Junk Rigged Trimaran

Hi, I too am interested in the Slieve McGalliard's variation on the traditional junk rig.

Do you know if he ever finished his book?

Here is a very interesting paper, funded by CEC, Gifford Technology of Southampton, on the relative performance of various sail-plans. I think it's safe to say that this raises questions to a lot of the conventional wisdom.

I find it very disheartening to read in these forums about individual's testimonies of having sailed a single variation and then making sweeping generalizations.

A comparison would be having flown the Wright Flyer and then saying aircraft are worthless.

LINK--- http://bateaubois.free.fr/file/rigs.pdf

"The sprit sail proved to have the best overall performance. Beating it was closer winded and sailed faster, giving a speed made good to windward some 30% faster than the bermudian rig. When reaching the margin was smaller, the sprit being on average 5-10% faster. Directly downwind the two rigs gave very similar speeds."

Critical in the paper is this part:

"They also only apply to sprit sail, gaff and lateen rigs sailed with vangs, lines attached to the yards and used to hold them up to windward. This reduces sail twist, which has a dramatic effect on windward and close-reaching performance."


We see that the junk rig has the same ability to hold its trailing edge to windward and has the additional benefit over the sprit of being able to be held square or even more forward, allowing performance to exceed the bermudian downwind.

 

What is it about junk rig fans that so often makes them throw out allegations of prejudice? A lot of the claims that JR promoters make are simply incorrect; we've seen it a fair bit around here.

The guy that the junk rig association members have referred to as having the most efficient junk rig says that it's about 10% slower than a bermudan, all-round. That means that the sail is NOT as good as a bermudan upwind and faster downwind.

Essentially you are saying that the creators and users of foilers, America's Cup boats, speed windsurfers, round the world racing multis, Open 60s, skiffs and Mini Transats are all idiots who could use a better rig but choose not to. Those would-be idiots include leading academics, leading practical sailors, leading sailmakers, and leading engineers. Maybe the prejudice is going the other way to the way you think it is?

 

Hey! Sweeps are like oars. If we talk sweeping generalizations we need the visuals.

 

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Given your last sentence, maybe you should stop claiming that it's others who are prejudiced?

 

There are many drawbacks to relying on limited test results compared to the real world of thousands of boats sailing millions of miles in all conditions. For example, those catamaran tests were only done in flat water and in very light winds, F3 max.

Furthermore, a boats performance is not just dependent on its rig, but also on its leeway preventing system. For the forces must balance for the boat to move forwards. From the drawings and photos it looks like the hull had no leeway preventer, so would sail at very high leeway angles. And the bermudian rig looked a poor design

For what its worth, I have sailed a similar length catamaran with a sprit rig quite extensively

Next, many of the "improved junk rigs" shouldn't really be called a junk rig. In the same way, few squaretop mainsail sailors call their boats "gaff rigged" although in effect that is what they are. Modern materials and technology do a better job than the old ways.

I think it would also be a relevant question to ask the OP and some others. "What experience do you have sailing multihulls" and "What experience do you have with junk rigs?" We know both Cav and CT249 are very experienced sailors

Reading books and articles, however extensively, is never enough

Richard Woods

 

The later passages show the flaws in the paper. No half-decent conventional bermudan mainsail - even something as cheap and simple as a copy of a Laser sail - has problems with excessive twist. If the Gifford "tests" had problems with excess twist in a bermudan rig it must have been due to exceptionally poor handling and/or construction.

It's interesting to see that apparently no academic paper was ever published. The magazine article seems to show why - it was basically a deeply flawed "study".

EDIT - I forgot the massive blunder in the Gifford paper where it says that no one had ever tested a bermudian rig and an alternative rig on identical hulls before. It really is such a stupid claim that it's hard to work out whether anyone honest could be so ignorant. Such trials, or very similar trials, had been made on numerous designs, including Redwings, International 14s, Stars, Sharpies, Suicides, Z, N and H Class Renjolle, Half Raters and innumerable other boats and classes.

Any work that includes such a yawning error shows a complete and damnable lack of proper research, or an equal lack of honesty.

