Electro-Chemical Damage In Wooden Boats Update – Revisited

rudder electrochemical damage

 


ELECTRO-CHEMICAL DAMAGE IN WOODEN BOATS UPDATE
A Special Post By Chris McMullen

Recently I received a note from Chris where he questioned if the story we posted last year on ww about electro-chemical damage to wood  was a little too long & were people reading it. Well I can tell you that the post is the single most visited story on ww, ever, & gets read by people all over the world. Its frequently referred to on the hugely popular WoodenBoat Forum in the USA. The link below takes you to the original story.

https://waitematawoodys.com/2015/05/15/electrochemical-damage-to-wood-the-marine-version-of-leaky-homes/

For the impatient ones out there 🙂 Chris has done a ‘Readers Digest’ version & refers to a vessel that recently featured on ww.
I encourage all of you to read today’s story & if you own a classic wooden boat – read both versions – the problem is the biggest risk to the life of our classic boats.

In Chris’s words:
“I received the above disturbing images of another woody being destroyed by an owner who I believe is unintentionally loving his boat to death.

The use of anodes and bonding on a wooden boat is fatal. The cathode or protected metal makes hydrogen gas and this combined with saltwater makes Sodium Hydroxide (Caustic Soda). This chemical is used to pulp wood in the paper making industry. Not on my boat thank you! I say again, there is no reason to use anodes and bonding on any boat. The only exception, steel hulls require anodes. If copper or bronze are being corroded it is due to a positive DC leak and Zinc anodes will not help. Find the electrical leak is the cure. If there is brass or manganese bronze underwater it will corrode due to the
zinc in the alloy. Anodes will possibly stop the corrosion but at the expense of wood damage. A better plan is to replace the brass with proper marine bronze.

Bronze and copper should last indefinitely in the sea. To prove that statement, I ask you to look at the Roman coins and artifacts salvaged from ships wrecked in the fourteenth century. There was no anodic protection and the metal is well preserved. So what is the difference to the copper and bronze on your boat? There is absolutely no difference so why waste your money buying anodes that will in time destroy
your wooden boat.

Three or four bottles of wine will cost the same as anodes and will make you and your boat happier.”

Note: ww is read all around the world, if there is water & boats, there are people reading ww. So a little about the man for non kiwi’s  – Chris is one of NZ’s most respected boat builders (retired) and at one time was the Lloyds (Honorary) Wood Boat Surveyor in Auckland. Chris’s (the original company) ‘McMullen & Wing’ built and repaired wood, steel and marine aluminium vessels. They built the first welded aluminum vessels in NZ. Chris is the current holder of the Classic Yacht Association of New Zealand ‘Outstanding Achievement Trophy’ for services to classic boating.

14-05-2016 Photo Update
Gavin Gault sent in the below photos of a Nova skeg floor that he believes were probably damaged due to engine – anode bonding failure. Pretty graphic !!

 

10-07-2016 Reply from Chris McMullen

“Wow. Thank you Gavin Gault for sharing your very graphic images. Very sad, small consolation but yours will not be the only wooden boat affected by this scourge.
Maybe, at last some of the Flat Earth Society will start to believe what I have been saying. The worst detractors are some in the Marine Industry who have been preaching the Anode, Bonding party line for years.  Now there is no where to run for cover,  they continue to conjure up excuses and it seems, refuse to accept a simple scientific fact.
“If you have a positive and negative electrode in salt water, the negative cathode or protected metal makes hydrogen gas and this combined with salt water makes Sodium hydroxide.”
This chemical is also known as caustic soda and removes paint and destroys wood.  There is no doubt about this fact. You do require a power source and bonded dissimilar metals ( zinc and copper) provide sufficient current to do the damage, but slowly.
If there is a negative DC leak (to the sea)on a bonded boat the process is accelerated. If there is a positive leak any metal becomes an anode and will waste away. It is important to isolate the DC power from contact with the sea. Again bonding is just asking for trouble. Please remove Anodes and Bonding from your wooden boat now!
Chris McMullen”

06-09-2106 In case you were not to sure what to look out for – the below photo should be a wake-up call to a few woodys 😉

IMG_1120

 

Building the Mullet boat ‘Tamatea’ by Chris McMullen

Tamatea 17

1961 – the build begins @ 67 Waiatarua Road, Remuera

Tamatea 22

Tamatea 1

Tamatea 29

 

Building the 22’ Mullet boat ‘Tamatea’ – Sailing Sunday

photos & story by Chris McMullen. edited by Alan H

After Chris McMullen saw last weeks ww story on ‘Tamariki’ he contacted me re sharing his ‘Tamatea’ photos that had been languishing in an album kept for him by his dear mother, Vera McMullen. I couldn’t let Chris escape with just sending the photos to me, so I asked him (nicely) to write us a story. Now that’s something he is always a tad hesitant to do, why I don’t know he tells a good yarn. But being the great guy he is, he put pen to paper, in doing so Chris commented that he hoped that bringing these photos into the daylight may encourage others to share their boating or boat building history on waitamatawoodys.

