Bonding vs No Bonding

[Donn]

I've searched and I've read. I want today's opinions. My boatwright wants to remove the bonding from my boat...he's rabidly anti-bonding and anti-over zincing. He say's it's cheaper to replace hardware than wood.

What's the latest thought? Cleek, Chemist, mmd, RGM, Fleming, holzbt, all you boatbuilder guys.

Hold forth...spare no expletives. The boat is bonded, and lives in the water in a relatively low salt environment at the end of a canal. Zincs last a very long time here.

Pull the bonding, or leave it in place?

I await your wisdom.

[Bob Cleek]

Well, the biggest advantage to bonding is that it insures that the stray currents and electrolyis damage is equalized throughout every fitting in the bonding circuit. That way, everything gets eaten up at the same rate. Theoretically, this reduces the chance of one through-hull blowing all of a sudden, and makes sure they all go at the same time.

The overwhelming conventional wisdom is that bonding all metal-water contact items is not a good idea. It was a fad at one point and I have books written years ago which adamantly claim that it is a MUST. Curiously, these are only books about power boats. Today's writers say just the opposite. In my experience, none of the good yards recommend it.

Over-zincing is probably one of the most common causes of damage to wood boats. When I first got my boat, I had some very worrysome deterioration in the teak stern post around the shaft bearing casting. Fortunately, an old timer set me straight and told me to take the (huge) zinc off the damn thing. Patched up the scorched wood and haven't had a zinc, or a problem, with cooked wood or electrolytic damage anywhere on the boat since. Zincs are important where there is dissimilar metals in proximity to one another, for sure. They SHOULD waste away. They are intended to be sacrificial. If you have a zinc on your boat that isn't wasting away, you have one zinc too many. Too much zinc (the less noble metal) only reverses the process. You want a balance. The zinc should maybe last from haul out to haul out (a year or two). Beyond that, it's better to have a small one that does its job than a big one that just creates a bigger battery.

At least that's what I've learned about it over the years.

[On Vacation]

I don't know anything about your area. I don't anything about your shipwright. I only know that in the past experience of electrolysis is it is too late when you find out about it as the water is flooding in the hull from fittings eaten into as a result of bonding wire eaten off and not corrected, whether you are on the boat or not.

[Dave Fleming]

What material are your shafts and props?
Where are the zincs located? Where is this bonding strip you speak of and how is everything connected to it?

You are in relatively still waters but still salt not brackish, correct?
You have just found dissimlar metal fastenings in your hull, correct?
How may zincs are we speaking about here?
Do you keep a electrical cord attached to the boat when moored? If the last question is answered yes, go to Radio Shack and buy a simple MultiMeter and set it up to take some readings in the boathouse with the electrical hookup and without.

Thems the questions and now for the answers.

[Concordia..41]

Giffy Full stated not to bond and just 1 small zinc in the book Concordia Yawls – The First Fifty Years. He also stated it again at his seminar, Ask Giffy at The Wooden Boat Show last month.

Sarah appears to have never been bonded and the wood at the thru hulls and the bronze thru hulls and seacocks are in good shape.

I have a Corrosion Meter and the Boat & Yacht Corrosion Control Workbook from Yacht Corrosion Consultant, Inc. (Professional Mariner). Page 37 – “Wood boat mounting bolts, zincs and bare metal bonding straps should be insulated from contact with the wood as electricity from a bonding system attempting to flow through the damp wood cause the wood to foam and soften much like wood rot.” They only present one example of a corrosion survey on a wood boat and several on fiberglass. On the wood boat they recommend installing a zinc controller and a zinc saver, both high dollar pieces of equipment they sell. The zinc saver is a installed corrosion meter – another thru hull to install – and a variable resister inline with the main bonding conductor and the zinc. This has to be monitored and adjusted constantly. The zinc saver is a grounding transformer that is installed inline with the shore power ground wire aboard the boat.

Sarah will go with the old school of Giffy Full and what has appeared to have worked for 47 years.

Dave

Sun over the foreyard.

[CharlieZ]

Not a boatbuilder, but I've pulled the bonding from the Cuttyhunk. That boat could have been in Giffy's article.

[holzbt]

Every bonded boat that I have ever worked on had serious problems around the metal fittings. My own experience is that removing the bonding and decreasing the amount of zincs has stopped the wood degradation. I think Cleek has it right about the zincs. Use enough to protect the running gear/fittings but not enough to make a battery out of your boat.

[Ed Harrow]

The recent article in Woodenboat by one of "our" own mentioned that the boat, built by Paul Luke, had been bonded, and all (well most) of her troubles had been around the bonded fittings.

[Mr. Know It All]

If it ain't broke, don't fix it. we like to say in the Rustbelt. :D

[imported_Conrad]

My boat, and a number of other Egg Harbors that I've looked at have been very badly damaged by bonding, all of the wood from the engines aft along the keel appears to have been flooded with acid, badly deteriorated and eaten away. First thing we did was remove all of the bonding wires, straps and fastenings. The boat really should have a whole lot more wood replaced than it's going to, with probably 80% of what's damaged the result of the bonding. The kicker is that the boat is almost entirely bronze fastened and would probably be great shape if it hadn't been bonded.

