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Death throes of rusty boat


Horace42

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I have a steel boat and it is going rusty.  I was not warned about this when I bought 33 years ago (but you live and learn) - and it also need a lot of cleaning and painting - that I have done regularly (almost annually to make it look pretty) - except  hull blacking (only 3 times). And when recently in the dry dock I paid a surveyor to inspect and value my boat (for fully com insurance - and pending sale).

The surveyor as good as condemned my boat. In fact he did a better 'blacking' job than the boat yard.  He did not inspect the interior at all...I should have saved my money!

Due to excessive rust 'pitting' in numerous places the surveyor recommended it was necessary to have the patches cut out and refilled with new steel - or the hull replated etc, etc, ..

and waffle about the ineffectiveness of each option  ....but subsequently refused to tell me what standards of minimum hull thickness applied - or how long I had before my boat would become 'unseaworthy' and not allowed on the canals....or when replating became a requirement, all I got was 'clever' answers with smug arrogance. 

I did not have my boat replated. The insurance company accepted the report and renewed my fully comp, policy at the survey value.

 

From this questions arise,

1, Are there any standards for minimum thickness of rusty hulls?

2, What is the death profile of a steel narrow?

3, Who would buy a rusty boat?

Any idea please,

 

 

 

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13 minutes ago, Horace42 said:

I did not have my boat replated. The insurance company accepted the report and renewed my fully comp, policy at the survey value.

Just check that your policy doesn't include a phrase like "has a survey within the last 5 years with all recommendations carried out" as many do for older boats.

 

If your policy has that wording and you haven't had the work done then you are not insured, even if they took your money.

 

Note that you can still get 3rd party only insurance without this requirement, it's for fully comp policies that it applies.

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1 hour ago, Horace42 said:

I have a steel boat and it is going rusty.  I was not warned about this when I bought 33 years ago (but you live and learn) - and it also need a lot of cleaning and painting - that I have done regularly (almost annually to make it look pretty) - except  hull blacking (only 3 times). And when recently in the dry dock I paid a surveyor to inspect and value my boat (for fully com insurance - and pending sale).

The surveyor as good as condemned my boat. In fact he did a better 'blacking' job than the boat yard.  He did not inspect the interior at all...I should have saved my money!

Due to excessive rust 'pitting' in numerous places the surveyor recommended it was necessary to have the patches cut out and refilled with new steel - or the hull replated etc, etc, ..

and waffle about the ineffectiveness of each option  ....but subsequently refused to tell me what standards of minimum hull thickness applied - or how long I had before my boat would become 'unseaworthy' and not allowed on the canals....or when replating became a requirement, all I got was 'clever' answers with smug arrogance. 

I did not have my boat replated. The insurance company accepted the report and renewed my fully comp, policy at the survey value.

 

From this questions arise,

1, Are there any standards for minimum thickness of rusty hulls?

2, What is the death profile of a steel narrow?

3, Who would buy a rusty boat?

Any idea please,

 

 

 

1) No

2) When the steel thickness gets to 0.0mm in any spot below the waterline

3) Everyone who buys a steel boat buys rust.

 

(Some) Insurance companied have recently introduced a requirement for a minimum thickness of 4mm for fully comp insurance, and a survey every 5 years for boats over 20 / 25 / 30 years depending on insurer..

If you insure it 'third party' only then there are no thickness or survey requirements.

 

Few folks will buy a boat with a 'thin bottom' unless it is at 'scrap-pricing'.

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I think my boat is about sixty years old, maybe a bit more.  It's been replated twice - wouldn't have needed the second replating yet if the first had been done properly, but there you go.  If you've only had it blacked three times n thirty years I suspect the surveyor was right and it's almost ready to sink. (Sounds like a survey i had on a house once, which more or less implied the surveyor thought he'd been lucky to get out without the house falling on top of him, and advising me not to go back in without wearing a steel hat!).  Mine, before I had it done last, was so thin it was only the blacking keeping the water out - when they cleaned it off to reweld, you could see daylight through the hull.  Very pretty it was too, like little stars... it started sinking for other reasons and the boat only survived because I was gazing sadly into the engine bilge at the time and saw the hole develop and the water start to come in.

You have to work out whether it's cheaper to resteel the boat or buy a new one.  I would think that with a survey like that it would be virtually unsaleable, though the "we buy any boat" mob might give you a few quid for it, but if they're anything like the car ones, they'll rip you off good style.  My resteeling cost me nine grand, if the boat's worth less than that after doing it, and you don't want it,  then it's scrap.

