In this video, Multihull expert John Marples shares his new concept for a Diamond-shaped, double “roller furling” sail rig.
John currently thinks this Diamond Rig will can offer the following benefits/advantages …
— More efficient overall than a Marconi rig
— Can be made with lower cost “off-the-shelf” materials
— Is unstayed (less lines, block & tackle and stress upon a multihull platform)
— Less cost to build (see above)
— Much greater “ease-of-use” … especially for sailors who no longer want to work very hard
— Can be run with a simple motor totally within the protected area of a cockpit/deckhouse
This is amazing in both its “forward-progressive-thought” and extraordinary simplicity.
It once again shows that true innovation, more often than not, doesn’t lie in creating something totally new … but rather in forming an idea, a new approach (i.e., way of looking at something) that borrows from already-proven, existing concepts.
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Very neat. The thought crosses my mind if the “boom” could be below center to lower the CE of the rig allowing more area for the same righting moment.
I’m impressed, as you say, no flapping around, no boom swinging, no matter how you change your course, the sail is always in an optimal position, amazing how during reefing the sail holds its original shape, just a bit smaller. I think you have discovered the advantages of the big schooner rigs, which where more or less optimal in any heavy weather not to mention what it does for the boat stability on waves. Also I think for having the boom disappear gives you much more living space on deck. I’m not quite sure what the missing wing profile does, but the diamond shape would definitely be checked in a wind channel. the triangle shape must also have a balancing effect on the whole length of the mast…
I have long had great respect for the Brown/Marples design team. One of my concerns with this rig is the amount of windage aloft in storm conditions. As it is combined wind and wave generated forces in storm conditions that most threaten capsize wouldn’t this rigs high aspect ratio plus high windage high aloft limit its usefulness to cruisers?
After the product development stage is finished, each rig would be custom fit to match the need for any boat. One great advantage to this rig is the ability to reef down to absolutely zero (down to the bare crosspoles) with ease. So it would be easier to use than a traditional sloop … and a great advantage to use in “storm conditions.”
Interesting concept
I wonder if it can be retrofitted to a small trimaran say 16 or 18 ft. Most small tris will use a hobbie or prindle mast 26 ft or so.
Great idea if it works on real boats, I wonder, is the diamond sail/rig suitable for use on a Jim Brown Searunner 40, or a 46′ Ferro Cement Samson? I know they are completely different boats but I’m trying to decide on which one of the afore mentioned boats to check-out before making an offer to buy, and I think the diamond sail would make life easier on either vessel…If it works on 40′ plus sea going boats.
Great idea, John. It could really be most any symmetrical shape, optimizing for whatever conditions a particular boats calls for. I’m thinking basically a triangle that’s big on the bottom and small up top- that should help Merle’s concerns above. I can only imagine a harbor full of monohull sailors scratching their heads in wonder as a diamond rigged multi goes flying past…
So, what are the possibilities for putting a diamond rig on my newly acquired Marples 35. I hate booms,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
I’m sure this new rig needs an investor to take the development all the way up to a full-sized sailboat.
looks like a crabclaw with a pointy top to me.
If you watch the video you’ll see why it’s soooo much more than a traditional crab claw.
What about the very high point of aerodynamic pressure against the sail? A too high mast and a high sail could be difficult in heavy weather. It can be reduced, of course, but a gren don’t offer time, usually.
Anyway, it’s intersting.
How do you think that this rig would go when placed in a proa. Logic suggests that it should work well as the center or effort should be close to the center line on either tack/shunt.
Is there any reason why the yard cant be a fraction lower, so as to reduce the center of gravity. Also I cant really work out how the roller reefing works, both sides of the sail wrap around eachother? How is that matched with the tension acrosswise, because if the sail was more furled, the diameter would be greater, thus one rotation of roller furling would take the sail in more.
John, I’m wondering, since the last comment was 4/12, if any trials for a full size Trimaran have been attempted? Has anyone built one yet(furling rig)? In greneral, what would the cost(appox.) be for a full size rig for a 35 to 40 ft Trimaran?
