Poured concrete ballast

[GlenBlk]

I have seen a narrow boat of less five years which required bottoming because of rust

 

This is not a wise move.

 

Keith

Why did they need replating within 5 years?

thats highly unusual!

Well it's as heavy as paving slabs, which is what quite a few people use.

My query is, why its ok in a barge but shite in a narrowboat?

Why not use gravel instead (although it holds moisture)?

Concrete contains lime I think which has an acidity that can be corrosive.

Just bung heavy scarp in there!

[fudd]

Well you've answered your own question there. Moisture. Have you read any of my posts in this thread? If so, you will understand that I'm not wanting to 'bung' anything into my bilge.

[Beaker]

 

Concrete contains lime I think which has an acidity

 

 

Lime is alkaline.

[GlenBlk]

Well you've answered your own question there. Moisture. Have you read any of my posts in this thread? If so, you will understand that I'm not wanting to 'bung' anything into my bilge.

No I've answered your 1st question and underlined it for you I'M not answering for my own entertainment!

People don't pour concrete into steel hulls unless they are donald ducked and they have no intention of keeping them!

Removable ballast is used for a reason which is pretty self explanatory.

I didn't suggest bunging anything in there did I?

If your that bothered go and pay a surveyor.

 

Lime is alkaline.

Its corrosive but go ahead and split hairs if you wish.

Edited November 22, 2013 by GlenBlk

[fudd]

About 10 years ago I was looking at selling up and buying a Dutch barge. During my research, I read about concrete poured directly onto clean grit blasted steel. It supposedly bonds to, and protects the bilge. I've not heard of it in the narrowboat world. Any reason why?

 

That's my first post. You haven't answered any questions I've asked. As for the rest you are just wrong on all counts

 

Replying to gblik

Edited November 22, 2013 by fudd

[GlenBlk]

About 10 years ago I was looking at selling up and buying a Dutch barge. During my research, I read about concrete poured directly onto clean grit blasted steel. It supposedly bonds to, and protects the bilge. I've not heard of it in the narrowboat world. Any reason why?

 

That's my first post. You haven't answered any questions I've asked. As for the rest you are just wrong on all counts

 

Replying to gblik

Think about it....

How old are old dutch barges compared to relatively new by comparison flat bottomed narrowboats?

Even poured concrete retains moisture compared to any kind of movable ballast including gravel which can be sacked!

I'M wrong based on your lack of experience and knowledge either way I was trying to help but sod ya...

Edited November 22, 2013 by GlenBlk

[fudd]

 

Think about it....

How old are old dutch barges compared to relatively new by comparison flat bottomed narrowboats?

 

What's your point?

 

 

Even poured concrete retains moisture compared to any kind of movable ballast including gravel which can be sacked!

 

So concrete contains more moisture than gravel! Rubbish

 

I'M wrong based on your lack of experience and knowledge either way I was trying to help but sod ya...

 

What lack of experience and knowledge are you talking about?

 

You said 'bung some "scarp" in there'

Edited November 22, 2013 by fudd

[GlenBlk]

Having dealt with hull problems and poured concrete in hulls I am already starting to wonder why I even bothered trying to give you some information in the first place!

 

I did not say ''concrete contains more moisture than gravel''

I said it contains more moisture than ''any type of movable ballast'' that would also include ''sacked'' ballast.

 

Go pour wet concrete in the bottom of your boat and learn the hard way..

Edited November 22, 2013 by GlenBlk

[blackrose]

Not at all determined to do it. As of yet I've not had a 'concrete' reason not to do it apart from a couple of cases where it went wrong. But was the preparation done correctly?

Concrete sticks to steel like glue. So can anybody with any evidence of a properly prepared surface failing?

It's outlawed in France but nowhere else.

Reinforced buildings would be falling apart all over the place if it was shite.

 

They are. One of the problems of reinforced concrete buildings is unless they get the concrete exactly right the reinforcement can corrode inside and blow the concrete. There are plenty of examples of cracking concrete even on good buildings where they've done it properly. Remember that unlike a building, a boat moves and bumps into things too. The steel hull flexes and may also be more prone to temperature variations than a building so you get more expansion and contraction. If you get cracks in the concrete or any separation of the concrete and steel then water can penetrate and then there's sod all you can do about it.

 

What exactly do you see as the advantages of poured concrete over slabs? The only one I can think of is reinforcement of the hull, but we are on the inland waterways. If the hull has been properly built then that shouldn't be an issue anyway.

 

Lime is alkaline.

 

So is sodium hydroxide (caustic soda), which is highly corrosive.

Edited November 23, 2013 by blackrose

[fudd]

My point was that the concrete adheres and protects the hull from corrosion due to its alkaline properties. It's been done for years in Dutch barges. The post was one of inquisitiveness.