 

No, it's not as simple as keeping a mono pointed into or out of the waves. Many monos have got into trouble while lying to sea anchor or running with the waves.

Basic physics also says that a mono with a big hole in it will sink. Would you rather be on a flipped multi or a sunken mono?

Yes, people have put both junk rig and conventional sails on the same hulls several times. Annie G, the X 99 that the junk rig association chaps have referred to as a racing machine, races against other X99s and its owner says it's 10% slower. Practical Boat Owner tested a split junk against a conventional bermudan sloop with a small headsail and found that upwind "No matter what we did, Whisper – the Bermudan-rigged Splinter – was by far the quicker boat. She felt lighter, more powerful and more eager to go. She was also faster through the tacks, carrying much more speed into them and accelerating rapidly on the exit. Even though Steve leaves the spinnaker pole on the mast and the babystay inevitably gets in the way, tacking was easy because the headsail needs little winching until the breeze really picks up.....Upwind the Bermudan rig clearly had the pace over the junk, not always pointing higher but going significantly faster". Apparently we are prejudiced for believing this, of course.......

Downwind the junk rig was faster when the sloop's headsail was covered by the main. Reaching the sloop was faster. Short tacking, the sloop was faster. The bermudan rig in the test was a 40 year old design using basic dacron sails and what looks like a shorter overlap than usual.

It's interesting looking at the junk rig association's racing section. Here's some quotes;

"Should have gone for Carbon Fibre, even if it was a little more.
My Aluminium mast is surprisingly heavy and with the centre of effort rather higher in a junk rig, then this has made a slightly tender boat, rather more tender! Just means I have to reef earlier than otherwise."

Hmmm, that's interesting given the claims about bermudan rigs being the expensive high-tech option!

 

It is amazing to me that no ones has taken scale models of different sailing rigs of the same size and put them in a wind tunnel to see how they perform. Many purists would say this is not a fair test because it doesn't take into account the boat. But a standardize test some kind of results would be very informative.

 

I found the discussion of mono versus cat versus tri pretty off base really. The real world performance of the tri versus cat tends to put that to rest. Of course most trimarans tend to be lighter and more performance oriented. Tank tests show that a trimaran will recover at far more angle than a catamaran, and they also surf on the waves better as a rule. My interest in multihulls is based on several factors. Speed of course is an important plus. It means you can probably run away from weather systems where a comparable monohull can't. Far less heel means a far more comfortable environment at sea, which is a lot of why catamarans are increasing in popularity. Shallow draft is a huge benefit in many areas. The three hulls argument as compared to two is unrealistic. depending on the craft, in most cases the two amas are lightly loaded and draw very little water in "level flight", and in any sort of reaching conditions one is likely to be nearly clear of the water.

Monohulls can and do survive knockdowns and even a capsize, but very often are so crippled that they are ultimately abandoned......... at least after a capsize. More often than not the standing rigging has failed and the mast is dragging alongside the boat threatening to pound a hole in the hull. The huge amount of ballast that allows the boat to right itself now becomes a liability in a boat that is swamped and being swept by waves with windows broken out and washboards gone, and bilge pumps not functional because of floating junk in the bilge. This scenario is repeated again and again in the case of virtually every monohull that has been abandoned. The multihull on the other hand is far less likely to capsize because it rides the surface of the waves surfing ahead of the wave crests like a water bug. If it is capsized at sea, it's likely not coming back up, but experience has shown that it isn't going to break up or sink. They seem float indefinitely inverted, until they fetch up on the shore or a reef somewhere. You can't live in an inverted catamaran. You might live in a life raft tethered between the two hulls, and dive for supplies, but once you pierce a hull, it's going to sink. On the other hand you can live inside the main hull of a trimaran, cutting an access and ventilation opening. The two amas will keep the main hull afloat and stable. There have been numerous cases of this, in fact many racing trimarans have hatches in the main hull for this eventuality. Racing in the southern ocean is a guarantee that someone is going to capsize, and many have.

