Why blacking???

[Lord Belvoir]

I can understand back in the day blacking a wooden hull but why apply the same method to steel??....after all you don't see a cruise liner or a battleship blacked and they're in the sea.....just one of those little thoughts running around in my head 

[dmr]

I expect proper ships are done in epoxy or other high quality paint.

 

................Dave

[cougie]

Battleships probably aren't rubbing up against things as much as Narrowboats do ?

[David Mack]

Jannel hire boats used to have orange hulls. And by the end of the season they looked very tatty.

[blackrose]

32 minutes ago, Lord Belvoir said:

I can understand back in the day blacking a wooden hull but why apply the same method to steel??

 

Because it's cheap and easy for the average boat yard or DIYer without any technical knowledge to slap on a few coats of blacking. 

 

There's not really any excuse now for boat builders not to apply epoxy or some other coating system from new, but most are still using blacking because it's cheap and easy to apply. In the majority of cases this then means that the boat will always be painted with blacking because getting it off and starting again with a better paint system is messy and expensive. Of course there's nothing wrong with bitumen based blacking if the boat is repainted every couple of years, but there's the rub, a lot aren't.

[Lord Belvoir]

1 hour ago, cougie said:

Battleships probably aren't rubbing up against things as much as Narrowboats do ?

Even blacking doesn't help there especially if some frigger has bilged out a load of diesel in the cut....Oops there goes the water line

[Kudzucraft]

I have wondered about this and can't come up with a great answer. I suspect part of it is "Because we have always used it" (tradition) is the main reason.

 

Here in the States I have never heard of Blacking except in restoration of a traditional boat.  If a boat sits in the water the bottoms are usually painted with an anti-fouling paint that prevents the growth on the hull and the build of it things like fresh water muscles too. I have never compared it price wise but I don't think it is that much different. It will last about two years.

 

I had a sailboat for several years and if you can any growth on the hull the drag really slowed you down. Not that big a deal with a narrow boat with an engine but the drag is still there. While minimal most likely it does take extra power to overcome it and that means burning more fuel.

Edited September 24, 2019 by Kudzucraft

[David Mack]

Narrow boats which regularly move never seem to have much hull growth. Whereas some of those that have been static for years have luxuriant weed growth extending several inches from the hull.

[Dr Bob]

4 hours ago, Lord Belvoir said:

I can understand back in the day blacking a wooden hull but why apply the same method to steel??....after all you don't see a cruise liner or a battleship blacked and they're in the sea.....just one of those little thoughts running around in my head 

 Cruise liners and battleships, and most other sea going craft are antifouled to stop marine growth which would slow down the boat and increase the fuel costs. Big money is lost due to excessive fouling on long distance boats....ie crude oil tankers. I dont think it would be wise antifouling over blacking!

As above, blacking is a cheap option for instances where it is easy to get a steel boat out of the water every 2 years......not always easy for sea going vessels.

[pearley]

I've noticed that many boats on the Bridgewater have black hills do to the waterline and blue below.

[pete.i]

As said it's relatively cheap in comparison to other methods and reasonably easy to apply but, as also said, diesel in the water and bang goes the most vulnerable bit of a steel hull at the waterline.

[ditchcrawler]

4 hours ago, David Mack said:

Narrow boats which regularly move never seem to have much hull growth. Whereas some of those that have been static for years have luxuriant weed growth extending several inches from the hull.

The ducks eat it off mine

 

5 hours ago, Kudzucraft said:

I have wondered about this and can't come up with a great answer. I suspect part of it is "Because we have always used it" (tradition) is the main reason.

 

Here in the States I have never heard of Blacking except in restoration of a traditional boat.  If a boat sits in the water the bottoms are usually painted with an anti-fouling paint that prevents the growth on the hull and the build of it things like fresh water muscles too. I have never compared it price wise but I don't think it is that much different. It will last about two years.

 

I had a sailboat for several years and if you can any growth on the hull the drag really slowed you down. Not that big a deal with a narrow boat with an engine but the drag is still there. While minimal most likely it does take extra power to overcome it and that means burning more fuel.

Antifouling id toxic, that is how it works

[Dr Bob]

3 hours ago, pearley said:

I've noticed that many boats on the Bridgewater have black hills do to the waterline and blue below.

There are black hills in North Dakota too.

