Jump to content

Does a new hull need shotblasting? And source of steel?


Featured Posts

10 minutes ago, NB DW said:

Some pedantry going on here.  I don't think many would relate Poundland and Aldi with positivity, or it being questionable that you can buy a fully fitted boat for the prices mentioned.

 

Nobody was unpleasant about Aintree directly, they hadn't been named at the point it was said.

 

But anyway...

Enjoy your boating.

 

Goodnight.

 

 

Edited by The Happy Nomad
Link to comment
Share on other sites

3 minutes ago, NB DW said:

I don't think many would relate Poundland and Aldi with positivity, or it being questionable that you can buy a fully fitted boat for the prices mentioned.

It's purely a price thing.  many shell builders will charge you around £50k just for a sailaway.

Link to comment
Share on other sites

Just now, WotEver said:

It's purely a price thing.  many shell builders will charge you around £50k just for a sailaway.

Fair enough.

 

If Aintree shells are decent enough, and priced low, plate thickness and steel source aside as it sounds as though they're sourced from the same place, what makes another shell 'better'/more expensive?  Design?  Prestige?  Or just because?

Link to comment
Share on other sites

6 minutes ago, NB DW said:

what makes another shell 'better'/more expensive?  Design?  Prestige?

Yes, both of those, plus how well it swims, detailing of the shell (lots of possibilities here for nice touches), sweep of the roof, angle of tumblehome, customisability (is that a word?), the list goes on and on. Probably the biggest difference though will be the underwater shape; complex compound curves on the swims are difficult and time consuming to fabricate, and time is money. 

Link to comment
Share on other sites

1 minute ago, WotEver said:

Yes, both of those, plus how well it swims, detailing of the shell (lots of possibilities here for nice touches), sweep of the roof, angle of tumblehome, customisability (is that a word?), the list goes on and on. Probably the biggest difference though will be the underwater shape; complex compound curves on the swims are difficult and time consuming to fabricate, and time is money. 

 

Thank you.  Makes sense.

Link to comment
Share on other sites

1 hour ago, NB DW said:

Thanks.

 

I watched the video linked below.  Really interesting and they do mention the BS/EN standards etc but go on to mention air pockets and so on in the steel with lower quality steel.  So I'm guessing there's still low quality steel that still conforms to these standards!?  All very confusing to me.

 

https://www.youtube.com/watch?v=PZCjrKd6fYU

I wouldn’t take too much notice of that bit. His enthusiasm for Mr Hudson’s product does get the better of him somewhat. 
 

He suggests you want “BS or EN 43A steel quality” which is a statement that could be paraphrased as being the equivalent of saying “imperial metric bog standard”. It’s misguided at best and nonsense at worst.
 

BS 4360 Grade 43A is the old British Standard description for ordinary mild steel. Today that would be BS EN 10025 S275. Note the use of the word “Grade”. Nothing to do with quality as in how good the product is, but simply that it conforms to a set of specified parameters defining characteristics such as strength, hardness and chemical composition.
 

Steel can be purchased from anywhere in the world to that specification and while it will all have slightly different characteristics particular to the materials and plant in which it was produced it will all conform to the designated specification and be an entirely interchangeable product.

 

In terms of strength and hardness Grade 43/S275 is actually an entry level hot rolled steel for general fabrication work but still has engineering properties that no narrowboat will come close to testing. It also has absolutely no specific requirements in respect of corrosion resistance.

 

Bear in mind that mild steel is pretty much 99% iron. No matter the ‘quality’ of the steel it’s going to rust the same; environment and protection are key to corrosion prevention not the steel itself unless you use a specific alloy or stainless steel which to say is rare in narrowboats is probably overstating things.

 

JP

 

PS - did anyone else note “traditionally applied rivets” and “the only narrowboat with a keelson”?

 

 

  • Greenie 1
Link to comment
Share on other sites

37 minutes ago, NB DW said:

Some pedantry going on here.  I don't think many would relate Poundland and Aldi with positivity, or it being questionable that you can buy a fully fitted boat for the prices mentioned.

 

Nobody was unpleasant about Aintree directly, they hadn't been named at the point it was said.

 

But anyway...

Nowt wrong with Aldi or Lidl they are giving the big boys a run for their money

 

  • Greenie 1
Link to comment
Share on other sites

Many thanks for that explination.  Appreciated.

 

So in a nutshell, thickness aside, shell quality in terms of steel will be much of a muchness wherever and it's all down to decent protection?

