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Old 04-02-2015, 23:49   #181
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Re: GUNBOAT Dismasting

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Gunboat has all the bases covered:

Gunboat Catamarans Feature GOST Security

But then, there is this from the report published in YACHTING WORLD:

This registered with me when I read it, as it was the first time I can recall of the CG supplying a tracking beacon to a yacht being abandoned. It certainly didn't happen with the Alpha 42 last winter, for instance. And, watching these CG videos, one has to wonder how the placing of such a tracker aboard was actually carried out, the rescue swimmer obviously has a higher priority in getting the people out of the water, than in ferrying a tracking beacon aboard the yacht. While these videos are always somewhat incomplete, never do we see the rescue swimmer getting any closer to the boat than is necessary in order to rendezvous with a crew swimming away from the boat... Especially, with time running as short as it did with this particular rescue, and the helo not even having the fuel to make it back to Elizabeth City...

Again, this report strikes me as a bit curious. Is this some new procedure the CG has instituted? Or, is it one simply reserved for $2 million CRUISING WORLD Boat of the Year Winners, owned by fabulously wealthy venture capitalists?

;-))

Can anyone recall having heard of the CG placing a tracking beacon on an abandoned yacht during the course of a helo evacuation before? I'm inclined to believe the YW report is simply in error, and the 30 day beacon mentioned is part of the GOST system referred to in the link above...
Installing a satellite tracking beacon takes all of a few seconds, I installed over 100 of them down in LA as part of the BP Deepwater Horizon cleanup effort. Just slip it into one of his zippered pockets, and once aboard, remove the tape backing from the VHB and slap it onto any dry horizontal surface. We used Energizer Lithium batteries which lasted over 9 months @ 12 updates per day.
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Old 05-02-2015, 04:46   #182
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Re: GUNBOAT Dismasting

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THOSE are NOT TOUGH conditions. Tough conditions are when the waves are high enough that when you are in the troughs the tops are mast height.
I remember a couple of typhoons while on a 600ft naval cruiser when on the 02 deck about 40 ft from the water while in a trough the horizon was above your head! That was definitely a little rough.
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Old 05-02-2015, 06:52   #183
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Re: GUNBOAT Dismasting

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BTW, at that location they are still in an area where there are huge eddies that are entirely random.
Yea, well, the eddies don't come and go every day. They persist for long periods and routers know where they are. Chris Parker has advised us on every Gulf Stream crossing we've made about the location of the eddies and we've been able to avoid them or use them to our advantage if any are on or near our intended route.

Dave
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Old 05-02-2015, 06:57   #184
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Re: GUNBOAT Dismasting

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Installing a satellite tracking beacon takes all of a few seconds, I installed over 100 of them down in LA as part of the BP Deepwater Horizon cleanup effort. Just slip it into one of his zippered pockets, and once aboard, remove the tape backing from the VHB and slap it onto any dry horizontal surface. We used Energizer Lithium batteries which lasted over 9 months @ 12 updates per day.
Thanks, I don't doubt that at all, seems it could be accomplished fairly easily, if indeed the rescue swimmer ever got close enough to the boat to transfer one aboard... But, with the swimmer remaining hooked to the wire as was done in the evacuation of RAINMAKER, there's good reason why they prefer to keep their distance from the boat...

It's just that in all the examples of yachts abandoned offshore recently, I've never heard of it being done before... In the wake of the abandonments of BE GOOD TOO last January, the 38 Island Packet abandoned 60 miles off Charleston during TS Andrea in 2013, and the Island Packet SP Cruiser off Hatteras 2 winters ago, the claims were made that salvage efforts would be forthcoming... And yet in none of those cases, were the boats ever seen again... Especially in the case of the IP ditched off Charleston, seems that would have been a fairly easy one to locate and salvage, had there been a tracker left aboard...
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Old 05-02-2015, 08:29   #185
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Re: GUNBOAT Dismasting

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BTW I have not looked closely at this particular Gunboat design, but I believe I do not see the 'usual' forward cockpit on this vessel as utilized in the majority of their previous vessels,...and certainly not the 'walk-thru' to that forward cockpit. My guess is they had to 'interrupt' this walk-thru in order to provide for a bulkhead across this region,...as there is very little 'upper boxing structure' (cabin top or other) to help keep this cat from folding down the middle.
I really liked this design. The lines are right there inside at the helm. But you can slide the window open and 2 convenient small steps lead forward through the window. You can clearly see the middle beam which supports the mast and that's the one you walk over. It doesn't look interrupted to me.

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Old 05-02-2015, 15:33   #186
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Re: GUNBOAT Dismasting

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I really liked this design. The lines are right there inside at the helm. But you can slide the window open and 2 convenient small steps lead forward through the window. You can clearly see the middle beam which supports the mast and that's the one you walk over. It doesn't look interrupted to me.

You can bet they have run finite analysis software on the structure. I very much doubt there are any issues with the hull. Rigging is another matter.
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Old 05-02-2015, 17:27   #187
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Re: GUNBOAT Dismasting

Why wouldn't they run FEA on the rigging?
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Old 05-02-2015, 17:45   #188
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Re: GUNBOAT Dismasting

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Why wouldn't they run FEA on the rigging?
Maybe GB have done FEA on the rig. But dynamic loading is a complex problem. Many (most?) FEA tools don't handle it particularly well. Using FEA on structures that don't move (much) is much easier than on a structure that undergoes considerable movement. Also, it's very difficult to apply all the loads (static and dynamic) to a rig for all conceivable scenarios. Someone may claim to have done it but within a few minutes a clever structural engineer can usually devise a scenario for which the FEA has to be run again. There are often too many variables to do an exhaustive analysis of every combination of static and dynamic loading.

