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Getting work done at the same time?


jetzi

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There is a belief that there is less oxygen to rust the base plate on the mud layer at the bottom of a canal, maybe so, maybe not.

Steel rusts less in winter due to the lower water temperature, fact.

How are you going to clean and paint the base plate? If its a dry dock the plate is partially hidden over the stocks anyway and maybe only 2' off the ground.

If its a drag out you will not get under it at all.

Paranoia about boats rusting through and sinking is normal but unfounded, very few do sink. Many are now 50+ years old and were built with thinner steel than 'yours' , some are only 3mm thick from new!

If you get iced in this winter and have to move you will destroy the blacking/epoxy anyway so leave it till spring.

 

If you are still worried about pitting, rock the boat over by loading up one side with drinkers, get a 12v bulb on a stick, put it in the water before you turn it on, and have a look at the top 6" of the sides, that's the bit which will be the worst.

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42 minutes ago, ivan&alice said:

 Seems the forum generally recommends a pressure wash, the two pack epoxy, applied in Summer, plus anodes. I'll take that under advisement when comparing the prices and options.

 

No they do not. Anyone who recommends a pressure wash on a 'blacked' surface followed by 2 pack epoxy is just wrong.

For longest life (and hence value for money), apply a 2 pack epoxy to a grit blasted surface. There are surface tolerant 2 pack epoxies but they are a compromise and they cannot be applied over a previously blacked surface unless you are looking for premature failure. See my previous post.

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I hand scraped and wire brushed my hull back to clean bright steel and used the epoxy I mentioned 20 years ago. Couldn't afford the grit blasting at the time. But it was very hard work. Its now 29 years old.

 It has been out and touched up only 3 times since first being done, had 2 sets of anodes replaced and apart from scrapes it is in fine condition.

Never even looked at the base plate.

The makers of the epoxy were Leigh Paint of Bolton, taken over by Sherwin Williams. They quote a 20 year life for the coatings I used.

It had one coat of epoxy zinc phosphate onto the bare steel and 2 coats of the black epoxy originally. Since then it has been cleaned and touched up where scraped off and one thin coat overall each time it has been out. Its a mistake to put too many coats of epoxy on, its only the last one that protects anyway.

I put new anodes on when needed, leaving the old ones on as well if there is anything left of them. Zinc of course, its never been in salt water.

Edited by Boater Sam
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40 minutes ago, Alan de Enfield said:

I think it would be advisable to get a full list of work needed BEFORE booking work to be done.

 

If you book in for (say) blacking and part way thru the hull blasting you find that you have made a hole and now it needs overplating, then the yard will have other boats booked in, and will not be able to fit in your extra work. 

 

Dry-docks are booked up for months in advance and if you overrun the knock on effect could be enormous.

 

For the boat to leak, the metal thickness must be 0.0mm, anything above that and it won't sink.

Don't overthink, and don't panic.

 

(No - the bottom of the base plate is rarely painted - it would be rubbed off within the 1st couple of miles.) 

 

23 minutes ago, Mike the Boilerman said:

 

Have a guess. I thought you might be assuming that!!!

 

Wow, well, today I learned that the bottom of narrowboats are coated in rust! I suppose at 10mm it doesn't really matter that much - perhaps it's kind of like train tracks, which I believe they allow to rust because they are so thick the thin rust layer actually just protects the structural steel, and the fatigue of the trains passing over them causes faster deterioration than corrosion could.

 

This is all rather reassuring. The boat was built to 10-6-4mm specs (pretty good standard on newer boats, in my experience) and the survey shows up to 1mm less all around below the waterline. That seems like rather fast deterioration (or slightly inferior materials than spec) but even so, that means another 100 years before she's rusted through if she keeps up that rate.

 

11 minutes ago, Boater Sam said:

Paranoia about boats rusting through and sinking is normal but unfounded, very few do sink. Many are now 50+ years old and were built with thinner steel than 'yours' , some are only 3mm thick from new!

If you get iced in this winter and have to move you will destroy the blacking/epoxy anyway so leave it till spring.

It's true, I am worried about the ice destroying the coating, and by the sounds of the weather forecast we're in for as cold a winter as the summer was hot. I'm not sure how it's going to work since if the canals are iced over we aren't going to be able to continuous cruise. Is it a case of musical moorings - when the canal freezes over everyone keeps their spot? I've looked a little into winter moorings, seems they can be had for 6.7 GBP/metre/month even within the M25.

 

10 minutes ago, Dr Bob said:

No they do not. Anyone who recommends a pressure wash on a 'blacked' surface followed by 2 pack epoxy is just wrong.

