I do not doubt that some insurance companies require that boats be bonded but the fact is that there are also reputable marine insurers that do not. If the data showing less strikes and less damage was so conclusive then I'm sure they would all be requiring it. To my knowledege the marine insurance industry has not commisioned a scientific study that conclusively has demostrated that bonding is the best course of action. In the absence of such a study the personal opinions of individual underwriters is just that opinions. Underwriters and some companies may feel it is their duty to support the ABYC guidelines to justify their actions to shareholders. As has been pointed out they really have no solid understanding of the lightning issue and only as it refers to property losses and the justifications for their actions.
One could say that when you look at property loss claims paid out, and see less damage and less cost in claims associated with boats that are lightning bonded, that is a pretty good data set. Considering the insurance companies are the ones to pay in a strike they get to make their own rules.. When we were hit one of the first things on the insurance companies claim sheet was for the surveyor to inspect for a lightning bonding circuit.. I am sure they still would have paid, but then likely made me install one if none was there.
The hole in the;
"I am not going to bond/ground my mast & rigging to minimize a strike" is that people forget that you have still placed Earth potential at the top of nearly every sailboat spar out there.
VHF, wind speed, tri-color, all round, masthead, windex light, TV antenna & spreader light are all connected to Earth on-board the vessel. The neg/ground of each of these appliances is directly connected to the boats DC system/battery and then off to the engine for the starter connection and then to the ocean for Earth potential. Heck half the keel stepped spars I see are sitting directly in bilge water right next to a keel bolt. In one strike the mast step bonding wire was missing and when the strike hit the water in the bilge was vaporized to the point that it blew the cabin sole cover boards off. Boat has massive pin holes in the hull, delam and was totaled.
So even without a large gauge wire to
help pass at least some of that energy more easily to ground you have placed Earth potential 45'-80' above the surface of the water. IMHO I have yet to see an "isolated" sailboat, as it relates to lightning...
Even my neighbors 18' Hobie Cat was hit about 8 years ago. This boat has no electrics what so ever and no path to ground. Lightning hits what it wants to. You can only try to minimize damage, and we have data that shows a good lightning bond does so. No one, as of yet, has found a way to minimize the potential of a strike, not even Dr. Thompson..
As I previously mentioned, on the same night our boat was hit a little Cal 22 was also hit. The boat had no down conductor between the mast and the keel and no lightning system to speak of. It blew holes in the hull where the VHF cable had been run back to the radio where it was resting / laying on the hull behind the settee. The VHF cable is where the lightning apparently found the Earth it was looking for. It had no other "exit" point and the combination of a damp bilge and VHF wire resting on it likely gave it the path of least resistance even though the boat was not "lightning bonded" it was still hit hard..
Our boat, struck during the same exact storm. She suffered zero hull damage and uses the keel as the main down conductor lightning ground along with secondary bonding conductors.
Everything electric on-board was fried but she did not sink like the little Cal 22.. The lightning grounds also picks up chain plates, engine and other metal fittings as secondary conductors. We have plenty of wires in the boat near the waterline that the strike could have used to blow holes in the hull but I have to surmise the more direct path & LARGE wire to the keel, with less resistance, took the brunt of it.
When this strike happened there were over 1100 sailboats moored in Falmouth Foreside.
(Image Courtesy SkyPic.com)
The two
The two boats hit that night could not have been more different. The Cal 22 had one of the shortest masts and according to the surveyor, no lightning system what so ever. It had holes blown in the hull from the VHF cable. So there goes the
"taller masts will get hit first" urban myth.
Perhaps 97% of the boats in Falmouth have a taller mast than a Cal 22.... It still got blasted... It also blew the myth of
"don't provide a path to ground and you won't get hit".. This boat had no
low resistance path to ground from the mast to the keel or a lightning plate. It still got holes blasted clean through the hull....
Our boat has a medium sized mast for the anchorage and is wired to ABYC standards with regards to lightning. She had ZERO hull damage, but still got hit. A few years ago I was feeling pretty smug when the boat directly behind us, about 20 yards away, got hit. He had just spent nearly 4k on the "latest and greatest" lightning system including a brand new fuzzy dissipator/lightning attractor.... His boat was hit no less than 3 weeks after spending 4k on this "latest & greatest" lightning system. His boat also did not sink or have holes blown in it, so maybe it worked, but his entire boats electronic systems were toast.
The Cal 22:
I've come to realize that if lightning wants your boat, it will get it, and there's not a darn thing you can do. Other than to try and minimize hull damage and minimize the potential for side flashes if you get hit your gear is likely toast or will be shortly there after..
If you do get hit get your own surveyor and be sure to write up EVERYTHING electronic on-board. We had a couple of items still "operable" after the strike and they died within a month or two. Lucky we had a good surveyor who wrote it up for 100% replacement of all electronic devices.
Just be glad your boat does not have a carbon fiber spar. My friend Kim & her husband were hit to the tune of nearly 6 figures because a carbon spar hit by lightning is quite often a total loss..... Their boat had $65,000 carbon rig as well as sails that had holes burned in them. The spar was bonded and the hull suffered zero lightning damage...
People can do what they want but I would urge anyone to at least bond the spar to an external plate or the keel to try and minimize the potential of a sinking or total loss of not jsut the electronics but the hull as well.