden mast.

We have motor sailed the boat in the video at http://www.youtube.com/watch?v=8chR6DAFjGA. No obvious jib related problems, but even if there were, dropping the jib in motor sailing conditions is hardly a deal breaker. Reefing is also not a big deal. The first reef is automatic as the mast bends, spilling power. The second reef is to drop or furl the jib and use a winch for the mainsheet. Third reef is a deep reef in the main.

I appreciate the difficulty of keeping FAQ's up to date, but with all due respect, yours are well out if date.

The ballestron advantages are correct, especially the 95% efficiency possible for Joe average vs the 70% he will achieve on a sloop rig, which is very relevant to this thread and masalai's and RHoughs points.

The disadvantages you list as cost and weight. Both are correct for Carbospars (out of business 5+ years ago) masts, but are wrong compared to what is currently available.

The mast on the boat in the video weighs 120 kgs, comparable to a stayed alloy rig for a similar rm cat. It cost less than a stayed mast bought from Allspars, Australia's biggest rig supplier. By the time the extra bits required to support the stayed mast were added (forebeam, seagull striker, substantial bulkheads, chainplates, winches and traveller tracks, multiple headsails or a furler), the ballestron is way cheaper. If the ballestron rig was home built (no harder than the rest of the boat and not an option for the stayed alloy mast) it would have been one quarter the price.

Lightning is a worry for any boat, although strikes are very rare. I would be interested in the details of any carbon mast strikes you know of, maybe on a new thread. I guess you need to ask whether dissipating the energy by melting the mast (I have never seen a melted carbon mast) is a better bet than it blowing a hole in the bottom of the boat, possibly after passing through the crew holding onto the backstay.

Painting carbon masts is a no brainer. We supply big stickers for people who want the world to know what the painted mast is made of. ;-) Electrolysis is a big deal with different materials, notably stainless steel and aluminium. Modern unstayed carbon masts have no metal in contact with them, so it is not a problem. Nuts, bolts, screws, rivets and structural metal really have very limited use in modern boats generally and modern masts specifically.


regards,

Rob

 

Rob,
The ballestron rig has much to recommend it. The jib area is useful over a wide range of sailing angles. The gust response is correct and assuming the sails and spar are matched well it should be a near ideal cruising rig. I like the idea very much. It seems to retain all the advantages of a sloop rig while eliminating some of the weaknesses.

IIRC this rig was tried on a moderate displacement mono and the expected increase in performance was not realized. Perhaps it is time to take another look?

For cruising, weight carrying ability governs the range of the boat. Interior volume to LOA is a common measure, how does interior space on a 50' PROA compare to a 50' cat? Is comparing total displacement to interior volume a better comparison? Most 50' cruising cats are sleep 8, feed 16, cocktail 32boats. How does a 50' PROA compare? For a 4500# boat does the PROA have the same tankage and storage as a 50' cat?

 

backing una rig

Richard
You wrote: "You cannot sensibly "back" a una rig except on a dinghy when it is easy to push the boom into the wind."
Not true, mon ami. I learnt to sail backwards like an expert (from getting caught in irons and wanting to escape) on my 32 foot cat Supplejack but also did it on 58 foot catamaran Sundreamer with just the main up (headsail sheet off) at a photoshoot at Great Mercury Island years ago when Sundreamer had just been launched - (and had just taken line honours in the Auckland/Tauranga). We sailed on the wind for the camera, came head to wind, Chis Barker (designer's brother) winched the boom back and off we merrily reversed half a mile back into the bay to start up for another pass. No one thought it would be possible with such a large boat. You steer facing aft reversing everything. We did four times until the photographer (Ena Hutchinson) was satisfied.
And on my una rigged 11 metre foiler, absolutely no problem to sail in reverse - but I hold the wing mast spanner back so the mast acts like a jib. IMO it is an essential skill for light multihulls. And I'm sure you'll get similar stories from monohull sailors.

 

G'day,

Rhough,
"Near ideal for cruising" sums up modern ballestrons pretty well. Doing away with the jib and foreboom is the next step towards simple, but does require some layout changes at the design stage.

Ballestrons have been tried on a few boats. Handling has been easier and maintenance less in every case i have heard of. Performance has been difficult to compare. The only actual tests I know of were done by Yachting World on a couple of Sigma 36's (I think), one with the standard rig, the other with a ballestron, with the following results: ballestron is a little less good upwind as long as the standard rig is being tweaked continually (until a tacking match was started when the ballestron was much quicker), faster on a reach and much faster downwind, even when the sloop got their headsail poled out. Safer and easier on all points.

These was an expensive carbospars rig, with small headsails and no roach mains. Ours have big jibs and a lot of roach and from now on, most of them will be wing masted, which is less drag, stiffer and almost as light and cheap as a tube mast.

