GUNBOAT Dismasting

[SailingMum]

Originally Posted by Delancey

FWIW nothing disruptive about rotating wing masts, they've been around for prolly thirty years now. As far as single spreader goes, something to be said for KISS most of the time.

Agree. What's the boat with the red wing mast, Delancey?

[Delancey]

Possibly an old Newick tri? Not sure found it image searching and the source doesn't say. Here's another shot.

[Delancey]

Talk about disruptive! Here's your 30 knot multihull capable of short handed circumnavigation!

http://www.stevencallahan.net/images...ck-dec2010.pdf

[Stumble]

Originally Posted by SailingMum

That's sort of right Greg, but actually they haven't avoided all disclosure. GB has made a few posts on SA and the skipper has given his account to them (yet to be published).

I agree that the mast going doesn't condemn the design. But to me it looks like the marketing of it could be condemned. The impression is that it's sufficiently flighty that you either need good expert crew and very careful weather routing, or to use a delivery rig with cut down sails, castrating the supposedly incredible passage times boasted of.

Either way, it's not quite the boat that inexperienced but rich buyers would have expected from the marketing.

I'd like one though! But I think the average family cruising, with the typical risk profile of family cruisers, will likely post faster passage times in an old outremer 55light, which will also be safer in a storm. You can geut a decent one of those for about 300k, which for me personally would be in the ballpark of what the GB55 is worth. Still, all that carbon goes well with the Breitling and the pacemaker.

It is notoriously difficult to control the owner of a large company. What his attorney is saying and what he is doing may be in conflict. He wants to get out and defend, or inform the public, or both. His attorney just wants everyone to shut up untill they know exactly what happened.

As for the advertising... My guess is that GB really believes what they are saying, and designed to do what they claim (with the assumption of adversity puffery)m that doesn't meanthey didn't make a mistake in the design of the rig. The design brief almost certainly encompassed making this type of passage, and I would guess they really thought that the design was sutable. But they were wrong.

ASSUMING that the above is correct the real question is how they handle it. If the problem turns out to be a design defect then it needs to be corrected and a new rig needs to be designed. If the problem was a manufacturing defect (I doubt it) then Hall spar may need to adress their QC.

To me this is in no way a criticism of GB generally, just an acceptance that when you push the envelope sometimes you get it wrong and have to redesign to fix the problem. In a similar vein I know an Andrews 70 that went thru two masts in three years (the old Pegasus owned by Phillip Kahn) before the rig design was worked out.

Again, I think this is just a teething problem with a new design (albeit a major one), and it will be sorted.

[SVNeko]

Originally Posted by Dave852

Ok, if it was a slow enough cat and or the squall came with a wind shift favorable to your argument I could see your method working. But let me be more descriptive. Let's say close reaching means sailing 45 degrees off the apparent wind. And let's also say we are discussing fast catamarans. Now let's say we are close reaching in the fast cat in 18 knots of true wind. At what angle do you suppose the true wind is at? Well I am sure someone with some math smarts will be able to calculate that if they had all the data needed but for the sake of this visual let's say the true wind is at 85 degrees when a 50 knot squall hits with no direction change. For a second until the boat speed increases the apparent angle will increase. If your instinct is to bear off you will only have to turn though 10 degrees or so before she starts to de-power but if you decide to head up you have a long way to go and in fact will power up before ever getting there.
Your boat, while not a gunboat and depending how much weight you are carrying should be able to mimic this scenario as she is capable of a turn of speed. Next time you are sailing fast enough to bring the apparent wind forward try bearing off and then bearing up. See which one gets you to a calm place faster!

I could be wrong but at 10 kn boatspeed it seems that the TW is still only at about 50 - 55 deg. The boat in the example could have been going faster but for a cruising cat reefed down in squalls (remember even this GB was only going 6) 10 is plenty fast. That still seems like a pop your head to wind situation to me. I think you are envisioning a lighter wind or deeper angle scenario. God knows I have had the bejeezus scared out of me rounding up to drop sail a few times from deeper angles. By the way, in controlled situations, I reef, and even drop the main, by sheeting in the headsail and using its backwash to put pressure on the back side of the main.

