Talpidae: problems,

[Gibbo]

1 If an adjacent boat has an RCD on it's power bollard would this not have tripped if such a fault occurs?

 

No.

 

2 If a nearbye boat has such a fault will it show as 12V if a meter is put across hull to hull or hull to earth or hull to pilings?

 

Yes. Any voltage above about 1 volt measured between hull to real ground is an indication of a problem.

 

3 Would you recommend earthing your boat either by using the shore line or coupling to the piling to protect against corrosion by other boats?

 

Doesn't really matter. But remember that a direct bond leaves the hull open to galvanic corrosion (as opposed to stray current corrosion).

 

Good eh!

 

Gibbo

[Moley]

Thanks again for all the comments and good wishes, which I promise I will read and re-read until I understand it all.

 

Talpidae is generally 'reverse parked'. The corrosion may be marginally worse to the left (Tetty's side) but it is only marginal. There is more pitting to the front half than the back half.

 

However, I would be grateful if some nice kind moderator could edit the title of this thread and delete the word "major".

 

I am awaiting a 'phone call anytime now from Mr. Godding (surveyor). When I went to the dock to meet him he was halfway into his inspection but was already fairly happy to say that he thought the problem probably looked worse than it was, that if we decide to keep the boat for any length of time we might think about starting to save towards plating work in the next few years, but that she doesn't need any doing just yet.

 

I don't know how much metal is left, he hadn't got his ultrasound out by that point and was still working with hammer, cordless angle grinder and tyre tread depth gauge, but Mr. Godding seems 'old school' and of the opinion that if you need to rely on ultrasound you shouldn't be doing the job.

 

Andy (dry-dock man) has been instructed to proceed as was originally planned and to get a couple of good coats of black stuff on.

 

====================================================

 

That's it, he's just called while I was typing.

 

Baseplate was originaly quarter inch (6.35mm). In places it's down to 5.1mm

 

Sides were originally 3/16" (4.7mm). They still are! The lowest he measured was 4.5mm towards the bow. Some of the worst pitting is approaching 2mm deep. However, these are relatively small and isolated patches and he can't see any great concern at present. Get her out again in a year or two and check again, but for the time being, quit worrying.

 

Written report will be in the post.

 

We're off to the pub

[alan_fincher]

Bloody marvellous !

 

Sounds like the surveyor has a closer handle on things than some of the others that "clocked" it.

 

:lol:

 

Have a good drink - you have certainly earned it.

 

[Big Steve]

Glad to hear that, I now see the anodes, thanks.

[Catrin]

YAY!!!!

 

Cath

[Neildudman]

Now you've got that sorted and off your mind, can you get back to the more important job of quiz master?.

 

Seriously, bloody great news...

[Janet S]

Fantastic news!

 

Have one on me...

 

Janet

[cheshire~rose]

Brilliant News!!!!!!!!!!!!!!!!

 

 

:lol:

[Ray]

Magic. I'm glad it has all turned out OK.

[MoominPapa]

Excellent news! Is there any explanation available for your natty silver propellor?

 

MP.

[Keeping Up]

Hooray. Thank goodness for a surveyor with some experience and a brain. Drinks all round are definitely in order.

 

I wonder if you could install a suitable electrical system, that will turn your boat into a giant cathode and will slowly re-plate itslef with ste4el leeched from neighbouting boats' hulls (oops sorry Trev the Rev, yuo didn't read that here!)

[jake_crew]

Great news.

 

Celebrate by getting a few coats of black on, either yer tummy, or on the hull !

 

:lol:

[Guest]

Great news Moley and family.

[Bones]

phew.

 

so will you be able to stop it getting worse so you wont need to overplate it in future??

[Sue1946]

Such good news!

[Big COL]

Hi Moley

 

A few beers will get the old heart rate down. Pleased for you and Mrs Mole that you can get back to boating.

[Moley]

phew. so will you be able to stop it getting worse so you wont need to overplate it in future??

Surveyor has given me a few good pointers and a few things to check. Problems are most likely external but there are things onboard I can improve upon and which may have exacerbated.

 

Excellent news! Is there any explanation available for your natty silver propellor?

It's stainless

 

No, seriously, there is a problem which still needs to be investigated / dealt with / moved away from.

