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Sharks?? Storms ??
http://www.hobie.com/au/en/forums/viewtopic.php?f=71&t=19594		 Page 1 of 1
Author:  Wojtek722 [ Sun Jan 10, 2010 4:26 pm ]
Post subject:  Sharks?? Storms ??
Are there any sharks here? If so are they dangerous and/or will they attack?

Also, in case of a thunderstorm would it be advisable to lower my mast or it wouldnt make a difference ?
Author:  Cowsgomoo [ Sun Jan 10, 2010 10:22 pm ]
Post subject:  Re: Sharks?? Storms ??
Wojtek722 wrote:
Are there any sharks here? If so are they dangerous and/or will they attack?

Also, in case of a thunderstorm would it be advisable to lower my mast or it wouldnt make a difference ?


No, you should be safe from sharks reading these forums..... :D

As to thunderstorms, I don't think I'd like a big carbon fibre ligntning rod up. Then again, if you drop it your head becomes the highest object....

Maybe leave it up and sail to safety quickly?
Author:  skymax [ Mon Jan 11, 2010 12:52 am ]
Post subject:  Re: Sharks?? Storms ??
Acording to the Shark Shield ppl sharks are only dangerous when in, "Full predatory strike mode", how you determine this before a "Shark event' I do not know.
But really, sharks know what their normal food looks like and if you are not fishing you would be pretty uninteresting to them, usually only an old or sick shark that can no longer pursue it's normal food will try something odd but slow.
As many reports as I could find of kayak/shark encounters consistently show the shark losing interest after taking an "investigative bite", even when the kayaker(s) were tipped into the water by the contact.

Leave the mast up, the energy wants the quickest path to ground and will pass right through the frame to the water, Lightning can sometimes behave in freakish ways though, don't sail in storms.
Author:  walt [ Thu Jul 15, 2010 9:41 am ]
Post subject:  Re: Sharks?? Storms ??
Where I sail, I often run into thunder storms. Does anyone know if the AI mast is actually carbon - and conductive? Mine is black but Im not sure if its carbon or not and I would guess its NOT simply because I think Hobie would advertise this - and I don't think they do.

FYI, I think a carbon mast would be GOOD for lightning on an AI or TI. There was a windsurfer in New Mexico who's mast took a direct strike while sailing and the energy all went through the carbon mast and excited at the bottom of the mast directly to the water surface. Of course, it blew a hole in the board directly under the mast but the guy sailing was relatively unharmed. If the conductive mast had not been there and everything else was unchanged, the strike may have used the guys body as the conductor..

Ie, a conductive mast would somewhat form a "cone of protection" for the person piloting an AI. And the AI is well set up to for this with only a small distance between the bottom of the mast and the water surface with relitively good distance between the bottom of the mast and the pilot. It would damage the hull pretty bad but the AMA's would still float you.

Some would argue that a conductive mast increases your chance of receiving a strike. My opinion is that this could be true - but it would only have a tiny influence on where a strike hit - possibly only causing a direction change in the strike just before it hit the water surface. But the conductive mast would likely have a large effect on personal safety if you were unlucky enough to be in the direct path of a strike.
Author:  whosyerbob [ Thu Jul 15, 2010 12:29 pm ]
Post subject:  Re: Sharks?? Storms ??
walt wrote:
Does anyone know if the AI mast is actually carbon - and conductive? Mine is black but Im not sure if its carbon or not and I would guess its NOT simply because I think Hobie would advertise this - and I don't think they do.

I suspect it's just black fiberglass; carbon fiber is seriously $$$ and I'd be surprised if it was included in the base price of a TI.
Author:  KayakingBob [ Thu Jul 15, 2010 12:58 pm ]
Post subject:  Re: Sharks?? Storms ??
Well, the instructions that come with the AI (& TI?) warn to watch for wires overhead when handling the mast, and fiberglass is non-conductive as far as I know...
Author:  tspbrady [ Thu Jul 15, 2010 1:46 pm ]
Post subject:  Re: Sharks?? Storms ??
I can't confirm the material, but I just tested it and I am 100% sure that it whatever it is made of, it does conducts electricty!
Author:  NOHUHU [ Thu Jul 15, 2010 3:14 pm ]
Post subject:  Re: Sharks?? Storms ??
I'm 100% sure I've been getting fiberglass fibers in my skin, handling my 2007 mast. :cry:

And I could be dead wrong about this, but I would prefer the Hobie sail and peddles to a paddle in the electrical storm scenario. That metal drive is in the water though, so pack your rubber booties!

If the mast was to release a large lightning strike, seems to me that it's going to travel down the metal mast V-frame supports and melt or vaporize the hull attachment points. Great! Watching your mast blow over, as a hole opens in your hull should really add to the thrill.

And let's not forget the open scupper holes near that very sensitive area on which you sit. For the sake of future generations, think I'll pack some rubber shorts too. :shock:

Anyway, there must be tons of entertaining bar tales out there about Hobiecats being struck by lightning. Some may even be true.
Author:  walt [ Thu Jul 15, 2010 4:28 pm ]
Post subject:  Re: Sharks?? Storms ??
Whatever the stats are on sailboats for lightning strikes, they usually occur in a marina and its possibly simply because that is where the boat spends most of its time. Im not real concerned about getting hit while sailing.. but I do live in a high lightning area (Colorado). I have been shocked pretty good while windsurfing many years ago during an unexpected close by lightning strike - so I at least think about this.

These are some simulations of a lighting strike on a boat (pictures are real - I took them) of what a spark does when it reaches the water surface - it radiates out on the surface (likely in the air just above the surface)

This shot is in fresh water

Image

This shot is in salt water

Image

The surface "radials" are similar but salt water has a much lower resistance and also a much faster surface charging time so the radial patterns are much smaller.

If the mast did take a lightning strike and it jumped to the water surface, I imagine one of the radial surface streamers finding your crotch would "leave a mark"..
Author:  tspbrady [ Thu Jul 15, 2010 4:46 pm ]
Post subject:  Re: Sharks?? Storms ??
I was contemplating a lightning strike on the mast over dinner with the wife. I think we agreed that it would be very bad, with the bolt traveling the path of least resistence, generally following the mast (conductive or not) and melting (more likely blowing out) the bottom of the boat and probably some if not all of the person sitting in the front cockpit. Probably a good idea to get out of the way when one sees a storm brewing.
Author:  NOHUHU [ Fri Jul 16, 2010 12:31 am ]
Post subject:  Re: Sharks?? Storms ??
Wait - Does your wife know you play with electricity in the tub!?!
Author:  Chekika [ Fri Jul 16, 2010 4:02 am ]
Post subject:  Re: Sharks?? Storms ??
People, mostly guys, get killed in the summer regularly here in SFL. Last summer a guy in the middle of the Everglades on his "swamp buggy" was hit & killed. A yard man was hit about 3 pm in my neighborhood--some people claimed it was during a clear sky, others disputed that. I was out at the time and there definitely were clouds around. I remember thinking it was going to rain.

People get hit on their powerboats--with at least one death per strike. I don't hear of many sail boats, but that may be because there are more powerboats out.

We got caught in a heavy downpour about 3 weeks ago. This is my wife Nancy off Key Largo. It is about 90 deg F. Felt good, but there was no lightling around (kind of like that yard man above, huh?)
Image

Keith
Author:  rusty_sojah [ Fri Jul 16, 2010 6:15 am ]
Post subject:  Re: Sharks?? Storms ??
interesting thoughts, but i think you have a higher chance of getting into a fatal auto accident while towing your AI/TI to go sailing then you do by getting hit with a lightning strike while actually in the water. call me a pessimist :D
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