You only need one pit to go through to sink.  Then you have to pay recovery costs on top of having a worthless boat.  I'd treble check your insurance policy for phrases like "as long as properly maintained" and the rest of the weasel get out clauses. They may well refuse to pay for the refloat now they've seen the survey, but they'll always be happy to take your money, especially if they think they'll be able to turn down any claim.

A surveyor can't tell you how long before you sink - too many variables.  They won't put anything in writing in case they're wrong and you sue.  And you're allowed on the canals until you sink, then you're only allowed under them... CRT don't care as long as you pay to hoick it out again.  There aren't any standards of hull thickness either - you just get the thickness and quality of steel you choose and pay for.

I really can't see how you can complain that you weren't warned that a steel thing, sitting permanently in water might go rusty.  First, it aint rocket science, and second, you must have had a clue when painting it every year that some of this brown stuff that appeared had something to do with damp!

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To be honest with you if you've enjoyed your boat for 33 years you'll have probably had better 'value' from it than most boat owners get. I'm not sure if you liveaboard or use it for play but if you put it in the 'like a car/caravan' rather than 'like a house' category in your head (i.e. it is a liability requiring maintenance as it depreciates rather than an asset which increases in value (sometimes) without significant investment) then you might get a better perspective on it.

 

Surveyors generally focus on the stuff you can't see easily as an average person whilst the boat is in the water (e.g. I'd rather they spent time using their ultrasound on the hull than looking at the quality of the kitchen cabinets which I can judge myself). You've clearly invested time and energy (and probably some £ too) in the parts you can see - and those are what will attract a new buyer. They may also want a hull survey (I don't think you're obliged to show them yours although it would come across odd not to if you mention it and they ask) but by that time they've already basically 'fallen for' the bits you've kept pretty.

 

Options are

* sell, without mentioning your survey, at a price which reflects the condition of the visible bits

** reduce price significantly (to close to 'scrap' value) after they get a hull survey to reflect what it is likely to say

 

* sell, with mentioning of your survey, priced at scrap value, with a comment along the lines of 'price reflects work recommended by recent survey to get hull up to standard of living accommodation'

 

* fix and sell - you'll need to speak to a few brokers/ppl on here/browse appolo duck/... to get an idea of if the returns will be worth it to you

 

Edited to add...

1, Are there any standards for minimum thickness of rusty hulls?

** as above, only for some insurance/insurers

2, What is the death profile of a steel narrow?

3, Who would buy a rusty boat?

** dreamers/the poor/the ambitious/the unaware/the 'fallen for the fit out' types/someone spotting a potential bargain/... lots of boats near me are in pretty shocking nick.

Edited by TheMenagerieAfloat
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50 minutes ago, ditchcrawler said:

A friend of mine gave away his Springer when it started leaking , the new owner now has it afloat and cruising again.

 

The boat is usable until the water stars coming in


It will still be useable after that point, with a suitably-sized bilge pump fitted. :)

 

1 hour ago, Horace42 said:

 

2, What is the death profile of a steel narrow?


There is no death profile. A steel Narrowboat can always be repaired, and nearly always will be. 
 

 

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2 hours ago, Horace42 said:

I have a steel boat and it is going rusty.  I was not warned about this when I bought 33 years ago (but you live and learn) - and it also need a lot of cleaning and painting - that I have done regularly (almost annually to make it look pretty) - except  hull blacking (only 3 times). And when recently in the dry dock I paid a surveyor to inspect and value my boat (for fully com insurance - and pending sale).

The surveyor as good as condemned my boat. In fact he did a better 'blacking' job than the boat yard.  He did not inspect the interior at all...I should have saved my money!

Due to excessive rust 'pitting' in numerous places the surveyor recommended it was necessary to have the patches cut out and refilled with new steel - or the hull replated etc, etc, ..

and waffle about the ineffectiveness of each option  ....but subsequently refused to tell me what standards of minimum hull thickness applied - or how long I had before my boat would become 'unseaworthy' and not allowed on the canals....or when replating became a requirement, all I got was 'clever' answers with smug arrogance. 

I did not have my boat replated. The insurance company accepted the report and renewed my fully comp, policy at the survey value.

 

From this questions arise,

1, Are there any standards for minimum thickness of rusty hulls?

2, What is the death profile of a steel narrow?

3, Who would buy a rusty boat?