[Dr Bob]

48 minutes ago, ditchcrawler said:

 

Antifouling id toxic, that is how it works

Not all are.

We used to race our lumpy water boat so that was antifouled using a 'hard' teflon type coating that just made it hard for the sea life to adhere to. There are coatings that try to mimic 'water' ie very hydrophilic coatings so the sea life doesnt think it is a surface to stick to.

The best are obviously toxic to marine life but then they keep banning the best ones.

[The Dreamer]

9 hours ago, Lord Belvoir said:

I can understand back in the day blacking a wooden hull but why apply the same method to steel??....after all you don't see a cruise liner or a battleship blacked and they're in the sea.....just one of those little thoughts running around in my head 

I have often wondered why cruise ships don’t just rust away too.  They are nothing less than floating villages, with power generation to match and they are lucky if they come out of the(salt) water every 20 years. Now I know they are made of 30mm plate, or thicker, nevertheless the oldest are half a century old (like the best of us) and show no signs of giving up (unlike the best of us)!

[Dr Bob]

14 minutes ago, The Dreamer said:

I have often wondered why cruise ships don’t just rust away too.  They are nothing less than floating villages, with power generation to match and they are lucky if they come out of the(salt) water every 20 years. Now I know they are made of 30mm plate, or thicker, nevertheless the oldest are half a century old (like the best of us) and show no signs of giving up (unlike the best of us)!

They are coated with 2 pack epoxy under the antifouling.

[The Dreamer]

4 minutes ago, Dr Bob said:

They are coated with 2 pack epoxy under the antifouling.

That accounts for it then!  Mind you, even two pack is not going to save them from an errant, escapee, shipping container bobbing just below the surface, or indeed a river cruiser that just happens to get in between them and the Venice dockside!

[ditchcrawler]

But they do go into drydock https://www.cruisecritic.co.uk/articles.cfm?ID=2957

[sueb]

Programme this afternoon on impossible  railways showed the Forth Bridge. It is painted in a coating containing glass flakes and will last 25 years. Why not use on narrowboats?

[blackrose]

17 minutes ago, sueb said:

Programme this afternoon on impossible  railways showed the Forth Bridge. It is painted in a coating containing glass flakes and will last 25 years. Why not use on narrowboats?

 

Maybe some people do. I've used a Jotamastic 2 pack epoxy with aluminium particles to give a better barrier (2 coats) followed by 2 coats of the same paint without the aluminium in black. In the same range Jotamastic do a glass flake version for improved abrasion resistance. I think if a narrow boat scrapes along a concrete wall it's going to be difficult for any paint to resist that. It might last 25 years on a static bridge but I wouldn't give it more than 10 years on a narrowboat. I chose aluminium mainly because I was familiar with the product from using it at work.

 

https://www.paints4trade.com/jotun-jotamastic-90-gf-glass-flake-high-solids-epoxy-paint-263734-p.asp

 

Edited September 25, 2019 by blackrose

[Dr Bob]

1 hour ago, sueb said:

Programme this afternoon on impossible  railways showed the Forth Bridge. It is painted in a coating containing glass flakes and will last 25 years. Why not use on narrowboats?

Three reasons.

The coating used on the Forth bridge is not an immersion coating. It is not designed to be used underwater. The guy who project managed the bridge repaint in 2005-2008 used to race with us on our lumpy water boat so I know the job.

Glass filled epoxies will be damaged more by impacts and give pathways for moisture to get to the steel surface, so not the best choice if you are preparing the surface to SA 2.5 where normal epoxies excel. You dont need glass flake in it if you have good surface preparation/good application.

2 pack coatings can fail via moisture getting to the steel via osmosis. Including glass flake provides additional paths for the moisture to get through. If glass flake worked in immersion coatings then all 2 pack epoxies used underwater would contain them. They dont.

I agree with Blackrose's comments above.

[Mike Todd]

14 hours ago, sueb said:

Programme this afternoon on impossible  railways showed the Forth Bridge. It is painted in a coating containing glass flakes and will last 25 years. Why not use on narrowboats?

The Forth Bridge does not go through locks nor does it contend with the Shroppie Shelf!

[Murflynn]

many fixed marine and waterways structures are coated with bitumen paint or tar because that was the most effective and economical method.

 

perhaps most narrowboats are painted in the same manner because they never move.

 

 

 

 

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