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hull thickness


juragirl

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Just now, Boater Sam said:

We see it every year at Cropredy, the purple (mauve?) is unmissable.  You never know who is watching!

I wish that you had introduced yourself, as it's always a pleasure to put names to faces. I don't remember seeing your boat; where did you moor?

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Its better than shuffling your ballast.

1 minute ago, Athy said:

I wish that you had introduced yourself, as it's always a pleasure to put names to faces. I don't remember seeing your boat; where did you moor?

We have spoken in the past, missed this year though,.

We moor down past the mill, with all the fairy light and flags brigade, you know us well.

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21 minutes ago, alan_fincher said:


Slightly intriguing that a 2013 survey showed the hull to be in good condition, but that another just 3 yeras later revealed the need for some remedial work.  It would be interesting to lay both surveys alongside each other!

Exactly, and another one now would be interesting. No mention of what the remedial work was though.

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1 hour ago, juragirl said:

Thanks - I thought I had seen it on sites for a very long time. Any idea what it is worth in reality?

The inside looks very nice,but there is a question mark over the hull.

Personally I would offer £10K,and if not accepted,I would look elsewhere.  There is going to be considerable expense having the work done on the hull,lift out/dry docking fees,labour costs of £45-48 per hour plus materials.You will probably only bring it up to it's market value,which I think for a 30 year old Springer in reasonable condition would be about £15K 

 

 

 

 

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10 minutes ago, Furness said:

The inside looks very nice,but there is a question mark over the hull.

Personally I would offer £10K,and if not accepted,I would look elsewhere.  There is going to be considerable expense having the work done on the hull,lift out/dry docking fees,labour costs of £45-48 per hour plus materials.You will probably only bring it up to it's market value,which I think for a 30 year old Springer in reasonable condition would be about £15K 

 

 

 

 

Many thanks this is a great help. I loved the inside but there was work - new water heater, new bow water tank, no fridge, new floor needed. Re the hull - if the survey is correct and it is 3.1/3.2 and in good condition what work might be needed please? 

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1 minute ago, Boater Sam said:

If you want full insurance, a complete overplate job. Else you will have to hunt for insurance on a 3rd party only basis which may not include expensive removal if it sinks.

Not worth anything if it needs overplating, its scrap really.

Thank you - do you think it has to be overplated? If it does what would this cost for a 35ft boat any idea whatsoever?? Really appreciate the views and help thank you all 

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1 minute ago, Boater Sam said:

If you want full insurance, a complete overplate job. Else you will have to hunt for insurance on a 3rd party only basis which may not include expensive removal if it sinks.

Not worth anything if it needs overplating, its scrap really.

 

How about asking the seller if s/he had it comprehensively insured and if yes, with who?

 

Chances of it sinking are vanishingly small so you may elect to take the risk. Three or four NBs a year seem to sink, out of tens of thousands of them.

 

 

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It seems supremely pointless overplating a hull built from 1/8" steel that is still in good condition.

 

Once overplated for £6k to make it insurable, it won't be worth anything approaching the price paid plus the cost of the overplating, so might as well just insure it third party. Make sure the TP insurance includes wreck removal if the worst happens.

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Just now, juragirl said:

 

Many thanks this is a great help. I loved the inside but there was work - new water heater, new bow water tank, no fridge, new floor needed. Re the hull - if the survey is correct and it is 3.1/3.2 and in good condition what work might be needed please? 

Worst case is ,a full hull overplate at £180 per foot.If the survey is correct then,steam cleaning or grit blasting,rust pits spot welded,and blacking.However,if you haven't commissioned the survey yourself,be wary.It might be correct,but on the other hand,it may not be worth the paper it's written on.

When buying a used boat,you are swimming in shark infested waters.  [I do speak from bitter experience]

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1 hour ago, Boater Sam said:

Well Athy, with the polished Gardner Trojan just went up £20K !  Must think about my Garry Gorton 50ft 1990 and its insurance value: after all is said and done the 1.8 BMC is a vintage engine now by that reckoning. Who will give me £50K?

All joking aside, with the current prices of boats it may well be worth considering the insured value on many boats - especially if they have been owned for a long time.

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23 hours ago, juragirl said:

Thank you everyone for the info so far. There is very slight pitting which does not affect hull integrity apparently....

