Hull wear an tear

[MichaelG]

Hi all, I've just bought my first narrowboat. The survey reports that the base plate was originally fabricated in 10mm (nominal) steel. Ultrasonic measurements show it now to be between 10.1 and 9.6mm with pitting upto 1mm. There is no excessive wear to the sacrificial edge.

The hull sides are originally fabricated in 6mm (nominal) steel and now shows between 6mm and 5.6mm with pitting between 0.2mm and 0.4mm.

I was wondering if from others experience if that would be typical wear and tear for a 12 year old boat.

Also presuming use and maintenance remains the same as the last 12 years can the hull be expected to wear at a similar rate or does it not quite work like that? 

[Alan de Enfield]

Pitting can be caused by stray 'electrical worms' and particularly if connected to a mains land-line .

A boat can be perfectly fine and 6 months later when lifted out for blacking the pressure washer goes thru the hull (threads on here with examples)

It is not just maintenance it is how it is 'kept' (water type, electric hook-up, etc)

It is so variable it is impossible to say what is normal, or what will happen in the future.

I had a 1998 NB with a supposedly 12mm base plate, in 2015 when it was blacked, it did not have a single 'pit' (non found) and the base plate measured 13mm

[Bee]

I think you can reasonably assume that everything else being equal then that is the case. So many variables though. Many older boats suffered from a hope that steel would last forever, that a coat of bitumen every 5 years or so was sufficient, that a bilge that drained water from the well deck all the way to the back was ok, that poor insulation and condensation was not damaging and the bottom didn't need painting. Newer boats tend to be spray foamed, have (hopefully) dry bilges, use better paint and tend to be hauled out more often. I think that so long as you keep a decent coat of paint on the underwater steel and its not rusting from the inside then all will be well. If you add poor electrics to the mix though then odd things can happen.

[Sea Dog]

30 minutes ago, MichaelG said:

Hi all, I've just bought my first narrowboat. The survey reports that the base plate was originally fabricated in 10mm (nominal) steel. Ultrasonic measurements show it now to be between 10.1 and 9.6mm with pitting upto 1mm. There is no excessive wear to the sacrificial edge.

The hull sides are originally fabricated in 6mm (nominal) steel and now shows between 6mm and 5.6mm with pitting between 0.2mm and 0.4mm.

I was wondering if from others experience if that would be typical wear and tear for a 12 year old boat.

Also presuming use and maintenance remains the same as the last 12 years can the hull be expected to wear at a similar rate or does it not quite work like that? 

Firstly, I'd be happy to take on that hull based on what you've said.

Secondly, no, it doesn't quite work like that.  However, you'll be looking after her now and there's plenty of advice to follow about how to keep her at her best.  Nothing unduly expensive or out of the ordinary though.

Congratulations!  I hope you cruise many happy miles together.

[mrsmelly]

1 hour ago, MichaelG said:

Hi all, I've just bought my first narrowboat. The survey reports that the base plate was originally fabricated in 10mm (nominal) steel. Ultrasonic measurements show it now to be between 10.1 and 9.6mm with pitting upto 1mm. There is no excessive wear to the sacrificial edge.

The hull sides are originally fabricated in 6mm (nominal) steel and now shows between 6mm and 5.6mm with pitting between 0.2mm and 0.4mm.

I was wondering if from others experience if that would be typical wear and tear for a 12 year old boat.

Also presuming use and maintenance remains the same as the last 12 years can the hull be expected to wear at a similar rate or does it not quite work like that? 

In a nutshell. Its fine.

[WotEver]

13 minutes ago, mrsmelly said:

In a nutshell. Its fine.

Virtually as new, in fact. 

[MichaelG]

3 hours ago, Alan de Enfield said:

 

A boat can be perfectly fine and 6 months later when lifted out for blacking the pressure washer goes thru the hull (threads on here with examples)

 

That would be disappointing.

[Alan de Enfield]

13 minutes ago, MichaelG said:

That would be disappointing.

I don't think "disappointing" was the word used when the yard finished blacking it, put it back in the water and it sank.

[Sea Dog]

1 hour ago, Alan de Enfield said:

I don't think "disappointing" was the word used when the yard finished blacking it, put it back in the water and it sank.

That did happen, didn't it, to a bloke who had had his boat regularly blacked up Cheshire way and the same yard blasted and 2 packed it for him. Sank overnight after they put it ask on his berth, iirc. Now, Michael, the OP, is new to this so let's not alarm him too much on day one!

Michael, your hull is almost certainly fine, and the cautionary tales should just serve to make you aware of the importance of taking care to keep that way. 