Sorry - this was me not reading properly. Pressure wash if you are going to re-black with bitumen, grit blast if you are going to upgrade your coating to something more modern.

 

15 minutes ago, Boater Sam said:

If you are still worried about pitting, rock the boat over by loading up one side with drinkers, get a 12v bulb on a stick, put it in the water before you turn it on, and have a look at the top 6" of the sides, that's the bit which will be the worst.

This makes sense from what I learned in physics, that electricity flows over the surface of water - electrolytic pitting is likely to occur at the waterline. I'm actually not overly concerned about that on this boat, as she doesn't have a shore power hookup and hasn't been hooked up to shore power since her last survey.

My main concern is if she might have a shopping trolley shaped dent from CCing London over the last three years, that rust has attacked it and that we're going to have an internal water feature before long.

 

I'm absolutely terrified of that scenario, can just picture me like a modern day Hans Brinker with my thumb in a rusty hole as smelly canal water starts pouring in.

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Ivan,

 

It's nonsensical to worry yourself about things you chose not to establish when you had the chance. You made that decision so you have to live with it, it's doing you no good worrying about it and it's almost certainly unfounded anyway.

 

This business about blasting the complete hull back for ultrasonic testing isn't necessary. No test can cover 100% and it doesn't need to. Rusting simply doesn't work that way. The bottom side should be pretty uniform since it's the same material in the same environment. On the top side of the baseplate there may be enhanced corrosion where water has stood and particularly if that is grey water as that could have some aggressive chemicals in it. If you want more certainty do more testing under the kitchen, bathroom and engine bilges.

 

If you blast the hull you will see the evidence of any pitting and it should be clean and measurable. You won't see rust unless you have been had so I think Neil2 must be lumping rusting and pitting corrosion together. They are not the same process. Are you sure the survey you refer to said there was 1mm of wasting through rusting or that 1mm of pitting was evident all round? The former seems unlikely to me because natural oxidisation of steel under water is very slow unless there are undesirable chemicals in the water.

 

4 years used to be the normal timescale for blacking and it has become 2 in recent times. I very much doubt it will be a problem to wait until spring but if you do choose to blast it back to bare metal it would be a nonsense not to apply a 2 pack epoxy system.

 

Nice link to railway tracks by the way. You could learn a lot by expanding that thought process. Rails are never replaced due to corrosion by normal environmental processes (i.e. by air and rain) and they are 11mm thick at the edge of the foot. They are however routinely replaced as a result of the impurities and inclusions inherent in older steels. They do suffer pitting on the underside where they are in contact with other materials but not on the exposed surfaces where only rain and air are in play. The steels are specific alloys designed for hardness rather than corrosion resistance. Standard mild steel is used for sleepers in the same environment and is also uncoated. These have a projected lifespan of 75 years.

 

JP

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3 minutes ago, Boater Sam said:

If you hole the base plate it ain't smelly water that will pour in but thick mud that will ooze in on the average canal.

The old elm bottomed boats used to be deliberately run into the clay banks near Braunston to reduce the leaks through the planks.

Spey did this a couple of month back after coming out of the dry dock, watched her rub along the offside of the T&M at Anderton

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On ‎22‎/‎09‎/‎2018 at 20:24, ivan&alice said:

Today we had an offer accepted on our first ever narrowboat!

 

When we take occupation in November we want to haul her out of the water to have some work done. To save on craneage and boatyard costs, we want to have all the out of water work done at the same time. She was last blacked and surveyed in March 2015, so we want a full service.

 

Our plan is:

 

  1. Have her hauled out
  2. Shot-blasting her back to bare metal
  3. Have a comprehensive survey (the bare metal should facilitate this?)
  4. Have her blacked
  5. Have her put back into the water.

 

We're going to call around on Monday to get quotes on the above. The boat is in London so we're prepared to sail her to a boatyard further out if it's likely to be cheaper.

 

  1. Are we going to be able to have all this done at once?
  2. How long should the above take?
  3. What if the survey turns up that we need extra work (such as welding or overplating) done - would we be able to squeeze this in?
  4. Any ballpark ideas of what this should cost us?
  5. Will we be able to supervise any of this to get an idea of what went on and that it was up to standard?
  6. Anything else we should consider?

 

Thanks for your time and advice!

P & S Marine at Watford do everything on your list:

 

http://pandsmarine.co.uk/

 

There is a price list on the web site

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1 hour ago, Captain Pegg said:

This business about blasting the complete hull back for ultrasonic testing isn't necessary.