I find it interesting that two construction techniques- bonding, and letting the frame ends into the keel, both of which were supposedly the hallmark of first class construction in the 1960's, have both proven to be wrong and are largely responsible for leaving the boat in such poor shape that only an idiot would attemp to restore it. But I am, and that's another story.

[Concordia..41]

Donn -

You are dangerously close to what I believe is the first official Forum Consensus. I would a) mark this date on your calendar; and b) look long and hard at lightning protection. ;)

Hope your and Loon's day is good.

- M

[Donn]

Margo..I think you're right. The bonding system goes. I'll also look into a lightning dissipation system.

[ 08-23-2002, 07:28 AM: Message edited by: donnwest ]

[On Vacation]

FYI

http://boats.com/content/default_detail.jsp?contentid=2190

http://www.boatingworldonline.com/Archives.htm?CD=18&ID=178

[Scott Rosen]

What Cleek said. An additional and likely danger of bonding is that you will be wiring togeter fitings that are not of exactly the same metals and alloys. Bonding effectively turns your boat into a battery.

Over zincing, as others have said, is a huge problem.

[mmd]

Oh my God!!! Consensus?!! Who'd a thunk it? :D

Yep, I agree that bonding dissimilar metals and pocketting frames on a wood boat aren't great ideas. Wanna start a fracas over the best method of lightning protection for small boats?

[thechemist]

Jeez....

Well, yeah.

Pretty much.

What everyone else said.

Unless you want to go to cathodic protection and a hundred square meters of Niobium plate under the boat......but even then, hmmmmm....well.....Naaah. Forget it.

[Ian G Wright]

Unbond, and only zinc what you must.

IanW

[Donn]

I've begun removing the system. Got rid of the keel zinc that it all lead to today, and will be tracking the system back to remove the wiring.

Thanks all.

[Bob Adams]

And the consensus continues. Like Conrads my Egg Harbor had a nasty case of fuzzy wood at every bonded fitting. Use good bronze hardware and cut all the bonding wires!

[htom]

I think it's one of those things that's very good in its place (probably metal hulls), indifferent in others (fg and cement), and very bad in ours (wooden hulls).

[Phil L]

I have a 67 Grand Banks 42 with lots of burning around the bonding system. I recently had a bonding system expert look at the boat and he wanted to put a very expensive meter system on the boat to adjust the current.

After reading the comments, I am under the openion that the best bet is to remove the system entirely. I wonder however, if you should still leave the zinks on the shafts and steel rudders.

I am a Yacht Broker and we sell wood Grand Banks. I know that the Marine Surveyors are not going to like not seeing a bonding system. I would be interested to see other comments.

[On Vacation]

Before going off the deep end, I would only like to comment on the furring up around hardware. There are reasons for this. Different boats have unigue problems with electrolysis. Many boats have furring because of the lack of moving air in closed or stagnet bilges. I would not be swayed by a talk forum to do something that may not be in the best interest of your particular situation.

[ 08-27-2002, 05:54 PM: Message edited by: oyster ]

[Donn]

My boat's bilges are very well ventilated, but the key to the decision for me was the fact that the only "fur" in the bilges is on metal connections to the bonding system. At my bonnaker's suggestion, I'm tracking the bonding system back...cleaning out the "fur," cutting out all the wire, and painting the surrounding wood with Cuprinol. There will be a shaft zinc and a rudder zinc on each side of the drivetrain. AND (This should bring comments) he wants the bottom painter to paint the shafts, struts and props.

[ 08-27-2002, 06:11 PM: Message edited by: donnwest ]

[On Vacation]

Let me just say this as a matter of fact. On a true wooden boat, the planking is wet. The weak ventilation creates the problem. The Coast Guard requires bonding in all wooden inspected boats. Many Grand Banks are closed area bilges with alot of hardware.
http://www.maritimeusa.com/metconts/section44.html
This is a great site for all to inquire on infomation about this.
http://www.maritimeusa.com/metconts/section44.html
This is a good site for your area, Donn.
THE TECHNIQUES USED IN THE VESSEL SURVEY UTILIZE THE LATEST IN TECHNOLOGY TO DETERMINE MOISTURE CONTENT, VOIDS IN LAMINATE, BONDING, AND GALVANIC CORROSION.

[Andrew Craig-Bennett]

What everyone said. Mirelle is 65 and unbonded and un-zinc-ed and whilst the edges of the manganese"bronze" prop are a bit ragged, that is the sum total of it.

Another thing; I am very uneasy about electric bilge pumps, of the type that is left on when the boat is unattended. Volts in bilge = bad idea, in my book.