 

[WotEver]

3 minutes ago, Sea Dog said:

Michael, your hull is almost certainly fine, and the cautionary tales should just serve to make you aware of the importance of taking care to keep that way. 

Precisely. And Alan’s cautionary tale about what could happen in 6 months, whilst being true, is also exceedingly rare. In fact I’m only aware of one instance. 

[Alan de Enfield]

18 minutes ago, Sea Dog said:

 

Michael, your hull is almost certainly fine, and the cautionary tales should just serve to make you aware of the importance of taking care to keep that way. 

 

 

13 minutes ago, WotEver said:

Precisely. And Alan’s cautionary tale about what could happen in 6 months, whilst being true, is also exceedingly rare. In fact I’m only aware of one instance. 

Indeed it is, but it is correct as an answer/warning to the question "if it corroded / pitted by 0.4mm in the last 12 years, will it do the same in the next 12 years".

The answer is undoubtedly NO, but no one can tell you what it will do.

The truth is it may have no further corrosion or pitting, or it may sink in 6 months / 1 year / 5 years / 25 years / 50 years ...................

[WotEver]

4 minutes ago, Alan de Enfield said:

The truth is it may have no further corrosion or pitting, or it may sink in 6 months / 1 year / 5 years / 25 years / 50 years ...................

Yup, the only thing that you can say with any degree of certainty is that if it is treated exactly the same as it has been over the last 12 years then it is likely to suffer by the same amount (ie nothing). 

[Alan de Enfield]

19 hours ago, WotEver said:

Precisely. And Alan’s cautionary tale about what could happen in 6 months, whilst being true, is also exceedingly rare. In fact I’m only aware of one instance. 

Was it yourself that had some problems ?

Did you not post "....hull to have been electrolysed away in the previous 2 years", or have I got the wrong person.

 

Edit to add - Apologies - Found it - It was 'Keeping Up' posting in 2017

I had exactly the same problem with a Sterling charger last year. As it was quite old, and had a few other minor faults, I decided to replace it - particularly as at the time I was taking no chances while trying to find out what had caused my hull to have been electrolysed away in the previous 2 years.

Edited March 30, 2018 by Alan de Enfield

[WotEver]

17 minutes ago, Alan de Enfield said:

Was it yourself that had some problems ?

Did you not post "....hull to have been electrolysed away in the previous 2 years", or have I got the wrong person.

 

Edit to add - Apologies - Found it - It was 'Keeping Up' posting in 2017

I had exactly the same problem with a Sterling charger last year. As it was quite old, and had a few other minor faults, I decided to replace it - particularly as at the time I was taking no chances while trying to find out what had caused my hull to have been electrolysed away in the previous 2 years.

Yup. That’s the only example I’m aware of where the hull (on one side only if I recall correctly) had dissolved away in a very short period. 

[Alan de Enfield]

32 minutes ago, WotEver said:

Yup. That’s the only example I’m aware of where the hull (on one side only if I recall correctly) had dissolved away in a very short period. 

 

20 hours ago, Sea Dog said:

That did happen, didn't it, to a bloke who had had his boat regularly blacked up Cheshire way and the same yard blasted and 2 packed it for him. Sank overnight after they put it ask on his berth, iirc. 

 

There was much heated discussion about the 'Cheshire' one - threats of court etc etc.

Readers might be interested to know that even with my own vigilant hull maintenance regime which was completed bi-annually at a local marina, our boat was actually seriously damaged while in the care of that marina, and during the routine maintenance of grit blasting and blacking. They had been given the task of completing this maintenance year on year without my direct supervision, and it later transpired that they had not warned me of the need for further investigation into the effects of galvanic corrosion that on the last occasion resulted in the hull being holed, and the boat being sunk within their marina and while in their care. Further issues with insurance, (or the lack of cover that transpired only after a claim was made) and the marina's refusal to provide their own insurer's details until a settlement on my own had taken place, resulted in the loss of our boat. Never never trust any third party to do work to a suitable standard. They must always be supervised to your own satisfaction or better still - DIY.

The original blog appears to have been deleted but here is the link to the forum discussions :

 

Edited March 30, 2018 by Alan de Enfield

[WotEver]

But the above story (disregarding the ‘blame game’ nature of the subject) doesn’t suggest that this happened overnight or even over a 1, 2, 3 or more year period. This was a boat which was regularly aggressively grit blasted and a small hole went unnoticed resulting in a sinking. I don’t believe we know over what period this happened, only that no-one seemed to have ever checked the hull for putting.