Thru Hulls

[Dave]

Ok, it's haul out time in the Pacific Northwest.
This is the year I had planned to take out the bronze thru hulls for the marine head that is no longer in the boat.
Should I?  Shouldn't I?  What do you all use for grounding the rig for lightning if you don't have the seacocks?
Any of you have seeping, leaking, or catastrophic failures in these through hulls?
Opinions please and thanks.
--Dave on Puget Sound.

[ebb]

Where are all the pundits on this subject?   Hmmmmm m m?   Well I'll wade in,  and if I'm wrong, then connect me.

I believe now that the concensus is that you should NOT wire your in the water metals together.   A hot marina will eat you alive.   I have heard that the best thing to do is ISOLATE your underwaters - if you have dissimular metals or maybe metals touching or bearing on one another (like the ruddershaft/shoe connection, you wire a zinc close at hand.   If you have a s.s, propeller shaft and a bronze prop, you zinc the shaft close to the prop.   But all isolated metals like your thruhulls are better left alone.   So,  I would remove the wires if the original Pearson installation is present.

The DC ELECTRICAL load and all the branch circuits go to a bus and then to your inboard engine.   NOT part of the general "grounding system."   The battery negative is grounded to the same engine point.

AC.   Should be an extension cord,  IMCO.


Lightning ground is another kettle of fish.   It has nothing to do with normal metal parts in the briney.   Basically we should have installed under the waterline somewhere  (probably near the compression bulkhead) a bronze or copper plate (NOT THE SINTERED BROnZE PLATES which are radio grounds only!) about a foot square - nice fat bolts (1/2" or larger) coming thru thr hull to which thereto we attach #4 cable from the base of the mast (through the deck) AND cable from each of the shroud plates AND the forestay fitting.   These are all lead with round sweeps  to the bolts that hold the solid plate on the hull.   This will give the mast the same electric potential as the water (ground.)   This is an entirely SEPARATE wire grounding system - which will end up looking like an electric company sub station.

A BIG problem with the lightning protection setup (as I read it) is keeping all mast electrics isolated from the mast.   Tricolor and steaming light are relatively easy but the VHF coaxial cable / antenna installation could be ground to the mast thru  fasteners.   The coax has to have a block put in it that keeps current out of the cable and sheild.   Something like that.

338 had everything wired together,   including #10 or 12 solid wire, that probably at one time had been attached to the mast,  routed into grooves in the compression bulkhead under the woodtone micarta.   But the different grounding needs of 2004 require separation.    Do not bond any thru hulls or ruddershaft and shoe to anything inside.   It is far better that metal parts are isolated from each other AND the engine.   On top of that, normal zincing in a hot marina won't work either.  Or will require close attention,   like the zinc on your shaft next to the propeller.

OK,   that's whot I think I know,  is close to what I will do.   The SEARCH bar above will give you a huge number of posts on the subject,   but it is probably better to raise hell with it here again.:eek:

[willie]

Guess i'll wade in too--

I just replaced all my thru hulls. With epoxy and fiberglass. Only two left are the cockpit drains, which i assume would sink the boat? As i'm going engineless, didn't see the need for more drag from the protrusions. And we're day sailing anyway. I didn't consider lightning, and haven't read much about it on boats. I do know from being a wildland firefighter that the safest place to be is in the truck, which is not grounded to the earth. (rubber tires)

So my thought is if the mast isn't making continuity to the water, it's not really a lightning rod, is it? Is the glass a conductor? Not too good i would think.  I also think if you're gonna get zapped, there isn't a whole hellof a lot you can do. My neighbor just had 7 cows fried. BIG bar-b-que.

Guess i better read up on it. Here's a most excellent article everyone should read:

http://www.sailnet.com/collections/articles/index.cfm?articleid=barron004


Back to the cockpit drains, anyone replaced the thru hulls there, and with what? One of mine looks kinda hokey, like it used to be sort of a tee that isn't any more, with some kind of plug. Another project!

[dasein668]

Originally posted by willie
 I do know from being a wildland firefighter that the safest place to be is in the truck, which is not grounded to the earth. (rubber tires)

What actually makes you safe in the truck is the sheeting effect (I'm not sure what the technical term for this is). Basically the current flows over the outside skin of the vehicle rather than through the interior. The paltry amount of rubber in your tires won't actually stop a lightning strikeÑit just blows right by the bottom of your car and jumps to ground. Most cars struck by lighting will have all the tires blown out.

[Bill]

". . .One of mine looks kinda hokey, like it used to be sort of a tee that isn't any more, with some kind of plug."  

That fitting is where the original sink drain was connected to the port side cockpit drain.  Because the galley was moved on your boat, the drain was obviously no longer needed.  

Some of us have seacocks on their boat's cockpit drains.  Especially those of us with the original galley sink setup.  

[ebb]

There's this nagging suspicion,
that if I set the lightning ground system up to specs
- that's including a foot tall aluminum spike
sharpened to a  point
projecting above the mast head


 - as stated above -
And 338 goes out and attracts a nice million volt lightning bolt to herself
it'll instantaneously jump down  mast,  shrouds,

and copper braid right to that nice copper grounding plate and
blow a one foot square hole out the bottom of the boat.