 

They are. One of the problems of reinforced concrete buildings is unless they get the concrete exactly right the reinforcement can corrode inside and blow the concrete. There are plenty of examples of cracking concrete even on good buildings where they've done it properly. Remember that unlike a building, a boat moves and bumps into things too. The steel hull flexes and may also be more prone to temperature variations than a building so you get more expansion and contraction. If you get cracks in the concrete or any separation of the concrete and steel then water can penetrate and then there's sod all you can do about it.

 

The buildings only fall apart if its not constructed properly.

 

What exactly do you see as the advantages of poured concrete over slabs? The only one I can think of is reinforcement of the hull, but we are on the inland waterways. If the hull has been properly built then that shouldn't be an issue anyway.

 

 

So is caustic soda.

[blackrose]

Thanks for all the replies.

A lot of them have gone off in a tangent but nonetheless have been informative. I have said that I had no intention of doing it, but I still have no hard and fast reason not to, if it was done with the right mix, maybe some sort of mesh reinforcing and with the proper preparation to the steel, ie. grit or shot blasting.

We may never know!

 

I think we do know - there's plenty of evidence to show that poured concrete can potentially lead to problems. You say you have no hard & fast reason not to do it, but what is your hard and fast reason to do it, especially since there are other methods which have don't have those potential issues?

My point was that the concrete adheres and protects the hull from corrosion due to its alkaline properties. It's been done for years in Dutch barges. The post was one of inquisitiveness.

 

Yes, that could be another advantage, but to me it's eclipsed by the potential problems it may bring. The point is that if the hull of a boat with loose ballast is kept dry then there's no reason for it to corrode from the inside.

 

I'm not a chemist so I don't know about the alkaline properties of concrete protecting steel. I do know that like acids, alkalis can also be corrosive.

 

I've no idea how a welder/fabricator would go about replating sections of a steel boat with poured concrete ballast when it gets thin. Is it the same as replating a boat with loose ballast?

Edited November 23, 2013 by blackrose

[Beaker]

So is sodium hydroxide (caustic soda), which is highly corrosive.

 

Your point being?

[Jigsawged]

Off topic, but not a bad thing at this stage,

"You could have filled it with soil and put a few plants in it "

I had to climb a ladder to reach the deck which sat about twenty feet above ground! Someone did fancy sticking it in the ground and filling it up as a pool but they wanted me to pay the cranage and transport costs so that didn't happen.

[Beaker]

 

So is sodium hydroxide (caustic soda), which is highly corrosive.

What's that got to do with anything?

 

I merely pointed out that lime was alkaline, not acidic, I never said anything about any corrosive properties.

Edited November 23, 2013 by Beaker

[blackrose]

 

Your point being?

 

That alkalis can be just as corrosive as acids.

What's that got to do with anything?

 

I merely pointed out that lime was alkaline, not acidic, I never said anything about any corrosive properties.

 

No you didn't, so I did - is that ok? There's really no need to be so defensive...

Edited November 23, 2013 by blackrose

[Neil2]

Just for the record, caustic soda has corrosive properties but not where iron/steel is concerned. It is widely used in cleaning applications. In fact iron/steel does not corrode, in the real sense of the word, with strong alkalis of any type.

 

It's the strongly alkaline properties of cement/concrete, in this case calcium hydroxide, that creates the corrosion barrier when it is applied to steel as in the case of reinforced concrete. The alkali has an oxidising effect on the surface of the steel but it serves to protect it from further attack and the fact that the steel in encased and surrounded keeps the oxidised barrier intact. You could get the same effect by keeping steel immersed in a strongly alkaline solution, but once you removed the alkali from the steel the oxidisation would carry on ie it would corrode/rust.

 

This is sort of replicating what happens to aluminium when exposed to moisture - an oxidised layer is formed which protects the underlying metal. But in the case of aluminium it doesn't need any other covering to stop the process continuing and becoming corrosion.

 

So the theory of pouring concrete inside a steel hull has a theoretical basis, but I still wouldn't do it.

[The Pipe]

I have a boat with 2 sections with poured concrete ballast.

 

 

 

 

The first area is in the bows, no thickness readings could be obtained on the hull steel and there was no indication of corrosion around the edge of concrete and inside hull steel, a moisture measurement was also taken with no significant readings. The surveyor has recommended that the concrete should be 2 pack epoxy coal tarred to keep moisture out.

 

 

 

 

The second are is a bit more of a concern as the stern tube is set in concrete and of cause it drips continuously on to the concrete. Moisture content is "wet" slight corrosion around the concrete and steel edge, again no thickness readings could be taken on the hull steelwork.

