Electrolysis or plain old rust!!!!!!

[max_hyde]

The surveyor picked up that the engine wasn't mounted as secure as it could be, what he failed to miss was this engine mount, this is the result of 6 months (yes 6 months from brand new, in the water from date of fixing) without any bonds on the engine, apart from one bond from the zinc to the alternator, the zinc was three years old and virtually as new!!!



So what do you think, galvanic corrosion or good old rust, as I say the brand new engine and mounts was put in 18 months ago, but the boat has only spent 6 months in the water!!!!!

Cheers Max

[s/v Faith]

Do you have a battery charger hooked up to shore power by any chance?

  That is pretty bad for such a short time...   but not WAY beyond what can happen with mild steel and salt water.

What was the mount treated with when it was installed?  Was it painted with zinc primer and a couple good coats of paint? 

[max_hyde]

I have only just aquired the yacht, the new engine was installed by the PO.

The boat was on a swinging mooring, so I assume no mains electricity, the angle iron appears to have been painted with a sort of gloss paint, definately not epoxy. The only bonding strap from the zinc went straight to the alternator.

I am grinding the old frame off on friday, then will have a new one fabricated, hot dip galvanised and with correct bonding I hope this will sort any problem it may have had.




Cheers Max

[maxiSwede]

Hi, hard to tell from the pics if it's electrolysis. From what you're telling my (Q)WAG would be 'plainr old rust'

It doesn't take long if the monts/brackets sits in warmish salt water.

Your idea of having the new ones galvanized sounds brilliant.

Unfortunately we hadn?t got time to do that when we (unplanned  ) had to install the new engine (2 y ago) in 'R?de Orm'.

What I did was maybe the next best. I treated the engine and monts/brackets with aerosol corrosion pretection based on linseed oil. Environmentally friendly, quite cheap and easy to apply. I tend to give it another spray every time I do an oil change. I also check most other 'stuff' on the engine, including hose clamps and nuts, at the same time.

Good luck with it!

[Mario G]

I would try Por-15 as a coating,  your mounts look like mid-80's chevy rear transmission mounts  just incase you were looking for replacements. 

[max_hyde]

They are so rusted they look like they came from a mid 80's car 

The engine is a yanmar 1GM10 engine, so will probably play safe and go for the proper mounts, especially after the problems i've had.

just a question on galvanising, galvanised iron is more noble than zinc, will this mean it will deteriorate worse than the zinc, if its bonded? acting as a zinc for the zinc 

Cheers Max

[maxiSwede]

Welcome to this friendly place!

for ourselves, we are slowly moving towards the country you were born in too. Maybe we'll be there this time next year or so...


Congratulations to the classic beauty of a boat you chose!!  Almost make me drool 

There's nothing like a classic loooks wooden boat - esp. when someone else does the upkeep