Possibly one of the ones built from ex gasholder 1/8th inch imperial plate which was at the time reputed to be superior to the then best quality UK steel the time frame of some of the early boats tends to support this; Don't be put off by the none to elegant lines in there day the were well put together shell wise & although in some cases the welding was a bit agricultural it was sound

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On 5 September 2018 at 17:54, juragirl said:

Hi - only the survey which says all plate was originally 3.2... Could it have been 5 originally?

Realistically, no. If you have a consistent set of readings of 3.1/3.2mm then the original plate was 1/8" thick. There may no irrefutable evidence of that but it isn't a surveyor making things up.

 

It's also worth bearing in mind that the actual measurements received by the probe of the ultrasonic test meter will be a load of unfathomable pulse signals that a black box magically filters and applies an algorithm to which gives a lovely round number that gives folks who get their science from the internet a false sense of accuracy.

 

Steel really doesn't rust very fast at all and even less so in a low oxygen environment such as underwater, providing that the water is broadly pH neutral which it naturally will be. It's catalysts to corrosion and nasties in the water that cause aggressive corrosion and pitting. In good conditions I would expect minimal loss of section in a plate in low oxygen conditions over 30 years. It will though look rusty on the surface because the surface of mild steel as manufactured is chemically unstable and the initial oxidisation forms a chemically stable surface. If left undisturbed it forms a layer that protects the metal beneath.

 

JP

 

 

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12 hours ago, Captain Pegg said:

Realistically, no. If you have a consistent set of readings of 3.1/3.2mm then the original plate was 1/8" thick. There may no irrefutable evidence of that but it isn't a surveyor making things up.

 

It's also worth bearing in mind that the actual measurements received by the probe of the ultrasonic test meter will be a load of unfathomable pulse signals that a black box magically filters and applies an algorithm to which gives a lovely round number that gives folks who get their science from the internet a false sense of accuracy.

 

Steel really doesn't rust very fast at all and even less so in a low oxygen environment such as underwater, providing that the water is broadly pH neutral which it naturally will be. It's catalysts to corrosion and nasties in the water that cause aggressive corrosion and pitting. In good conditions I would expect minimal loss of section in a plate in low oxygen conditions over 30 years. It will though look rusty on the surface because the surface of mild steel as manufactured is chemically unstable and the initial oxidisation forms a chemically stable surface. If left undisturbed it forms a layer that protects the metal beneath.

 

JP

 

 

The part about leaving rusting steel  undisturbed is interesting. Does that mean you should not scrape off the rust before blacking? and simply pressure wash or steam clean?

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12 hours ago, Captain Pegg said:

Steel really doesn't rust very fast at all and even less so in a low oxygen environment such as underwater, providing that the water is broadly pH neutral which it naturally will be. It's catalysts to corrosion and nasties in the water that cause aggressive corrosion and pitting.

I have no evidence to support this assumption - but - I would doubt that vey much of the canal system has 'pH neutral water', maybe at the top end of the Llangollen as the source runs off the mountains, but in the major industrial conurbations I would suggest it is no-where near 'neutral'.

 

The surface water run off from car parks, huge area of concrete, building roofs etc will be seriously affected by 'pollutants' of one sort or another. - remember that C&RT's income from allowing water extraction and discharge licences is almost as much as the income from boaters.

In rural areas the surface water run-off from agricultural land will be heavily affected by animal dung &/or fertiliser - the dykes running across our land have very aggressive growth of weeds, rushes etc due to Nitrogen run off.

 

Certain areas will be heavily affected, and certain areas will not be - badly affected water may be 'watered down' (diluted) as it moves down the canal.

 

It is for these reasons I have thoughts that rarely moving boats suffer worse corrosion and pitting than those that move a lot.

If you moor in an area with a factory discharge close by then who knows what problems that could cause.

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On 05/09/2018 at 18:17, Mike the Boilerman said:

 

Do you have a reference for that please? 

 

I ask because it seems highly unlikely to me that that nice Mr Springer would go scratching about recovering scrap steel from demolished gasometers to build a few boats when most of his prolific output MUST have been made from new steel. How many gasometers were actually demolished during his period of trading anyway? Very few if any, I'd bet! I think it's more likely to be an 'urban myth'.

