Square Top Mains for Cruising ?

[monte]

I'm just wondering whether to get a square top main for a new Lagoon 380.
Any pros, cons etc. sail shape ok when its reefed , easy to handle and reef?
I will be primarily short handed cruising tradewinds.

[Kiwikat]

About 3 hours ago I observed a Lagoon 380 sailing down the coast here at the Gold Coast. She had a square top main and it looked sweet. A relative of mine with a square top main on his tri says it is a bit of a pain in the bum for cruising cos you have to loosen of the top batten when you drop it down, to stack it away properly but I heard somewhere that lagoon? or someone has solved that issue. Very keen to hear others' opinions.

Cheers

[careka]

Yes its no work at all.
i have it to. works very well. lower down close the zipp-pack and open a cold one. thats all.
here are some pictures.
Lagoon380 Careka: Erfaringer

[monte]

thanks...
how about sailing with a reef or two in? does the head still pull in hard to the mast and the sail shape still ok?

btw I found this interesting A square deal! | Lagoon Inside

[colemj]

When we had a new mainsail made, we got rid of our square top. The thing was always a pain trying to raise and store it in the bag. Sailmakers can mitigate the loss of the extra small amount of the square top through proper design of a non-square top. In other words, we didn't loose any significant sail area and now have parallel battens that raise and store easily. We have noticed no difference in performance (well, our new sail performs much better than the old blown out one, but I still remember how the old one used to perform when new). Personally, I think they are one of those things sifted down from racing that just look cool and make you a cooler person for having one, but doesn't improve anything on most cruising boats.

Mark

[ozskipper]

In MHO aside from aesthetics, the extra power gained may be limited. As square tops are usually on racers, who have plenty of body mass on the rail to provide stability. The COE will move up the sail somewhat, I would assume. Meaning you either need more bums on the rail or an earlier reef. I am still yet to figure out how there isnt just one massive tip vortex at the top of a square top. Someone smarter than me will know of course.

[senormechanico]

Careka,
Very slick solution !

[boatsmith]

My understanding is that it provides better airflow. It would also seem to me that for a given sail area the overall mast height would be lower. And by gawd I do so want to be cool

[Hydra]

If I understand correctly, the purpose of these sails is adapting automatically (through good choice of batten stiffness) to changes in wind speed and direction, when close-hauled or close reaching.

I am not sure that it is relevant for what monte has in mind.

Alain

[threadkiller]

Well, from what I understand, they do a number of things.
1) Extra sail area aloft, where there is more wind away from the boundry layer/shear caused by drag. Up to 20% more.
2) They twist off in stronger puffs, depowering naturally. In the light they stay firm to give the extra power.
3) The flat edge give an "end plate" effect, the reason racing yachts have deck sweeping headsails, and airliners have canards on the wing tips. It REDUCES tip vortex/drag.

2 cents.
I want one.

[Tropic Cat]

They just look so cool .... I want one too

[Bash]

Originally Posted by boatsmith

My understanding is that it provides better airflow.

They also improve light-air performance, because when it's light you'll tend to find better breeze farther from the water's surface.

[senormechanico]

Originally Posted by Bash

They also improve light-air performance, because when it's light you'll tend to find better breeze farther from the water's surface.

Boy do we know that around here!
In summertime, I've often seen a 30 degree difference in apparent wind direction from masthead to deck.

[Hydra]

Originally Posted by threadkiller

3) The flat edge give an "end plate" effect, the reason racing yachts have deck sweeping headsails, and airliners have canards on the wing tips. It REDUCES tip vortex/drag.

Unfortunately, this is not true. To be sure to reduce the tip vortex and the associated drag, you need either a winglet at the tip or a rounded (neither square nor pointed) tip, such as on Spitfire aircraft of WW II vintage.

On modern planes with square wingtips, the end vortex is controlled by carefully designing the twist in the wing. This is made possible because planes fly only within a narrow range of incidence.

Alain

[ozskipper]

Originally Posted by threadkiller

SNip

3) The flat edge give an "end plate" effect, the reason racing yachts have deck sweeping headsails, and airliners have canards on the wing tips. It REDUCES tip vortex/drag.

2 cents.
I want one.

Actually, I have always wondered why a smarter person than me hasn't put a little wing (canard) at the mast tip to try and remove some tip vortex. Especially on boats with Tri colors, aerials and other disturbances up the top.