Lightning Protection Question...

[Nik]

Well here goes it gang... Lightning protection on keel boats is (relatively) straight forward. BUT, how about on a dagger board boat? The Mac26D is deck stepped, dagger board is all FRP. NW Indiana and Lake Michigan see a lot of electrical storms during the summer that can come out of nowhere. Or should I just try and find a bigger boat that has more than 38' sticking up to shadow going in or moor next to and hope they get hit instead (LOL). What are your ideas?
Thanks,
Nik

 

[David in Sandusky]

Some ideas

1. The builder. First of all, what does MacGregor say about grounding?

2. Grounding plate. A copper plate (a square foot of surface I seem to remember) somewhere on your hull under the mast with a grounding strap from it to the mast is another approach.

3. Grounding wire. I have a large tinned copper wire that I can attach to the mast and trail over the side in a storm. The diameter and length of exposed wire provide a square foot of grounding surface. This is designed to supplement the grounding through our keel, and has not been approved by any design authority.

 

[Jonrod222]

I have an oday 222 that was hit by lightning a few years back. It fried all the lights, electronics (except vhf, I had a couple of ferrites on the power cord, don't know if that is what saved it) and the charging coil on my outboard. It blew up the mast head light, its switch on the control panel, and my windex. All the wiring was fine and after replacing bulbs and electronics and getting the motor fixed, it wasn't that bad cost wise, didn't put it on insurance. Lightning wants to go to ground, which in this case is the water. The skeg of the outboard was in the water, so the current followed the ground wires to the outboard motor to the water. Even though all of the switches were off for the lights and electronics, the grounds are all connected. If my motor was out of the water, the lightning might have exited through the hull and sunk the boat. I now have a 2 foot long 1 inch copper pipe connected to an aligator clip by battery cable that I clip to the backstay during storms. My boat stays on a trailer except when using it.

 

[Capt. Ed]

Nik Forget about morring near a taller boat. 3 years ago we witnested a 24 foot power boat get hit and burn to the water line . It was surrounded by 30 + foot sailboats ,mine being one of them .

 

[woodster]

hum just wondering ....does any one know if the S2 has a grounding device on the 9.2a keel ...all my ground wires in the hull lead back to the prop shaft strut....and i have removed it to have it checked out , as it is very brittle and may not be useable...the boat must have sat in the water a long time with out anode protection.....bad news is it may have to be replaced$$$$$$...good news is i found the original mfger of the strut......they still have the pattern and seem to know it well .....

when i think about this problem all i can see is the public service add about praticing safe sailing ( hidden word here sex) who knew....

any thoughts .....

regards

woody

 

[sailingdog]

First, there are basically two schools of thought about grounding a boat for lightning protection.

The first is that grounding a boat makes it safer and helps prevent catastrophic damage in the case of lightning strike—prevents sideflashes, holes blown through the hull, etc... but most of your electronics will still be fried. However, it is thought that a grounded boat is more likely to get hit by lightning.

The second is that an ungrounded boat is less likely to get hit, but will suffer more catastrophic damage to the boat in the case of a lightning strike—such as sideflashes, holes blown through the hull, etc. Lower chance of getting hit, but getting hurt worse if you do.

That said, I'd point out that you need a relatively straight path to the water for the lightning grounding system. A deck-stepped mast without a good metal compression post is going to require running a fairly heavy gauge wire down through the interior of the boat to ground the mast step. At least 2 AWG at a minimum IMHO.

You will need a lightning ground plate in the bottom of the boat. IIRC, the linear edge length of the plate is more important than the size of the plate. Four linear feet of edge is generally required, and this could be done by having a single 1' x 1' plate or a 2" wide strip that is 24" long... IMHO. the 2" wide strip that is 24" long makes a lot more sense and is easier to fair into the hull.

1. The builder. First of all, what does MacGregor say about grounding?

2. Grounding plate. A copper plate (a square foot of surface I seem to remember) somewhere on your hull under the mast with a grounding strap from it to the mast is another approach.

3. Grounding wire. I have a large tinned copper wire that I can attach to the mast and trail over the side in a storm. The diameter and length of exposed wire provide a square foot of grounding surface. This is designed to supplement the grounding through our keel, and has not been approved by any design authority.

 

[Benny]

Install a grounding plate if it makes you feel better. It may or may not help depending on which school of thought you follow. From the study of known ocurrences no one can categorically deny or ascert whether a grounding system in boat works or not, some or all of the time. Would it hurt to install a grounding path? Some think it does by attracting lightning strikes but that cannot be ascertained either. What about the cone of protection afforded by the mast height? There maybe something behind that as death by lightning strikes are more common on land than on boats in the water and the majority occur on powerboats which have no masts. I have been sailing for many years and have heard of just one fatality due to a lightning strike on a sailboat and I believe the boat was in an inland waterway. These brings us to a risk assesment of the probability of being hit by lightning and the odds seem to be clearly on our favor whether a grounding system is in place or not. Now that makes me feel better.