Any idea please,

33 years ago you bought a steel boat and didn't know that it was going to get rusty? Really?? Sorry, but I find that very difficult to believe.
And you've only had it blacked 3 times? Frankly I'm not surprised the surveyor has condemned it. As he is obviously a wiser and better informed man then you I would suggest following his advise might be a good idea.

1/ Yes, the thickness that stops the water getting in.
2/ See 1.

3/ No,

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1 hour ago, TheMenagerieAfloat said:

To be honest with you if you've enjoyed your boat for 33 years you'll have probably had better 'value' from it than most boat owners get.

 

That's about as long as I've had mine.  i don't think it owes me anything and I don't begrudge it the money I've spent on it, it's been 30 odd years of pure happiness (and occasionally expense).  It sounds like the OP is thinking of moving on to another boat, in which case (as he can presumably afford a new one) it would be probably best to sell it for whatever he can get for it without bothering too much.

If mine fails to get its engine fixed, that's how it'll go and I'll pick up whatever I can afford to potter about on, but it won't be another narrowboat.

 

ETA final piece of crucial advice... fit TWO automatic bilge pumps, because one will certainly fail as soon as you need it.  Mine always have.

Edited by Arthur Marshall
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You have had the boat 30+ years. IF you had bought it brand new it would very likely need some plating by now so you have done well with it. Do you like the boat? Enough to give it another 30 + years? If you do then get it overplated. Do you Really like it? then get the old steel removed and new put in (you might find this then leads to a re- fit as well). With a survey like that its really just a project boat and worth E Bay auction money - a few thousand at most. Your questions have pretty much been answered by others but a steel boat really is endlessly repairable if the owner wants to do it. If you go to Holland there are very many old (and ancient) iron and steel boats still in use, some of these are not classics either but because they are useful they get repaired.

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Cutting out and replacing plate is the gold standard treatment for thinning hull plate, but is disruptive to the internal fitout and can be costly. The alternative is overplating - welding a new steel skin over the existing bottom and sides up to just above the water line. The detractors will point out that corrosion can still occur between the old and new skins, and that the added weight can make a boat sit dangerously low in the water if there are ventilation openings in the hull sides. On the other hand there are hundreds of replated boats around the system, which have been given a new lease of life. Martin Kedian, occasional contributer here, reckons he can overplate without doing any damage to internal fitout or hull insulation, and is prepared to give prices on his website. Have a chat with him via http://www.kedianengineering.co.uk.

The you can decide whether to get the work done, or sell the boat as is.

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I know I have posted this previously but there may be some who haven't seen it.

 

The dangers of overplating

Posted on March 17, 2017 by News Hound
Surveyors take note - overplating does not constitute a repair on a steel hull Surveyors take note – overplating does not constitute a repair on a steel hull

Feature article written by Alan Broomfield MIIMS, who tackles the thorny subject of overplating on steel hulled vessels, in particular Dutch barges and Narrowboats.

It is common practice when in the field surveying steel vessels to find mild steel plates welded to the hull, a practice regularly carried out on leisure vessels as a permanent repair. If any defects are found on the shell of a metal boat during a survey, surveyors are all too quick to recommend that the area concerned be overplated. Marine surveyors who deal with steel vessels will find that very often – Dutch barges and canal boats in particular – are frequently heavily overplated and should remember at all times that such overplating does NOT constitute a repair. It merely hides the defect.

Doubling or overplating can only ever be regarded as bad practice, a cheap bodge job and is intellectually dishonest. It is often carried out on leisure vessels to cover over areas of pitting which is not necessarily the best solution. Pitting, if small in area and localised, is often best dealt with by back filling the pits with welding rather than extensive overplating. Pitting on non structual interior bulkheads can often be satisfactorily filled with a plastic metal paste such as Belzona but this method of repair should not be used on shell plating. Plastic metal should only be used on single pits on water/ballast tank plating or in areas where heat is not allowed or unsafe (fuel tanks).

Finally, the marine surveyor should remember that overplating, though a common practice, is often carried out without thought as to the unintended consequences.
We should realise that it adds weight to the vessel’s structure without adding much compensating volume and, as a direct result, the vessel necessarily sinks lower in the water. It also has a number of other unintended and often unrealised side effects.