[transmitterdan]

Originally Posted by Southern Star

Bearing off while letting out/releasing the sheets is the best way of avoiding capsize/strain on the rig when suddenly overpowered while sailing a cat on a close reach/beating. There are three reasons:

1. As has been pointed out, if you head up the apparent wind increases, thereby effectively increasing the force of the wind on the sails. Conversely, if you bear off, the apparent wind decreases, thereby effectively reducing the the force of the wind on the sails.
2. The force generated by a sail is typically about 15 degrees forward of perpendicular to the boom, or foot of the sail. That is why boats heel more when sheeted in and sailing close to the wind (more of the force generated goes to the side -i.e., towards heeling, than forward). Conversely, when reaching/the sails are let out, more of the force generated by the sails is directed forward, rather than to the side. This results in less heeling even with equivalent force of wind on the sails. Until you are luffing, heading up will only move more of the force on the sails to the side and increase heeling.
3. As you turn up, the centripetal force will tend to increase the roll to leeward, further increasing the risk of capsize (think of the sway/roll of a car away from the apex of a tight turn). If you were in a jeep which started to lift its inside wheels in a tight turn, would you continue to turn up, or turn away in order to bring the inside wheels down? Same thing with a cat.

Therfore, when suddenly and dramatically overpowered when sailing on a close reach or beat, in order to avoid capsize one should let off on the sails while steering to leeward. This, of course, may make reefing/dropping the sails more difficult in the short term than successfully heading up into the wind. However, if the boat capsizes while heading up, you will no longer have the opportunity to reef or drop the sails at all!

Brad

If going close to the wind and suddenly become over powered releasing the sheet will de-power. But going down wind releasing the sheet may make things worse. But in either case I think heading up while releasing sheets should not increase capsize forces. But I'm a mono guy and don't think/fret too much about capsize. On my boat if going close to the wind and sudden increase in wind the boat will head up on its own.

But once you head down you are committed and the risk to the rig increases dramatically. If one or both bows punch into a big wave doing double digit knots a lot of energy has to be dissipated quickly. This sounds a bit like what might have happened to RM.

[Polux]

Originally Posted by smj

The Gunboat 55 has sliding hatches to close the hulls of from the bridge deck, they looked pretty water tight to me. I'm sure she was designed as an open bridge deck concept. Seems to me that any large volume of water that made its way into the bridge deck area would shed out the sterns at a rapid rate.

I would not understand if it had not them but I looked on movies and pictures and could not find them. Do you know of any picture or movie that shows them?

PS. Ok I have found them. They don't seem really watertight but I agree they are enough for the job on that location.

[Jon Eisberg]

Originally Posted by transmitterdan

If going close to the wind and suddenly become over powered releasing the sheet will de-power. But going down wind releasing the sheet may make things worse. But in either case I think heading up while releasing sheets should not increase capsize forces. But I'm a mono guy and don't think/fret too much about capsize. On my boat if going close to the wind and sudden increase in wind the boat will head up on its own.

One thing that really had me wondering about soma's account posted on SA and above, is it sounded to me like it presented a great risk of an accidental gybe, which could be catastrophic in such a situation... Another poster followed up with the question of whether he was practicing "leech feathering" in that situation... Needless to say, there was no response given... ;-)

Originally Posted by transmitterdan

But once you head down you are committed and the risk to the rig increases dramatically. If one or both bows punch into a big wave doing double digit knots a lot of energy has to be dissipated quickly. This sounds a bit like what might have happened to RM.

Agree, that seems a very likely scenario, to me... Especially, given Mr Johnstone specifically mentioned the "large South swell" they were running into, making the conditions particularly boisterous...

Perhaps I've missed it, but one question I'm a bit surprised that hasn't been given a more attention, is the role that RAINMAKER's "wave piercing" bows might have conceivably played in the accident... With the loss of the Alpha 42 last year, that was a much-debated aspect of the design, and how it might have contributed to being punched by that wave...

Much earlier in this thread, I questioned someone who had made a reference to a heavy wave strike over the bow being the cause of the dismasting... A cite for that reference couldn't be found at the time, and I never came across one in print... However, turns out that poster was right (my apologies, I've forgotten who it was):

"There was 40 knot winds and 13 foot seas and they took a wave over their bow that appeared to be a little bit too much for their boat and the mast split in half," said Coast Guard Officer First Class Allen Facenda.

