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ContinuousWave: Small Boat Electrical
Lightning Protection on Boston Whaler Cabin Model Boats
|Author||Topic: Lightning Protection on Boston Whaler Cabin Model Boats|
posted 03-20-2010 12:54 AM ET (US)
Considering that non metal boats have a lightning disadvantage, does [Boston Whaler provide] any lightning mitiation on their boats? Open boats are pretty indefensible, but what about cabin model [boats from Boston Whaler]?
posted 03-21-2010 01:44 PM ET (US)
Hi Ed -
Hope you'll join us for Isle Royale (see thread in rendezvous forum).
Here's some links to past discussion of the subject:
posted 03-21-2010 01:57 PM ET (US)
In one of those threads the question was brought up if you can "outrun" lightning (i.e. is it harder for lightning to hit a moving target?)...well, I don't know if it translates to ground/water level, but at high altitudes, there is a not-well understood phenomena called "Hyper-Lightning".
There are some out there who believe that this is what may have caused the space shuttle to explode on re-entry, although I think that these are individuals seeking to leverage a tragedy to further awareness of their work.
It is an interesting concept though.
Lightning is fascinating to me - and at very high altitudes above major storms, there's some weird (aka: cool) stuff going on...
posted 03-21-2010 02:02 PM ET (US)
Correction: the phenomena is called "Mega Lightning".
For good information on the theory as it related to the Columbia disaster, see:
Section 4 addresses this phenomena.
posted 03-21-2010 11:10 PM ET (US)
What is lightning mitiation?
posted 03-22-2010 08:41 AM ET (US)
I don't know what lightning mitigation is.
Perhaps it asks if some form of protection is provided on Boston Whaler boats. The only form of protection for boats of which I'm aware is the practice of bonding all the metal parts electrically to a low resistance connection to a metal (grounding) plate in the water. Perhaps in the case of an outboard engine powered boat the engine could serve as the plate.
That sounds like it would be difficult to do. I think I'll take my chances and continue to be on the water when the forecast is favorable. If the forecast proves faulty, as is too often the case, I'll run for cover at the first sound of thunder.
posted 03-22-2010 08:48 AM ET (US)
Fiber and wood boats are not electrical conductors thus offer poor protection if hit by lightning. The electrical jolt simply does not have an efficient path to reach ground. In sailboats and very large fiber boats the equivalent of lightning rods are recommended. The "ground" contact is a steel plate that is attached to the hull and the size of which is determined by the size of the boat (its proportional). Since most whaler are open boats the point is largely moot, the only real option is to squat and pray (if you were not able to avoid the storm to begin with). However, I wonder if the cabin boats have any provisions for lightning mitigation. By studying the schematics there isn't an obvious rod-cable-plate system, nevertheless, I wonder if the electrical system has some direct to water "ground" connection. In that manner lightning hitting the radio antenna, for example, would fry the electrical system but would probably spare you. Particularly since whalers come with very shiny steel steering wheels! As SOuthfla can propably attest lightning storms in Fla can be terrifying, with virtualy thousands of bolts hitting an area in a matter of minutes. Not only that, lightning can strike miles ahead or behind the actual storm.
posted 03-22-2010 09:21 AM ET (US)
Buckda thanks for the link. The installation done on the 23 is excellent. The info provided, particularly the availability of a lightning "arrestor" for the antenna is very good info. The install pics were excellent.
Unfortunately, I'm working the week of the Isle royale meet this year. If next year's is arranged before December I can try to arrange my schedule for next year's event. Again thanks for the great links. Edgar
posted 03-23-2010 08:21 AM ET (US)
This thread reminds me of one I started around the same time of year back in 2008. It's not really about "mitigation" of lightning but I thought it may be of use to you in your quest to not become a lightning rod out on the water.