1. By increasing the draft, it reduces the available freeboard and, therefore, the amount of reserve buoyancy.
2. It also, therefore, reduces the transverse metacentric radius (BMT), and slightly, increases the height of the centre of buoyancy (KB) usually with very little compensating reduction in the height of the centre of gravity (KG) so that the end result is a reduction in the metacentric height (GM) and a negative alteration to the characteristics of the statical stability curve i.e. a reduction in the maximum GZ value and the range of positive statical stability. [The average metacentric height of a narrowboat is about 150 mm (6 inches)].
3. It may also, depending upon where the overplating is sited, alter both the longitudinal trim and the transverse heel of the vessel with further indeterminate alterations in her statical stability curve.
4. It lowers the deck edge immersion angle and, therefore, any downflooding angle(s).
5. The double plating is usually not secured to the primary supporting structure – the shell side framing. It is also rarely fitted with centre plate plug welds and is dependent only on the edge weld for security.
6. The double plating is secured only at its edges and the greater the area of plate, the smaller the length of the attachment weld per unit area and, therefore, the greater the stresses in those welds.

7. The corrosion or pitting, being the reason for fitting the doubling plates, means the corrosion or pitting will still remain there and, if it is on the inside of the original shell plate, will still be increasing. Doubling, therefore, is merely hiding the problem, not repairing it.

 

Full article here :

 

https://www.iims.org.uk/the-dangers-of-overplating/

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OP, I have a 30+ yr old boat for sale at present which does not require over (or any other) kind of plating as it has been well looked after. And, I'd imagine, pretty well built to start with. Recent survey by a colleague of the author of above article.

 

Inside medium-pretty (very pretty, but unconventional as tug style). Hull really decent. 

 

BUT someone has to fall for the medium pretty inside before they survey to see the hull loveliness and buy. 

 

Swings and roundabouts...  

 

Edited to add: 33 and a bit years actually!

 

To be honest people are expecting the hull to be I worse condition than it is so I kind of wish it was younger with a cr*appier hull as ppl discount for the age more than necessary with mine! 

 

Edited by TheMenagerieAfloat
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33 minutes ago, Bee said:

If you go to Holland there are very many old (and ancient) iron and steel boats still in use, some of these are not classics either but because they are useful they get repaired.

You do not have to look as far as Holland as there are numerous old iron and steel 'historic' boats on the UK's waterways.

 

My boat dates to 1936 and worked pretty hard right up to 1970, and has worked less hard since then. It has been re-bottomed and re-footed at least twice (possibly three times - last in 2003) by removing and replacing the steel, and has been subject to some over-plating - although some of this has recently been removed with the thin steel cut out and replaced. Dealing with thin steel / iron on 'historic' boats has been ongoing for donkeys years, but as pleasure boats age it will inevitably effect them in a similar way :captain:

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2 hours ago, Arthur Marshall said:

That's about as long as I've had mine.  i don't think it owes me anything and I don't begrudge it the money I've spent on it, it's been 30 odd years of pure happiness (and occasionally expense).  It sounds like the OP is thinking of moving on to another boat, in which case (as he can presumably afford a new one) it would be probably best to sell it for whatever he can get for it without bothering too much.

If mine fails to get its engine fixed, that's how it'll go and I'll pick up whatever I can afford to potter about on, but it won't be another narrowboat.

 

ETA final piece of crucial advice... fit TWO automatic bilge pumps, because one will certainly fail as soon as you need it.  Mine always have.

Steelworms - they bloomin' hate the trombone.  Your boat is good for another 30 years.  :icecream:

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8 minutes ago, Alan de Enfield said:

I know I have posted this previously but there may be some who haven't seen it.

 

The dangers of overplating

Posted on March 17, 2017 by News Hound
Surveyors take note - overplating does not constitute a repair on a steel hull Surveyors take note – overplating does not constitute a repair on a steel hull

Feature article written by Alan Broomfield MIIMS, who tackles the thorny subject of overplating on steel hulled vessels, in particular Dutch barges and Narrowboats.

It is common practice when in the field surveying steel vessels to find mild steel plates welded to the hull, a practice regularly carried out on leisure vessels as a permanent repair. If any defects are found on the shell of a metal boat during a survey, surveyors are all too quick to recommend that the area concerned be overplated. Marine surveyors who deal with steel vessels will find that very often – Dutch barges and canal boats in particular – are frequently heavily overplated and should remember at all times that such overplating does NOT constitute a repair. It merely hides the defect.

