Really Pronounced Draft Stripes On an Extreme Boat!

[rardiH36]

An outing yesterday afforded my first encounter with an AC72. Only the Swedish team since the American Oracle boat was wrecked a few months ago during a collision with the water it was sailing on.

Couldn't help but notice the very pronounced draft stripes on the two head sails.

Per the pictures.

I wonder if the highly visible color and size is so sail trim can be observed by the support team from afar and then the info radioed to the skipper? And/or is useful for the post practice video review?

Being a midweek off-season winter afternoon, and just before the arrival of a Pacific Coast rain storm at that, it was pretty much just me and the AC72 on the bay. Pretty cool.

 

[RichH]

Could also be 'air battens' as well, dunno as its just a guess.

Im thinking of changing from aux. battens on my sport boat's jib (enhanced 'leech roach') to air battens for better shape control .... just as soon as the class rules allow it. Jib air battens are starting to become quite evident on some 'open development' classes.

The different 'thicknesses' seem to indicate that it would be easier for the 'bowman' to simply look up and compare ... the 'widest top batten/stripe', the somewhat wider mid-batten/stripe, etc. would probably 'seem' optically/visually to be the same width when seen from directly below hence a more precise visual comparison of all three simultaneously.

 

[rardiH36]

RichH:

"Air Battens" - Not being anywhere near the racing scene, this is the first time I've heard of them. I can visualize (I think) that they would sort of be a like soft version of a full batten on mainsail. How do they work? Are they pumped firm before each race? The headsails on the AC72 are on roller furlers I think. Can air battens be furled? Do you have url link to a website that describes them?

rardi

 

[rardiH36]

I just looked at some of the other AC72 pictures I took yesterday and found the one below -- the genoa definitely is being furled (or unfurled).

Interestingly on the other pictures of when the boat is sailing with the smaller jib, I can't see any evidence of the furled genoa. Appears that the genoa/furler/stay is detached from the bow-sprit and stowed against the mast?

 

[Jackdaw]

I'm pretty sure that a AC72s have on-board video cameras at deck level looking upwards and recording the sail shape anytime they are under way.. they review that with wind and boat data to optimize shape & speed.

 

[RichH]

Here's some info on some of the earlier versions of air battens, originally used in a vertical orientation. The air pressure is controlled from a cockpit central panel: inflate/deflate switch. Originally they were conceived to remedy the deplorable shaping and mal-performance of in-mast furling mainsails. Since vertical air battens have proved to be of benefit, the next logical progression would be to use them horizontally, just deflate/inflate during a tack when the jib LP is greater than 100% (jib foot length larger than the distance from the tack to the mast).

As previously stated, Im starting to see discussed horizontally oriented air battens (but not yet full length) on foresails - to help with sail shaping.
Such discussions have also included those with cruising true cutter rigs as full battens on the staysail would help solve the 'usual' shape problem with staysails - undue over-twist when the staysail clew is eased/released to 'outboard' as when on a reach or run.

http://www.sail-world.com/CruisingA...36441&SRCID=0&ntid=39&tickeruid=0&tickerCID=0

.... and to think that ancient Chinese mariners had already solved most of these sail shape problems over 1000 years ago: the 'junk rig'.

 

[RichH]

I'm pretty sure that a AC72s have on-board video cameras at deck level looking upwards and recording the sail shape anytime they are under way.. they review that with wind and boat data to optimize shape & speed.

Its been some time since I had any connection with AC, etc. boats ... but it has been strictly illegal for a boat to be 'coached' by any means than other than ON THE BOAT. Such discussions have always been in regard to 'only fair means to sail a boat' .... otherwise the one who can buy the most sophisticated computer, etc. will always win and thats not sailing but 'gizmo' usage in the eyes of the 'purists'.

 

[Joe]

I just looked at some of the other AC72 pictures I took yesterday and found the one below -- the genoa definitely is being furled (or unfurled).

Interestingly on the other pictures of when the boat is sailing with the smaller jib, I can't see any evidence of the furled genoa. Appears that the genoa/furler/stay is detached from the bow-sprit and stowed against the mast?

Not really a genoa.... rather an off wind sail, such as an asymetrical spinnaker, code zero, etc.. They are all carried on wire luff, detachable furlers. These are multihull boats, remember, with much smaller number of crew than the old monohulls.