Foiling cruising cat wipe out

[AngusMcDoon]

Angus, the boat started to get overpowered at 43s and the crew were considering which side to jump off at 49! Ain't a cat's chance in hell anybody could have twigged the risk and then dumping the main halyard between 44s and 46s. Easy to do from behind our computers mind

I know that. I'm not criticising them for not having done it, just saying it's the quickest way to dump power from the main if it's possible to do. I have sailed a high performance multihull for the past 12 years so I am acutely aware of the difference between what's a good theory and what can actually be done in the heat of the moment.

 

[dom]

I know that. I'm not criticising them for not having done it, just saying it's the quickest way to dump power from the main if it's possible to do. I have sailed a high performance multihull for the past 12 years so I am acutely aware of the difference between what's a good theory and what can actually be done in the heat of the moment.

I guess the question is, could you/would you double it up for cruising?

 

[NealB]

I guess the question is, could you/would you double it up for cruising?

She wouldn't be pushed to anywhere near that limit if she were cruising.

 

[Neil]

If you compare the position of the boom with that of the monohull it passed, it seems the boom is sheeted in hard and over the centre line suggesting the traveller is to windward - seems a bit much to me in anything more than light airs. The genoa sheet looks as if it's been released as it starts to capsize, but I don't see much difference in the main.

I sometimes crew on a First 37.1, which is quite tender, and whoever's on the man sheet has to be prepared to dump at a moments notice.

These comments made on the basis of little experience though.....I did recently read the RYA book on sail trim......

 

[dom]

She wouldn't be pushed to anywhere near that limit if she were cruising.

Not so sure - the envelope is very narrow when up on a foil!

 

[Hambler Rambler]

I just feel for the crew member who climbs onto the side of the hull (like a dinghy dry capsize), only to find himself violently thrown off when the rig hits the water, then colliding with various pieces of rigging on the way down.... cringe....!

 

[cobolt]

If you compare the position of the boom with that of the monohull it passed, it seems the boom is sheeted in hard and over the centre line.....

Yes, but then the Gunboat's AWA would be significantly further forward than the monohull's!!

 

[Neil]

Yes, but then the Gunboat's AWA would be significantly further forward than the monohull's!!

Yes, this is very true. Would you still have the boom so centered, though?

 

[Iain C]

As I'm guessing one of the few foiling forumites, the thing that surprises me is the leeward heel. The Moth is horrible with leeward heel...you must be at the minimum flat or ideally over to windward to have decent control. I get that the G4's mast is to windward of the foil, but it still looks odd sailing with that amount of heel. To me, the thing simply doesn't look wide enough (probably as it's a cruiser) to sail flat enough. But I've never sailed a foiling cat so that might be totally wrong.

There are many, many other dynamics going on with a foiling boat that your average sailor won't realise. With the main sheeted on hard, there's a lot of mast foot pressure pushing the boat down against the foils. Easing the main even a bit releases this mast foot pressure...for example to get through a lull, you can ease the main a bit...the boat will slow but normally gain altitude, you get through the lull and then it's back onto full power. If you'd kept the main on hard, the MFP will overcome the lift and you will fall off the foils. A boat foiling slowly is still going at the very minimum twice as fast as a boat in lowrider mode. This may partly account for why the G4 seemed to rear up a lot when the sails were eased.

The other is ventilation...there's an area of very low pressure across the top of the foils (more the rudder in this case as the main foil is a J foil, not a T foil. When the horizontal part of the foil gets near the surface, it can literally take a gulp of air which travels down the foil vertical, and you can lose all steerage, but not nesessarily lift. I have seen 23 knots in my moth and been able to move the tiller through 45 degrees and nothing happens. It's a horrible feeling...lots of speed and no brakes or steerage. If the horizontal foil is at an angle and the tip gets near or pierces, the surface, it's the same thing.

Looks to me (from the comfort of my armchair) like they were getting in trouble, COE was about to go past the COG, the eased the main, MFD reduced a lot so she reared up, rudder ventilated so no steerage, and from that point it was just a classic round up/wind gets under everything fall over kinda scenario.