Below is Chris’s story on the building, launch & sailing of the 22′ mullet boat Tamatea. Remember you can enlarge photos by clicking on them 😉

“In the early 1960’s I was apprenticed to boat builder, Morrie Palmer who was also an enthusiastic Mullet boat sailor. Sailing, cruising and Mullet boats were the conversation most lunch breaks.
Morrie had in mind to build a 22ft Mullet boat but family and business commitments at the time, delayed his plans. He had a new steel centre board plate, a profile plan and the offsets of a design for a hull that was supposed to be the Charlie Colling’s design ‘Tamariki’. I am not sure how he got these offsets but the original lines plan were in safe keeping at the R.N.Z.Y.S and not available to anyone at the time.

Morrie encouraged me to build this design and gave me his centre board plate and loaned me the offsets. I managed to scrounge some primitive basic machinery and set out to build the boat. As an 18 year old apprentice boatbuilder I had no money, no car and no girl friend but I was full of enthusiasm and wanted to go sailing. And yes, I had read Johnny Wray’s book. “South Seas Vagabonds” many times.
The Tamatea was built in my parent’s back yard at 67 Waiatarua Rd Remuera. These days such a project would not be possible due to the noise regulation’s but in the early 1960’s people were remarkably tolerant and it was not unusual to see half built boats on people’s quarter acre sections.

 Riveting of Tamatea at night was not really fair on the neighbours. I got one complaint by working too late. I had to enlist my friends to back up the nails with a dolly. If they came late, we worked late. I was desperate to get it done. Another source of irritation was my Fathers Desoutter electric drill. It had no suppressor and affected the people who had TV’s. I was the neighbour from Hell for a while.

Now to the photos.

The photos feature some of my friends who helped. Recognised in the photos are
John Jennings, Des Laery, Ken Wilding, Murray Napier, sorry but I can’t remember all the names but Alan Bell and Neil Gillard would have been there. In the dinghy sculling is ‘Snow’ (Neville Stacey) who was / is a well known helpful character; he loved boats and spent much of his time at the ‘Okahu Bay’ hardstand.
The young man painting the Tamatea in the colour picture is the late John Eastwood. In the same image but in the cockpit is a another young man, John Court, also since deceased. My Model A truck alongside the boat, used as a work bench. The sailing cockpit shot shows Ken Jaspers and with me on the helm. These three guys and John MacDonald built and loaned me gear and helped finish the boat. I guess this was the year after she was launched. I was grateful for their help as I could not afford to run the boat myself at that time.  

You may notice in some of the images, the concrete blocks on the roof of the shed. These allowed me to force rocker (bend) into the keel using a timber prop under the rafters, their weight prevented the roof lifting. Looking at it now, I am lucky the lot never collapsed on top of me.

I never lofted the hull; I just made the temporary frames (moulds) direct from the offsets and cut the plank rabbet’s (rebate) by eye using battens.
The hull was planked with kauri over temporary frames or moulds. The planks were tapered towards the ends like a wooden barrel. The garboard plank was steamed but most was bent cold and edge set. I broke some planks! They should have all been steamed but with my primitive steam box it would have taken too long and I was in a hurry and wanted to go sailing.  
The short planks left out in some of the photos are called stealers and have to be spiled. I remember the frustration of not having a thin plank to use for a spiling batten. I could have borrowed one from my boss but with no car or trailer, how could I get it from Devonport to Remuera on a motorbike?
The ribs were Tanekaha, all steamed and held with riveted copper nails. The centreboard case was demolition kauri held to the keel with galvanised bolts.

Some of the images show the most distinctive feature of a proper Mullet boat – the hollow sections aft and the deep built down deadwood. The boats are a built to certain design and scantling rules.

Tamatea was transported to the water using a trailer kindly loaned by Sandy Sands of Sea Craft and towed by a neighbour Mr Picket with his (at the time) huge truck. A dangerous load? Well maybe, but we got there!

Tamatea was the last planked 22 foot Mullet boat.

My boss, Morrie Palmer forced change to the class rules by building “Controversy” using 3 diagonal layers of ¼” kauri over stringers instead of carvel planking caulked over ribs. Now Mullet boats can now be built in G.R.P.

I was about 18 when I built Tamatea, she was rather amateur built as I was a second year apprentice and although, I thought I knew it all, I was very green. She was built under difficult conditions almost in the open and exposed to the weather, I had very primitive tools and no transport or money to purchase anything other than what went into the boat. Later, I replaced a damaged plank in the “Contessa” built by Cal Crooks and sailed on the”Patiri”built by Bob Harkin. Both these Mullet boats were beautifully built by apprentice boat builders but to be fair, they were older and more experienced than me.

