Getting ready for FL 120: Projects . . . .

Started by Charles Brennan, May 11, 2024, 11:10 PM

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Charles Brennan

MANY years ago, I ran a wire from a bolt on the mast step plate through a big honkin' knife switch and down to the 400 lb cast-iron swing keel on Urchin for potential lightning strikes.
Florida is the Lightning Capital of America.  Texas may have numerically more strikes since it is 4 times larger, but Florida has much more damage per capita.   :(
The intent of the switch was to reduce or minimize electrolytic galvanic corrosion from dissimilar metals, so I only turned it on when bad weather was imminent and left it open the rest of the time.
I fully recognized that a lightning strike could use the higher impedance of the switch connections to fly off into space in whatever direction it decided to.  (Called flash-over.)
Also, I originally ran the wiring before I knew much about lightning and had some unfortunate sharp bends in the installation.   ???
Lightning likes to go in straight lines.  You give it a sudden 90º turn and the lightning usually doesn't turn; it simply blows a hole in the conductor and flies off into space.
So I never felt all that comfortable with it, but decided it was better than nothing.
And it WAS better than nothing.
Had proof of two lightning strikes, minimized by having a grounding wire from the mast step to the swing keel.
The first strike welded the mast step bolt to the mast step on one side of the step and had to be cut off with a hack saw blade and had visible arc marks.
Had to cut it free to un-step the mast.

The second strike, for whatever reason, traveled down the side stays and made a carbonized path through the gel coat on the side of the hull, down to the waterline.
One of the lightning strikes just off my stern, during that summer thunderstorm reached all the way to the bottom of Biscayne Bay.
The sudden boiling of seawater on the bottom turned into steam and exploded large chunks of coral rock into my cockpit and on top of my cabin roof.  I missed seeing it, but heard it while curled up into a fetal position in the cabin, all the while studiously avoiding anything metallic inside the cabin!   :o   
So I know it's better than nothing.
Intellectually, I know the very next lightning strike could easily blow a hole in the bottom of the swing keel trunk, or worse.
But I always figured that doing SOMETHING, even if it didn't work was better than doing NOTHING and second-guessing myself the rest of my life for NOT doing something, after a catastrophic strike.

Knife switch with # 8 ga wire:
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Last year, I made a new electrical connector lug for my centerboard.  The old attachment was simply copper wire wrapped around the bolt and compressed between two washers on the swing keel pivot bolt.
This was not an optimum method of connection and was also potentially a severe flash-over point.
Started with a piece of .125"  316 stainless steel plate and a fender washer for a pattern.
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Cut, grinded, (ground?)  ???  and filed into shape, then drilled to 5/8" for the swing keel bolt.
I was forced to fabricate a connector, because the electrical industry doesn't have connectors this big.
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Bent over a form to hold the wire.
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A little Tef-Gel and ready to go!  :)
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Installed on keel bolt.
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After thinking about it for a while and after not seeing significant electrolytic corrosion in over 40 years, I decided I wanted three improvements:
1) To remove the knife switch, so as to have a point-to-point connection from mast step plate to swing keel bolt and minimize possible flash-over.
2) Beef up the wire gauge from 8 ga. to 3 ga., which more than triples the cross-sectional area of the copper conductor. (8.34 sq. mm vs 26.7 sq. mm.)
(Lotta Electrical Engineering-ese for: Make it easier for the lightning to go elsewhere, down the wire.)
3) Avoid sharp bends and re-route more gradual sweeps for the wire run, from the cabin top down to the swing keel.

So I made myself another new connector from the unused portion of my previous S-S plate.
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I also made the  connector fitting longer, to provide an insulation strain relief clamp, which my previous attempt had omitted.
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MUCH Heftier!  :)
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Tef-Gel is on the other side of the fitting; wasn't so sloppy, this time.   :-[
Connector bolted to swing keel.
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And the new electrical connector bolted to the mast step bolt in the cabin.
No more knife switch.
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Very happy with the results.   ;D
I'm bringing my Grandson with me on the FL 120 this year, so storm safety is paramount to me, since I don't want to drag home a fried Grandson, to my wife and daughter.
I'd never hear the end of it!   :o

Other projects were:
Sanding and re-painting the outboard lower unit and installed new sacrificial zincs.
Fixing the tilt lift and shallow-water running tilt on the outboard. (Been busted for a while and I'll need it functional, to eventually sell the boat.)
Replacing the safety cable that holds the outboard to the hull while trailering, since I'd hate for that motor to go through somebody's windshield, at Interstate speeds.

I also need to re-paint the topsides and cockpit with Interlux Interdeck Squall Blue non-slip paint.
This is problematic, as it seems nobody is stocking it, just now. All the usual International Paint distributors are not showing it in stock.
The only place I could find any, is shipping it from England.
Someday.   >:(
I need it re-painted, so I can list the boat for sale in order to have enough funds to finish my SCAMP project.
But, after 46½ years, there's not too many improvements to make!  8)

Charles Brennan

Brian N.

Charles - Always better to have some alternate path for a lightning strike than to have none. As a Ham radio operator, lightning protection is always a concern. I use a dipole antenna, rather than a vertical antenna, which reduces the incidence of a potential strike. Sailboat masts are obviously subject to strikes. Lots of Hams use a wire braid strap (can't say what gauge) for grounding as it offers more surface. From what I remember, a grounding path bleeds off charge, greatly reducing the chance of a strike. Hopefully you'll have clear weather. Best of luck to you on your adventure!
Fair winds
Brian N.

Riley Smith

Having one of those Gulf Coast lightning shows while you're out on the water will make a Believer out of you!!!

I have been considering making a run down to P'Cola Wed morning. I don't know if I CAN deal with it, but thinking about it. Weather is prolly going to decide me.
Riley

Ed

I'm bailing on the 120 this year.  The weather is too wet and windy for using our umbrella tent (standing headroom and side decks are covered) at anchor and the canvas camping cabin (kneeling room only and everything gets wet we stick into aft cockpit, even with a tarp boom tent) gets really old by the second day. So now it's another BEER Cruise in June!   We switched the dog's boarding reservation, our DIL's vacation days to take care of grandkids/goats/chickens/cats during our absence this morning, so bring it on.  This will be our 5th or 6th BEER Cruise, unless the weather sucks again.  If it does we'll fly to Vegas and hope our luck changes.

Noemi - Ensenada 20


Charles Brennan

HAH!!  ;D

KNEW that would get you out of your lair!!   ;D
Teachers just can't help themselves!! :)

Charles Brennan

Wolverine

Boat is packed and hooked to the truck. My friend is already in Pensacola. I'll be leaving at 1st light. I'll be sailing the Compac 19 with a bad green paint job.
1985 Compac 19/II  s/v Miss Adventure
1986 Seidelman 295 s/v Sur La Mer