Video Captures Coast Guard Rescue After Pinterest Investor's Boat Hits Stormy Seas - ABC News

Could be just me, but I've never understood the appeal of a "wave piercing" bow on a boat designed to be an offshore passagemaker... None of the higher bows on most of Gunboat's older models would be considered 'bluff', by any means, but for a boat intended to be taken offshore, they sure look a lot better to my eye...

[tp12]

Originally Posted by Jon Eisberg

Well, I've certainly done my share of "speculating" about this incident, but I would suggest we still do not "know" many of those things on your list...

I'm proud of you Jon!

[Polux]

Originally Posted by Jon Eisberg

....
Could be just me, but I've never understood the appeal of a "wave piercing" bow on a boat designed to be an offshore passagemaker... None of the higher bows on most of Gunboat's older models would be considered 'bluff', by any means, but for a boat intended to be taken offshore, they sure look a lot better to my eye...
..

The so called wave piecing bow contrary to what most think has normally a bigger buoyancy than a normal bow. True, it allows for less drag and a bigger waterline length but also helps to keep the bow up. It all has to if they are well designed or not. I cannot see any disadvantage (if they are well designed) and can see several advantages.

They are also increasingly used on fast monohulls and this particular one is a very seaworthy one, not to mention dam fast. You can see that even on nasty seas surfing at full speed that bow is really high, so high that they had a problem...over 20K they lost the speed instrument information cause the sensor was in the air

https://www.youtube.com/watch?v=xPkfpLx3CB0

[neilpride]

Then according to the CG dude this is getting more clear to me, no lowers, DW fast and seconds later stop dead in the wáter , mast snap in 2 pieces and game over, is not even a Gun Boat flaw or whatever, it happen at monos to with CF mast or Alu, there is obviously a lack of midle support in RM mast, 2 lowers and maybe would be talking about a diferent isue..


Lesson learned , dont sail to fast against step seas....my 2 cents.

[Imprezza72]

Originally Posted by Polux

The so called wave piecing bow contrary to what most think has normally a bigger buoyancy than a normal bow. True, it allows for less drag and a bigger waterline length but also helps to keep the bow up. It all has to if they are well designed or not. I cannot see any disadvantage (if they are well designed) and can see several advantages.

They are also increasingly used on fast monohulls and this particular one is a very seaworthy one, not to mention dam fast. You can see that even on nasty seas surfing at full speed that bow is really high, so high that they had a problem...over 20K they lost the speed instrument information cause the sensor was in the air

I always wondered about them but even the Volvo 65's have them.. This a quote from the Volvo Ocean Race website:

4. Reverse bow
The reverse bow is mainly a cosmetic feature, in the most photographed area of the boat, but it will also help keep water off the bow.

[GoingWalkabout]

Jon, I'm one of those who mentioned the wave crashing over the front and then the mast came down. I carefully read every quote I could find from the Coast Guard. This piece of information is amazing and so very important. I am sure that since the helo arrived after the event the Coast Guard Officer didn't make this up but was told about the large wave and the mast then splitting in half by someone from the Gun Boat.

I find it very strange indeed that all of the crew making self serving statements on SA (another site) have not mentioned a word about this. I think an eyewitness account fresh at the time of the incident is worth a great deal more than clever sanitised versions that come out later.

[donradcliffe]

Originally Posted by neilpride

Then according to the CG dude this is getting more clear to me, no lowers, DW fast and seconds later stop dead in the wáter , mast snap in 2 pieces and game over, is not even a Gun Boat flaw or whatever, it happen at monos to with CF mast or Alu, there is obviously a lack of midle support in RM mast, 2 lowers and maybe would be talking about a diferent isue..


Lesson learned , dont sail to fast against step seas....my 2 cents.

I think you are right on any mast which can pump forward in the middle. In a mono, the solution is easy--put the runner on. On a GB, knowing what I know today, I'd rig a temporary runner from the spreader to the stern.

[smj]

Originally Posted by Polux

I would not understand if it had not them but I looked on movies and pictures and could not find them. Do you know of any picture or movie that shows them?

PS. Ok I have found them. They don't seem really watertight but I agree they are enough for the job on that location.

They slide fore and aft and have a decent gasket. I can't see them taking on much water.