He or a closely allied company had the contract to demolish gas holders& there was a fair #that ended their life & considering the amount of steel plate in one a number of boats could be built def not a myth Joe Gilbert at Charity dock bought an amount from him I carried 3pairs worth from Mk Harborough basin to Charity dock think Joe had several stretching jobs on the 20 odd ft model I have no idea of the #of boats buint from new plate but I know a good #were built with ex gas holder plate

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16 hours ago, Captain Pegg said:

Realistically, no. If you have a consistent set of readings of 3.1/3.2mm then the original plate was 1/8" thick. There may no irrefutable evidence of that but it isn't a surveyor making things up.

 

It's also worth bearing in mind that the actual measurements received by the probe of the ultrasonic test meter will be a load of unfathomable pulse signals that a black box magically filters and applies an algorithm to which gives a lovely round number that gives folks who get their science from the internet a false sense of accuracy.

 

Steel really doesn't rust very fast at all and even less so in a low oxygen environment such as underwater, providing that the water is broadly pH neutral which it naturally will be. It's catalysts to corrosion and nasties in the water that cause aggressive corrosion and pitting. In good conditions I would expect minimal loss of section in a plate in low oxygen conditions over 30 years. It will though look rusty on the surface because the surface of mild steel as manufactured is chemically unstable and the initial oxidisation forms a chemically stable surface. If left undisturbed it forms a layer that protects the metal beneath.

 

JP

 

 

Hi JP thank you very much for your post - very interesting!  A huge thank you to everyone who has helped me with this. I did make an offer but it was refused so back to the drawing board! I have found another one I am interested in so will start a new thread with a few questions soon. Once again a huge thank you to everyone - I have learnt so much and look forward to learning lots more!

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9 hours ago, Furness said:

The part about leaving rusting steel  undisturbed is interesting. Does that mean you should not scrape off the rust before blacking? and simply pressure wash or steam clean?

No. Coatings should be applied to clean, dry parent metal wherever possible. The point is more that if you have rust patches don't mechanically remove the rust unless you subsequent apply a coating to the exposed steel as soon as possible afterwards.

 

I was mostly responding to the notion that steel rusts significantly and quickly by pointing out that any untreated steel will appear to be corroded by nature but it isn't really a problem in the case of something like a baseplate on a boat.

 

If you think about it there are many industrial applications where steel components and sections are used without any surface coating.

 

JP

 

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9 hours ago, Alan de Enfield said:

I have no evidence to support this assumption - but - I would doubt that vey much of the canal system has 'pH neutral water', maybe at the top end of the Llangollen as the source runs off the mountains, but in the major industrial conurbations I would suggest it is no-where near 'neutral'.

 

The surface water run off from car parks, huge area of concrete, building roofs etc will be seriously affected by 'pollutants' of one sort or another. - remember that C&RT's income from allowing water extraction and discharge licences is almost as much as the income from boaters.

In rural areas the surface water run-off from agricultural land will be heavily affected by animal dung &/or fertiliser - the dykes running across our land have very aggressive growth of weeds, rushes etc due to Nitrogen run off.

 

Certain areas will be heavily affected, and certain areas will not be - badly affected water may be 'watered down' (diluted) as it moves down the canal.

 

It is for these reasons I have thoughts that rarely moving boats suffer worse corrosion and pitting than those that move a lot.

If you moor in an area with a factory discharge close by then who knows what problems that could cause.

The pH scale is logarithmic with means it takes large variances in acidity or basicity to make modest changes to the pH number. Urine has a pH of about 6 and seawater a pH just above 8. Groundwater is generally in the range between these values so I am pretty comfortable in suggesting that the average bit of canal water is too, which I described as "broadly neutral". That's not to say there won't be significant local and temporary variation for reasons such as you state but I don't think the average stretch of canal is normally akin to a pot of undiluted p1ss or the sea be it urban or rural.

 

I was originally just trying to allay the fears of folk who worry that boats dissolve in water.

 

JP

 

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1 hour ago, Captain Pegg said:

The pH scale is logarithmic with means it takes large variances in acidity or basicity to make modest changes to the pH number. Urine has a pH of about 6 and seawater a pH just above 8. Groundwater is generally in the range between these values so I am pretty comfortable in suggesting that the average bit of canal water is too, which I described as "broadly neutral". That's not to say there won't be significant local and temporary variation for reasons such as you state but I don't think the average stretch of canal is normally akin to a pot of undiluted p1ss or the sea be it urban or rural.

 

I was originally just trying to allay the fears of folk who worry that boats dissolve in water.

Cobra venom is about 6.8 pH, but I wouldnt want to swim in the stuff!

 

 

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