I built the Tamatea for cruising and she was a raised deck Mullet boat. She was very spartan when launched. Second hand sails and a poor rig. We cruised north to Whangaroa the first season but some time later lost the first mast. Insurance paid Baileys to build a new box section oregon mast and my new crew of engineers made all new mast fitting and a set of backstay levers. Their efforts made a huge improvement to the yacht.
Leo Bouzaid (‘Sails & Covers’) built a new dacron mainsail and gave me a year to pay. That was in April 1962 I still have the original invoice for 126 Pounds!

I/we sailed in the Lipton Cup but with poor results. Since then the raised deck has been cut down to a conventional sheer and she has a modern rig. Sailed by others she has won the Lipton Cup a number of times.

Further – looking back to the early 1960’s to give my story some context :-
• I crossed the harbour every day usually on a steam ferry.
• There was six o’clock closing at all bars.
• There were few restaurants where you could buy a drink with your meal.
• A quart bottle of beer cost 2 shilling and sixpence or 3 shillings and sixpence at the   Mansion House, Kawau Island in ‘The Snake Pit’ sly grog bar.
• Many cruising boats carried a rifle on board.
• There were no imports except for essential industries or you could apply for special licence but it would be most likely declined. You could only buy a new car if you had overseas funds.
• A few importers had import licence and charged accordingly.
• There was death duties and high tax.
• There was black and white poor quality TV and manual calculators.
• There were No mobile phones.
• No double insulated power tools.
• No  epoxy  Glue.
• No GRP boats and very few synthetic sails
• No moorings in Matiatia.
• No marinas or travelift’s
• Most pleasure boats were hauled out for the winter.
• There were NO IMPORTED BOATS and you could buy kauri so wooden boat building was a competitive but viable business.”

 

Electro-Chemical Damage In Wooden Boats Update

rudder electrochemical damage


ELECTRO-CHEMICAL DAMAGE IN WOODEN BOATS UPDATE
A Special Post By Chris McMullen

Recently I received a note from Chris where he questioned if the story we posted last year on ww about electro-chemical damage to wood  was a little too long & were people reading it. Well I can tell you that the post is the single most visited story on ww, ever, & gets read by people all over the world. Its frequently referred to on the hugely popular WoodenBoat Forum in the USA. The link below takes you to the original story.

https://waitematawoodys.com/2015/05/15/electrochemical-damage-to-wood-the-marine-version-of-leaky-homes/

For the impatient ones out there 🙂 Chris has done a ‘Readers Digest’ version & refers to a vessel that recently featured on ww.
I encourage all of you to read today’s story & if you own a classic wooden boat – read both versions – the problem is the biggest risk to the life of our classic boats.

In Chris’s words:
“I received the above disturbing images of another woody being destroyed by an owner who I believe is unintentionally loving his boat to death.

The use of anodes and bonding on a wooden boat is fatal. The cathode or protected metal makes hydrogen gas and this combined with saltwater makes Sodium Hydroxide (Caustic Soda). This chemical is used to pulp wood in the paper making industry. Not on my boat thank you! I say again, there is no reason to use anodes and bonding on any boat. The only exception, steel hulls require anodes. If copper or bronze are being corroded it is due to a positive DC leak and Zinc anodes will not help. Find the electrical leak is the cure. If there is brass or manganese bronze underwater it will corrode due to the
zinc in the alloy. Anodes will possibly stop the corrosion but at the expense of wood damage. A better plan is to replace the brass with proper marine bronze.

Bronze and copper should last indefinitely in the sea. To prove that statement, I ask you to look at the Roman coins and artifacts salvaged from ships wrecked in the fourteenth century. There was no anodic protection and the metal is well preserved. So what is the difference to the copper and bronze on your boat? There is absolutely no difference so why waste your money buying anodes that will in time destroy
your wooden boat.

Three or four bottles of wine will cost the same as anodes and will make you and your boat happier.”

Note: ww is read all around the world, if there is water & boats, there are people reading ww. So a little about the man for non kiwi’s  – Chris is one of NZ’s most respected boat builders (retired) and at one time was the Lloyds (Honorary) Wood Boat Surveyor in Auckland. Chris’s (the original company) ‘McMullen & Wing’ built and repaired wood, steel and marine aluminium vessels. They built the first welded aluminum vessels in NZ. Chris is the current holder of the Classic Yacht Association of New Zealand ‘Outstanding Achievement Trophy’ for services to classic boating.

14-05-2016 Photo Update
Gavin Gault sent in the below photos of a Nova skeg floor that he believes were probably damaged due to engine – anode bonding failure. Pretty graphic !!