A few people and one or two manufacturers have built monohulls to be "unsinkable", but this calls for large amounts of flotation, and or water tight bulkheads. I don't see a rush to buy or a demand for unsinkable yachts. Do you? Liners in modern yachts virtually guarantee that they will sink if punctured. The rush of water behind the liner will fill the entire boat quickly and there is no possibility of staunching the leak because you can't access it. I have a huge objection to liners, and more to structural "grid liners" for that and other reasons. Google it and read with marine surveyors have to say. Take to the life raft, and your chances of survival if you are not in coastal water where you can expect rescue rapidly are very low. All your supplies are in that boat that you are watching slip beneath the waves, and you are in a flimsy ill supplied raft designed to give shelter for a very short period of time. Hopefully when you set out in your 30' monohull from Cabo San Lucas to Fatu Hiva, you can push these things out of your mind as you cruise at 5 or 6 kts on a good day on a 3000 mile trip. Most of us can and do. We may accept the risks, or pretend they don't exist, and only occasionally does someone vanish into the vastness of the Pacific. It happens occasionally, and it's heart breaking when it does. We can only hope that they were victims of a propane explosion and it was all over before they knew what hit them. I personally would rather not have a "death raft" when sailing 1500 miles from the nearest land. I want my boat to be my life raft. A multihull can be a life raft, a monohull is going to the bottom ....... period!

Case in point is the Rose Noell saga where 3 men survived 9 months in the hull of an overturned trimaran......in surprisingly good health.

The breakup of cruising multihulls is largely the stuff of myth and legend. The only case that comes to mind happened between Australia and Fiji or Tonga as I recall in the 60's. I believe pieces were found as I recollect, but no survivors. A dead whale with a huge gash that was attributed to the keel of the trimaran was found nearby.

On the other hand such things as a sea cock that won't close after a hose failed or a fitting snapped off, or a rudder strike resulting in forces that damaged the hull where the rudder passed through, or as in the notorious case of Cheeky Raffiki loss of the keel, have sent many monohulls to the bottom. None of these events would sink a multihull completely. It would create a serious problem that might result in the need for assistance, but it wouldn't sink your boat. At least one hull would remain afloat, and the other(s) would probably not "sink". You wouldn't have a couple of tons of lead trying to drag your boat to the bottom. You'd have a "fighting chance" at least.

pardon my long wordy post. Clearly I don't see things through the same color of glasses as some people, and that's OK with me. My life story seem to be a story of drawing my own conclusions that are often in conflict with the "common wisdom". That is not to say that I do not read and consider...... and respect... the opinions and experience of others. In the end, it's up to me, and the consequences of my decisions are 100% on my head. I appreciate the input and ideas of others, and evaluate them carefully, sifting them for insights and wisdom that is of value to me, and others.

H.W.

 

I answer some of these posts not because I believe I will change the minds of those dead set on something but to prevent some other poor soul trying to sail across the ocean ill-equipped.

First, I know of no boat, no matter it's size, or make ,that is well equipped to cross an ocean when you buy it. They all have to be refitted in many ways. Otherwise, they are death traps. If your boat can't take a capsize or two it does not belong crossing oceans.

Secondly, a mono-hull is usually alot heavier than a comparable multi-hull that are by designed lighter. This lightness is the problem. Their only form of defence in a storm is to get out, therefore you need to switch sails fast and get out of there.

On monohulls sinking, the first thing you do in any ocean boat is have multiple compartments. I have 3 major ones in mine not counting double hull over half of boat. Everything can be closed to be completely water tight. On multi-hulls an axe is standard equipment for cutting through the floor, others have a hatch already. Kind of tell you something.

A 40 foot monohull sail boat is many times heavier and have a much thicker hulls than a comparable cata or tri.

Now the myth of the fast Cat or Tri. A light Cat or Tri can be very fast when new. GO sailing on them for two years, and all the crap you bring on board makes them heavier and much slower. They don't take the weight nearly as easily as a monohull.

Going back to Junk Sail Rig. Since by your own admissions a Junk Sail, even a modern one is 10% slower than a Bermuda, and since in a storm it would be harder to work with. And since it is less common and therefore harder to find people to work with them. What is the advantage of a junk sail again besides looking cool?