 

Hooray. Thank goodness for a surveyor with some experience and a brain.

Seems like a good bloke. Compliments also to Andy Downing, who has only recently taken over the dry dock at Stourbridge. He is turning that into a very nice facility and seems to have a lot of useful contacts.

 

I wonder if you could install a suitable electrical system, that will turn your boat into a giant cathode and will slowly re-plate itslef with steel leeched from neighbouring boats' hulls (oops sorry Trev the Rev, you didn't read that here!)

Oi! Out of order! I know it's the British way to seek humour in adversity but I seriously doubt that it's just our boat being attacked.

 

Now you've got that sorted and off your mind, can you get back to the more important job of quiz master?.

Yes Sir! On my way. My apologies for allowing myself to get distracted.

[smileypete]

Surveyor has given me a few good pointers and a few things to check. Problems are most likely external but there are things onboard I can improve upon and which may have exacerbated.

 

What were they?

 

cheers,

Pete.

[Liam]

Excellent news... dead chuffed for ya, Moley!

 

However, I would be grateful if some nice kind moderator could edit the title of this thread and delete the word "major".

 

Done

[David Schweizer]

Glad to hear things are not as bad as suspected Adrian.

 

It seems that the degree of localized pitting is similar to that found on my boat, which is of similar vintage. It sort of supports my theory that it is just as much signs of old age rather than any serious galvanic problem (hopefully).

[RLWP]

Surveyor has given me a few good pointers and a few things to check. Problems are most likely external but there are things onboard I can improve upon and which may have exacerbated.

 

Seems like a good bloke. Compliments also to Andy Downing, who has only recently taken over the dry dock at Stourbridge. He is turning that into a very nice facility and seems to have a lot of useful contacts.

 

That's a good outcome, and can I say that I think I know what you have been through. Tawny Owl's hull wear scared us silly when it was found, but it all came good in the end thanks to our surveyor.

 

Any talk of shoes?

 

Richard

[stuart]

Nice one Moley, nothing like a quick scare to get the heart racing !

[BlueStringPudding]

Blimey, thank goodness for that. Scary though, eh?

[Moley]

I’d just like to add a note here, based upon Daftmare’s “Flat Batteries” thread:

 

When I came to try to start our boat for the trip to dry dock she was somewhat reluctant. This can be attributed to:

1) - I don’t think the starter battery had been replaced anytime recently when we bought the boat and I certainly haven’t changed it, and

2) - I don’t think any of my glow plugs were doing anything.

 

However, although that battery seemed to lack ‘oomph’ (or cranking amps), it had volts, around 12.4v.

 

Bilge pump with float switch is connected to starter battery, as is a small solar panel (approx. 10 x 7”) which only gives a tiny trickle charge of 1.5W (from memory).

 

Even if I’ve turned her over or run the engine over the Autumn and Winter it’s only been for a couple of minutes at a time and no charge has been put back into the domestic bank (3 x 110ah, approx. 2.5 years old) since October. Domestic bank still said 12.5v.

 

Someone else can do the sums but this seems to me to confirm that when my batteries are isolated, keys out, nothing untoward is happening.

[MoominPapa]

Someone else can do the sums but this seems to me to confirm that when my batteries are isolated, keys out, nothing untoward is happening.

Are you asking if this is evidence that there's no leakage currents from the batteries? I suppose it is, but very weak evidence. If I wanted to know what current might be flowing around wiring when everything was switched off, I'd use a multimeter to measure it. I'd not try and infer it from the drop in open circuit voltage of a lead-acid battery whose condition is unknown, whose initial state of charge is unknown and which has been subject to an unknown amount of self-discharge subsequently.

 

As in all diagnosis, the trick is to eliminate unknowns and multiply knowns.

 

MP.

 

An an aside, if I've calculated right, assuming 8 hours daylight per day, your 1.5W solar panel is producing enough current to rust about one gram of steel per day, all by itself.

 

(1.5W at 12V is .125A, .125A for 8 hours is 0.125x60x60x8 = 3600 coulombs per day. Apply Faraday's law, with atomic weight of iron = 56 and valency = 2 (should that be 3?) gives (3600/96485)*(56/2) ~= 1g)

 

Faraday's law clicky.

 

Arrgh, I'm turning into chrisw!

Edited February 24, 2009 by MoominPapa