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Old 08-10-2015, 11:51   #1
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Mainsail choice

I have a light weigh crushing cat. 1984 37ft Fontaine pajout"Louisiane" cruising wgt is 9000lb. Mainsail area is 392sf with a moderate roach. The Genoa is 376sf.
My question is would the newer style "square top" style mains be much of an improvement in speed considering the additional cost and possible gear change?

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Old 08-10-2015, 14:20   #2
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Re: Mainsail choice

I fought that battle with my new main. Ended up keeping it simple and had as much roach as possible put in without going with the diagonal batten. Yeah, I lost a little sail area, but I don't have to climb the mast to attach the top car or have the complexity and expense of the other systems to pull the headboard up.
The square tops do look cool, though.....

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Old 09-10-2015, 07:09   #3
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Re: Mainsail choice

If you can take the expense (new main, lazy jacks, sailbag, etc), square top would be my choice. With proper "accessories" no problems at all at least that was the case on my prior mono.
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Old 09-10-2015, 11:55   #4
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Re: Mainsail choice

Square tops are a PITA. First you may need to add some steps to the mast to climb up a few feet to attach the main halyard to the headboard, not something I enjoy in a light chop (or even calm water). A square top is heavier so you will need effort to raise it (on a brighter note they drop like a guillotine when the halyard is released). You will also need a bigger Mack Pack or similar sail cover along with lazy jacks. You will have to open the Mack Pack before raising the sail, not always that easy. You will need to be careful raising a square top that the battens don't foul in the lazy jacks or the topping lift, not always that easy especially in a shifting wind or even with an auto pilot.

When sailing the square top will often act like the first reef spilling the wind when it twists which is a good thing. No question there is a speed benefit. For me this is worth it. I spend a lot more time sailing that I do raising and lowering the sails.

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Old 09-10-2015, 12:38   #5
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Re: Mainsail choice

I found a compromise that gets me most of the square top. I used a short (about 30" if I remember correctly) permanent horizontal batten about 12" from the top followed by a lot of roach. The headboard is also very wide and close to this batten. The sailmaker will need to play with the measurements a bit.

It's a very powerful sail.

I leave the halyard shackle attached but grab a bight with a boat hook and pull down some extra slack and tie it off so as to not slat on the mast.

I remember that Steve Dashew wrote about the power benefits of getting a longer cord in the upper sail. And this was before square tops were common. I can't remember the details.
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Old 09-10-2015, 23:38   #6
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Re: Mainsail choice

Im in the same situation myself catnap - looking at replacing mainsail this year anyway and wondering if i would see much improvement in going from an already decent roach to a square top. I started a thread on this last year but there were multiple conflicting responses and no definitive conclusions. worth a read though if you do a search on square top mains here on CF.

Alot of the responses that were pro the squaretops were from mono sailors who obviously saw the benefit over a pin head but vs a typical high roach cat main the jury was mixed with real world comparisons not really that conclusive. ie slight improvements but maybe not enough to justify any rigging changes and raising / lowering hassels.

Like Tom says they do look cool though and it might be more to do with that than actual real world performance gains in cats.

Im tempted to spend the extra cash on a code 0 or better mainsail material at this stage but interested in any other real world examples if people have any?
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Old 09-10-2015, 23:55   #7
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Re: Mainsail choice

as we are due for a new main anyway,we are loking at extending our mast 10% and making it rotating. the sail would be fathead style as there is no better way(?) to get that much extra area up there.
The "new" thing seem to be to have a crane at the top of the mast that extends backwards and makes hoisting and topcontrol easier? Can anybody explain the benefits of this setup as opposed to a normal straight mast with FH main?
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Old 10-10-2015, 00:34   #8
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Re: Mainsail choice

Cat_nap2, Firstly, welcome to CF.

With regards to your question, yes, these types of main definitely ad a lot performance wise. Not just due to their extra area, but in particular, due to their greatly boosted lift to drag ratio.
Because of their shape, it's like getting a lot of sail area for "free". And if you do some digging, you'll find the "math" which explains this. And there's data out there which will tell you how much. I just can't recall where to find it at the moment.

And not to derail your thread, but this is a topic which likely has gotten & would get a lot of input over on Sailing Anarchy (forums).
Especially given the high percentage of Performance, & Multihull junkies & experts over there. Basically I'm just saying that it's a good resource is all.

Also, I'd wager an Extra Large sum, that there's a lot of info on these sails in places where skippers & crews of F-boats (Farrier trimarans) congregate. As, much of the time, these boats & fleets, are at/on the cutting edge of new (sailing) tech developments.
For instance, they were doing synthetic rigging a couple of decades ago. Including the various shrink on coverings for the shrouds & all.

If you do pursue (and find) links to good info on the performance gains on this type of sail, I for one, would surely appreciate it if you'd come back here & post them.
That, plus if do you go with this type of sail, I'd be interested in reading your thoughts on it.

Though, bottom line, there's little question that they work. As pretty much everything which floats, in the higher end racing fleets has them. From windsurfers, all the way up to Maxi multi's & monohulls.
As the saying goes: "How fast do you want to go? ...How much $ do you want to spend"?


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