 

dauphin You really don't understand multihulls. The scantlings are up to the job. I suspect the owl has read enough of the literature to know this so trying to freak him out this way won't work. If you made your voyaging decisions based on this premise I suggest trying the alternatives while you have time to escape from the dark side. Ballast sucks..... literally, gravity is a weightsome thing.

Owly, A decent trimaran can make almost anything work gracefully, if you are willing to accept the performance compromises play around, epoxy and time will fix anything. Because of the wider performance envelope of a tri I'd say you'll probably be taking closer to a 15% cut over a stock rig but if it makes you happy and gets you on the water go for it. It is silly, though, to post with a set attitude . Progress has to be approached with a open mind.

 

I approached this thread with a project in mind, and I have not heard a single valid and supported argument to dissuade me. Just prejudice and ill informed or outdated opinion. You imply that I am not approaching this project with an open mind. Nothing could be farther from the truth. It's clear to me at least, that I'm in many ways better informed with regard to current multihull and junk rig technology than those who seem to be trying to dissuade me from the project. One has to be able to sift the wheat from the chaff and judge the merit of the various opinions based on both the knowledge and experience of the topic of the person expressing that opinion, and it's relevance to my specific design criteria.
Nearly all cruising multihulls within the class I'm looking at are home built, which does not mean that they are inferior to factory built boats. There are poorly constructed examples, and superbly constructed examples. They have a very good safety record as compared to factory built GRP boats, and the "cold molded" epoxy / plywood construction has proven rugged and long lasting if properly constructed. I have no more safety concerns with a well found cruising trimaran, than any other cruising boat.
The junk rig, which everybody seems to equate with the slow flat panel sails has come quite far with regard to performance. I suggest that you read Slieve McGalliard's article about the performance of his split junk rig Poppy on the Junk Rig Association website using the link below, rather than simply throwing out numbers based on your personal observations of whatever junk rigs you have sailed against. One of the problems is matching up boats for comparison. The modern camber panel junk rig is an airfoil sail, and as such is not limited by the speed of the wind, which of course is also true of a good Bermuda rig. There appears to be nothing inherent in the design that would make it slow as is being implied here repeatedly. While you are reading the article below...... if you can be bothered to..... and I would hope you would lest you be guilty of the very close mindedness you accuse me of, I suggest you peruse the site, and educate yourself on the current state of junk rig development. Slieve has written a considerable amount which is in the public domain, and designed to help other junkies to duplicate or advance on his work. My opinions started out much like those I see being expressed here, but they have evolved over time. Not being closed minded, I've evolved, and it's a continuing process.
You don't strike me as being of a closed mind and smugly opinionated. learning is an ongoing process. In my profession and many others, continuing education is critical. You learn or become an anachronism.

H.W.

http://www.junkrigassociation.org/resources/Documents/Slieve's%20Files/AYRS%20Catalyst%2037.pdf

 

Charming Owls, about par for your course. Once you put down the books and start sailing you'll get some practical experience. What are you hoping to get from this forum besides practicing a defensive attitude? Are you interested in construction conversion from a deck stepped mast to a unstayed rig? Rig location and balancing? Have you ever sailed with a junk rig? I have. Have you ever sailed? If you are in Montana or just about anywhere else I'd suggest building something like one of Richard's small tris so you can can get out on the lakes and practice with rig ideas without spending a fortune. I just noticed your join date and am reminded of my rule not to post with someone who hasn't been around for a few months so catch you later. If you want more reading and history on the modern pursuit of the junk check out the AYRS and their back issues starting from the 1950s for more research and ideas. It is interesting how far back some things have been tried.

Cheers!

 

There really is no point in pursuing this further. I grew up in the Pacific Northwest, and am no stranger to sailing. I'm familiar with AYRS, and have read quite a bit of their downloadable material. I hadn't run across any junk rig material. The Junk Rig Association is probably the best resource in this area.

H.W.

 

Progress has been made when the pursuit of misunderstanding gives way to reason.