10-07-2016 Reply from Chris McMullen

“Wow. Thank you Gavin Gault for sharing your very graphic images. Very sad, small consolation but yours will not be the only wooden boat affected by this scourge.
Maybe, at last some of the Flat Earth Society will start to believe what I have been saying. The worst detractors are some in the Marine Industry who have been preaching the Anode, Bonding party line for years.  Now there is no where to run for cover,  they continue to conjure up excuses and it seems, refuse to accept a simple scientific fact.
“If you have a positive and negative electrode in salt water, the negative cathode or protected metal makes hydrogen gas and this combined with salt water makes Sodium hydroxide.”
This chemical is also known as caustic soda and removes paint and destroys wood.  There is no doubt about this fact. You do require a power source and bonded dissimilar metals ( zinc and copper) provide sufficient current to do the damage, but slowly.
If there is a negative DC leak (to the sea)on a bonded boat the process is accelerated. If there is a positive leak any metal becomes an anode and will waste away. It is important to isolate the DC power from contact with the sea. Again bonding is just asking for trouble. Please remove Anodes and Bonding from your wooden boat now!
Chris McMullen”

06-09-2106 In case you were not to sure what to look out for – the below photo should be a wake-up call to a few woodys 😉

IMG_1120

 

SPECIAL ANNOUNCEMENT – CYA Outstanding Achievement Trophy

SPECIAL ANNOUNCEMENT – CYA Outstanding Achievement Trophy

Last night (Dec 5th 2015) at the 2015 CYA Patio Bay weekend BBQ / Xmas party CYA member Chris McMullen was presented with the CYA Outstanding Achievement Trophy for services to classic boating. The trophy has only been presented once before (Haydon Afford).

Now Chris is a regular on ww & has sent most of his life in & around wooden boats. As a founding partner in McMullen & Wing boatbuilders there would not be a medium that Chris has not applied his skills to – wood, steel, alloy & the f word (fiberglass), the great thing is that thru-out his career he has remained true to his passion for wood. Even today Chris  is at the forefront of trying to raise awareness & educate classic wooden boat owners on the issue of electrochemical damage to wood.

There is no other living, New Zealand wooden boat enthusiast more deserving of this award & I was proud to stand alongside Chis when he received the award.

photos ex Fiona Driver 

Venture

VENTURE
photos ex AH, Chris Miller & Rod Marler

On the weekend CYA cruise to the Riverhead Hotel we were joined by (to me) a new classic on the CYA scene, Venture. Keen to learn more about her & what lies underneath the ‘addition’.

Neil Lineham has advised Venture was built in 1961 by Morrie Palmer and apprentice Chris McMullen for Stuart and Peter Opperman. The boat built after her (1963) was Neil’s fathers boat Oranoa, built in the old police station at Clarance St Devonport. Oranoa is still owned by the Lineham family.

04-11-2015 Input from owner Jeff Norris (edited by Alan H)

Venture was built by M. G. Palmer at Devonport launched in 1964 the first owner was a Mr Hudsmith he owned her for 30 years . The design for the 36′ Venture was ‘influenced by’ Colin Wilde. She is powered  by 86hp 6cyl Ford Trader she used to have a 30hp Perkins wing motor it was removed by the owner before Jeff. Jeff has owned venture for 15years and is in the process off doing a tidy up and a repaint off the top sides . They are going to glass the hull next year and maybe a re-power as the trader is getting very old but still runs perfectly, Morrie told Jeff , there is a sister to Venture but it is a bridgedecker , Morrie built Venture for himself but had to sell her before she was finished . Venture was a very good game boat in her day but now she is just a cruiser.

02-05-2016 Photos of Venture at the CYA Raft-up at Salthouse Boat yard (Alan H/Ken R)

VENTURE 30.4.16

And just in, a trip report from CYA chairman Rod Marler, currently in New York. Rod did a circumnavigation of Manhattan on this fine ship yesterday. I would say she is a replica but her heart is in the right place 😉

 

A Visit to Chris McMullen’s Boat Shed

One of Chris’s experiments

And of a few photos of one of the prettiest boats on the Waitemata – Wirihana, the 1933 Colin Wild launch.

A Visit to Chris McMullen’s Boat Shed

Yesterday was a biggie on the wooden boating front – Barbara Cooke & myself organized for the Classic Yacht Association a visit to Chris McMullen’s workshop & boat shed. I have posted photos of the shed & its contents on ww before & ww has published several of Chris’s posts on the topic of electrochemical damage to wooden boats – but it was special for the members to meet the man himself & hear him speak on his past, his current passions / projects & future plans. The reproduction 1898 Herreshoff steam launch project just has to be one of the best kiwi ‘can-do’ tales around. The day she hits the water will be a very special occasion, I just hope I’m around to see it 😉

Today two things stood out for me:
1. The turn-out of two wooden boating icons – John Salthouse & Max Carter
2. The healthy number of sub 35 year old guys with a new found passion for classic wooden boats in attendance

If your a CYA member & you didn’t make the effort to come to the event – more fool you – as one of your most respected members said to me “today was a privilege, Chris is a one of a kind, his practical knowledge on boat building and engineering is unique”.

