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[idlerboat 116]

To make this concept more real, the pivot point of the rig needs to be in line with the mast step , fore and aft.

Given that a lot of big cats dont have back stays it is only needed for the forestay (furler) to be on a bridal (a lot already have this.

The caps, D2s and lowers are not a problem because these are the ones we are going to change angle.

With continuous rigging...(most) it leaves us with one stay to deal with...

No differant than a tabernacle mounted system with much higher loads......

[buzzook 0]

In the original article on Farrier's website which I read some time ago, http://www.f-boat.com/pages/background/capsizearticle.html he discusses the options of releasing the stays closest to the water surface to allow the hull to pivot around the chainplates of the uppermost stay, thus improving the righting ability.

 

He shows it on a tri, of course, but no reason why it shouldn't work on a cat....

 

One of the reasons I think the masthead airbag system would be of use is that, especially in the case of bigger, production, cats (rather than lightweight racing machines like Ninja or the AC boats), they tend to invert completely, rather than fall sideways, like a mono dinghy.

 

So the airbag would be necessary to raise the masthead itself back to the surface - as a first step in the self-recovery operation.

 

Try and imagine a cruising cat or tri in mid-ocean. Whatever idea is used has to work there, and for short-handed crews....

 

Inshore, most people need only a space blanket and a lifejacket, as someone will eventually come to the rescue, in most places - so this system is probably not sensible for racing cats...although if it could be made light and compact enough, it might....I'm more focused on single-handers and cruising sailors, who without external help simply will not be able to right their vessel.

 

As Farrier (I think) mentions, offshore the wind and swell could be used as another aid for righting...the trick is to avoid being blown right over again....

 

So Step 1 is get the masthead back to water level

 

Step 2 get the sails off as best you can

 

Step 3.....flood hull; muck about with stays; fold akas if able to...and so on.

 

Another option to the add to the whole *system* is the option of additional airbags - either on the inside or outside of the ama at deck level.

 

Even a few inflatable bags, like those readily available for divers and salvage operators, could be carried and, with appropriate lines attached, led to the outside of the underwater hull, and there inflated, creating additional buoyancy that *should* help raise that hull from the water, making the boat less stable in its side-capsize position, and thus assisting with the self-recovery.

 

So a cat would probably benefit from such aibags being beneath the lowermost hull (once in the side-capsize position, thanks to the masthead float), whereas tris it might be more sensible to have them inside the hull and beneath the tramp or wingdeck.

 

And to the poster who referred to the cream-whip canisters as nitrous - that's correct (for cream whip) - but they are also available as CO2, which is cheaper, and the ones for paintball marker guns are also CO2 and much bigger..!!

 

My *guess* is that, for larger vessels, needing a much larger cyclinder, BOC or similar gas cylinder trader will be the appropriate place to exchange the necessary cylinders.

 

At a pinch, the airbag(s) could even be inflated with propane, which most boats carry these days for cooking or BBQs...so there are definitely options for the inflation gas.

[Guest]

Or compressed air from a dive tank.

[rigger 47]

Rather than a compressed gas has any thought been given to the system that is used in car airbags?

 

Might be too expensive?

[buzzook 0]

CO

yeah, exactly....one of the thigs I've noticed is that there is a smaller compressed air divers bottle made of fibreglass that is about the size of an in-car fire extinguisher.

 

I think it's caled a 'buddy bottle' and is for when someone runs out while decompressing on the way up, just to tide them over and avoid a rush to the surface and the bends...

 

As these are relatively readily available, might be a suitable candidate for the bigger boats, and there are dive shops to refill them *everywhere* - even in third world countries, for the cruisers..

 

Judging by what car maufacturers charge to re-arm an airbag, I'd ay it would not be feasible, hence why I haven't bothered to go down that path.

 

KISS principle, at all costs...

[GregW 28]

Interesting thread which I originally ignored because of the subject line. Reminded me of this you tube clip.

which shows that if you stop the boat becoming completely inverted the potential for getting going again without outside assistance is a realistic possibility. Not a new idea - Gougeon Bros offered a similar setup on the G32 20 years ago. While they have used a solid masthead float on the Firebird the idea of some sort of air-bag device to replace it is certainly intriguing - particularly if it can be made easily re-usable.

[Hurts 6]

This thread is getting interested now that it has stabilized. I don't think you need to solve the problem of cruising cats - they flip only rarely and huge forces involved by the time they are in trouble.

 

The main customers in Auckland that I would see are your racing cats and tris that occasionally do some soundings of the seabed with their mast heads. Aim for that market and get a few likely suspects to trial your product, rig up for cameras and probably within 6 months you may possibly have a great you tube video of it working (or not). The comment by Jono on post #2 sounds like they are onto it already - now they just need to push Ninja hard again and await results, be great if they can come up with a practical solution.

[Guest]

One of those larger hand pump bellows things that you can pump up at slow but grunty pace of easier high volume pace. Trigger that with a small cylinder of some sort for deployment speed and ease. The same pumps can also suck so once back on it's feet can be used to suck the bag back into it's home. The pump mounted at the base of the mast somewhere with small tubes running up to the mast top to save weight, windage and other stuff. Bit manual putting it away but one crew can do that while the rest tidy the boat up again.

