Plastic coated hull

[0000]

Just browsing narrowboats for sale and came across this in the details: "the boat hull was grit blasted and a coat of flame applied durable plastic" This was on a 57ft steel hulled boat. I have always thought of this site as the font of all narrowboat knowledge yet a search results zero for plastic coated hulls and google is not much better. Is this a one off do we think or is it just me that has missed out knowing about this particular type of hull coating? Any plastic coated boats owners out there care to comment?

[TheBiscuits]

3 minutes ago, BrandyMark said:

Just browsing narrowboats for sale and came across this in the details: "the boat hull was grit blasted and a coat of flame applied durable plastic" This was on a 57ft steel hulled boat. I have always thought of this site as the font of all narrowboat knowledge yet a search results zero for plastic coated hulls and google is not much better. Is this a one off do we think or is it just me that has missed out knowing about this particular type of hull coating? Any plastic coated boats owners out there care to comment?

 

Having seen how easily it flakes off, there is no way I'd go for a powdercoat layer on a boat.  

[Tony Brooks]

and any damage as the hull will almost certainly sustain will allow water and rust to work its way under the coating. Then it will probably be complicated and expensive to rectify.

[BEngo]

Would not want that.  "Durable plastic" is not going to be shopping trolley or lock knuckle proof.  Then any damage would seem likely to set up an ideal crevice corrosion trap under the plastic coat.

 

N

 

 

 

[Mike Tee]

This particular boat has been for sale for quite a while - and I know was the subject of at least one offer, which a while after being made, I assume was withdrawn. I'd imagine any further interest would include a highly specific out of water survey. I do like the boat though (quite a lot!!)

I tried getting some info on Google about this coating, specifically about removing it to successfully put on something more 'known', but could find nothing.

[BEngo]

I am sure a grit blast will get it all off.  A more aggressive medium might be needed but a decent abrasive blasting outfit will know what to use or will be prepared to experiment to find what works best.

 

Do you know where the plastic was put on?  They might be able to tell you what it is, or at least the makers name.  That gives you a start for how to get it off.

 

N

[TheBiscuits]

https://www.screwfix.com/p/heavy-duty-scraper-4-/16530

 

 

 

Only slightly tongue in cheek - I use one of these for first prep on my hull when blacking it, followed by cup brushes on an angle grinder.

 

I call it Swedish Chef 2.5 standard, which is related to Swedish Standard 2.5 but done by a muppet!

 

[Mike Tee]

I believe it was called 'Poly-Hot-Cote' - can't find anything online, so it might now be called something else. I did wonder if it was geared more towards offshore boats rather than sewer tubes.

[WotEver]

10 minutes ago, Mike Tee said:

... can't find anything online, so it might now be called something else.

This similar?

https://www.hmy.com/yachting/news/the-viking-yacht-companys-powder-coating-process/

[Tony Brooks]

8 minutes ago, WotEver said:

This similar?

https://www.hmy.com/yachting/news/the-viking-yacht-companys-powder-coating-process/

Maybe but hang the hull from the roof? Must be a big oven?

 

I get the impression the process may be more like metal spraying to build up shafts where the metal is sprayed through a flame to melt it onto pre-heated and kept hot shaft. Can't see how you could do that with a narrow boat hull though so I would be doubtful about how well the plastic adheres to the surface.

 

[Bee]

Epoxy paint is a sort of plastic coating I suppose, a couple of coats of it followed by a layer of glass mat of some sort and more paint might be effective but I am not going to be the one to try it!

[Tony Brooks]

36 minutes ago, Bee said:

Epoxy paint is a sort of plastic coating I suppose, a couple of coats of it followed by a layer of glass mat of some sort and more paint might be effective but I am not going to be the one to try it!

Back in the early 70s when I think two pot paints started to appear we did the plywood roofs on a series of modern cruisers like that and maybe 10 years ago I saw one on the GU and it still looked intact. However I don't think it was epoxide, it was onto new wood, and it was never submerged and regularly abraded.

[David Mack]

But isn't that just an updated version, using modern materials, of the traditional paint and canvas treatment of wooden boat cabin tops, railway carriage roofs and the like?

[Mike Tee]

I'm only guessing, but it might be more like the zinc process that is sprayed on hot - have a look at Debdale's website, where instead of zinc, it was probably a form of molten plastic that adhered to the steel and dried to an allover skin. The boat in question mentioned having it done in 2011 and then four years ago, power washed and damaged areas 'touched up'. 