In my time as CYA launch captain one of my personal goals was to help deliver up events & access to people & ‘cool stuff’ that people would not normally have access to without being CYA members – from the comments & the smiles as people where departing today, Barb & I got it right today 🙂

To read / view more on Chris, his boats & the topic of electrochemical damage to wooden boats just enter – Chis McMullen – in the ww search box 😉

Electrochemical Damage To Wood – the marine version of ‘leaky homes’

Electrochemical Damage To Wood – the marine version of ‘leaky homes’

Story & photos by Chris McMullen. Edited by Alan H

NOTE: The photo above is the residue left from a heart kauri floor. The keel bolt had been bonded for ten years. Impossible to affect a proper repair as the bolt went through the deadwood.

Today’s post appears on WW for three primary reasons:-

#1 the author Chris McMullen is someone I & most intelligent, thinking boaties respect.

#2 waitematawoodys is all about the study & appreciation of classic kiwi wooden boats – if people do not wake up, there wont be any to appreciate.

 #3 this information needs to be stored somewhere like waitematawoodys so when people are searching the topic of electrochemical damage in wooden boats, they will find this & be able to make their own decision based on sound, robust debate like the below.

Most people are aware that Chris is one of NZ’s most respected boat builders and at one time was the Lloyds (Honorary) Wood Boat Surveyor in Auckland. Chris’s (The original Co) “McMullen & Wing” built and repaired wood, steel and marine aluminium vessels. They built the first welded aluminium vessels in NZ.

Public opinion back then was, “They were mad” and the hulls would fiz and corrode in salt water. Not so, and now aluminium is used for not only yachts but all types of commercial vessels.

Chris is also the custodian of the magnificent classic Colin Wild launch ‘Wirihana’.

Chris is constantly asked for advice on kauri vessels with wood degradation problems. His view is somewhat different to many marine industry technicians in NZ but backed up by Yacht Surveyors in the USA and the UK.

If you don’t have time now to read this post today, please bookmark it, as I guarantee it will at the least have you doing a double take.

Update 06-06-2015 – if you are time poor scroll to the bottom, new info & photos added

I’ll let Chris tell the story. Alan H

Chris McMullen – I am absolutely convinced that any wet wooden (caulked) vessel is doomed to a slow death if dissimilar metals or zinc anodes are fitted and bonded by wire to underwater metal. I do not reject the theory of cathodic protection; in fact I use it and zinc anodes on my steel floating dock. The problem is the wet wood component. There is a voltage between any two connected (bonded) dissimilar metals and the wet wood completes the circuit. Any voltage in the wood (from any source) breaks down the lignin in the wood round the cathode (protected metal) and that is the issue.

The white corrosion byproduct formed, Sodium hydroxide, is used for pulping of wood in the paper making industry! Want this on your wooden boat? Yuk!

Included below are some links to technical papers written by wood chemists rather than by metallurgists. These articles are not new but quite convincing and are parallel to my thinking and experience.

It seems however that people don’t like reading technical stuff. And it’s (I guess) easier to read and believe what is written in a local boating publication.

I decided to do an experiment to prove my point.

I used a length of 6”x 1” pine.  I bolted to it an old zinc anode and about a metre away bolted two bronze objects. I connected one to the anode with a copper strip and the other is close by but not connected to the anode.

I hung these on a rope in the water of the Tamaki River (salt) off my floating dock.

After six months, I pulled the test rig out and cleaned off the considerable marine growth.

I removed the bronze objects. Under the one connected to the anode was a black stain and the bolt fell out of the hole. The other, the bolt had to be punched out and the timber was clear bar some copper residue.

I photographed the test & also took the voltage readings between the metals and also the metals potential against a silver-silver chloride reference. (click photos to enlarge)

The minor damage done to my test piece is the result of only six months submersion. I will put it back and check in another six months.

It is however, quite obvious to me some thing is wrong and in time the wood will deteriorate further. If this is due to a voltage (less than half a volt) well, you can imagine the damage coursed by electrical stray current, and that is likely on old boats. My test rig is very basic and not influenced by other factors.

Sure, the wood may be less effected if painted and if the bronze was insulated by bedding compound. The damage can take years but our kauri boats should last indefinitely if we don’t do things that destroy them. Someone is bound to say I have over sized the anode on my test and thus the timber damage. I know that is the case but I had to accelerate the process.

On a boat it is almost impossible to size an anode correctly due to wasting and wiring faults in inaccessible areas of the bilge.

The point I am trying to make is:

Eliminate any current flow in the wet wood.

If you bond metals underwater you are inviting problems.

Further, a stray leak from the ships battery will do far more damage in less time. I believe most metal corrosion problems originate from this source. Cathodic protection will do nothing in this case.

Again, bonding will encourage a circuit. Remove the bonding and you have no circuit.