I get that it's not necessary as it's not usually done. But I still would feel more comfortable having the surveyor look at bare metal and find any faults before they become serious, and if we're going to be replacing the blacking anyway it seems to make sense to me to go the whole hog.

 

1 hour ago, Captain Pegg said:

On the top side of the baseplate there may be enhanced corrosion where water has stood and particularly if that is grey water as that could have some aggressive chemicals in it. If you want more certainty do more testing under the kitchen, bathroom and engine bilges.

This is good advice, and once I'm on the boat I'll see how easy it is to lift the floor and look for these kinds of problems.

 

1 hour ago, Captain Pegg said:

Are you sure the survey you refer to said there was 1mm of wasting through rusting or that 1mm of pitting was evident all round?

The survey is just a one-page table of spot thicknesses measured by ultrasound. It doesn't say anything about rusting or pitting. The sides are between 5.0 and 5.9mm with an average of 5.6mm, the base plate is between 8.8 and 9.8mm with an average of 9.4mm. That's all I meant by 1mm deterioration over the specs (6mm sides and 10mm base).

 

1 hour ago, Captain Pegg said:

4 years used to be the normal timescale for blacking and it has become 2 in recent times. I very much doubt it will be a problem to wait until spring but if you do choose to blast it back to bare metal it would be a nonsense not to apply a 2 pack epoxy system.

I've been told that the reduction in recommended blacking interval was a ploy for the boatyards to make more money and that every 4 years is ample. Kind of like how your dentist tells you to come back every 6 months.

 

1 hour ago, Tim Lewis said:

P & S Marine at Watford do everything on your list:

 

http://pandsmarine.co.uk/

 

There is a price list on the web site

Thanks for the recommendation, I've emailed them to ask them about availability. I see they also advertise a half price dry dock during winter to allow you to provide more time for the coatings to cure, which seems very fair of them.

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15 minutes ago, ivan&alice said:

Thanks for the recommendation, I've emailed them to ask them about availability. I see they also advertise a half price dry dock during winter to allow you to provide more time for the coatings to cure, which seems very fair of them.

But unless it is a closed &  heated dry-dock you will never get a proper cure.

Being cynical - the lack of anyone wanting to do painting during the winter means they earn 'nothing' from dry-dock hire. Better to get half price than nothing, and then get another 'full price' hire when the guy who did his blacking in the Winter has to come back in the Summer and do it all again.

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1 minute ago, Alan de Enfield said:

But unless it is a closed &  heated dry-dock you will never get a proper cure.

Being cynical - the lack of anyone wanting to do painting during the winter means they earn 'nothing' from dry-dock hire. Better to get half price than nothing, and then get another 'full price' hire when the guy who did his blacking in the Winter has to come back in the Summer and do it all again.

I'll keep that in mind. I asked for a quote on both, plus an extra couple of days in case the survey turns up welding work that needs doing.

 

It's going to suit us better to wait until spring to do this anyway.

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3 hours ago, Mike the Boilerman said:

 

Can you back this up please? How many? I'm not sure this is true. Narrow boats sinking from a pitted baseplate are exceedingly rare in my personal experience.

 

The only one I can think of ever, is one of my own. The baseplate was well over 100 years old though. 

If you want names and addresses, no.  But I hear accounts all the time and in fact there is currently a boat on the hard a few yards away from me now that was hauled out a couple of weeks ago as it was taking on water through the hull.  What is interesting about that one is that it was a newly purchased boat and apparently the surveyor reckoned the hull was sound...   When I was at Calcutt IIRC there were two instances of boats going under overnight.  Yes I suppose it is a "rare" event but there must be scores of boats with 6mm bottoms that are pitted to within a millimetre or so with the owners oblivious.   My point is, it's reckless to assume a narrowboat has a sound baseplate based on what many folk choose to believe about (not) protecting it.

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56 minutes ago, ivan&alice said:

I get that it's not necessary as it's not usually done. But I still would feel more comfortable having the surveyor look at bare metal and find any faults before they become serious, and if we're going to be replacing the blacking anyway it seems to make sense to me to go the whole hog.

 

This is good advice, and once I'm on the boat I'll see how easy it is to lift the floor and look for these kinds of problems.

 

The survey is just a one-page table of spot thicknesses measured by ultrasound. It doesn't say anything about rusting or pitting. The sides are between 5.0 and 5.9mm with an average of 5.6mm, the base plate is between 8.8 and 9.8mm with an average of 9.4mm. That's all I meant by 1mm deterioration over the specs (6mm sides and 10mm base).

