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Old 24-05-2013, 06:58   #61
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Re: Square Top Main vs Roachy Main


I've sailed extensively with both sails on catamarans. Actually I even sailed the same cat with this two different type of sails in all kind of weather in every angle to the wind. There absolutely is NO difference ...
I am not interested in what the theory suggests but this is my conclusion after 20.000 nm of sailing on cat, both coastal and offshore.

I agree, there are good mainsails and bad mainsails, either square tops or not but, I am convinced that a good square top main will be superior to a good pin head main.
I have seen some square top mains with too much shape or with very tight leeches, these sails are usually slow. The same with square top mains with loose leeches, these sails lack power and have excessive twist in a breeze. So, in some cases, yes, a square top main can be the same performance or slower, than a better designed pin head main.
I bought a Belize 43 cat and replaced the 6 batten pin head main with a 7 batten elliptical head main. The performance difference was big in the light to moderate breezes.
We have been a leading sail maker for the Corsair trimarans pioneering the square top mains for these boats. You simply can not be competitive against the boats with square top mains using a pin head main. Now, the new generation mains have wider heads and less lower girths making the total sail area the same. This avoids an extra handicap with PHRF ratings. But, the performance advantage is noticeable with these new profiles.

There is special hardware designed by some of the major hardware manufacturers to accommodate the new square top mains allowing the heads to come away from the mast when the sails are lowered but, these are quite expensive. Other methods use quick release pins to remove the main sail heads from the head slide assemblies but, this requires removing, than, attaching the head when lowering and hoisting the sail. Some mainsail heads, with the diagional batten, can be quite high above the boom and hard to reach. Not the best for cruising boats.

The elliptical head mains can have virtually the same sail area and wide tops providing similar advantages of the square top mains but, have a couple horizontal battens, spaced close together, to support this. These battens will stack nicely when the sail is lowered for the sail covers.
This profile can be a real improvement over some stock OEM sails supplied with production catamarans.
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Old 24-05-2013, 07:04   #62
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There is no question that a high aspect squaretop mainsail is dramtically more efficient than a typical marconi rig pin top. Nothing theroetical about it.

Every race boat whose class allows for this uses them, all the high speed race cats use them as well.

The main benefit however is found hard on the wind while beating there is less and less benefit as you are farther off the wind.

Since most cruisers, especially when sailing cruising cats, do not spen alot of time going upwind the benefits of a high aspect main will be less.
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Old 24-05-2013, 15:06   #63
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Re: Square Top Main vs Roachy Main

Quote:
Originally Posted by foolishsailor View Post
There is no question that a high aspect squaretop mainsail is dramtically more efficient than a typical marconi rig pin top. Nothing theroetical about it.

Every race boat whose class allows for this uses them, all the high speed race cats use them as well.

The main benefit however is found hard on the wind while beating there is less and less benefit as you are farther off the wind.

Since most cruisers, especially when sailing cruising cats, do not spen alot of time going upwind the benefits of a high aspect main will be less.

Many thanks to dc for clarifying.

I personally think there's more to it. Crossing oceans is mostly downwind, but cruising cats, as I see them, are the vast majority who spend their time in the Med, the Carib and all the other popular cruising grounds. Those folks are pretty much upwind as much as down, mostly reaching. Maybe it's just me... but in the Caribbean it seems like everywhere is upwind.

My background is 20+ years of wind and water sports retail. During that time I've seen and sold all the countless innovations that came along. Some good, some bad, some great, others pointless. To me, its important to understand and judge, not only what that change was intended for but also to identify the resulting implications and unintentional side-effects, more often bad than good. There are typically characteristics that are not easy to quantify: How does it "feel"? When the going gets tough, is it kindly or does it kick my butt ? Even when to reef is subjective. I don't think it's possible to make the extent of changes to a sail that we are talking about here (relative to conventional cat sails), without affecting virtually all of its performance and handling characteristics.

I'm retired now but I still feel its a crying shame when I see a good innovation dismissed for the wrong reasons.

On a heavy cat with these new sails, speed and efficiency may well be unnoticeably different and if that's what was expected then I can easily understand the disappointment. However, in my experience, sails that actively twist off at the head under load, have a softer, more user friendly feel when the wind is gusting and nasty. We all know that cats don't heel and that we rig for the gusts. Here's a chance to ease that pain with a product that bends and twists in a beneficial way, not necessarily what the designer had in mind, but a plus none-the-less. How great is that !

Personally, I'm OK with a line that pulls the head in to it's car as the leach tensions but I can well sympathize with those who don't want the added chafe and potential failure point, nor the expense of patented hardware. I think if the "elliptical" top accomplishes the same with no hassle ... that's double great and should be standard on every cat out there !

Dave L38 #38
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Old 25-05-2013, 01:16   #64
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Re: Square Top Main vs Roachy Main

We also have a lot of experience designing and testing different mainsails.

I think there is a lot of marketing hype regarding square heads.. 10% faster for the same area, what a load of rubbish.

We did some flow analysis which showed good reduction in drag.. But in the real world there is very little in it.

the 12ft skiffs are good example, they had square heads almost before anyone else. Then they went to big rounded roaches and now they are a mix of both.. Who won the last international regatta? Sail-World.com : 12ft Skiff Interdominion Championship

This is a class that is not restricted in mast height. if you are restricted in mast high and trying to get maximum power of out of a certain sqm while also being able to depower.. then a wide square top is what you go for, or over square like the 18ft skiffs.

A lot of classes benefit going square

For your average cruising cat which is under powered (because its a cruising cat) then you will get a performance gain by increasing the sail area doesn't make much difference if its a square or a rounded head.
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Old 08-12-2016, 07:58   #65
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New Square top mansail problem

I haven't had time to read thru this subject thread, and I see quite a number of related subject threads on this forum.

One reoccurring theme I seem to detect about these relative new square top mainsails is the difficulties encounter with handling them,...particularly for the average cruiser.
I ran across this discussion this morning:
New Square top mansail problem

http://www.cruisersforum.com/forums/showthread.php?7044-New-Square-top-mansail-problem

...just another in a LONG list of items invented to 'tame the mainsail' (a sail I have chosen to eliminate with my single-masted ketch proposal)
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