Bonding

Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
My OEM bonding system of questionable original quality is a mess and I've got something electrical going on. There are also things like the strut where no bonding wire was installed. I suspect the system is doing more harm than good at this point due to voltage drops and differentials.

I know there is a body of opinion that fiberglass boats with bronze underwater fittings do fine without bonding. My rudder heel fitting, which isn't connected to the bonding system, is the best looking metal on the boat.

Re-doing my bonding system would be a big job and I still couldn't get items like the strut and heel fitting. I have encapsulated ballast so there is no big chunk of metal hanging under the boat.

Would it make sense at this point to just pull out the whole bonding system?
 
woodster

woodster

.
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
Roger Long said:
My OEM bonding system of questionable original quality is a mess and I've got something electrical going on. There are also things like the strut where no bonding wire was installed. I suspect the system is doing more harm than good at this point due to voltage drops and differentials.

I know there is a body of opinion that fiberglass boats with bronze underwater fittings do fine without bonding. My rudder heel fitting, which isn't connected to the bonding system, is the best looking metal on the boat.

Re-doing my bonding system would be a big job and I still couldn't get items like the strut and heel fitting. I have encapsulated ballast so there is no big chunk of metal hanging under the boat.

Would it make sense at this point to just pull out the whole bonding system?
Click to expand
not speaking here with techinal knowledge ......but my boat had bonding... all connected to the propeller shaft strut and it is toast causing me to have to replace it ....after much chaseing and hunting i have it on order and not going to hook it back up the the system and for that matter i dont think i will bond any bronze fittings unless there is a way to have a zinc on each that is...i just hope that i have the correct approch to this problem .....i do have a plate that i am installing to the boat for the ground but not sure that this grounding and a bond should be one and the same....

regards

woody
 
kloudie1

kloudie1

.
Nov 6, 2006
10,093
Hunter 34 Mandeville Louisiana
Best to get a reference cell and check the boat with and without the bonding hooked up.. I suspected a problem with my strut being un-bonded (it cracked because of electrolytic damage) and my survey with a borrowed reference cell verified that it should be connected to the engine .. I did.. but I have a cast iron keel that is also connected to grounds/bonding.. If your ballast is encapsulated, then the only thing you have underwater is bronze (thru-hulls/shaft/prop/strut) and your idea sounds correct.. The only other possibly electrolytic stuff around there is the heatex and housing.. ?? I would do a electrolytic survey per Calder to verify the removal is OK.. Best to do one at mooring and one at a marina, plugged in to shorepower ..??
 
Johnb

Johnb

.
Jan 22, 2008
1,461
Hunter 37-cutter Richmond CA
From that West Marine article:

"Do not bond any thru-hulls or other immersed metal that can be electrically isolated. Specifically, keep your metal keel/ballast, your metal rudder shaft, your engine/prop, and all thru-hulls electrically isolated, from each other, and from the engine."

Yes yes yes. Other boats and badly wired marinas can result in voltage differences in the water between one spot and another. If your propeller is in one of those and your keel is in another the current will flow in/out the propeller, through the bonding and in/out the keel. The result is rapid destruction.

The same thing can happen if you connect the incoming AC ground to engine/keel or whatever without a galvanic isolator.

That is a great article.

As a final comment, one of the most effective ways of making electric power safe is to include ground fault protection.
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Johnb said:
That is a great article.
Click to expand
Looks like it and makes sense to me. This is Maine Sail's forum. I want to see it from him on carved into a stone tablet before I rip all the green wires out:)

I installed my new buss and reconnected all the negative wires today. The greens are still hanging out in the air though awaiting final word. Actually, they are going to go anyway because they are 1980 un-tinned wire. If I should decide there is a reason for bonding, they all need to be replaced so they'll probably come out tomorrow.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,709
Canadian Sailcraft 36T Casco Bay, ME
Roger Long said:
Looks like it and makes sense to me. This is Maine Sail's forum. I want to see it from him on carved into a stone tablet before I rip all the green wires out:)
Click to expand
Roger,

This subject, like lighting, is controversial. Capt David Rifkin is perhaps the foremost authority on the subject and I just finished a great ABYC course with him. He is a staunch advocate for bonding. On my own boat I do not bond because for my own use it is just not necessary and I have a known system properly installed, grounded and measured with a reference cell. Would it hurt? No but I don't really have a dire need to crawl around my bilge interconnecting my underwater metals when I don't have an issue. Every boat and situation is different though.