[Tom Jackson]

Giffy Full is adamant in his opposition to bonding.
Refer to his article on the subject in WB No. 115.

Giffy also participated in a joint industry/Coast Guard
group, whose results were published as NVIC 7-95. This
NVIC specifically refers to the problems of bonding
in wooden boats, which the Coast Guard does not
require. My understanding is that the Coast Guard either was
requiring or was about to require bonding in wooden
boats, and it was largely due to the professional input
by Giffy Full and others that turned aside the requirement,
wih the belief that it would do much more harm than good. I
believe it was this input that precipitated the creation of the
working group that led to NVIC 7-95.

Refer to
NVIC 7-95 (http://www.uscg.mil/hq/g-m/nvic/7_95/n7-95.htm)
with particular attention to Section H, on page 31.

This is, by the way, a very useful document.

[On Vacation]

Tom I see this issue was written in Aug. 1995. The last inspected vessel I did any work on was 1992. At that time it was required. But I can say that up till last year, when our local inspector retired, unless you had a problem don't remove it. The largest issue of cause was the wet and stagnet bilge areas.
My post simply stated a fact as directly related to our past experience. I did find this part of particular interest.

FIGURE D-2: CATHODIC PROTECTION DISTRIBUTED BY THE BONDING SYSTEM
When there are no stray currents, the shaft zinc may protect not only the shaft and prop, but also any fitting connected to the bonding system. This often results in alkali damage to the wood around those fittings.

On wooden boats, bonding systems can cause unexpected problems. First, by connecting together a number of underwater fittings and fastenings, the bonding system may provide the metallic links which turn otherwise isolated dissimilar metals into a galvanic cell. Second, the bonding system often inadvertently supplies unneeded or unwanted cathodic protection to objects connected to the bonding system by connecting those objects to the propeller shaft's sacrificial zinc anode. This cathodic protection of underwater metal hull fittings often causes damaging alkali delignification of the surrounding wood.

This addresses the wet work effect:

"The fittings on a wood boat which are most susceptible to stray-current corrosion are those in the bilgewater or those which are in close physical proximity to wires, while those most susceptible to alkali delignification are those above the bilgewater level, but below the waterline. In this area the wood is wet enough to be a fairly good electrolyte, but there is little flushing action to remove accumulations of cathode reaction products. The hydroxyl ions produced by the cathode reaction on cathodically protected metals can concentrate in these locations, damaging the wood and often producing visible deposits of sodium hydroxide (lye) crystals which appear as a white mound of salt around fastenings."

Bonded vessels should be checked with a electrical potentiometer by a qualified electrical specialist for electrical leakage to ensure that the boat is not over zinced. This is especially true after a vessel has been found to have extensive wood repair due to alkali deterioration.

This stands out to me:

"Repairing the wood, without determining the cause (via a corrosion survey) is a poor practice as it would only be treating the symptom. "

[ 08-28-2002, 09:15 AM: Message edited by: oyster ]

[Ken Baker]

This bonding thing can be a big mess, no doubt about it. Trying to balance the needs of 120V safety, stray current corrosion, lightning protection and RF grounding on a woodenboat (or any boat for that matter) is not easy or cheap. Bonding adds another whole level of complexity to onboard systems, which needs to be maintained if it is to do any good. I think if this keeps up, at some point, the cedar bucket approach may come back into favor...

The cruiser I'm working on was all unbonded except for one seacock that must have been added during the bonding rage several years ago. The mahogany plank around this area is pretty well shot.

The only other area I found with a problem was back in the oak shaft log. A lead sleave had been fitted to seal the shaft tube. One of the steel drifts or bolts tying the keel/deadwood/horn timber and shaft log together must have come in contact with the lead as there a clear signs of alkali rot which I'll need to repair. The fix will be to remove the lead sleave and replace it with a fiberglass stern tube.

I don't intend to do any bonding and will keep all the underwater metals isolated (except for one plate - see below) as I get things put back together. My approach will be to either stay away from shore power or install isolation transformers to keep my 120V system away from mother earth. Any type of corrosion will be minimized by not bonding. I will be putting a zinc on my SS prop shaft (with a bronze prop), on the manganese bronze rudder and support skeg to protect against corrosion in these areas. Lastly, a dedicated copper plate will provide a lightning and SSB RF ground path. If I do run into stray current problems, this should be the only piece of underwater metal effected.

Regards,
Ken

[On Vacation]

current as of Oct.1, 2001 and enforced upon inspection.

http://frwebgate4.access.gpo.gov/cgi-bin/waisgate.cgi?WAISdocID=62373421575+25+0+0&WAISaction=retrieve

[Bob Adams]

A progress report, this is the first year I ever hauled my boat and still had shaft and rudder zincs left. Changes? Removed bonding system as I mentioned above, and, added a galvanic isolator to the shore power ground wire. About $120.00 from Guest. This provides a safety ground while preventing your boat from being a sacrifical anode for the boats around you. I am very impressed with it!