[buzzook 0]

I think motobike has hit the nail on the head - the airbag system will vary depending on the length of the boat and it's usage.

 

For example, as the Orion cat vido shows, a permanent float at the masthead, plus release of the stays closest to the ewater surface, greatly assists with self-recovery.

 

The video of the Orion crew performing just that confirms what Farrier suposed many years ago.

 

But it also highlights how quickly the airbag would need to be deflated and recaptured, which makes me think that, for racing boats needing a quick solution, the 'model' discussed previously of a fully self-contained unit hauled to the masthead and triggered by a lanyard to the deck, would probably be the most appropriate.

 

The crew could be hauling it down and repacking it while the helm re-stayed the mast, which would be easy to do with Hyfield levers or similar set-up.

 

And for cruisers who, lets face it, apart from the very wealthy and retired few, are not out on the water, offshore, year round, the ability to haul the airbag unit down to deck level and store it below decks; to inspect it at regular intervals (like all other maintenance items this would need to be done regularly), and would be a lot easier to perform if it could be hauled down and checked - or re-charged after dployment and re-righting.

 

So I'm beginning to think that the idea of a permanent airline in the mast and a permanent mount at the masthead (or caps: point taken..), might not be the "best" way to go.

 

In which case, the idea jon mentioned that the Ninja boys appear to be working on - using a lifejacket inflator as the trigger (at least) is looking good.

 

My thinking is that the airbag would need to be packed down and be longer than wider, so it could operate either atop the mast, or perhaps, as this are is most often used for lighting ands instruments, on the leading edge of the mast below the cap.

 

As such, if it had an alloy baseplate, curved to the shape of the mast edge, and wrapping perhaps a third of the way round each side of the mast, another piece of alloy could be formed into a flat-Z-shape, to provide a flange into which the baseplate would slide.

 

The halyard cleated off, plus the flanges on the sides, would sedcurely anchor the baseplate. Once the manual trigger line is tugged, the bag would pop out of its wrappings or cover (and vlcro is probably enough to use as a restraint which the air pressure would force apart) and thus deploy, but be restrained by the baseplate being 'locked' against the surface of the mast.

 

The bigger the boat, the bigger the airbag, the bigger the baseplate and securing flanges, the bigger the air canister.

 

The canister(s) [might be more aerodynamic with two slim canisters rather than one larger diameter one] would be mounted vertically to the mast onto the baseplate, with an integral baseplate for the airbag mounted over them.

 

The sides of the unit could be curved in such a way to minimise the disruption to the airflow at the top of the mast.

 

How does that sound?

[ex TL systems 63]

seems like the first step would be to have bouyancy in the mast,, my cat has been over once and has a 50 ft x 1 ft wing mast , too hard to try and seal that watertight but what about filling it with blown ie liquid expanding foam, go around any wiring ie that would be set in place and have all halyards winched up tight when the foam is setting, then next day pull the ropes free on the winch , they should have formed thier own :tunnels, If the boat goes over in a pitchpole, well it should be easier to get the mast head back to the surface , and if it went over sideways it should/may be enough bouyancy in the mast to keep it from going right over. Not much weight in the foam as long as it doesn,t absorb water, that and whether it may cause corrosion in the alloy mast would need to be considered, if you needto remove the foam later that can be done by dissolving with a solvent. If you were already upside down you may be able to winch down bouyancy ie fenders etc on the halyards and thier winchs. A heavy water filled mast will act like a 50 ft ballasted keel and make recovery very difficult to achieve,even with a mast head float unless it is substantial.

[buzzook 0]

The expanding type foams are polyurethane - and are not *100%* waterproof - they eventually absorb water and become a sponge.

 

The best foam for buoyancy/floatation is Extruded polystyrene (XPS) which has much tighter and smaller bubbles than the cheaper Expanded polystyrene (EPS).

 

Accept no imitations!!

 

Having said that, if you were adding buoyancy foam into a pocket at the top of the mainsail, you could use EVA foam (ethylene vinyl acetate) which is as waterproof as XPS but has the added benefit of being somewhat flexible, whereas the XPS can only be formed using heat.

 

It seems from what the Orion crew have determined that a fixed masthead float of glassed over XPS, plus quick releases on the shrouds, is enough to enable a lightweight racing cat to self-recover, and very quickly.

 

See the video a few posts back.

 

This it appears would be WAY quicker and easier (and therefore more *competitive* than an airbag, despite the small amount of additional top hamper and drag....in racing, getting up quickly after a knockdown is ALL of the battle....

 

As for filling the mast with foam, remember that *all* the floatation effect needs to be at the mastHEAD, not just along the mast, as it is crucial for the self-righting ability of the vessel to get the mast as close to horizontal as possible.

 

Sure, a foam filled mast will float, so that's good, but not as high above the water as one with the correct amount of floatation at the masthead, which could be critical for self-recovery.