I was not comparing the harryproa to a 50' cat. I was comparing it to a "comparable cat". ie one with two queen size doubles, two singles, huge galley, toilet and shower, enclosed cockpit seating 8 and able to sail at wind speed up to 15 knots. And cost $400,000 pro built, ready to cruise. The harry weighs 2 tonnes ready to sail. Any cats with anything close to these specs that weigh less than 4 tonnes?

The best comparison I can offer to the 50' cat is the charter harryproa half way down http://www.harryproa.com/newsletter0608.htm Four queen size double cabins, each with en suite shower and toilet, 2 of them with island beds. Unstayed schooner rig, electric motors, 7 tonnes chartering weight. And costing less than the 50 footer above. Probably won't do wind speed in charter mode, but in cruising mode it should. It is not built yet, so no proof of the numbers, but the spreadsheet was as detailed as the 50 footer, which came in bang on the design weight. Any cats with this capacity, speed and price weighing less than 14 tonnes charter ready?

Gary,
Sailing skills we kiwi sailors take for granted are considered unusual elsewhere. ;-). It's a small world, I raced to Hobart with Chris, back when I was young and foolish.

regards,

Rob

 

Hi, Rob.

With all due respect, a stayed rig on a small catamaran will be certainly cheaper.

The reason it would be cheaper is that the boat builder of this voyager can build the mast himself. It can be either solid, box sectioned, or birds mouth. The stays don't have to be expensive and they can be engineered to a very high safety factor. I have known such rigs that have stood for decades. It's only on certain racing boats, where they are engineered to very low safety factors, to cut the most weight possible, that you see a lot of failures.

There is really no restriction on the height of the mast if a fractional sloop rig is used. The top part of the mast does not have to be supported.

Unlike a HarryProa(r), a catamaran usually has its mast stepped near the centerline of the deck. That along with the wide beam of the boat provides an excellent staying base. To put an unstayed mast there would require a massively reenforced deck house or bracing rack.

Un doubtably, the unstayed mast system, if it could be afforded, would have certain advantages. But I just don't see my voyager building his/her own carbon mast system. Nor do I see her/him repairing it should it get damaged. The stayed mast can be easily jury rigged, if it should fail. Depending on how it is made, the unstayed mast could be jury rigged as well, by pulling out the shorter broken section and putting the longer section in its place. The stayed mast would definitely be cheaper to replace, especially if it is built by the owner. And it can be done anywhere in the world where there is wood or suitable metal. The replacement carbon mast would have to be shipped.

So, I think you win out on most of the arguments, but with the 'it's cheaper' one, I think you are all wet.

As for efficiency. If it were my boat to be used for this stated purpose, I would have the following design priorities for my rig, in descending order:

1.) strength,
2.) repairability,
3.) ease of construction,
4.) ability to balance the sail plan easily with a wide variety of sail areas set,and
5.) efficiency

I think much of this is ironic, because, so far, the only masts I have designed are unstayed ones

Go figure.

Bob

 

I haven't yet done nearly enough multihull sailing, nor am I as skilful as any New Zealander or as brave as any Frenchman. Furthermore, both Jetti and I are getting old and frail. However that does mean I am much more "normal" than those who are more expert than me and so I feel can relate to most peoples sailing abilities better than others.

So having said that, I still think it is much easier to unroll part of a headsail than hoist a mainsail and winch it to windward to bear off. I know for sure which Jetti would prefer to do. It's crazy to suggest you have to take the anchor warp to the stern to raise it if you want to sail off the anchor. OK, even I could do it on a small boat, but on a big boat, with no stern roller or anchor winch aft???? And what's this about having to start the engine to hoist a mainsail????

From reading the rest of Rob's posting it seems that at least one America's Cup boat must be a Harry proa.

More seriously, I think Rob would advance his cause greatly if he were to fit one of his rigs on say a F27.

A F27 is cheap enough and anyway his rig would presumably increase its value so he cannot lose money (especially as they are so cheap to make). Then if he lends the boat to an average sailor (if there are any in New Zealand) and races it against standard F27's we would know for sure which was the better rig.

No doubt he has already worked out how to easily step an unstayed mast.

I was hit by lightning when sailing my Eclipse. When sailing in the tropics in the rainy season I reckon you have a 1 in 3 chance of being hit. I write more about it on my website (see my Articles page). I know at least one carbon mast that shattered when hit by lightning, apparently shards of carbon mast pierced the deck (a good thing everyone was below). A monohull superyacht sank last winter after being hit by lightning. I once saw a J24 that had been hit 4 times. Ewen Thompson, the world expert on lightning strikes on boats, told me that he'd replace a carbon mast if it were hit by lightning.

Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Richard, The f 27 test bed for the rigs is a great idea. It would certainly shorten this debate considerably.


We often sail on and off our mooring. Quite often we get under- way by unrolling the head-sail and hoist the main later . Mainsail hoisting is easily accomplished when sailing to windward as the head-sail tends to back-wind the main as it is hoisted, keeping it off the shrouds and nicely lined up. No motor is required.

 

G'day,
Bob,

Let's talk specifics.

Randy Quimpo says he is looking at a 27' cat. Let's use Richard's Gypsy design for some numbers. This is 28'/8.8m long, weighs 2.4 tonnes fully loaded and is 5.4m wide, say 4.6m between hull centrelines. Therefore the righting moment is 4.8*.5*2.4 = 5.5 tonne metres. Sail area is 38 sqm.

Richard, do you know how heavy the mast and standing rigging are on this boat? Maybe the current cost? If you can also tell us the weight and cost of the forebeam, striker, (or extra material required for the split forestay), traveller, chainplates, bulkheads, jib tracks and the additional material to beef up the boat to take these it would be a bonus.
Using the single main sail rig, based on a 12m harry rig http://www.harryproa.com/Builders/Ba...son/Bain_4.htm, which we have built and know that it works. The harry has 31 sqm mainsail and 6 tonne m righting moment, which is less sail area on a stiffer boat but near enough for a first stab. This mast weighs 60 kgs complete. I would provide the materials for this for $Aus1,387.00. Need to add on some wastage, which will depend on the user, say 10%. $US12/lb, 16 Euros/kg. Plus another $100 for a vac bag, sealant tape, bleeder and mdf for the mould frames. Say $1,650 all up. A complete novice could build this mast in a couple of weeks, including doing some samples to learn how to vacuum. Someone who had just built a boat would do it in a week. An unstayed wing mast would cost maybe 20% more, and is almost as easy to build.
Maybe Randy could scrounge some demolition timber, gal wire, bunch of bulldog grips, hounds fitting, curtain track, baling twine, old clothes line, worn out second hand headsails and some lumps of steel to make the chainplates for an 11m rig cheaper than this.

But let us assume he buys the materials and uses best practise to put them together, the same as for the unstayed mast. Over to you for the gal rigging, wood mast option and Richard (ss and alloy) for the comparable weight and cost of the alloy and timber rigs.

Re stepping it on a beam. See prior post on the 11m open deck cat. Building the beam up for an unstayed rig is no more of a big deal than making it strong enough to support a stayed rig. Putting it in the hull is a smarter move, but you need to learn to live with assymetry, or build two masts.

Re repairing damage. A well built carbon unstayed mast can be subjected to simple static bench tests to prove it's suitability for a given boat. Barring capsize or hitting a bridge, it will never exceed these specs. There is no rigging to set up wrongly, wild gybes, flogging sails or other causes of stayed mast failure. Carbon/epoxy has excellent fatigue properties so the mast will not wear out. The main halyard sheave may eventually get worn, but that is all there is to go wrong. There are no other fittings to check, maintain, replace or break. Therefore, there will never be any damage to fix. This feature alone makes unstayed masts the best option for cheap cruising.

Of your 5 criteria for a cruising rig, the first is a given, the second does not apply to unstayed masts which win on the 3rd, lose on the 4th (with reservations) and win on the fifth.

I thought i knew most of the unstayed mast designers. Do you have a web page i could look at?

Richard,
Apologies for my tasteless joke.

It would be interesting to compare sailing on and off moorings with the two rigs. While we were at it, we could compare the ease of hoisting the mainsail on the mooring vs on the open sea, upwind and down, crewed and solo.

Mooring is one of many scenarios where both rig types work, but there are vastly more, mostly safety related, where the unstayed rig is superior.
Gybing in a breeze, sailing in gusty winds, reefing, performance while reefed, windage with no sails up, maintenance and cost to name a few. Whether you sail backwards or back the jib to leave a mooring really is really pretty small beer.

The America's Cup and harryproas is way off topic, but seeing as you mention it, it may be relevant that the fastest sail boats (not boards) on the planet for the last 30 odd years (Crossbow, Crossbow 2, Yellow Pages, Macquarie Innovations, maybe SailRocket and Wotrocket) have all been proas. All the AC guys need to do is figure out how to make them go in both directions (they could look at www.harryproa.com for some ideas), and maybe they would be the fastest round the buoys as well. Unstayed masts were shown to be viable on Team Phillips, one of (maybe the) fastest offshore boats ever built, so they would be smart to check these out as well.

