Cautionary Tale

[by'eck]

I think one needs to define 'working' too. Do we mean is it performing its design function and isolating galvanically, or do we mean is it preventing electrolytic hull damage? The latter involves the anodes too (I think). But on reflection no. The anodes are to protect the brass and bronze bits from dezincification IIRC.

 

MtB

Yes there are two aspects to consider. Since it could be functioning correctly but still in conduction due to excessive stray voltages.

 

The sacificial anodes are there to protect the hull as is the GI. In fact the latter are sometimes referred to as zinc savers.

[Alan de Enfield]

All these people having their hull "Zinga'd" (Galvanised)

 

Galvanising is Zinc

 

Fresh water anodes are made from Zinc

 

Your whole boat now becomes one huge anode.

 

Paint over the Zinga, scratch the paint and expose the Galvanising, your galvanising starts to quietly erode away.

 

From the Zinga website :

 

Zinga's unique formula provides environmentally safe cathodic protection to steel comparable with hot-dip galvanising, with the added advantage that it can be applied as though it were a paint.

 

Zinga is a film-galvanising system comprising precisely milled zinc particles suspended in a unique liquid base. It bonds to any prepared steel substrate to form a finished surface layer of 96% zinc

 

To me there seems to be little point in making your boat a big anode, to then paint over it ?

 

Can anyone explain why you would do it ?

[Alf Roberts]

to protect the steel once the paint coating is compromised.

[Theo]

 

Fresh water anodes are made from Zinc

 

 

Point of order, sah!

 

My fresh water anodes are made of magnesium.

 

Salt water anodes are zinc.

 

N

Edited November 30, 2014 by Theo

[costalot]

To date the most important point I have taken from this terrible incident is that under the 1906 Marine Insurance Act your policy probably doesn't cover you against sinking by galvanic corrosion.

 

The people most affected by this are the thousands who leave their boat for months unattended in a marina.

 

In this particular instance the problem was compounded by the sub-standard performance of the marina. If they had a rather simple policy of checking the bilge after relaunching a boat this sinking wouldn't have happened.

[Alan de Enfield]

 

Point of order, sah!

 

My fresh water anodes are made of magnesium.

 

Salt water anodes are zinc.

 

N

 

Brain-fart - slipped back to lumpy water days.

[LoneWolf]

To date the most important point I have taken from this terrible incident is that under the 1906 Marine Insurance Act your policy probably doesn't cover you against sinking by galvanic corrosion.

 

The people most affected by this are the thousands who leave their boat for months unattended in a marina.

 

In this particular instance the problem was compounded by the sub-standard performance of the marina. If they had a rather simple policy of checking the bilge after relaunching a boat this sinking wouldn't have happened.

 

After wading through most of the recent blog posts it seems that the insurance would pay out - the problem was that they would only pay out for a 'no betterment' repair ie refurb the alternator & starter motor rather than get new ones. They also had trouble getting quotes for a 'no-betterment' repair to the insides, this was also compounded by the costs of moving the boat (by road) to where it could be repaired

They were only paying £138 for their insurance (sadly, they dont say which insurance co they used)

 

They didn't keep the boat in a marina either, they had an on line mooring - against piling but I couldnt tell if they had a shoreline from the pics though

 

Funnily enough i was thinking of taking my boat to this marina nxt year for its blacking. The most important lesson i've learned from this thread is that I'll be doing the blacking myself

Edited November 30, 2014 by LoneWolf

[ukdiggerboy]

has anyone thought the marina had the young lads do the painting (looking at the bits missed and bear steel behind the annodes) and wouldnt know what they were looking at if it bit um ?

[ditchcrawler]

I passed a boat that was floating with an inch hole in his utuxitor (spelling?) plate, He had put 25 lt plastic drums under it and was holding just about above the waterlevel. It was at Rugeley opposite the water point

[Boat&Bikes]

Bet your bottom dollar that any of the boats built abroad, ie:- Poland, etc are not made of EN43A Steel. I am thinking there are a few boat building companies now using foreign shells, New and Used boat company may be one? Also from what I have seen most of them start of with rusty steel sheets in the first place, also don't know what effort they take to remove mill scale before blacking and painting a new boat!

I am sure your right. I mean can you imagine any company outside of the Uk being able to build a boat of quality?

 

Ian.

[Giant]

On the matter of automatic bilge pumps, these were the very first things we fitted after purchase and brought us considerable peace of mind.

 

I would caution anyone fitting such things to do some research, though.