Add sails (halyard tension, sheet/halyard length, sheet/halyard elongation vs. tension, wind speed, angle of wind, variation of wind speed vs. height, etc.) and the combination of variables quickly becomes astronomical. I would be surprised if someone claimed they had exhaustively analyzed the dynamic loading stresses on any sailing rig. I would not call them a "liar" but would be skeptical.

It's a bit like trying to analyze a skyscraper in Los Angeles under the simultaneous threats of an earthquake and a hurricane. The variables get out of hand.
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Old 05-02-2015, 19:08   #189
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Re: GUNBOAT Dismasting

Someone had a thread about a mast replacement on a mono. The carbon mast was defective on arrival and they had to buy a new one from another supplier and lost a s@#tload of money. GB uses Hall spars. I'm not sure if this was the good one or the bad one.
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Old 05-02-2015, 19:12   #190
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Re: GUNBOAT Dismasting

Hall was the good one.
Expedition Sailboat Rejects GMT Carbon Fiber Mast
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Old 05-02-2015, 19:12   #191
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Re: GUNBOAT Dismasting

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Maybe GB have done FEA on the rig. But dynamic loading is a complex problem. Many (most?) FEA tools don't handle it particularly well. Using FEA on structures that don't move (much) is much easier than on a structure that undergoes considerable movement. Also, it's very difficult to apply all the loads (static and dynamic) to a rig for all conceivable scenarios. Someone may claim to have done it but within a few minutes a clever structural engineer can usually devise a scenario for which the FEA has to be run again. There are often too many variables to do an exhaustive analysis of every combination of static and dynamic loading.

Add sails (halyard tension, sheet/halyard length, sheet/halyard elongation vs. tension, wind speed, angle of wind, variation of wind speed vs. height, etc.) and the combination of variables quickly becomes astronomical. I would be surprised if someone claimed they had exhaustively analyzed the dynamic loading stresses on any sailing rig. I would not call them a "liar" but would be skeptical.

It's a bit like trying to analyze a skyscraper in Los Angeles under the simultaneous threats of an earthquake and a hurricane. The variables get out of hand.
I would think that it's not necessary to analyze every variation to the nth degree, but they could have done enough analysis to cover 80 or 90% of scenarios to ensure structural integrity up to a known point. Like many things, as you pursue that last few %, costs and effort go up astronomically, but a lot can be done without going that far. Just thinking out loud. For $2.5M, I'd hate to be the owner asking the builder why the part that just failed didn't get the same FEA that the hull did. For that kind of money, I'd be surprised if they left anything, much less the rigging, to chance.

I dunno, maybe I'm giving GB too much credit?
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Old 05-02-2015, 21:58   #192
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Re: GUNBOAT Dismasting

Hi guys,
just a question. Remember a few months ago there was a 78ft carbon fibre gunboat mast for sale complete as they were replacing it with a much bigger rig? I'm curious whether it's the same boat? The rig was from 2001 and hailed from NY. I considered modifying that mast for our boat, but it wasn't economically viable as it was 3 metres taller, bit too much. I'm wondering whether it's the same boat. I can't find the email backwards and forwards with the skipper but thought someone on the forum might know whether it's the hot-rodded gb that lost its rig.
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Old 06-02-2015, 04:42   #193
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Re: GUNBOAT Dismasting

It's been a full week since the rescue and there's no news about salvage of the boat or follow up from any of the crew. Gunboat / Peter Johnstone have also stopped communicating since the first post on SA and on Facebook.


What's the probability of salvage in a situation such as this? Probably not high and the cost to salvage and repair may quickly surpass the value of the boat. It would be interesting if the boat makes it to shore somewhere. Be Good Too never made it.


I'm also really interested in what would happen if you were dismasted and a running rigging line fouled your propellers. If the mast is hanging off your sail drives at some point I'd think it would pull them out.
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Old 06-02-2015, 05:59   #194
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Re: GUNBOAT Dismasting

Looking back at GB Slim crossing the stream Newport to the Bahamas. They were crossing in 30 - 40 kts, using their solent, doused the main and tightened down their re-enforced topping lift as a back stay. If this was a known procedure why didn't Rainmaker follow suit?
Just wondering....
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Old 06-02-2015, 06:27   #195
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Gulf Stream Eddies

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Originally Posted by 2Hulls View Post
Yea, well, the eddies don't come and go every day. They persist for long periods and routers know where they are. Chris Parker has advised us on every Gulf Stream crossing we've made about the location of the eddies and we've been able to avoid them or use them to our advantage if any are on or near our intended route.

Dave
I really do not know that much about these eddies, so I went looking via google. Here are but a few sites I skimmed thru:

https://www.classzone.com/books/eart...2403page06.cfm

Finding Offshore Currents and Eddies - Florida Sportsman

Eddies in the Ocean

Gulf Stream Moved 125 Miles North in 2011 : Discovery News

I don't know that I have ever been 'officially' in an eddy, but I have certainly seen a fair number of 'chaotic seas' produced by complex wave interactions. These can be some very 'peaky' waves that seem to just rise up suddenly, then disappear as suddenly. They are totally out of the ordinary waves that might be present in the general conditions at the time. I think this was the type of 'rogue wave' that Phil Weld was trying to describe that caught him by surprise and flipped his tri called Gulf Streamer. In defiance, he named his next boat Rogue Wave...ha...ha

Since many of these eddies are anti-cyclonic to their surroundings, I have to imagine that there are huge possibilities for a great number of these mini-rogue waves to develop at the edges of these gulf stream eddies.
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