Standard Vs Fully-battened mainsail on cruisers or racers

[Resolution]

I have a fully battened main with Harken cars and a stackpack. Hoisting needs careful lining up to windward, but dropping is a delight.

Do any of the fully-battened brigade change the tensions on their battens in response to different wind conditions? Long ago in a highly competitive Hobie 16 fleet one of the key factors in setting the boat up was to get the right compression on the battens and thus the right inbuilt curvature on the sail. Back in today's big cruiser, I very occasionally slacken off the batten to flatten the sail if we are expecting a windy weekend.

 

[Birdseye]

If batten tension controls shape on a fully battened sail what if any effect does halyard tension have? Is it as effective on fully battened as on normal sails?

 

[horatio_nelson]

Great answers

I still want one...

Can a standard sail be retro-fitted as fully-battened?

 

[Sundowner 39]

+1 I would like to know.........

 

[AngusMcDoon]

If batten tension controls shape on a fully battened sail what if any effect does halyard tension have? Is it as effective on fully battened as on normal sails?

Same effect, just less so.

 

[dom]

Same effect, just less so.

Not quite; on a fully battened system the shape of the main is principally controlled by batten tension and taper (these two parameters predetermine each batten's shape under tension). If for example you want to flatten the sail: winding on the backstay (fractional rig) and tightening the outhaul work in exactly the same way as on a regular sail. However, you will not be able to pull the draft forward much by increasing halyard/cunningham tension; for this reason racing boats generally individually set each batten's tension depending on wind and sea conditions.

Fortunately for cruising sailing this kind of sophistication is totally unnecessary - just don't overload the sail with heroic halyard/cunningham tensions.

 

[sailorman]

+1 I would like to know.........

You might ask MichaelWs sail maker ( Happy Christmas :encouragement:

 

[GrahamM376]

Yes, if the sail is sheeted in tight first and topping lift raised (as you normally would), but if I'm going to turn down wind I drop the main and use twin headsails

+1

Need to go to the mast though and pull it down far enough as the top section tries to wrap over lazy jacks until lowered some way.

 

[AngusMcDoon]

However, you will not be able to pull the draft forward much by increasing halyard/cunningham tension; for this reason racing boats generally individually set each batten's tension depending on wind and sea conditions.

It can be pulled forward a bit, which is why I said "less so".

 

[dom]

It can be pulled forward a bit, which is why I said "less so".

OK a smidge perhaps; but mast bend, then batten tension, then outhaul become the dominant parameters. Which makes me wonder how suitable masthead rigs are to fully-battened sails, in particular when hard on the wind. I'd guess one could set an average batten tension before departure, but would be interesting to hear from the horses mouth.

 

[AngusMcDoon]

OK a smidge perhaps; but mast bend, then batten tension, then outhaul become the dominant parameters. Which makes me wonder how suitable masthead rigs are to fully-battened sails, in particular when hard on the wind.

On my boat with a fully battened main halyard tension is pretty much all I have to play with once the sail is up. The position of maximum draft can be changed more than just a smidge. My mast is almost totally rigid and cannot have further bend applied from sail controls, the outhaul cannot be changed when the sail is loaded, no Cunningham, and batten tension is not changed all season. Full battens allow a large roach though as I have no backstay.

Sailing performance on a Dragonfly comes more from brute force and ignorance than any twiddly sail shape tweaking.

'ere it is...

 

[flaming]

Fully batterned (or at least mostly - like TK) is absolutely what I'd specify for cruising. Gives a great sail shape without much effort, maximises area, helps keep the sail tamed and not flogging itself to bits when motor sailing etc.

The reason racers don't use them is largely that it is very difficult to depower them. Not a problem on a cruising boat, you just tuck a reef in, but you don't want to do that racing, as you're about to turn the corner and go downwind.

There is a trend now amongst the very high end boats to go for "square top" mains - like these.
http://www.mcconaghyboats.com/mc38-specifications.html

But even then, only the top couple of battens are full.

 

[AngusMcDoon]

There is a trend now amongst the very high end boats to go for "square top" mains - like these.
http://www.mcconaghyboats.com/mc38-specifications.html

Are they backstay-less using some form of rig like the B&R?

 

[flaming]

Are they backstay-less using some form of rig like the B&R?

No, twin backstays going to the aft most winches. Mostly a tuning aid I'm told though.

 

[dom]

The position of maximum draft can be changed more than just a smidge. My mast is almost totally rigid and cannot have further bend applied from sail controls

Sailing performance comes more from brute force and ignorance than any twiddly sail shape tweaking

Aha, I see you sail a Dragonfly, I've sailed a couple of those before and once with Jens Quorning in Denmark, I think it was a 920 Extreme. IIRC the central backstay is replaced by de facto running backstays on each of the two floats, which as you say cannot be over tensioned for structural reasons. I do remember there's a logic behind the circular mast section but forget what it's based on.

Nice sail, but for the life of me I can't see how you can change the shape of a sail much with so many battens using halyard tension alone, but I'm happy to take your word for it.

As for the performance thing, let's agree to differ; I was always taught it comes from brute force and "finesse", but each to their own.

 

[AngusMcDoon]

I do remember there's a logic behind the circular mast section but forget what it's based on.

It's a lot cheaper to make and more robust than a foil section, as simple as that.

I can't see how you can change the shape of a sail much with so many battens using halyard tension alone.

Lots of it. 2-1 Dyneema halyard, rigid almost straight mast, low friction cars all mean that the tension can be cranked up and effective.

As for the performance thing, let's agree to differ; I was always taught it comes from brute force and "finesse", but each to their own.

What I mean is that my boat has minimal sail tweaking controls, but a high sail area to displacement ratio - so it's brute force rather than finesse that makes my boat go. I realize that it's different on other boats with lots of bits of string and crew to pull them. I've edited my post above to make that clear.

 

[dom]

Lots of it. 2-1 Dyneema halyard, rigid almost straight mast, low friction cars all mean that the tension can be cranked up and effective.

I seem to recall that the mast section and taper was inspired by something, but for the life of me can't remember what.

Re sail shape, I'm familiar with 2:1 dyneema halyard systems and have the same on my boat. But I cant get my head around how off-axis forces on the mainsail could impart a significant change in the shape of so many battens, unless they're exceptionally light. I'd be genuinely interested to see before and after halyard tension photos.

 

[AngusMcDoon]

These are the battens...

http://www.fiberfoam.net/sailbattens/

sail trim pics will have to wait until my mast is back up.

 

[Woodlouse]

No, twin backstays going to the aft most winches. Mostly a tuning aid I'm told though.

It's a brave man who puts that supposition to the test on a downwind leg.

 

[dom]

sail trim pics will have to wait until my mast is back up.

Fair enough. BTW for cruising that's a nice main, very nice