Want to check your electrical system for stray voltage in your wet hull?

Connect a voltage meter between the positive on your battery and any bolt or fastening in your hull. You may get a surprise. It may be 12 volts but high resistance so you can’t light a bulb but enough to cause corrosion.

If you have bonded underwater metal, the surprise maybe an expensive. For a start, try tightening the lag screws fastening the stuffing gland to the shaft log. If you don’t, a surveyor will, if you ever want to sell your ship.

History

In Yachting World Magazine March 1957 Mr. MG Duff wrote a convincing article headed  “Stern Gear Corrosion” (cathodic protection for underwater metal fittings on wood yachts”.)  In the article he never mentions wood degradation! He did not know until the problem showed up years later, see below.

The subject article date (1957), ties in with my memory of Jack Brook (head of the old D.S.I.R) yes, Robert’s father, and Alan Odell (Professor of Chemistry) fitting an Anode on the Tobin Bronze(H/T Brass) shaft of Alan’s Logan yacht the “Mahaki”.

I was only a kid who happened to be at Devonport Yacht Club with the Odell’s that week end. I remember a crowd of onlookers thinking this was black magic.

I believe this resulted from the Duff article.  Later Jack Brook had the DSIR print a pamphlet on the subject.  Sadly, (like Mr Duff) these academics never thought about wood damage.

Back to M.G Duff Co.  Ironically, now on the company’s current web site (58 years later) they warn about the damage to wood. Please check it out.  http://mgduff.co.uk/support/knowledge-base/questions/what-is-electrochemical-decay-in-wooden-vessels

Now using anodes did not catch on here until the late1970’s when a local business man saw it as an easy way to print money. He, like the Duff article was very convincing and I am sure well meaning. Some wood boat owners now refer to him as Dr Death! (I never coined the name)

Since then almost every marine electrician has got in on the bonding scheme. It was a new subject for books and magazines, now some misinformed boat owners are pushing it too.

On a hard stand a boat without an anode stands out and in many eyes shows an uncaring owner and will draw criticism. This is mistaken thinking and sadly is self perpetuating.

Please consider, “Logan, Bailey and Wild never used cathodic protection. They had knife switches and crude electrical systems but no bonding! Their boats lasted 60 years plus. ” Why should we use anodes? 

As an apprentice wooden boatbuilder, we were told at night school, I quote “ “Never use dissimilar metals underwater” and further ” never use brass”. These days the advocates of bonding use zinc underwater! What could not be more dissimilar or further apart on the Galvanic scale?.

In the 1960’s and prior to that, boat builders used bronze and copper only. There were no stainless shafts available ex stock in New Zealand.

Despite working on all sorts of boats, I never saw the timber degradation I have sighted in recent times. Sad, as we no longer have the kauri or people with the skills to affect these sometimes major repairs.

The boating public and boating industry technician’s have been mislead by a situation rather like “The Leaky Homes”, just because everyone is doing it, does not mean that it is right.

This problem was aired in Wooden Boat Magazine (30 years ago) Also in Classic Yacht Magazine. I sent some information to New Zealand Boating magazine. They showed no interest. Their advertisers sell anodes! Big business!

Further, the NZ Marine industry is partly to blame. Locally made strut bolts were made from tobin bronze! tobin bronze (these days) is brass and in my opinion unsuitable underwater. Their “Through Hulls” were made of gunmetal that although a bronze, is in my opinion a very poor choice of material. Use aluminium bronze or silicon bronze or reinforced plastic.

Cheap propellers are made of manganese bronze. Again a poor choice (these days) and little better than brass! Use aluminium bronze for propellers.

Bronze gate valves have brass spindles. Use reinforced plastic valves.

A lot of confusion comes from reading old books. (See L Francis Herreshoff “Common Sense of Yacht Design”) He recommended tobin bronze (Trade Name) and manganese bronze.

These are now generic terms. Both materials were (possibly) once good marine metals but over the years the makeup of these alloys or the way they are cast has changed and as a result I believe their resistance to dezincification has been compromised. This is evidenced by. See https://www.flickr.com/photos/109707376@N06/11134934714/

This manganese bronze propeller (Mizen Head Ireland) had been underwater 100 years! I checked it out some years ago. The bronze blades with the “Stones” trademark look perfect. The Stones Co. built ships propellers all from manganese bronze! Yes, the iron hub was an anode and (possibly) protected the bronze. A perfect example of cathodic protection! Note.There was no WET wood involved.

I talked to the new owner of Chatfield Engineering. He tells me they are now using silicon bronze for strut bolts. I say “Not before time”!

Sopac Marine Ltd is importing “Groco” silicon bronze hull hardware from the USA. They also stock aluminium bronze plumbing fittings that will last forever.

Support the local manufacturers? Unless they tidy up their act, they do not deserve your support.