 

I wonder why, other than their slab-sided design, EastWest get such a slating if this is the case?  Lots of comments around them being crap, Chinese steel etc.  I'm told they were 2 pack painted from new and when surveyed most come out extremely well.

Link to comment
Share on other sites

2 minutes ago, ditchcrawler said:

Nowt wrong with Aldi or Lidl they are giving the big boys a run for their money

 

I don't disagree there.  So maybe it's all down to snob appeal, much like their boat building equivalents then.

  • Happy 1
Link to comment
Share on other sites

Any coating system is dependant on the adhesion and quality of everything underneath it all the way , and including the base steel. In my experience there is little variability in the quality of modern mild steels. There is though a huge variabitly, in preparing that first vital paint to steel interface.

Mill scale is incredibly variable in both adhesion and permeability. Incredibly undesirable as the first layer, and it will compromise the integrity of any coating system over the top of it, for the entire time any mill scale remains, in other words the entire life of the structure or boat.

You get only one chance of properly removing it, and that is before applying any paint.

Shot blasting is expensive but  it does reliably remove mill scale. Mechanical wire brushing just does not cope with areas of ceramic like mill scale, it just polishes it.

Initial painting is expensive regardless of what is underneath, but subsequent repainting is a lot lot more expensive because of the required prior surface preparation.

If you intend to hold on to your boat more then just a couple of years you are much better off to bite the bullet and go for a high quality initial paint system from a reputable manufacturer, and applied by a reputable painter, it will last a lot longer, and look better, not only to the first repaint, but between all subsequent repaints.

You will save both money and the disruption of more frequent repaints.

 

 

Link to comment
Share on other sites

9 minutes ago, NB DW said:

Many thanks for that explination.  Appreciated.

 

So in a nutshell, thickness aside, shell quality in terms of steel will be much of a muchness wherever and it's all down to decent protection?

 

I wonder why, other than their slab-sided design, EastWest get such a slating if this is the case?  Lots of comments around them being crap, Chinese steel etc.  I'm told they were 2 pack painted from new and when surveyed most come out extremely well.

Prejudice, protection of interests and reputation from a bygone era I suspect. There was a time when you wouldn’t have wanted Chinese steel but today their steel plants are far more modern than ours and are run on very tight quality assurance lines.

 

There is probably a vast amount of Chinese steel in the UK in finished goods - much of our white goods for instance - but very little still in terms of imported primary products. For now steel sections in the UK are broadly 40% produced in the UK and 40% in the EU with the remainder mostly from Russia and China.

 

Where is the proper evidence of East-West boats being ‘crap’? Unless it exists it’s wrong to entertain and promote the idea that they are.

 

Bear in mind that the company called British Steel is now owned by the Chinese and the only other primary iron and steel producer in the UK has been owned by an Indian company for over a decade.

 

I raised my eyebrows at the comments about ‘decoiled steel’ in that video too. I don’t know for sure but I doubt boat fabricators buy steel in coils as that’s generally thin gauge material for further processing. I’ve always assumed they buy plate and bar from a stockholder (I know the steel for my boat was bought in that way) and that most probably have little idea of the exact provenance of the plate beyond the details on the certificate of conformance. The last serious shaping action a steel plate of the thicknesses used for boat building will have seen would have been going through the roller at something approaching 2000 degrees.


JP

 

Link to comment
Share on other sites

4 hours ago, Captain Pegg said:

Prejudice, protection of interests and reputation from a bygone era I suspect. There was a time when you wouldn’t have wanted Chinese steel but today their steel plants are far more modern than ours and are run on very tight quality assurance lines.

 

I raised my eyebrows at the comments about ‘decoiled steel’ in that video too. I don’t know for sure but I doubt boat fabricators buy steel in coils as that’s generally thin gauge material for further processing. I’ve always assumed they buy plate and bar from a stockholder (I know the steel for my boat was bought in that way) and that most probably have little idea of the exact provenance of the plate beyond the details on the certificate of conformance. The last serious shaping action a steel plate of the thicknesses used for boat building will have seen would have been going through the roller at something approaching 2000 degrees.


JP

 

The documentation with my (3rd hand) boat includes the original steel order from the stockholder and more information than most people, including myself, would ever find useful about how it was cut and used in the build.

 

This may be another Orion peculiarity, I'm not sure.

Link to comment
Share on other sites

2 hours ago, frahkn said:

The documentation with my (3rd hand) boat includes the original steel order from the stockholder and more information than most people, including myself, would ever find useful about how it was cut and used in the build.

 

This may be another Orion peculiarity, I'm not sure.