Doubling or overplating can only ever be regarded as bad practice, a cheap bodge job and is intellectually dishonest. It is often carried out on leisure vessels to cover over areas of pitting which is not necessarily the best solution. Pitting, if small in area and localised, is often best dealt with by back filling the pits with welding rather than extensive overplating. Pitting on non structual interior bulkheads can often be satisfactorily filled with a plastic metal paste such as Belzona but this method of repair should not be used on shell plating. Plastic metal should only be used on single pits on water/ballast tank plating or in areas where heat is not allowed or unsafe (fuel tanks).

Finally, the marine surveyor should remember that overplating, though a common practice, is often carried out without thought as to the unintended consequences.
We should realise that it adds weight to the vessel’s structure without adding much compensating volume and, as a direct result, the vessel necessarily sinks lower in the water. It also has a number of other unintended and often unrealised side effects.

1. By increasing the draft, it reduces the available freeboard and, therefore, the amount of reserve buoyancy.
2. It also, therefore, reduces the transverse metacentric radius (BMT), and slightly, increases the height of the centre of buoyancy (KB) usually with very little compensating reduction in the height of the centre of gravity (KG) so that the end result is a reduction in the metacentric height (GM) and a negative alteration to the characteristics of the statical stability curve i.e. a reduction in the maximum GZ value and the range of positive statical stability. [The average metacentric height of a narrowboat is about 150 mm (6 inches)].
3. It may also, depending upon where the overplating is sited, alter both the longitudinal trim and the transverse heel of the vessel with further indeterminate alterations in her statical stability curve.
4. It lowers the deck edge immersion angle and, therefore, any downflooding angle(s).
5. The double plating is usually not secured to the primary supporting structure – the shell side framing. It is also rarely fitted with centre plate plug welds and is dependent only on the edge weld for security.
6. The double plating is secured only at its edges and the greater the area of plate, the smaller the length of the attachment weld per unit area and, therefore, the greater the stresses in those welds.

7. The corrosion or pitting, being the reason for fitting the doubling plates, means the corrosion or pitting will still remain there and, if it is on the inside of the original shell plate, will still be increasing. Doubling, therefore, is merely hiding the problem, not repairing it.

 

Full article here :

 

https://www.iims.org.uk/the-dangers-of-overplating/

The problem with most of that is that the theory isn't backed up by practice.

 

1: True, but not by an amount to cause concern in any case I have yet come across.

 

2: Potentially, but lets worry about all the coal and logs on the coachroof  first eh? Also, assuming the weight of steel added to the baseplate is greater than the footings then it won't apply will it?

 

3: Yes, but move the bags of coal (see above)

 

4: Take the coal off the roof altogether or lift the floor and take some ballast out if the boat is significantly deeper in the water. (Be careful how much coal you back up there afterwards though...)

 

5: Certainly can be an issue on dutch barges, but not on modern narrowboats where I would argue that the framing isn't vital to the structural integrity anyway. Decent overplating always has plug welds to support the plating. There are cleverer ways of doing it with short sheets and multiple tranverse welds too.

 

6: See point 5

 

7: Assuming the original platework is not holed, and the new welds are not porous, then there's no oxygen in there for corrosion to continue, surely? Brinklow Boats posted some pictures of a baseplate overplate they cut off a while back and the inside face of the overplate was still immaculate)

 

That said, given the option I'd always prefer to cut out and let in because it's the right thing to do (although potentially you could get issues that way too with weld stress) but it is by no means the only option.

 

 

 

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But @Rose Narrowboats. Much of that relies on (someone who has only had their boat backed once/decade) actually doing that. 

 

Boats have sunk due to sitting too low after overpating. 

Edited by TheMenagerieAfloat
I will probably/possibly not bother sorting out own ballast after all stuff is moved on from land...
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37 minutes ago, Alan de Enfield said:

1. By increasing the draft, it reduces the available freeboard and, therefore, the amount of reserve buoyancy.

 

12 minutes ago, Rose Narrowboats said:

The problem with most of that is that the theory isn't backed up by practice.

 

1: True, but not by an amount to cause concern in any case I have yet come across.

 

Here is one example :

 

Safety Lessons

The hull of the vessel had been completely double plated and the increased weight of this plating had resulted in a reduced safety clearance; with the bottom of the engine room vent being positioned approximately 65mm above the waterline.  With 3 persons positioned on the aft deck the bottom of the engine room air vent became submerged beneath the waterline by 50mm, the resulting downflooding and sinking of the vessel was inevitable.  