Please remember bonding poor quality underwater metals does not guarantee their security. Read about “Random Harvest” (Link below)

Boats are supposed to be fun but you really have to be an expert to keep your ship afloat.

It all comes down to attention to detail. Use the right marine materials, be sure your wiring is done properly and your boat will not suffer from metal corrosion. You certainly won’t need bonding or anodes.

Sadly, for most it is too late. Cut the bonding & remove the anode but the caustic soda corrosion byproduct previously formed will remain and continue to soften the timber. Remove the effected timber round the cathodically protected metal or live with the problem caused by LOVING YOUR BOAT TO DEATH.

Some hints to eliminate DC Voltage Leaks in Boats.

1. Insulate the negative connection from the frame, on alternators, generators and anchor windless motors.

2. Use two pole senders on the engine alarms.

3. Install a solenoid on the starter motor negative so it is only connected as the engine is started.

4. Battery switch’s can leak. Have a second switch on the negative.

5. Be sure your bilge pump is wired correctly and in good order.

6. Use an insulated gearbox to shaft coupling.

7. A Furuno depth sounder is two wire but the bronze housing (like an alternator) connected to the negative! Sleeve it with plastic so there is no connection to the wood. Leave it, and it is unintentionally bonded and you have a circuit.

8. If you have shore power, use an isolating transformer.

9. If you still must bond for safety purposes? Well, accept the fact you have made a circuit and face the consequences, maybe you should not have a caulked wet wooden boat!

Why go to all this trouble?

The negative wiring in the ship can act as bonding wires if the appliance on the end has been designed for automotive use (chassis metal is usually the negative ground on a vehicle.) and touches damp salty wood. Say, for example, you have a negative leak in the autopilot drive that is coupled to the rudder that carries an anode. You once again have made that dreaded circuit and the wood round the rudder gland will suffer.

On a metal boat all the above is mandatory.

Put up with some minor corrosion.

It is easier, to replace a metal fitting than the wooden hull structure. Further it is pointless putting an anode on a aluminium bronze rudder (as is often seen) Of course the anode will erode. The bronze is a marine metal and does not require cathodic protection. If it has a stainless Shaft well that is dissimilar metal underwater. If it corrodes, change the shaft to bronze is the best advice.

If you are worried about your stainless propeller shaft, have a cast iron (nut type) sacrificial anode made. It should only have contact with the shaft not the bronze.

I write this (as a boatbuilder and certainly not as an expert) It is the result of my experience and research into a problem, I first noticed thirty years ago but seems more prevalent in recent times.

I share my observations, for the benefit of classic boat owners to help assure the long life of their vessels.

There is nothing in this for me.

For those interested I would encourage you to click on these links & read carefully.  

If nothing else page 4. Written by a Wood Chemist in the USA.

http://www.fpl.fs.fed.us/documnts/fplrp/fplrp229.pdf

Page 6 at least http://www.michel-christen.com/2T-H.pdf

Read at least page 15 Section 2.5 This is ten years old!

https://assets.digital.cabinet-office.gov.uk/media/547c7179ed915d4c0d000131/random_harvest.pdf

Also Wooden Boat Magazine (issues)

Number 65  1985

Number 93   1990

Number 115 1993

Number 167 2002

“Prevention of Decay of Wood in Boats” (refer below)

Forest products research bulletin # 31 (Ministry of Technology (UK)

I can supply copies of the above if anyone is interested

Also Classic Boat Magazine.

And see.                   http://www.kastenmarine.com/_pdf/mbqCref.pdf

See beware of brass. https://www.proboat.com/beware-the-brass.html

See                http://coxengineering.sharepoint.com/pages/brassandbronze.aspx

See WW Dec 8 th 2011. Electrolyses.

Nothing has changed, except I gave up, trying to convince people. It is no fun swimming against the tide.

See below on how to make paper.

Soda Pulp

Soda pulp is the original chemical pulp and is produced by cooking chips of (usually) deciduous woods in a solution of caustic soda under pressure. This leaves a relatively pure cellulose pulp which is then washed and bleached. Soda pulp produces relatively soft, bulky papers (as a filler with other pulps) used in books, magazines and envelopes. Caustic soda dissolves most of the lignin in wood while having little effect on the cellulose. Cooking liquor is recovered during the washing process.

It Is Not Just A Wooden Boat Thing

The photos below show a carbon fibre boat and a fibreglass yacht bonded and with electrical issues.  The point here is that all boats can have electrical issues. On these boats it showed up. On a wooden boat the damage is invisible until it is too late.

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06-06-2015 A Short & Hard Hitting Update From Chris – Read It, Its Pretty Simple Really!! Alan H

Less zinc, more zinc, over zincing are terms used by those who have recommended bonding to their clients and when things go wrong and they will. They have to have an excuse.

Please consider the following.