Hi John L.,
To my knowledge, nobody has yet attempted to build a full-scale diamond rig. The current economic climate has put the spending brakes on a lot of great projects at this time. But who knows, it’s only going to take the right sailor with the right means to make this a reality!
Greets.., so it’s like almost 2015.., where does this prototype project stand? BTW: When looking at your RC cat’s movements.., thought I saw the top of the model mast swaying, actually wiggling while the craft’s almas appeared to not exhibit such movements in the water. Seems the mast step must be structurally strengthened somehow, i.e., spreading the forces down, and out into the designed bulkheads, or making bulkhead additions, or modifications in order to really tie-in the mast. Also it seems that lines could still be used on a wider craft like a tri. with a bearing collar at the top. What say ‘ye? I could see that that would not work on the cat model as that craft is not wide enough to accommodate said, let alone on an upscaled version. Please email me, as I’ll probably not be able to get back to this informative site for some time. Best Wishes to you all, stay safe, and enjoy happiness.
Hi Michael,
Please contact John directly with your question using the email address listed on his website at http://www.searunner.com
so in case of 9m length boat it will be approx 10-11 meter unstayed mast?
thats gonna be a pretty hefty mast stem, i.e. heavy – something that multihulls usually does not tolerate much…
another thing, if you furl it in heavy weather, mast with bend, will this furl work? even the good genoa rollers tend to stuck in nasty sgualls, not to mention those yuppie-oriented bs inner mast main sail rollers that will get stuck pretty easily, even in mild conditions as I have noticed
An un-stayed rig on a large boat could present a problem at the deck mounting. Another concern is the ability to maintain tension so the sail holds its shape as the wind increases. Finally, the system seems a little complicated, not to operate but to be reliable. One measure of a good cruising boat is its simplicity of repair.
However, assuming those problems can be figured out, the idea is quite interesting. It appears to perform well at model size, though the above mentioned problems wouldn’t be nearly so prevalent on the small test vessel.
Some people commenting on this site were concerned about the sail having a high centre of effort. I’m not one of them. If the sail shape can be controlled, the stronger and cleaner wind aloft should mean that this diamond sail could be smaller than a modern triangular sail for the same performance.
The largest area of a modern triangular sail is low where the wind is weaker and dirtier. The wind is weaker because of the wind gradient and it is dirtier because of disturbances caused by flowing over uneven surfaces (waves) and by flowing around the supporting vessel and its superstructure. Winds higher up are stronger with fewer disturbances. The mast destroys the flow of the otherwise stronger even-flowing wind over what little sail there is in the upper portion of the modern triangular sail. And you can add to that the weak control over the leach which negatively affects the sail’s shape. As such, I don’t believe the modern Marconi/Bermudian rig was well thought out.
The diamond sail is somewhat similar to a wing sail in the sense that it should hold its shape under normal operation because it is supported on all sides. It is interesting that the sail is symmetrical suggesting that the teardrop shape of modern sails is not terribly important, unless it is when scaling up to full size. I don’t know the answer to that but my guess is that it doesn’t matter much under cruising conditions.
It is also similar to the old square rig in that it cannot be tacked. Square rigs were efficient for transatlantic crossings using the trade winds but not so good for returning after a day sail. In a way, this design is a modern version of the old square rig but rotated 45 degrees and supported appropriately. The tacking maneuver (jibing) is not very efficient but long distance cruisers don’t tack often and the close hauled performance is much better than the old square sails.
My final take on this design is that it is a combination of the historical square sail and the modern wing sail. The benefits are many. It can be sailed while furled to any degree. It seems to sail well on all points. It’s easy to control. There is no boom. The sail area might be smaller because of more efficient use of better wind. The main drawback in this presentation is the lack of tacking ability. But everything is a trade-off when it comes to boat design.
Amazing idea !
Clean and simple
looking forward to its full development.
2021 now, but I haven’t seen this design implemented anywhere, even though it’s been over 10 years since this was posted. Does that mean it’s not the greatest thing since sliced bread?
No, it means nobody wanted to invest in it’s development. It’s a shame too. John is an amazing designer.