 

Decide what the largest hole you are trying to protect against is, and calculate how fast that will let water in given the depth below waterline. That will tell you how big a pump you want, they are marked in gallons per hour. Now factor in that the manufacturer's ratings are for ideal conditions with the pump not having to lift the water any vertical distance! Add in that factor and you will have to significantly over-rate the pump. Then start worrying about switches. Float switches are prone to mechanical failure. Electronic ones have different modes of failure.

 

In the end we concluded that the kit available in the local chandlery was grossly underspecified for the job.

 

I should probably start a whole separate thread about this.

[mark99]

That's all very well, but if other boats in your vicinity are on shore power, and their anodes are worn or not "working" the hull will be happy to use your anodes instead!

 

How? can you explain this circuit whereby a distant boat eats your anode.

 

To effect a galvanic circuit, the anode must be in contact with hull as well as both immersed in electrolyte and in this case your boat is not connected to shorepower.

 

ETA oh I see this has been picked up later in the thread.

 

In very simple terms think PP3 battery and lighbulb with two dangly wires. Connect bulb wires to each battery terminal (terminals = cathode and anode) and inside the battery is the electrolyte (canal water). Whilst the bulb is illuminated, the galvanic reaction is working.Remove or break wire connection to bulb and bulb goes out (nasty galvanic force broken). The anode and cathode must be electrically connected to create galvanic force as well as sitting in the electrolyte (so you need to break this connection).

 

For more info

 

http://www.indabook.org/preview/Yna31cnPIspvwg28-P9QfsHqgi0J4FHnyuj5CHp8JI8,/CORROSION-ELECTROLYSIS-BLISTERING-CATHODIC.html?query=STAINLESS-STEEL-AND-ELECTROLYSIS-A-PROBLEM

Edited December 1, 2014 by mark99

[costalot]

 

After wading through most of the recent blog posts it seems that the insurance would pay out - the problem was that they would only pay out for a 'no betterment' repair ie refurb the alternator & starter motor rather than get new ones. They also had trouble getting quotes for a 'no-betterment' repair to the insides, this was also compounded by the costs of moving the boat (by road) to where it could be repaired

They were only paying £138 for their insurance (sadly, they dont say which insurance co they used)

 

They didn't keep the boat in a marina either, they had an on line mooring - against piling but I couldnt tell if they had a shoreline from the pics though

 

Funnily enough i was thinking of taking my boat to this marina nxt year for its blacking. The most important lesson i've learned from this thread is that I'll be doing the blacking myself

My reading of the blog is the insurers marine surveyor was recommending that the insurer not pay out. However the boat owner had employed his own marine surveyor who was prepared to dispute the recommendation of the insurers surveyor. This is probably the likely reason why the insurer made their minimal offer to settle the claim.

On the matter of automatic bilge pumps, these were the very first things we fitted after purchase and brought us considerable peace of mind.

 

I would caution anyone fitting such things to do some research, though.

 

Decide what the largest hole you are trying to protect against is, and calculate how fast that will let water in given the depth below waterline. That will tell you how big a pump you want, they are marked in gallons per hour. Now factor in that the manufacturer's ratings are for ideal conditions with the pump not having to lift the water any vertical distance! Add in that factor and you will have to significantly over-rate the pump. Then start worrying about switches. Float switches are prone to mechanical failure. Electronic ones have different modes of failure.

 

In the end we concluded that the kit available in the local chandlery was grossly underspecified for the job.

 

I should probably start a whole separate thread about this.

The larger the pump, the faster the battery will be flattened. I suggest the boat also requires an automatic bilge pump monitoring system which can alert the owner when the pump is activated.

[Robbo]

The larger the pump, the faster the battery will be flattened. I suggest the boat also requires an automatic bilge pump monitoring system which can alert the owner when the pump is activated.

I agree, a bilge pump monitor will let you know if you have a leak and by how much. If you normally have a wet bilge it could be at the same level because the pump keeps it at the level bit the leak could be getting worse over time without you knowing.

[Gordias]

I've found the corrosion part of this thread very instructive. It's a difficult topic at best, because (like most things concerning electricity) most of the interesting stuff is "special cases" that aren't covered in basic education.

 

Would it be a good topic for an FAQ?

 

I'd like to see a comprehensive FAQ for all kinds of corrosion and corrosion protection.

 

For me (a potential first-time purchaser if my family doesn't spend all the money on a cottage "hull rot" is by far the scariest aspect of narrow boats, and it's not an easy research topic.

Edited December 3, 2014 by Gordias

[Proper Job]

I've found the corrosion part of this thread very instructive. It's a difficult topic at best, because (like most things concerning electricity) most of the interesting stuff is "special cases" that aren't covered in basic education.

 

Would it be a good topic for an FAQ?

 

I'd like to see a comprehensive FAQ for all kinds of corrosion and corrosion protection.