All the evidence to date is that me putting a rig on an F27 would have no more effect on the views of conventional rig pundits than any of the other unstayed rigs out there. Quite the opposite, in fact. What might change your minds is if you were to build and sail one. To that end, I will offer you, Bruce and any other doubters the materials at the above per kg rate for a mast to suit whatever boat you want to put it in. If the rig is not as easy to build and sail as I have said, I will take the mast and refund the money. If nothing else, at least we will both then be discussing it from experience.

Along with how to build them cheaply, I have indeed figured out how to step and unstep an unstayed mast. One person can do it and lay the mast on the deck under complete control, in about the same time as it takes to undo the forestay turnbuckle on a stayed rig. see post 12 at http://www.boatdesign.net/forums/showthread.php?t=23282 I have done this (afloat in a fresh breeze) with a 12m mast and a piece of 4 x 2, no reason why it could not be done with a 20m mast, as long as the gin pole is strong enough and has a winch.

One in three chance of sail boats in the tropics getting hit by lightning each year? I am sceptical. Are there any references for this?

I am also sceptical about the "carbon shards piercing the deck" after "the mast you know shattered". Why? Presumably it is the heating of the epoxy that causes the shattering. To do this with any force would require the epoxy to turn to vapour. Not sure what this temperature is, but i am pretty sure that it would cause the surrounding epoxy in a relatively thin laminate to heat up above 100C. At 100C mast epoxy goes soft, so carbon shards at this temperature would be about as sharp as lettuce leaves. Could be wrong, would welcome some more information, the name of the boat, any crew who are prepared to discuss it, magazine articles (would make very impressive photos) etc.

Your lightning article is interesting. I wonder if we would be discussing stayed vs unstayed rigs if you had been walking forward and touched the cap shroud when it struck? I would not advocate throwing away a carbon mast that had been struck. I would bench test it, maybe ultrasound test it and if nothing showed, then put it back in.

The terminal, earth and conductor are the solutions we are using for an unstayed rig we are building for a boat in the eastern USA. The owner found almost as many insurance companies and experts who said it would not help (and may even cause a strike) as he did that said it was necessary. Hence my interest.

regards,

Rob

 

I didn't know it was possible for a carbon fiber mast to be amateur built. Shows how far behind the times I am

No, I don't have a web page. And none of my mast designs have ever been built. Two of them are for tiny boats and the third is for an ocean going monohull which has such a small beam that staying is not convenient. All are made of wood, as I understand that getting carbon fiber to work requires a special knack. If you ever saw me with a paint brush, you would understand why I'm reluctant to try.

The ocean going boat I have in mind has very modest initial stability, so the shock loads of the boat rolling should be within the mast's ability to withstand.

As far as yachting quality goes, I think it is over rated. Especially as far as stainless steel rigging goes. My dad knew a guy who was killed when a stainless steel flying wire on his ultra light let go. It had treacherously corroded from the inside out.

Me. I would go with work boat finish any day.

So, if you saw me with a stayed rig, you might see me using 7x49 galvanized with hot dipped chain plates and bulldog clamps. Why go top dollar when cheaper is good enough?

As far as under cross beam spreaders go, I wouldn't have one on my boat. Too much of an invitation for trouble. It's fine for a racing boat which will spend most of its life hauled out.

I would reenforce the beam from the top rather than the bottom and put up with the weight penalty that implies. There are other reasons to go multihull than just speed, you know.

I can understand how how you can brace your unstayed mast beam for side to side loads, but what about fore and aft ones?

Best regards.

Bob

PS- I think your proa idea is the best new multi idea I have seen in decades.
I can see why the unstayed mast is central to its design. The only alternative I can see would be some kind of 'A' frame affair.

 

Well..... no, The gypsy mast I suspect is designed for a spinnaker. Lets take a guess at 60 sqm. So lets hang a kite off your harry rig at the same point and see what happens.

 

G'day,

As the mast is sized for a large headsail, then flying a spinnaker from the easyrig hounds would be no big deal. The mast would bend, the mainsail leech would tighten up (not a bad thing) and the spinnaker would fly pretty much as normal, but with some give in strong puffs or sailing into the backs of waves. I would prefer to have a larger rig with better light air performance and not mess with spinnakers and all their paraphernalia, but it could be done.

The great thing about unstayed carbon masts on multis is that they are stiffness limited. That is, if they are stiff enough they are way over strength. Therefore, all the spinnaker will do is bend the stick, it will capsize the boat before it breaks the mast.

regards,

Rob

 

Rob, its probably best you follow Richards advice regarding actual testing on actual sailing platforms ( F27 ). I suspect no one wants to see another one of your design disasters . ie , your proa rudder systems which have required multiple expensive rebuilds by the owners, as it appears some of your design solutions, which may appear to work in your head ,don't cut the mustard in the real world..