With an "unknown" electrical system it is not a bad idea to bond and keep all metals at the same potential. Very often the corrosion of metals is caused by your own vessel not others. I am always amazed at the sheer number of ground points I find on boats. Multiple ground points can cause galvanic issues and this is where you'd want all your underwater metals at the same potential. It is not an easy answer and there is no one right answer despite what WM states. Every boat and every situation/electrical system is different.

If you are in a marina then you really do NEED a galvanic isolator or isolation transformer and beyond that you'll need to read as much as you can then make up your own mind to bond or unbond..

Bonding systems also fail to do what they are intended to do as the corrosion on seacocks and metals below the waterline run rampant. There have been more than a few situations where I measured bonded systems where some "bonded" items were are a different reading. I was using my old and questionable "reference cell" though. I recently acquired a new better quality one thanks to another forum member!

I quite often see bonding wires simply dangling in the bilge leaving some metals at one potential and the failed one solo and on its own. I even have a photo of a BRAND NEW vessel with untinned wire hose clamped to the threads of a thru-hull fitting as the bonding system. That bonding will likely last a few months at best.

Stray DC current is the biggest cause of electrical issues but everyone assumes it is always marinas and AC. While AC does cause corrosion it is far less aggressive and far slower than DC issues. Your own boat is often your own worst enemy.

I will not suggest either way but would highly suggest you read beyond the WM adviser on this one including some of Rifkin's stuff.

Keep in mind on your wiring that your AC GREEN/GROUND wire should be connected to your boats on-board DC ground buss. Unlike a home the WHITE/NEUTRAL and GREEN/GROUND should never be connected on the boat. The AC GREEN should be connected to the boats DC ground and back through the shore power cord to earth ground.
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Thanks. Here's my thinking.

If it's controversial, that means two things:

1) The boat isn't going to automatically sink as soon as I take out the bonding system.

2) I'm unlikely to be able to predict from reading which is the better option in my individual situation. Probably only a full electrical survey would do that.

The way a bonding system works, it better be right. Any voltage drops or stray current getting into it is going to turn it from a protection into a problem.

My 1980 bonding system put together by south FL pot heads is clearly junk and I clearly have a problem.

The system has to come out anyway and it will be no less painful to replace it now than later. I've got plenty on my plate.

Conclusion: I should rip it all out (except the fuel system bonding) and assess later. If I have any money left, I'll have an electrical survey done in the water.
 
G

gettinthere

.
Nov 26, 2008
1,970
Endeavour 42 Cruisin
I got the impression (perhaps incorrectly) from my surveyor that my insurer wanted everything bonded for lightening protection. Safety trumps corrosion potential in their minds.

I had one bonding wire to the refer compressor disconnected and he made an issue out of it.
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
Lightning

Lightning :eek:

That is a a whole subject in itself. Adding lightning protection and a ground was going to be my big winter project a couple years ago until research convinced me it was futile and impractical on my particular boat. It's also the big flaw in my grand plan since my boat is especially vulnerable. I don't think those little wires are going to do much.

Here is a random list of what I learned, or think I learned:

Lightning is a huge energy flow or field. Every possible path over an area larger than most boats is energized. You can't lead it around with little wires. A lot will follow the path you try to set for it but what's left over on the other paths will still cause major damage in a big strike.

There is so much current that it wants to go in a straight line. Your mast is the largest conductor and is straight. If there is not a geometrically straight path to a big ground from the mast step, you are wasting your time.

Making a Faraday's cage out of the rigging by leading conductors to water may work with wooden masts (as long as they don't have wires or sail track) but not aluminum.

90% of the boats struck in FL suffer only minor damage even when unprotected.

A direct strike will overwhelm the fanciest expensive systems you read about on the net.

It's a crap shoot, like living south of Maine is with tornadoes.

Industry standards are a joke as far as complete protection is concerned.

A steel or aluminum boat with an aluminum mast resting on a structural mast step is about the only thing that is going to protect you, somewhat.

My posts here are going to stop if I suffer a direct strike because the straight line down my mast and metal compression post ends abruptly above a sloppily constructed ballast area of lead pigs that was gradually filled with the resin left over at the end of the day from other boats. It's almost certainly full of voids with water in them which will flash into steam. Side flash will arc to nearby through hulls, bonded or not, and probably blow them right out. Good thing I'm old and have lived a full and interesting life.
 
Auspicious

Auspicious

.
Mar 7, 2005
53
HR 40 Chesapeake Bay
Lightning has a potential of hundreds of thousands of volts. Do you know what one calls those little green wires when that much voltage is pushing current through it? A fuse. Lightning is going to push current through just about everything trying to get to ground (the water). These are huge forces that can induce substantial currents even in a near strike.