Hats of to Gunboat for doing it...I hope that they can sort it, however whilst the Wipeout music is good and getting spat round the front of a Moth at speed usually isn't that bad, this one could have been really, really nasty, either due to entrapment, entanglement or hitting something very solid on the way down. Yikes.

 

[Hambler Rambler]

Hats of to Gunboat for doing it...I hope that they can sort it, however whilst the Wipeout music is good and getting spat round the front of a Moth at speed usually isn't that bad, this one could have been really, really nasty, either due to entrapment, entanglement or hitting something very solid on the way down. Yikes.

hehe... maybe hats would have been a good idea actually! Kind of crazy to be doing that in shorts and polo shirts really

 

[jwilson]

why did they not dump the main?

+1, and bear away. I think they did let the traveler out a bit, but main or kicker let right off would have probably sorted it plus a bear away. It did go pretty fast though: there's an instinct to keep your crew weight up to windward rather than climbing downhill to let off sheets/kicker.

 

[Buck Turgidson]

Needs apeedbrakes or lift dump to make it safe for anyone other than a pro crew with support boat. Love it.
On aircraft that have unpredictable or undesirable stall characteristics an automated system to stall the aircraft artificially before the real thing happens is fitted. (stick pusher) Probably should be looking at something similar or a steer by wire system with alpha/beta limiting.
I know some blokes who design such systems but then the boat's going to cost a lot lot more.

 

[dom]

Needs apeedbrakes or lift dump to make it safe for anyone other than a pro crew with support boat. Love it.
On aircraft that have unpredictable or undesirable stall characteristics an automated system to stall the aircraft artificially before the real thing happens is fitted. (stick pusher) Probably should be looking at something similar or a steer by wire system with alpha/beta limiting.
I know some blokes who design such systems but then the boat's going to cost a lot lot more.

A tiller shaker and dynamic control systems to enable the super-maneuverability of fourth and fifth gen fighter aircraft in order to exceed the standard aerodynamic envelope. Love it

 

[crewman]

She wouldn't be pushed to anywhere near that limit if she were cruising.

But if it were not being pushed would it be able to foil? If not then it is not a foiling cruising cat, and I suspect the foils would slow it down.

 

[westernman]

+1, and bear away. I think they did let the traveler out a bit, but main or kicker let right off would have probably sorted it plus a bear away. It did go pretty fast though: there's an instinct to keep your crew weight up to windward rather than climbing downhill to let off sheets/kicker.

That is the recipe for a cart wheel. The top of the main then pushes the bows down, then you hit the back of a wave and deaccelerate rapidly (well the front of the boat does, the back just carries on.....).

I am expert in doing those (entirely unintentionally).

 

[AngusMcDoon]

+1, and bear away. I think they did let the traveler out a bit, but main or kicker let right off would have probably sorted it plus a bear away. It did go pretty fast though: there's an instinct to keep your crew weight up to windward rather than climbing downhill to let off sheets/kicker.

It doesn't have a kicker. Performance multis often don't. The crew did let the traveller out - you can see it between 44 and 48 seconds, but not quickly enough to be effective. You can't bear away when your rudders have lost effectiveness; I reckon that starts at about 40 seconds when the windward hull lifts and by 45 it's totally gone as the boat turns towards the wind.

 

[grumpy_o_g]

The boat luffed as it was starting to capsize. One thing you never ever do in a multi is luff when over-pressed. I suspect it was involuntary.

I'm just waiting for someone to come along and say it proves cats are unsafe!

I think it proves that, if you want to go quickly, you should by a displacement monohull, not a foiling multihull

 

[NealB]

But if it were not being pushed would it be able to foil? If not then it is not a foiling cruising cat, and I suspect the foils would slow it down.

Indeed...the term a 'foiling cruising' cat, seems, at the moment, to be a paradox.

 

[kengill]

I remember a cat on Grafham Water went so fast that when he lost it he cartwheeled at least two times we were planing all out with just the genny on an enterprise as he went past us.

 

[GrahamD]

Indeed...the term a 'foiling cruising' cat, seems, at the moment, to be a paradox.

So that's why they're called "scatter cushions"! I bet they spilled their tea, too.