 

 

 

 

The boat is 50 years old built by a "proper shipyard" with a 5mm thick hull and "T" section frames at 16" centres and it looks like the inside was "red leaded" with a hose pipe.

 

I would prefer not to have the concrete as I would like all areas of the hull to be inspected, unless something drastic happens I shall leave it all as is except epoxy coating the forward section.

 

As it’s done for the last 50 years it should see me out anyway.

 

PS. I come out of the aircraft industry and everything we do has a requirement to be inspect able, if you can work out how to do that with poured concrete let me know.

 

 

Cement lining is also used on water mains, usually to older systems (was being done in the 70’s anyway).

Edited November 24, 2013 by Jim Evans

[Tam & Di]

Off topic, but not a bad thing at this stage,

"You could have filled it with soil and put a few plants in it "

 

 

I wonder if hot-poured tarmac would be better than concreting the bottom?

 

Tam

[fudd]

 

I wonder if hot-poured tarmac would be better than concreting the bottom?

 

Tam

It was a thread that Bill Cooper started, I think, that I followed on the DBA website. There were pros and cons about it then too. It came down to the fact that the concrete actually sort of etched itself to the steel and also created a protective layer. Balliol Fowden stated that most rust occurred from the inside of the hull which would be protected by the concrete. Bill Cooper disagreed but there was an argument for it. A cement slurry is sometimes used in water tanks for protection.

Anyway, as I said, I don't intend to do it, I was just asking the question.

Steve P

[Timleech]

Our Humber Keel had concrete apparently from new (1925) in the 'forefoot' bilge (under the fore cabin), and the hold bilge had been cement washed under the shutts. Concrete was also sometimes used in the forefoot of composite Narrow Boats, applied over red lead in instances that I've seen. Pitch was an alternative here.

 

Tim.

[Ray T]

Not really sure if this is relevant, but

 

When Mallard was restored to steaming order by the NRM in 1985/6, I think, they had to chip away concrete in the base of the smoke-box. Apparently this was normal practise to do this in the days of steam.

 

When all the concrete had been disposed off, the base of the smoke box and the smoke box saddle ( made of steel ) had virtually corroded away.

 

Not too dis-similar to a narrow boat?

Edited November 24, 2013 by Ray T

[Timleech]

Not really sure if this is relevant, but

 

When Mallard was restored to steaming order by the NRM in 1985/6, I think, they had to chip away concrete in the base of the smoke-box. Apparently this was normal practise to do this in the days of steam.

 

When all the concrete had been disposed off, the base of the smoke box and the smoke box saddle ( made of steel ) had virtually corroded away.

 

Not too dis-similar to a narrow boat?

Lots of lovely sulphurous acid and steam/condensation when cold in the smokebox to add to the fun. You don't find that combination very often in a 'pleasure' narrow boat

 

Tim

[BEngo]

I have a 24 year old RW Davis hull. It has poured concrete ballast which I put in myself when it was new, straight onto the fabrication primed steel, and, last time I looked, it was fine. I know of other, much older, boats with poured concrete ballast and they are fine too.

 

It's a bugger to get the quantity right, it's even harder to adjust and it doesn't like riveted hulls, perhaps because the riveted structure moves a little or moisture gets in between the plates.

 

Concrete needs to be put in properly, with lots of vibration using a concrete poker to get a good seal to the steel and the steel to concrete joint should also be sealed against moisture- mine is covered by the sprayfoam.

 

I've not needed to overplate, but have welded anodes to the concreted areas without trouble.

 

Someone mentioned the Ark (Royal) earlier I think- both the proper carrier Ark and Hermes had very large quantities of concrete in the bottom, but they were both delayed in build for years, old, riveted and had spent their life in sea water.

 

N

[George94]

Two points.

 

First, there are probably more barges in France than anywhere else, including Holland. If anybody can be expected to know about problems in barge hulls it is the French. So if they have banned concrete (and they have), it is significant.

 

And I doubt if concreting is still done very much in Holland.

 

Second, If the concreting is done well, and if the hull can be kept free of moisture (a big if, but not impossible), then it is quite reasonable to expect a long lifetime for the hull.

 

But if it's not done well, and if it is allowed to get wet (concrete is porous), then rust can start and you won't know about it until too late.

 

I have a little bit of concrete in my hull, and wish I didn't. But it is at the stern, well above the bottom, and I doubt if it is going to give me any grief.

[richardf]

I once had a David Piper hull that had poured concrete bilges - carpet was simply laid on top. Unfortunately, there was a layer of polystyrene between the steel and the concrete (quite how and why they did that I never did find out) - but of course it had got damp over the years. New bottom required!