I worked for years on a program that didn't have a lot of financial constraints. I wasn't the lightning guy but the message was pretty clear in the program reviews. We grounded to minimize static accumulation and for radio system performance.
 
G

gettinthere

.
Nov 26, 2008
1,970
Endeavour 42 Cruisin
Do you know what the insurance company will call my lightening claim if I don't have the stinkin green wire? It's a river in Egypt.

I'm taking the "no fuel bulb in the ER" MaineSail tack.
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,709
Canadian Sailcraft 36T Casco Bay, ME
gettinthere said:
Do you know what the insurance company will call my lightening claim if I don't have the stinkin green wire? It's a river in Egypt.

I'm taking the "no fuel bulb in the ER" MaineSail tack.
Click to expand
When we suffered a 20k loss last summer due to lightning, the surveyor, who really was quite under skilled, checked for a mast to keel bolt/ground plate connection as one of his first moves. I have lightning grounds but don't honestly now how it would have gone had I not had it.
 
Roger Long

Roger Long

.
Nov 22, 2008
3,562
Endeavour 32 Portland, Maine
gettinthere said:
My Endeavour had a ground plate
Click to expand
I was going to install a ground plate a couple years ago until research revealed the futility of it. If there is a strike on the mast, the current going straight down the mast and the compression post (deck stepped) is going to keep right on going in a straight line. After all, it just came a few miles through the air, what's a few inches of fiberglass. Current at these magnitudes likes to turn corners about as much as a cannon ball.

The only solution I could think of was to get a honking big drill, one that can chew through lead pigs, remove the mast compression post, drill right through the keel and ballast, and epoxy in a length of 1 - 1 1/2 in diameter bronze propeller shaft. The bottom and leading edge of the keel would then be sheathed in copper bonded to the shaft. Of course, the energy of a major strike would heat up the shaft enough that I would then have a huge leak around the shaft.

This does bring up an interesting point though. If having an ineffective fig leaf of a ground plate that meets industry standards meant the difference between insurance paying and not paying in event of a near strike that took out the electronics and wiring, it probably would be worth installing and maintaining. Even with my super ground, a strike would fry everything.
 
kloudie1

kloudie1

.
Nov 6, 2006
10,093
Hunter 34 Mandeville Louisiana
I had a small strike several years back on my deck stepped mast.. When I took the compression post out to fix the beam it supports, I inspected the bonding wires (8 ga, think) and found no damage. I figured I would see tracking from the bond wire to a keel bolt but the charge followed the wire to another keel bolt after a 90 degree turn. I did see a lot of arc tracking on the back of the aluminum switch panel where it appeared that a large flash had run on the surface of the panel about 8-10 inches on its way to the green wire.. The reverse polarity light bulb and its lens was physically blown across the boat. As previously noted, the keel had branching lines under the barrier coat where the coat had dis-bonded but not blown free.. I suspect a lot of discharge happened at the keel.. She is in fresh water, so that probably limited the damage.. Attached is picture of the remains of the VHF antenna .. no damage to the coax but the radio was fried beyond repair. Stern nav light bulb was exploded in side the housing.. but the anchor light on top of mast was not harmed.. nor was the bow light. The led panel indicator lights were all undamaged.. The shrouds and stays/chainplates are bonded with 8 ga to the keel and batt neg is as well. Master batt switch was off but shore power was on.
 

Attachments

Bill Roosa

Bill Roosa

.
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
New guidance on how to handle lightning on boats from ABYC. The general view now is to "take it around the outside and not bring it into the boat in the first place" apparently the electrical properties of salt water result in a very thin film (<1/4") of charged surface (capacitor plate type charging) on the water surface. The use of the keel stuck deeply into the water is not as effective as any piece of metal near the water surface. This was indicated by the large number of "side flashes" at the water line in a lot of lightning strikes. Apparently the charge would rather go to ground through the side of the boat near a bonded metal item (gas tank, thru hull….. anything) near the water line than be forced under water and have to return back up through the water. Personally this makes sense to me from an electrical potential point of view. There is a short gap between the lightning charged metal item and the water surface with just some fiberglass in between resulting in very high voltage potentials across the gap. There is a keep ground which is actually beneath the charged surface and the potential would be actually working to drive current from the keel up to the surface charge. Almost like lightning in reverse or what happens to the non working side of a capacitor plate (the water surface)
So un-bond the mast from the keel and run a wire from the shrouds, fore and aft stay to the toe rail and then to the water surface. if you don't have a conductive toe rail then just ground the shrouds/stays directly to the water surface.
This is in keeping with the standard way of handling lightning on buildings but accounts for the odd charge behavior of sea water under highly charged clouds.
 
You must log in or register to reply here.

Top Bottom