My 1988 BCC #86 “Patience” was apparently hit by lightning while moored the other day. The bonding system has to be very good, because there was very little damage.
The mast - mounted metal whip VHF antenna is missing, a charred piece is all I found. Strangely, the VHF radio still works, as do all the electrical devices, GPS, alternator, except the radar. The radar, a vintage, beautiful Raytheon RL10 seems to be mortally wounded. It lights up but a high pitch alarm sounds continously and targets are not detected. I assume the radome has crossed over to the afterlife.
The other strange side effect is that 2 seacocks are seized. They where old and kinda drippy already, but they where greased and used to move easily. Now I can’t turn them, even after loosening the “packing” nuts…I assume they got zapped. They still weep, which makes me a little nervous. If I can’t figure out how to un-seize them and “pack” them properly, I am going to have to haul out and replace…lots of $$$$$. I need the boat in complete seaworthiness condition for an offshore passage to Nova Scotia.
If anyone has experience servicing these bronze seacocks (I forget the brand right now), let me know. They are all bronze and have 2 nuts that hold the pieces together (2nd one is just for locking the first one)
Very interesting. Julian, do you have grounding cables/straps from
your mast to the water? I had considered installing this a while
back, but never got to it. Godspeed has been hit by ligthning twice,
but never had damage, so I’ve not been eager to clutter the rigging
with cables hanging down into the water.
It would be interesting to know if others have taken any steps to
protect their vessel from lightning strikes…
How to free up a bronze seacock with tapered valve-shaft? What has always
worked for me in the past is to loose both of those nuts and than give the
shaft a stout whack with a reasonably heavy hammer. Back the nuts off far
enough to protect the threads at the end of the axle bolt so they don’t get
dinged-over. If there is still some grease in the joint, after retightening
this is usually enough to do the trick. If it still drips, sometimes a leaky
tapered bronze seacock can be made good by disassembling & using valve
grinding compound to relap the mating surfaces, sometimes not – all depends
on how badly scored or damaged it is.
I think in this case I would haul her first, in case the seacock to hull
bond has been compromised by the lightning strike, corrosion, whatever . .
… Necessary anyhow if you need to try relapping the valve. A good dollop of
grease is needed when it is reassembled. I wonder if the heat generated by
the lightning strike might have vaporized the grease in the valve? Probably
best to haul, disassemble, inspect and then decide.
We hauled Itchen yesterday in preparation for a run later this month from
the Chesapeake (Solomons) to Penobscot Bay – will replace zincs, repaint
the bottom, and free up one seized seacock that I feel nervous about
whacking too hard while still in the water! I was appalled to find the
MaxProp zinc and one of the rudder gudgeon zincs entirely wasted away,
though all had been replaced in late November. She’s been in the water in a
marina slip since then and I wonder if stray currents from nearby boats
might be a factor. No damage to the prop, fortunately.
The lightning strike went to ground (the water) via your seacocks and through hulls. Probably through your prop shaft too. My strongest hunch is that the lightning strike has welded your sea cocks together. More than that, from what I’ve seen of lightning struck hardware, it’s very possible that the thru-hulls themselves have been damaged. Without a doubt, I wouldn’t attempt much?without hauling the boat out. At the very least, have?those tapered softwood bungs and a?mallet handy! Could get quite exciting.?Another?casualty is often the compass! How is yours doing??The best recommendation I’ve seen on strike protection is a 1 square foot (or larger) metal (silicon?bronze) plate well below the waterline. Thru bolt this with S/B bolts around it’s perimeter. These bolts should be?wired to the mast and at least the cap shrouds with #6 or larger cable. Minimize bends.??Go to the trouble to isolate your VHF antenna at the masthead so that this plate isn’t?connected to DC negative in any way. You may use this plate for your SSB counterpoise provided you isolate it from DC ground with a capacitor. Ideally you would?connect ALL?of your standing rigging to this, as well as your lifelines, but it isn’t going to make?an important difference in a 240,000 volt?strike.?DO NOT connect your seacocks or other underwater metal objects?to this plate. Many risks, not the least of which is electrolysis. I’m not a?fan of ‘bonding’ underwater metal together. I keep?all underwater metal the same composition, e.g. bronze prop shaft instead?of a stainless shaft with a bronze prop. This keeps galvanic potential to zero volts.?Then, isolate your DC (negative) system from the water except at the prop shaft. If you really must have?an AC/shore power system aboard, it also must be grounded to the engine and you are begging for trouble in hot marinas.??
SV MINX
Roy Myers???
Well, I am hauling tomorrow and replacing seacocks (at least). I hammered the hell out of
them with no results. The radar is dead. The VHF radio works, defying logic. The VHF
antenna vaporized…otherwise, alternator, regulator, GPS, etc all work fine, go figure.
The boat has that special copper plate under water, “sintered” or something like that.
There is a grounding wire to the mast, but it was not connected at the time. I’m pretty
confused by the whole thing.
Thanks for all the postings with info. I’ll let you know what I find when I haul…
Dear Julian,
Sadly I have a great deal of experience with lightning
strikes. My Valiant 50 was hit and the strike caused
almost $150,000 of damage.
Because of the extent of the damage to the Valiant I
was very cautious about the lightning protection on
Cyrano my BCC.
What happens is that in addition to the massive amount
of voltage which traverses the boat there is an EMP or
electromagnetic pulse which also occurs. That is what
damages the 12 volt stuff in bizarre ways.
When your boat is hauled, carefully inspect the hull
for tiny pinholes or other evidence that the
tremendous heat generated by the strike boiled the
laminate or separated the layers of the laminate. Use
a flashlight to inspect the laminate for any evidence
of such holes or spider like cracks. Generally they
will appear near thru-hull fittings.
Also expect other electrical anomalies to begin to
appear with wiring and the like. Assuming you have
made an insurance claim insist on a survey by a
surveyor familiar with damage from lightning.
Good luck !
Jim