 

I've been told that the reduction in recommended blacking interval was a ploy for the boatyards to make more money and that every 4 years is ample. Kind of like how your dentist tells you to come back every 6 months.

 

Thanks for the recommendation, I've emailed them to ask them about availability. I see they also advertise a half price dry dock during winter to allow you to provide more time for the coatings to cure, which seems very fair of them.

P & S do not have a dry dock but have hard standings where they carry out any works. They have what is probably the largest boat yard crane on the system to lift boats out with!

 

We had some welding done there a few years ago which was carried out incredibly efficiantly

 

Edited by Tim Lewis
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Older narrowboats sometimes need new bottoms because the sacrificial edge has worn away, or the steel plate has worn thin from scraping along the bottom of the cut over many years, as well as replacement because of pitting.

 

However I don't think anyone keeps records of the reason for replacement. 

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47 minutes ago, Neil2 said:

If you want names and addresses, no.  But I hear accounts all the time and in fact there is currently a boat on the hard a few yards away from me now that was hauled out a couple of weeks ago as it was taking on water through the hull.  What is interesting about that one is that it was a newly purchased boat and apparently the surveyor reckoned the hull was sound...   When I was at Calcutt IIRC there were two instances of boats going under overnight.  Yes I suppose it is a "rare" event but there must be scores of boats with 6mm bottoms that are pitted to within a millimetre or so with the owners oblivious.   My point is, it's reckless to assume a narrowboat has a sound baseplate based on what many folk choose to believe about (not) protecting it.

I don't think anyone is assuming it is sound, just working on the basis that in the absence of facts a 19 year old boat with a 10mm baseplate that is currently floating is very unlikely to sink in the next 6 months. It is also probable that is perfectly sound and will remain so for the foreseeable future.

 

I think some hardened boaters see sinking as an occupational hazard. I moor next to a guy who has had two go down and it doesn't worry him. And that's probably a good thing judging by the hull of his current boat. 

 

Taking the examples you give what's so reckless about it? Boat in marina sinks overnight, no one dies, no one injured, possibly nobody even aboard. If you live aboard you will probably see the signs before it sinks and haul it out. Dare I suggest it's a worry mostly for folks for whom a boat is their pension fund afloat?

 

A bit of perspective is what Ivan needs from the forum, he's quite capable of doing all the worrying necessary on his own.

 

JP

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1 hour ago, mark99 said:

The over-worry about your new boat sinking is understandable it's characterised by an asymptotic curve - high at the start and as time goes on, it falls off rapidly but never quite goes away.  ;)

So sleep with one hand dragging on the floor.

 

It's uncomfortable, but you will feel the water rising in time to get up ... :icecream:

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2 minutes ago, TheBiscuits said:

So sleep with one hand dragging on the floor.

 

It's uncomfortable, but you will feel the water rising in time to get up ... :icecream:

I thought that was an old Navy trick to make you pee the bed, put a bowl of water just under a sleepers hand so the just touch it.

 

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9 hours ago, ivan&alice said:

 

Wow, well, today I learned that the bottom of narrowboats are coated in rust!

We have certainly blacked our base plate in the past, so hopefully not too rusty at the moment on the outside. The inside may well be coated in rust though:)

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It seems that there's almost as many differing viewpoints on painting the underwater bit as there are on Brexit, The only place I have ever seen the underneath left unpainted is on the British canal system, if you had a boat hauled out in Holland and you tried to tell the yard that the bottom didn't need painting they would think you were very odd., same everywhere else I've been. When boats had wooden bottoms that was the case, being elm it lasted well enough as it was. I think that is probably where the 'tradition; started., and, of course, its next to impossible to get under the boat at many old docks, I've laid under a boat to caulk a seam or two and stuff that for a lark. If it gets wet - paint it.

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2 minutes ago, Bee said:

It seems that there's almost as many differing viewpoints on painting the underwater bit as there are on Brexit, The only place I have ever seen the underneath left unpainted is on the British canal system, if you had a boat hauled out in Holland and you tried to tell the yard that the bottom didn't need painting they would think you were very odd., same everywhere else I've been. When boats had wooden bottoms that was the case, being elm it lasted well enough as it was. I think that is probably where the 'tradition; started., and, of course, its next to impossible to get under the boat at many old docks, I've laid under a boat to caulk a seam or two and stuff that for a lark. If it gets wet - paint it.

Lots of dry docks you cant get under to do it or if its pulled out on a trailer 

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