What Is Electrolysis?
I have published Chris McMullen’s comments below for 3 reasons:
1. Out of the blue, today I was sent the above 2 photos by a woody owner who has just discovered they have a time bomb ticking away. Bomb is a good analogy to use as the green wires in the bottom photo are the detonator 😦
2. The subject of electrolysis & wooden boats is topical at the moment
3. I’m passionate about saving our old wooden ladies.

You can read more on the subject here https://waitematawoodys.com/2016/04/28/electro-chemical-damage-in-wooden-boats/
To quote the dictionary – Electrolysis of water is the decomposition of water (H2O) into oxygen (O2) and hydrogen gas (H2) due to an electric current being passed through the water. Electrolysis of salt water or Brine – electrolysis turns NaCl + H2O in electrolysis will produce separated hydrogen gas, chlorine gas and sodium hydroxide*. *Sodium Hydroxide is also called Caustic Soda. It is used for pulping wood in the paper industry and on a boat it forms around any anode protected metal (Cathode) and softens the wood.
Lets check again in the dictionary – “The cause of Electrolysis?”
Electrolysis is due to an electric current being passed through the water or Brine. Surely, the way to prevent electrolysis on a wood boat is by eliminating any electric current passing through the wet wood.
There are two sources of electrical current on most boats.
1. The DC battery used for starting the engine and services. Stray currents are common,(can be very damaging) and hard to find on wooden boats. Any connected dissimilar underwater metals including anodes will create a galvanic current 24 hours a day. There should be no connected dissimilar metals underwater and keep the ships DC system isolated from any metal connected to the sea.
2. Bonding makes a circuit and encourages stray and galvanic currents; the result will be electrolysis and degradation of the wood around metal hardware.
Protecting marine metals (bronze or copper) with an anode is pointless and sets up a current and causes electrolysis that again produces sodium hydroxide that pulps the timber in a wooden hull. If you have brass or manganese bronze underwater, an anode may help protect the metal but set up a galvanic current with resultant damage to the wood surrounding the cathode or protected metal.      

See on Google – graphic descriptions of exactly what happens on our boats if we create an anode and a cathode. Chlorine gas is produced at the anode and hydrogen gas at the cathode.

http://www.google.co.nz/search?q=electrolysis+of+brine&rlz=1C1QJDB_enNZ596NZ625&espv=2&biw=1680&bih=944&tbm=isch&tbo=u&source=univ&sa=X&sqi=2&ved=0ahUKEwjh75ODuObPAhUUSGMKHcDKBkoQsAQIMA

Whether we like it or not, the brine around any cathode or protected metal converts to sodium hydroxide (caustic soda) and this is fatal to a wooden boat.

The solution is very simple – you should not use anodes on a wooden boat.
Anodes are necessary / desirable on steel structures where there is no wood. To use them on a wooden boat is a relatively new idea or myth designed as a solution looking for a problem. On wooden boats it has been proved worldwide to be a disaster but some in the NZ marine industry refuse to admit they have been wrong and continue to promote this profitable business.

The Logan’s, Baileys and Colin Wild never used anodes or bonding and neither should anyone who cares for their wooden boat.

 Read http://mgduff.co.uk/support/knowledge-base/questions/what-is-electrochemical-decay-in-wooden-vessels  

If you would like some more technical evidence read. http://www.mcclavemarine.com/text%20pdfs/Corrosion.and.Corrosion.Protection.Wooden.Boats.pdf

P.S. Chris would like to advise that he has had no input or involvement in any organised discussions on the topic of electrolysis & wooden boats.