Catamaran with 6 masts, is it possible?

[NevilleCat]

Yeah, those pesky strings!
And doesn't everyone hate constantly fixing those string and ropey bits.
More electronics I say!

[Breaking Waves]

Originally Posted by Johncobb

Larger area of sails so faster travel, isn't it so?

hmmm . . . . .

#1 generally no. Taller, higher aspect sails = faster sails (more efficient foils and more wind higher up)

and

#2 you will be limited by boom lengths - you could sketch it out on a napkin, I guess you will not get much more sail area than two big tall masts (one on each hull).

Either one big tall mast (see Dogzilla - larry Ellison's big AC boat), or Two big tall masts (one on each hull - see Team Philips) would seem to be the fastest solution. These were huge design efforts aimed at the fastest solutions - I really doubt they overlooked much.

You should look into kites

[Breaking Waves]

just a little further fyi adding to #2 - airflow off one mast will interfere with the airflow over the next mast unless they are quite widely spaced.

[MyCatLife]

Can it be done? Sure.

But 6 rigs / sails seems like a really bad idea from a performance perspective.

At least two of the leeward rigs will be in dirty air on most points of sail.

Build 2 identical r/c sailboat hulls and try out different configurations. Then match race if you want to test.

[tkeithlu]

What you get is more lift (propulsion) and bunches more drag. It's the same situation as comparing a modern glider, with one long wing, with a WWI triplane. The triplanes had lots of lift to overcome weak engines, but no where near the glade ratio of a modern glider. You would not point as high, or go as fast, as the same sail area on a single tall mast.

[Leighpilot]

Sure. You can build anything. With enough cash and disregard for practicality you could easily have it built.

The real question is this. What problem are you trying to solve with 6 masts and is there a better or existing answer to solving this problem that you think needs six masts to fix. Unless you just want six masts in which case it’s just a case of spending the money and living with the consequences.

[OneBoatman]

Sounds like it would at least look cool on a cat around 200 ft long with an 80 ft beam. I would still want them all to have one Ted Hood's coolest inventions, the stowaway mast. So why not build a trimaran with 9 masts and an LOA of 500 ft, Start a business and offer luxurious transatlantic crossings in 7 days or less or your money back.

[Adelie]

Originally Posted by NevilleCat

Presumably you are looking at freestanding masts? Otherwise such a mass of rigging....
Either way I suspect the engineering requirements will lead to small broken-up areas in each hull for the accommodation which is not ideal perhaps unless you were thinking of a pod cat.
One of the issues I see with wing sails is reefing them small enough for extreme conditions; having 6 of them could be a serious problem.

You could have a normally rigged mast if you stepped them on the inboard gunnel of each hull.

[GrowleyMonster]

https://www.youtube.com/watch?v=hYHDG9GhTak&t=37s

Generally, when you come in to an art or hobby or skill set bringing your fresh point of view with you as an outsider, and have what seems to be a better idea, ask yourself, before you commit time and money and reputation into it whether it might already have been tried before, and if the reason why nobody does it that way is because somebody tried and it didn't work very well at all.

Usually good ideas involving MORE or BIGGER or FASTER or MORE POWERFUL get tried with monotonous regularity.It is part of human nature.We are obsessed with the superlative. Now look around. How many catamarans do you see with 3 masts per hull, or one mast per hull, or three masts period? Even cats with two centerline masts is uncommon in spite of the obvious benefits of a ketch rig.I have never seen a cat with a schooner rig though that doesn't mean there aren't any. But you see the pattern? The market demands, and the industry provides, mostly cats with a single mast. It works. If it didn't work you wouldn't see it.

Having multiple masts on each hull will guarantee that on a reach, the windward masts will interfere terribly with the performance of the sails on the leeward masts. Ditto the after masts interfering with the forward ones when running. (that's downwind) The only point of sail where you would maybe see some worthwhile benefit is close hauled and pinching up as high into the wind as possible. You might also have some stability issues. Rigging everywhere. Unmanageable sail plan. Your most efficient sail plan would be a high aspect marconi sloop rig or maybe a fractional rig so you could put a little bend in the mast with the forestay. That means a very tall single mast with a boom for the mainsail aft of the mast, and a headsail or maybe two overlapping headsails forward of the mast. The simpler rig of course would be easier to handle.

[ewsponberg]

JohnCobb, one thing you have to remember about multiple sails in line with each other is that the flow off the sail ahead affects the flow onto the sail behind. For example, let's say your 6-masted cat is sailing upwind at such an angle that there is pretty good flow to the sails on both sides of the boat. That is, the boat is wide enough so that the windward sails do not blanket the leeward sails, although that is an issue the narrower the boat is. The forward-most sail has an angle of incidence to the clear wind, and as the air flow leaves the sail, there is a certain "downwash" effect wherein the air flow bends toward the windward side. All sails do this, some worse than others, but all sails have downwash--it is inherent in the creation of lift and drag on the sails. You can minimize downwash but you cannot get rid of it.

The downwash off the sail ahead effectively reduces the angle of incidence onto the sail behind. To compensate for this, the sail behind has to be sheeted in tighter than the sail ahead. For boats with two sails, like schooners, ketches, and yawls, this is not much of a problem. But once you go to 3 sails in line, the downwash effect can be quite bad.