 

[Shell]

How many people were injured by lightning strikes in your area?
If none, I wouldn't worry about it unless you are very unlucky.

 

[galynd]

I noticed that my (coated) copper grounding cable travels through my shower. Of course it's behind some (wooden) angle trim. So I won't shower during a storm.

 

[Pops]

Lightning, hah! I laugh in its face :dance:. I was hit under my house 6 or 7 years ago. The nerve damage is almost completely gone now.

 

[RichH]

The following is the website of the famous marine "lightning guru" who was responsible for all the marine industry's lightning info through the University of Florida. This represents his 'current' thinking on lightning protection for boats.
http://www.marinelightning.com/

 

[Bill Roosa]

Consider the mission

You are not going to be sailing in thunderstorms most likely so your protection mode is at the dock. So just bolt a lug on to the mast and attach a heavy gauge wire to a weighted metal plate and throw it overboard. Recover the plate when you sail.

 

[KD3PC]

sadly, the prevailing wisdom is that the strike is going to ground using the shortest least resistance path that it can find...plates, wires, bars and mast top eliminators may or may not work or help...

without some major investigative work you are not going to easily discover which of numerous paths are the best ones for lightning to pass through.

 

[Ron McCoy]

Last summer a schooner with wood timber masts was hit by lightening just 100 ft from my boat docked at the marina. Some interesting insights gained; it's mast height was the lowest in the marina as there were at least 15 other boats in close proximity all who had tall masts, the lightening entered the mast at the shroud fittings near the top travelled inside the wood mast and exiting near the base. The electronics were fryed, however being a live-aboard (but not on the vessel at the time), he was able to start the engine and "boogie" to the haul-out slings on the other side of the marina. One thru-hull was blown, but the hose was still intact enough for him to plug the hole sufficiently to stay afloat while he brought the boat to the sling. Seeing the mast after it was removed from the boat was an eye-opener. The heat generated by lightening is impressive if not discouraging if it happens to your boat. Why lightening hit the smaller mast is anyone's quess.

 

[zeehag]

Last summer a schooner with wood timber masts was hit by lightening just 100 ft from my boat docked at the marina. Some interesting insights gained; it's mast height was the lowest in the marina as there were at least 15 other boats in close proximity all who had tall masts, the lightening entered the mast at the shroud fittings near the top travelled inside the wood mast and exiting near the base. The electronics were fryed, however being a live-aboard (but not on the vessel at the time), he was able to start the engine and "boogie" to the haul-out slings on the other side of the marina. One thru-hull was blown, but the hose was still intact enough for him to plug the hole sufficiently to stay afloat while he brought the boat to the sling. Seeing the mast after it was removed from the boat was an eye-opener. The heat generated by lightening is impressive if not discouraging if it happens to your boat. Why lightening hit the smaller mast is anyone's quess.

he probably had lightning protection..lol..theonly boats i know of that were hit by lightning were protected--one was a boat owned by a nasa engineer--his was hit twice--second time nearly took out wiring to house--i use a kitty---no scientific rationale to lightning strikes--we sailed thru 2-3 days of it off fla last summer--not hit despite proximity of storms---we have a cat on board lol.......spend the money on nothing--have fun--i will sail with my kat lol....oh, btw--this topic has been covered many times in many forums and is welll argued....goood luck in your ventures ......

 

[walt]

Zeehag, males are about 4X times more likely to get struck than females. Is your cat a male?

 

[Ross]

Zeehag, males are about 4X times more likely to get struck than females. Is your cat a male?

That is probably because the girls are smart enough to come in out of the rain.

 

[zeehag]

Zeehag, males are about 4X times more likely to get struck than females. Is your cat a male?

he used to be--wasnt broken but i had him fixed--isnt smart enough to come in out of rain tho--likes to play in it..LOL....

 

[Stu Jackson]

Lightning, just lightening up,,,

....oh, btw--this topic has been covered many times in many forums and is welll argued....

Yup, it sure has, and by now you'd think people (other than you and some others here) would be able to at least spell it right!:dance:

 

[shemandr]

I'd just like to add a real world observation to this. My friend's Ranger was hit while in the water. The boat had copper or bronze web straps for grounding. The lightening exited through the hull holing the boat. It was at the curve of the grounding material. Evidently, the quickest way to ground was through the non conducter, fiberglass. The lightening didn't give a damn about what the books say. He also had a hole in the rudder and other damage. His boat was hit after the lightening hit another boat up on the hard and jumped to his.