 

For me (a potential first-time purchaser if my family doesn't spend all the money on a cottage "hull rot" is by far the scariest aspect of narrow boats, and it's not an easy research topic.

 

The best advice you can take from this topic is:

• Before you buy, absolutly, get a survey. A hull structural survey as an absolute minimum
• During ownership, when the boat comes out of the water for blacking, be there and carry out your own hull inspection (before they start blacking) or, employ a professional surveyor. Do not rely on the boat yard to tell you that you've got bad pitting or the like (it's not what you've employed them to do)

[Emerald Fox]

"I am sure your right. I mean can you imagine any company outside of the UK being able to build a boat of quality?"

 

Finland makes some decent ice-breakers.

 

Apart from Poland, what other countries make narrowboats for the English canals?

Why haven't the Chinese cottoned on to this and started to make cheap (but very good quality, cough cough!) narrowboats; they're missing out on this one.

 

The Australians & New Zealanders, who like canal holidays in the UK, could be building dozens of narrowboats over there and shipping them over to England in a huge ship...?

Same for the USA Americans, Japanese and Koreans.

Everyone keeps telling me 'competition' is healthy.

Would 'Hello Kitty' be a good name for a narrowboat?

[costalot]

UNBELIEVABLE

 

I've read the final blog post <link here>

 

• The marina received the boaters requirements in writing.
• Failed to notice/report the corrosion
• Did a poor job of the blacking
• Failed to check the boat on relaunching
• Allowed it to sink whilst in their care
• Refused to provide the owner and his solicitor with their insurers details (ie, ignored them)

 

When the owner told the marina he was coming to collect his damaged boat they demanded storage and hoist fees WHICH CAME TO MORE THAN THE ORIGINAL QUOTE FOR GRIT BLASTING AND TWO PACK BLACKING THE BOAT!!!!!

 

This marina appears to have no concept of customer service or business reputation. I most definitely won't take my boat anywhere near the place!

[MtB]

Decide what the largest hole you are trying to protect against is, and calculate how fast that will let water in given the depth below waterline.

 

Good advice, but I fail here. Can you expand on how to calculate how fast a given size of hole, say a rust hole in the base plate 5mm in diameter and 600mm deep, will let the water in please?

 

Must be quite straightforward but the day is still young...

 

Thanks.

 

MtB

[matty40s]

 

Good advice, but I fail here. Can you expand on how to calculate how fast a given size of hole, say a rust hole in the base plate 5mm in diameter and 600mm deep, will let the water in please?

 

MtB

I would say with a base plate over 1/2 a meter thick you would be sat on the bottom anyway.

[RLWP]

I would say with a base plate over 1/2 a meter thick you would be sat on the bottom anyway.

 

And have a very tiny living space

 

Richard

[Boat&Bikes]

"I am sure your right. I mean can you imagine any company outside of the UK being able to build a boat of quality?"

 

Finland makes some decent ice-breakers.

 

Apart from Poland, what other countries make narrowboats for the English canals?

Why haven't the Chinese cottoned on to this and started to make cheap (but very good quality, cough cough!) narrowboats; they're missing out on this one.

 

The Australians & New Zealanders, who like canal holidays in the UK, could be building dozens of narrowboats over there and shipping them over to England in a huge ship...?

Same for the USA Americans, Japanese and Koreans.

Everyone keeps telling me 'competition' is healthy.

Would 'Hello Kitty' be a good name for a narrowboat?

The Chinese do or did build some, Polish and Czech boats are plentiful on our canals aren't they?

 

Ian.

[MtB]

I would say with a base plate over 1/2 a meter thick you would be sat on the bottom anyway.

 

I take it you don't know how to do the calculation either then

 

 

MtB

[matty40s]

 

Apart from Poland, what other countries make narrowboats for the English canals?

Why haven't the Chinese cottoned on to this and started to make cheap (but very good quality, cough cough!) narrowboats; they're missing out on this one.

 

 

goog;e "East West" narrowboats a nd have a look. If you see them out on the cut they are the ones that usually have bashed cabin edges at the front as the Chinese didn't realise we had such low bridges.

[Gordias]

 

Good advice, but I fail here. Can you expand on how to calculate how fast a given size of hole, say a rust hole in the base plate 5mm in diameter and 600mm deep, will let the water in please?

 

Must be quite straightforward but the day is still young...

 

Thanks.

 

MtB

 

Velocity = square root of (2 x Acceleration due to gravity x Height) (a = 9.8 m/s**2 or 32 ft/sec**2)

Flow = Velocity x Area (cubic meters per sec or cubic feet per sec)

 

Friction is ignored (but shouldn't be in a pipe).

Edited December 3, 2014 by Gordias