Sodium hydroxide or caustic soda is the chemical that damages the wood. This chemical is used for pulping wood and used in the paper industry

To make sodium hydroxide in a laboratory see youtube https://www.youtube.com/watch?v=m0LADyIfHRs

You will find the requirements are a positive and a negative electrode of say carbon, a container of brine or salt water and a power source i.e. a battery charger or a battery.

Now on a bonded boat you have a zinc anode that is positive and the protected metal (the cathode) is negative. You have the sea water electrolyte and if you have any stray current (and that is likely) you have the power source.

You don’t actually require the power source as there is a natural battery with a continual current flow from the electro-positive zinc anode towards the protected metal or electro-negative cathode.

So in effect you have a sodium hydroxide manufacturing plant (factory) incorporated in your bonded boat. Now this plant runs 365 days per year or until you sacrifice the anode.

If there is an electrical leak on the boat, well the plant ups it production.

Now the sodium hydroxide coats the protected metal and the old wet wood assures an all over electrical connection.

So it is the sodium hydroxide that causes the degradation of the wood surrounding metal on all bonded wooden boats.

Unfortunately, there has to be a current flow between any connected dissimilar metals and zinc is way apart from copper and bronze on the galvanic scale.

So it is obvious you should not use zinc anodes and bonding on a wooden boat.

Sorry, this is not what some of you wanted to hear and it is contrary to popular belief in NZ. Remember, popular belief does not mean it is right.

If you don’t take my free advice, it will not be long before a boat repairer welcomes you to his yard. He may not be as charitable.

Chris McMullen

Auckland. New Zealand.

1/6/2015

Remember – click on the photos to enlarge & read captions 😉

Movie showing gas coming off the bronze cathode The Anode Zinc accelerated with 12 volts – click link below

04-07-2015 Additional reading below on the electrochemical degradation of wood in boats from Chris McMullen.

I have heard that some boat builders/ repairers are of the opinion that bronze and copper stern gear is the cause of damage to the wood in shaft logs.

Their fix is to remove this hardware and replace them with a carbon fibre tube and reinforcing.

Sounds like an answer to a problem that does not exist.

There is nothing wrong with the bronze and copper stern gear, it should last the life of the boat or longer. The problem is the fact, that the hull was bonded and catholically protected with a zinc anode. The unnecessarily protected cathode produced sodium hydroxide (caustic soda) and this chemical destroyed the wood.

Possibly, and likely there has also been an electrical leak and this has accelerated the process. The bonding encourages this scenario by creating a circuit.

Sodium hydroxide is a used to pulp wood chips for making paper!

I ask, why not just renew the wood, replace the existing bronze stern gear and remove all the bonding and anodes?

But no, that is too easy, the unfortunate bronze and copper get the blame and is sold for scrap and the new carbon fiber miracle material comes on the scene.

No one it seems has bothered to look at the ‘Galvanic Series of Metals’.

Carbon is right at the top. It is highly conductive and electro negative. All metals are anodes and sacrificial to carbon.

Zinc is at the bottom electro positive and anodic (sacrificial) to all metals.

So if there is any bonding (intended or otherwise) there will be a current flow from all the metals on the boat through the salt water to the carbon fibre and all the copper and bronze in the boat are anodic (sacrificial) to the carbon.

You now have an even bigger battery sitting in the marina than you had with the bonded bronze, copper and zinc. A floating sodium hydroxide factory! This is working 365 days per year making a chemical that will destroy the wood in your boat.

Don’t believe me? Check out the movie showing my experiment.

You can try it yourself. A piece of carbon tube, an old zinc anode and some salt water electrolyte in a glass or plastic container. Couple the positive of a battery to the zinc and the negative to the carbon. Wait two hours and you will have a thick layer of sodium hydroxide or caustic soda. Exactly what happens on your boat but accelerated.

If you have a wood degradation problem please insist the boat be repaired exactly as it was built and replace the hardware.

Remove all the bonding and the zinc anodes and I am sure you should have no further problems.

However, be aware that a bonded boat will have the dreaded caustic soda round all the bonded metals and that will remain even when the bonding is removed.

Sorry, there is not a lot you can do other than remove the hardware and wash it out.

Sodium hydroxide Na OH is an alkali. It is neutralized by acids (vinegar)

This can be a big job if done properly but less expensive than replacing timber. Stop the producing the chemical is easy and the most practical solution.

If you have already used carbon fibre underwater on a wooden boat (dread the thought) make sure it is not bonded. Do everything possible to isolate the carbon and on no account use zinc anodes.

Bonding and anodes are the biggest risk to our classic wooden boat fleet.

We are only custodians of our heritage boats. Eventually, someone else will take over our roll.

If you want your grand children to enjoy owning a classic wooden yacht, I urge you to remove all anodes and bonding from your boat.

I am an experienced boat builder, not an expert, this is just common sense. I write because I care about your classic wooden boat, unlike your bank balance it can’t be replaced.