posted 03-23-2010 02:49 PM ET (US)
Great stories! Hopefully I won't have to add any of my own :) Luckily my only bad weather story was on a 100ft ferry between PR and the Island of Culebra in 1984 during during Hurricane David. The ferry ran since the storm was supposed to stay south of the islands. What they didn't know was that though the eye of storm tracked south it still generated hurricane force winds and 20plus feet seas in the area. Though the voyage is only 20 miles or so it normaly takes the ferry 3 hours to get there, however, during the storm one of the engines konked out and the voyage took almost six! Everyone was puking their guts out, crying or praying. It simply isn't very conforting sitting on a ferry doing five knots while monster white caps are going right over the bow of a large ocean going vessel, to make things even more hairy you constantly see an oil drenched crew member going in and out the engine room with big parts in tow!
posted 03-23-2010 06:20 PM ET (US)
I believe it's incorrect to consider fiberglass boats to be nonconductors of electricity. Virtually all materials will conduct electricity although the very high resistance of some make them nonconductors of all but the very highest voltages such as those created by lightning.
Fiberglass boats have been known to conduct lightning bolts to ground, ie. water, and sometimes blast holes in the hull while exiting it to the water.
The idea of bonding all possible metal parts above the waterline and providing a low resistance conductor to a ground plate may, if we are lucky, have sufficient electrical capacity to route a lightning strike to the water while leaving the hull mostly undamaged except for the obvious heat damage.
There is the idea that a zone of protection can be created by use of a metal rod high enough above the deck to cause the rod to be a lightning attractant. The rod is wired to a ground plate in an attempt to cause the lightning to make a safe escape from the boat. I'm uncertain that there is a Boston Whaler boat of sufficient size to support a rod of a sufficient height to provide an effective zone of protection for the entire deck and cabin area. I'm also uncertain of the wisdom of installing a lightning attractant on a fairly low profile fiberglass boat. Perhaps lowering any antenna and hunkering down would be as effective.
The trouble with lightning is that it seldom acts in the same way all the time which makes a fool proof lightning protection/mitigation arrangement more than difficult to design and install.
posted 03-23-2010 09:51 PM ET (US)
I have never seen any smaller outboard boats that have any special electrical configuration designed to dissipate a direct lightning strike.
posted 03-23-2010 11:06 PM ET (US)
Considering the generally low height of boats with outboard motors, if you were to lower all antennas and lower the metal frame of any canvas tops, the overall height of a typical Boston Whaler or other outboard boat in the 15 to 25-foot range will only be 2-feet to perhaps 6-feet off the water. As a target for lightning, that is not much of an attraction.
The electrical system of most outboard boats has the battery negative bonded to the chassis of the outboard motor. If the outboard motor is in the operating position then the propeller, propeller shaft, and any anodes should be in the water and in electrical contact with the water. This would constitute a lightning ground system.
I have never heard of anyone installing a large grounding plate on the hull of a small outboard boat, and in the case of a Boston Whaler this is particularly unusual due to the hull construction.
posted 03-23-2010 11:33 PM ET (US)
Jefecinco is correct. The point about fiberglass is that compared to metal its resistance to current is immense, however you are correct essentially everything is a conductor at some point. However glass is as close as to a non conductor as you can get, as I'm sure you are aware many industrial "isolators" are made of borosilicate glass, essentially fiberglass without the resin.
On a fiberglass structure, unless channelized by a better conductor, current is more apt to pass through the water covering the boat than the fiberglass itself, however, as we are well aware, there are a number of metal structures within the boat where current will flow preferentially trying to find the lowest resistance possible on its voyage to ground. The idea is that you keep well away from the path since--as Star Trek gloriously put it--we could be considered bags of water
The install that was linked by Buckda is probably as good as it gets, though, as many have pointed out, probably more work than its worth given the relative rarity of the event.
One phenomenon well known to sailors in the past is Saint Elmo's fire, which nowadays we recognize are electrical feelers of static electricity trying to overcome the resistance of air and complete the electrical circuit between static charges in the clouds and the ground that we all know as lightning.
Another quick point in cars: tires are actually a fine isolator too, the car acts just like an aircraft would the electricity travels through the metal body then back to the air to the ground. In effect the car body acts as a Tesla cage. In the instances where a tire is damaged it is usually collateral, if the electricity makes ground connection very close to the tire, the heat of the ionized plasma is able to damage the tire itself. Cool Stuff. For thousands of years we all though it was that Thor or Zeus were angry :)
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