Moorers beware

[cuthound]

To maximise your boating time 3 is the best option.

We had shared in boats for over 20 yearsas owning a narrowboat didnt make financial sense until i retired.

It is a great way to see a lot of the system, and cheaper than hiring, but you only get 3-4 weeks a year plus short notice cancellations and possibly unbooked winter weeks.

[Sea Dog]

On 05/11/2017 at 15:58, manxmike said:

Moored in a Marina but not using the mains power? Don't imagine for a minute that you are not at risk of galvanic reaction from other people's boats!

I was horrified to discover that despite not using the mains supply for more than a few minutes every month, my hull had developed serious pitting causing the value of the boat to sink without trace. The buyer's surveyor said that the hull needed overplating urgently at a cost of some £8,000 to £10,000.

The only cause of the reaction I can think of is being bracketed on the Marina by live-aboard boats plugged in permanently to the mains power and possibly not having a galvanic isolator fitted, thus causing the problem with my hull.

When last examined (four years ago) the pitting was minimal and the hull was sound - now it is down to 2 to 3mm in places.

Sadly I had to cut my losses and accept a seriously low price for the boat. There was no way I could afford to have the overplating done. I had hoped to raise sufficient to make the first few payments on a new Sailaway hull, but those plans have now gone on hold for the foreseeable future.

Ah well, we learn from our mistakes and oversights. Maybe I should have gone for a GRP hull instead.

Going back to the original post, I wonder whether this might be a case of microbial pitting rather than electrolytic?  There was a thread with a link a few days ago, I believe provided by the Keelblack bloke, which was an interesting (if scary!) read about MIC.

[WotEver]

Just now, Sea Dog said:

Going back to the original post, I wonder whether this might be a case of microbial pitting rather than electrolytic?  There was a thread with a link a few days ago, I believe provided by the Keelblack bloke, which was an interesting (if scary!) read about MIC.

I strongly suspect that it was MIC. If he had only intermittent shore power use as described (not even plugged in for much of the time and therefore no earth connection) then all the talk of a mysterious ‘field’ around the boat sounds to me like so much sci-fi nonsense. MIC is a much more likely scenario. 

Here’s that link:

http://www.keelblack.co.uk/wp-content/uploads/2017/08/MICROBIOLOGICAL-CORROSION.pdf

[Sea Dog]

1 minute ago, WotEver said:

I strongly suspect that it was MIC. If he had only intermittent shore power use as described (not even plugged in for much of the time and therefore no earth connection) then all the talk of a mysterious ‘field’ around the boat sounds to me like so much sci-fi nonsense. MIC is a much more likely scenario. 

Here’s that link:

http://www.keelblack.co.uk/wp-content/uploads/2017/08/MICROBIOLOGICAL-CORROSION.pdf

That's the one! Thanks WotEver.

[malp]

1 hour ago, manxmike said:

Determination to get back on the canals has brought to the surface a number of thoughts.

3. Buy a GRP boat in need of tlc

To be honest the option I am favouring is number 3.

Be aware that GRP boats have their own nasty alternative to galvanic corrosion - osmosis.  Nigel Clegg has an informative article on the subject here:

http://www.passionforpaint.co.uk/downloads/osmosis3v6.pdf

[WotEver]

21 minutes ago, malp said:

Be aware that GRP boats have their own nasty alternative to galvanic corrosion - osmosis.  Nigel Clegg has an informative article on the subject here:

http://www.passionforpaint.co.uk/downloads/osmosis3v6.pdf

Although it’s not nearly as serious, only cosmetic. No boat ever sank from osmosis. There’s a thread running about it now. 

[Sea Dog]

53 minutes ago, malp said:

Be aware that GRP boats have their own nasty alternative to galvanic corrosion - osmosis.  Nigel Clegg has an informative article on the subject here:

http://www.passionforpaint.co.uk/downloads/osmosis3v6.pdf

I agree with WotEver above. Nigel Clegg, who was a lecturer on a surveyor's course I took, also says boats don't sink from Osmosis.

Edited November 10, 2017 by Sea Dog
Great reason for a price reduction though - whether you're buying or selling!

[JamesFrance]

There are plenty of salt mines not far from there, so maybe the salt water is spreading.

[malp]

43 minutes ago, WotEver said:

Although it’s not nearly as serious, only cosmetic. No boat ever sank from osmosis. There’s a thread running about it now. 

Agreed it is mostly a cosmetic problem, so calling it "nasty" probably overstates matters.  However it is not without risk although this is mainly financial.  For GRP boat owners the problem can arise not during ownership but when the time comes to sell.  So if the OP does go for his GRP boat he needs to factor this into the price he buys at, to avoid another hit when he eventually comes to sell.

[manxmike]

Just read the article on MIC. I recently spent a week in the canal between Chester and Ellesmere Port - almost exactly the conditions described in the text. Rotting vegetation clogging the canal, dead animals everywhere, I can't help wondering if that might have exacerbated the condition. 

[manxmike]

3 hours ago, malp said:

So if the OP does go for his GRP boat he needs to factor this into the price he buys at, to avoid another hit when he eventually comes to sell.

That's why I'm looking at the cheaper end of the market. 

[WotEver]

44 minutes ago, manxmike said:

Just read the article on MIC. I recently spent a week in the canal between Chester and Ellesmere Port - almost exactly the conditions described in the text. Rotting vegetation clogging the canal, dead animals everywhere, I can't help wondering if that might have exacerbated the condition. 

I suspect that MIC was 100% of your problem. You can’t have stray current erosion without an earth connection to your boat. 

[manxmike]

Just to keep things up to date, I have gone the GRP in need of TLC route. See the blog in "Build Blogs" called "Firbreglass re-build" which I will keep up to date whenever I manage to get some more work done! It's that stretch of water called the Irish Sea that causes a £200 problem every time I want to cross it to do some more work.