Checking the air flow off the second sail--it has downwash too that reduces the angle of incidence onto the third sail in line. Again, to compensate, the third sail must be sheeted in tighter than the second sail which is already sheeted in tighter than the first sail. Then, the flow off the third sail also has downwash which has a further component of flow back to windward. The upshot of this is that the flow along the third sail can conceivably generate total force angling backward, not forward. That is, the third sail can be acting like a brake rather than an accelerator. This is why 3-masted boats are not very common--it is hard to get the combination to work correctly so that all three sails are generating power in the same direction.

Remember that this example is for sailing upwind. As you bear off the wind, the downwash becomes less of a concern because he sail trailing edges are well away from the leading edge of the mast behind. The sails work better in reaching situations. But then with 6 sails of 3 in each hull, the windward sails would begin blanketing the leeward sails as you bear off the wind.

The final result, all things considered, is that there will be few times when all six sails will be working well at the same time. You would probably be far better off to try 2 sails/masts in each hull, 4 sails/masts total. You'll have fewer issues with downwash and blanketing effects.

I hope that helps.

Eric

[NevilleCat]

Or one freestanding in each hull. Contact Geoff Schionning

Or one in the centre of the boat with conventional sails.

[Jim Cate]

Originally Posted by ewsponberg

JohnCobb, one thing you have to remember about multiple sails in line with each other is that the flow off the sail ahead affects the flow onto the sail behind. For example, let's say your 6-masted cat is sailing upwind at such an angle that there is pretty good flow to the sails on both sides of the boat. That is, the boat is wide enough so that the windward sails do not blanket the leeward sails, although that is an issue the narrower the boat is. The forward-most sail has an angle of incidence to the clear wind, and as the air flow leaves the sail, there is a certain "downwash" effect wherein the air flow bends toward the windward side. All sails do this, some worse than others, but all sails have downwash--it is inherent in the creation of lift and drag on the sails. You can minimize downwash but you cannot get rid of it.

The downwash off the sail ahead effectively reduces the angle of incidence onto the sail behind. To compensate for this, the sail behind has to be sheeted in tighter than the sail ahead. For boats with two sails, like schooners, ketches, and yawls, this is not much of a problem. But once you go to 3 sails in line, the downwash effect can be quite bad.

Checking the air flow off the second sail--it has downwash too that reduces the angle of incidence onto the third sail in line. Again, to compensate, the third sail must be sheeted in tighter than the second sail which is already sheeted in tighter than the first sail. Then, the flow off the third sail also has downwash which has a further component of flow back to windward. The upshot of this is that the flow along the third sail can conceivably generate total force angling backward, not forward. That is, the third sail can be acting like a brake rather than an accelerator. This is why 3-masted boats are not very common--it is hard to get the combination to work correctly so that all three sails are generating power in the same direction.

Remember that this example is for sailing upwind. As you bear off the wind, the downwash becomes less of a concern because he sail trailing edges are well away from the leading edge of the mast behind. The sails work better in reaching situations. But then with 6 sails of 3 in each hull, the windward sails would begin blanketing the leeward sails as you bear off the wind.

The final result, all things considered, is that there will be few times when all six sails will be working well at the same time. You would probably be far better off to try 2 sails/masts in each hull, 4 sails/masts total. You'll have fewer issues with downwash and blanketing effects.

I hope that helps.

Eric

Eric, that was nicely and kindly done. The OP should really pay attention to this post for it comes from someone who actually knows something about rig design. Ignore it at y our own peril!

Jim

[Gerrit Coetzee]

Originally Posted by Johncobb

I have a question.
Is it possible to build a blue water catamaran with 6 masts? (3 masts on each hull).
Those masts will have (new technology) wing sails with non-manual but automated operation.
I know that it has been done but with 2 masts only, one on each hull. For example, on Energy Observer, Beneteau.
If it is possible then what will be involved. One thing, that this catamaran will have to be long??
Thanks in advance for comments.
John

I think go for 12 masts. 6 is nothing.

[PaulSommers]

Here is another example - Pete Hill has sailed this boat many miles in open ocean offshore voyages:

https://www.youtube.com/watch?v=WPL4...annel=MrTomooh

It demonstrates the use of something like the sail design the OP is talking about, but sticks to one sail/one mast per hull for all of the reasons other posters are mentioning.

[chris14679]

There's a very cool biplane catamaran for sale here:

https://www.trademe.co.nz/a/motors/b...ing/3088166833



A biplane rig is actually a great idea but I struggle to see why you'd need more than two masts, perhaps unless the catamaran is over 70ft long and you need to pass under bridges? Your rigs would mostly be in bad air from your other rigs.

Some of the big design problems with catamarans are getting enough forestay tension and supporting the downward force from the mast in the middle of the crossbeam. A biplane solves both these problems by putting the masts and forestays both in the hull so there's a single, very stiff structure between them.

Also by having two masts, they can both be shorter so there is less leverage on them, so you can carry significantly more sail for any given windspeed without worrying about capsizing.

With the biplane, the downwind rig is only in turbulent air when broad reaching, the fastest point of sailing so the loss of power on that point of sailing doesn't matter. Both upwind and downwind both masts are in clean air and perform well. Downwind you could put the booms out opposite sides and set a huge square sail between the masts.

I'm just talking generally about biplanes, I'm not sure that the rigs on Cool Change can actually do all of that. They appear to be unstayed and no jibs so forestay tension isn't an issue on that boat. Personally, I would have jibs for windward work but not use them all the time.