[Tony Brooks]

37 minutes ago, David Mack said:

But isn't that just an updated version, using modern materials, of the traditional paint and canvas treatment of wooden boat cabin tops, railway carriage roofs and the like?

I suppose so but it shows that open weave glass fibre mat and two pot paint can be very long lasting.

[zenataomm]

I was told of something like this by someone from St Pancras Cruising Club.

It was back in the mid 80s and he enthusiastically described it as the newest great thing which someone just about to take delivery of a new Sailaway was going to pioneer.

It was a game changer and showed the way forward for everyone planning a new build steel hull.

 

I was interested, but sceptical as I anticipated that like everything "soopah doopah" long term benefits depend heavily on preparation and conditions whenever applying some material to another different one. The big revelation of fibreglass and osmosis was just filtering through.  And who remembers "Spurs" being fitted to prop shafts?  There were some fads around back then that don't seem to have survived.

[0000]

4 hours ago, Mike Tee said:

I believe it was called 'Poly-Hot-Cote' - can't find anything online, so it might now be called something else. I did wonder if it was geared more towards offshore boats rather than sewer tubes.

Hi Mike, Just reading through the brochure for the boat and it states PolyHotCote thermal spray powder so you are right. My little knowledge of power coating was that the components were placed in a oven after spraying, a big oven required for 20 tons of narrowboat! Was done 9 years ago, be interesting to know at what cost and what condition its in now. When I started this post, I was kind of hoping that the person who had it surveyed might be a member of this forum and would comment.

[Mike Tee]

I don’t think it is powder coating, rather a solid (ie plastic) passed through a flame or high temp device to turn it to liquid and sprayed on. Then no further heating required. I’m intrigued as to how it can be repaired after damage.

[Bee]

I suppose the holy grail of hull protection is something that sticks (or 'bonds'  if I was flogging the stuff ) and did not allow water to get between the layers At present  its still looking like some sort of paint. I saw a steel cruiser that must have had a dent in the front plating that had been faired with some sort of filler and painted over, the filler had been removed in dry dock and the steel beneath was in a bad state. Not sure if I was that surprised really, its like old render on a house I suppose.

[WotEver]

15 hours ago, Bee said:

I saw a steel cruiser that must have had a dent in the front plating that had been faired with some sort of filler and painted over, the filler had been removed in dry dock and the steel beneath was in a bad state.

Just like primer, filler is porous, so once again it's down to prep and coating time.  If you remove or at least kill the rust, properly prep the surface, fill, prime, undercoat and final coat with an impervious topcoat then the moisture can't get in and it can't rust, as you know.

[PeterF]

19 hours ago, Bee said:

I suppose the holy grail of hull protection is something that sticks (or 'bonds'  if I was flogging the stuff ) and did not allow water to get between the layers....

I worked in the chemical industry and this reminded me of explosively bonded plate where we would have high strength carbon steel plate, maybe 30mm or more thick to provide the strength to resist the high pressure inside the equipment and have it clad with perhaps 3mm of stainless steel for corrosion protection. The 2 layers of steel were clean and flat and the StSt sheet placed on top with a layer of controlled burn explosive, which when set off bonded the 2 sheets together. For thick walled equipment it could be cheaper than building it from solid StSt. Welding was an issue to avoid cross contamination either way and exposed edges would need the carbon steel buttering with StSt weld overlay. It would probably be more expensive for boat thickness plates than using stainless for the hull.

[WotEver]

1 hour ago, PeterF said:

It would probably be more expensive for boat thickness plates than using stainless for the hull.

I recall someone asking here once if anyone had ever made a SS narrowboat and iirc besides the cost aspect, there were some technical issues with the idea. I can’t recall what though. 

[Tony Brooks]

18 minutes ago, WotEver said:

I recall someone asking here once if anyone had ever made a SS narrowboat and iirc besides the cost aspect, there were some technical issues with the idea. I can’t recall what though. 

Wasn't it some specific form of corrosion?

[WotEver]

1 minute ago, Tony Brooks said:

Wasn't it some specific form of corrosion?

Yes, I think so... or fatigue. 

[0000]

I think the reason for not using stainless steel is mainly the cost issue, going to be 3 to 4 times material cost depending on if you use 304L or 316L and its been done with choppy water boats so no reason it could not be done for inland craft. Its fairly easy to stick weld - made numerous brackets etc for my boat. I did see a narrowboat with a stainless steel deck moored at Hawn basin, I had a brief conversation with the owner about using steel and stainless and he said he had used dissimilar welding rods - I would have assumed this would lead to galvanic corrosion but he seem happy with the result.