Why would anyone want to purposely invite all that juice down below?

[Tony G]

Ebb
I've been going over and over this same nagging question.  It's sort of a damned if you do and damned if you don't issue.  I think I've read accounts from both schools of thought on the matter and read two swaying arguments from each side!  That's now four different ways to Sunday.:confused:
We haven't started 'slapping' the interior together yet so there's plenty of time to run heavy braid all over the place if I could just hear a convincing argument one way or the other.  I guess if lightning strikes it was just meant to be...or maybe not...

[ebb]

It is indeed a matter of opinion!!!

Has anybody one on this for us outboard motor Ariels......
Where is the ground for us.   Should a ground be installed like the solid metal plate for lightning protection?

Just so you know I'm not fooling;

...........Where should the ground to water be on an ob Ariel?
...........If one is really necessary,  I can see it installed under the bridge just above the turn of the bilge near the batteries.  YES?



Here's another:

..........Can we use lanolin on these plates to keep barnacles off,  or will that destroy the grounding function???

[ebb]

I'm of the do nothing school, I think, when it comes to connecting all the shroud plates and forestay together with a grounding plate on the outside of the hull.   It is a too neat and tidy way of soothing the paranoia of taking the high volt hit.

I don't know (literally) - and who does (literally) -  but I just feel there's something wrong with that picture.   The  www sailnet article says hundreds of boats take a strike every year...... I want to hear from skippers whose boats were all tweeked up with copper braid like we're 'sposed to.

Instead of being Ready Freddy and tediously lightning bonded,  IMCO it would be better and far easier to clip battery jumper cables to the shrouds and let them dangle in the water.   One would have to be aware that an electric storm was immanent and go forward with seven clips at the ready.   But at least I'ld be gently suggesting to the all mighty powers that be where the hell to go.   Not below.

What do you think?

[commanderpete]

This subject always gives me a headache.

I had white wires attached to both middle chainplates and one that was in the area of the starboard thru hull. I couldn't figure out what purpose they served so I ripped them out. Somebody tell me if I need to put them back.

They obviously won't help with a lightning strike, but are they necessary to ground the electrical system?

I say if you're not going to use the seacocks you should take them out and glass over the holes. A failed thru hull worries me alot more than a lightning strike (sound of wood knocking).

[Tony G]

Whoa-wait a minute!

I was/am under the understanding that lights, stereo, VHF, nav equipment and the like were grounded to a buss which in turn was grounded to the negative terminal of the battery bank.  I'm hoping I didn't nod-off during that chapter. Tell me I'm on the right track here, please.  I've nearly completed the new wiring schematic (again) and I don't think I could 'scrap it' one more time and start over.  
I have a good friend here that used to skydive.  His 'chute didn't open one time and he broke his back.  He doesn't skydive anymore.  If 113 gets struck by lightning and sinks I probably wont sail her anymore.  I think I'll take my chances.  Any thoughts on this?  anybody?

[Bill]

For what it's worth, and I know nothing about electricity, Good Old Boat has an article in the May/June 2004 issue on electrical wiring ("Wires, Dressed for Success").   GOB recommends Charles Wing's "Boatowner's Illustrated Handbook of Wiring" (1993) for help in wiring your boat.   I would assume the grounding issue is addressed.

[Hull376]

Capn Pete,

I've got white wires running from the chain plates to the starboard thru-hull, and they're also bonded to the battery neg.  I left them on.  Maybe I'll sail with them on for the first half of this summer, and disconnect them the second half.  That way, statistically, I'll have the correct solution at least part of the time.  How lucky do you feel today??

[dasein668]

Originally posted by Tony G
Whoa-wait a minute!

I was/am under the understanding that lights, stereo, VHF, nav equipment and the like were grounded to a buss which in turn was grounded to the negative terminal of the battery bank.  

Nope, that's right. But that's a different issue from attempting to ground the mast for a lightning strike.

On the electrical system front, I just recently finished rewiring my boat. You can check out my write-up on my website if you are interested. Not super detailed, but I'm happy to answer any questions about my project if you have 'em.

Cheers,

[ebb]

DC is separate from anything else.   Everytrhing is looped to the negative buss at the panel and is connected to the internal engine's negative buss.   No other metal in the boat is connected to this system.   Zinc your shaft and prop like nobody's business!

The lightning ground is a separate system,  has nothing whatever to do with the boat's DC.   Has nothing whatever to do with the thruhulls.

Bonded thruhulls are a mistake and should not be wired together,   Galvanic corrosion should be handled by isolating and zincs.

Grounding for the VHF is another separate issue and is not part of the boats DC grounding system.

Clear to me,  but I'm not there yet.

The fifth totally separate system on a boat is the AC which also green wire grounds on the engine's negative buss.   My research tells me this opens a huge can of worms.   And so, 338's AC will be an extension cord from the marina's plug in.

Electrical Apartheid is where it's at!