 

https://www.pla.co.uk/assets/sb1of2012-narrowboatsinking-inadequateventsfreeboard1.pdf

 

As you will be aware the minimum 'safety clearance' on private boats is recommended at 250mm.

The 250mm is compulsory on commercial boats

Edited by Alan de Enfield
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5 minutes ago, TheMenagerieAfloat said:

But @Rose Narrowboats. Much of that relies on (someone who has only had their boat backed once/decade) actually doing that. 

 

Boats have sunk due to sitting too low after overpaying. 

I think it's owners that sink after overpaying ;)

 

Generally I'd agree with Rose Nartowboats (who run a large fleet of boats for hire) in most instances the amount of steel added doesn't make much difference.

 

Lutine had overplating but was too high out of the water - not enough balast put back afterwards

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4 minutes ago, Rose Narrowboats said:

2: Potentially, but lets worry about all the coal and logs on the coachroof  first eh? Also, assuming the weight of steel added to the baseplate is greater than the footings then it won't apply will it?

 

3: Yes, but move the bags of coal (see above)

 

4: Take the coal off the roof altogether or lift the floor and take some ballast out if the boat is significantly deeper in the water. (Be careful how much coal you back up there afterwards though...)

Ok, but how many people with, or buying, an overplated boat have any idea of this?  I'd offer that most folk here, and I'd say they are are generally more interested than most in boating, will have little appreciation of stability let alone have heard of Metacentric Height or have an understanding of the effects of shifting it.  Bloomin' good job it's not rough, I'd say! :sick:

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2 minutes ago, magpie patrick said:

Generally I'd agree with Rose Nartowboats (who run a large fleet of boats for hire) in most instances the amount of steel added doesn't make much difference.

I have hired from Rose.

 

Agreed, if it is a properly done job then there is no problem.

 

I would suggest that boat 'overplating' is sort of a back-street business and for every well-done example ( properly welded, ballast corrected, freeboard checked etc) there would be an example of 'less than perfect' work.

 

Cost could well be a deciding factor in peoples choice of where to have it done, and think that price would be indicative of 'quality'.

 

Maybe a generalisation but in many instances boats that need overplating will be towards the bottom end of the market* and will probably be owned by people with limited 'discretionary spending'.

 

* There will always be the 'historic' or 'specials' owned by enthusiasts.

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10 minutes ago, Sea Dog said:

Ok, but how many people with, or buying, an overplated boat have any idea of this?  I'd offer that most folk here, and I'd say they are are generally more interested than most in boating, will have little appreciation of stability let alone have heard of Metacentric Height or have an understanding of the effects of shifting it.  Bloomin' good job it's not rough, I'd say! :sick:

Yep, that side what I was thinking... Better expressed and spelled. People here don't know steel rusts due to decades of submersion. The rest of the (over plated) cut are flipped. (Over, due to lack of stability). 

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20 minutes ago, Alan de Enfield said:

 

 

Here is one example :

 

Safety Lessons

The hull of the vessel had been completely double plated and the increased weight of this plating had resulted in a reduced safety clearance; with the bottom of the engine room vent being positioned approximately 65mm above the waterline.  With 3 persons positioned on the aft deck the bottom of the engine room air vent became submerged beneath the waterline by 50mm, the resulting downflooding and sinking of the vessel was inevitable.  

 

https://www.pla.co.uk/assets/sb1of2012-narrowboatsinking-inadequateventsfreeboard1.pdf

 

As you will be aware the minimum 'safety clearance' on private boats is recommended at 250mm.

The 250mm is compulsory on commercial boats

That's a downflooding issue though, and what I'd like to know is what the freeboard of that vent was in the first place? For three people to put the stern down by 65mm I'd suggest that it must have also been a very short boat. I'll stand three people on our 32' day boat next week and measure.

 

On a sixty footer, assuming 6mm thick overplate of baseplate and hullsides up to 500mm you are adding about 2300kg.

 

I don't think the article factors in how much weight the boat will have lost since built - presumably if it needs overplating (rather than pit welding) then a significant mass will have ..er...dissolved. I don't know if anyone has ever tried to work that out, or indeed weighed what they've swept up off the floor after the baseplate has been cleaned off, but how's 500kg for a starting point?

 

We have had overplated, boats from 34' to 60' which have not sat noticeably lower in the water, nor have we had to raise anything other than a weedhatch on one boat which was already marginal. If necessary, removal of ballast to compensate should be a viable option in most cases.

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