That’s interesting to know and that’s from one of the builders with a higher reputation. No mention of coil I’ll wager?

Link to comment
Share on other sites

3 hours ago, frahkn said:

The documentation with my (3rd hand) boat includes the original steel order from the stockholder and more information than most people, including myself, would ever find useful about how it was cut and used in the build.

 

This may be another Orion peculiarity, I'm not sure.

I've seen this paperwork with several Orions...improbably the most comprehensive build paperwork file I have ever seen from any manufacturer.

Link to comment
Share on other sites

3 hours ago, matty40s said:

I've seen this paperwork with several Orions...improbably the most comprehensive build paperwork file I have ever seen from any manufacturer.

Almost any Orion owner will know exactly what you mean by "improbably".

Link to comment
Share on other sites

18 months after launch, not a jot of the 2 original coats of Comastic was left on our Colecraft hull below the water line.  A well respected marine surveyor reported that it was caused by mill scale.  He recommended shot blasting and 2-pack.  We went for the additional "Zinga" treatment with 2 coats of 2 pack. At over £5k back in 2004, it paid for itself in spades as no docking  needed for blacking for 7 years; the hull was still in good condition when we did.

 

I would recommend shot blasting without doubt

Link to comment
Share on other sites

1 hour ago, rustynewbery said:

18 months after launch, not a jot of the 2 original coats of Comastic was left on our Colecraft hull below the water line.  A well respected marine surveyor reported that it was caused by mill scale.  He recommended shot blasting and 2-pack.  We went for the additional "Zinga" treatment with 2 coats of 2 pack. At over £5k back in 2004, it paid for itself in spades as no docking  needed for blacking for 7 years; the hull was still in good condition when we did.

 

I would recommend shot blasting without doubt

In their defence it is probable they have chosen a system for which they can at least meet the minimum surface preparation requirements of the coating manufacturer. That’s important because no one should be using the quality of a coating as a selling point if they can’t prepare the surface correctly for that product.

 

Otherwise I agree with your sentiments. Blasting will always be preferable as will the application of a high quality system over the entire hull. It’s not imperative though, there’s plenty of poorly maintained hulls around of c50 years vintage.
 

JP

Link to comment
Share on other sites

5 hours ago, rustynewbery said:

18 months after launch, not a jot of the 2 original coats of Comastic was left on our Colecraft hull below the water line.  A well respected marine surveyor reported that it was caused by mill scale.  He recommended shot blasting and 2-pack.  We went for the additional "Zinga" treatment with 2 coats of 2 pack. At over £5k back in 2004, it paid for itself in spades as no docking  needed for blacking for 7 years; the hull was still in good condition when we did.

 

I would recommend shot blasting without doubt

 

My Alexander shell was coated with International 954 2 pack over Zinga when new in 2006.

 

The boat had its first blacking last year, with dry dock inspections under my ownership in 2014 and 2018.

 

I too would recommend shotblasting, Zinga and 2 pack to minimise corrosion and reduce future hull maintenance.

Link to comment
Share on other sites

Hi there,

 

Thanks for the information - which all makes sense.  Wanting to the have a good-quality 2-pack coating on the hull is one of the significant considerations that I am making when thinking about builders for a sailaway. I am aiming at [what on the forums seems to be considered] a 'mid-range' builder: Tyler Wilson or Colecraft are both high on my potential builder list. One of the attractions of these builders is that they can apply a 2-pack from the get-go, as well as the generally good reputation overall on these forums.

 

So, I was a bit crestfallen to read rustrynewberry's experience with his Colecraft. Meanwhile, Tyler Wilson seem to say on their website  FAQs that their system of application, whilst admitting it is not quite as good as shotblasting, is plenty good enough. http://www.tylerwilsonboats.com/faqs 

 

BTW, I am certainly not (on my first post) trying to disagree with the comments in this thread. Instead I was wondering if people had thoughts about whether I should be crossing them off my list if they can't offer a top-notch 1st painting? Or am I getting too fussy?

 

Thanks for any advice, I have been lurking on here for a while  - an absolute goldmine of information whilst I leisurely plan out a fit out project. 

 

Cheers,  Standedge

Link to comment
Share on other sites

I have heard second hand that Colecraft may now have shot blasting facilities, they were apparently testing equipment 18 months ago. You may like to confirm this though rather than relying on what is now third hand information.

Link to comment
Share on other sites

Painting over mill scale is just plain daft. Mill scale is very difficult to remove from the steel  surface when you want to ...ie when wanting to paint....but it just falls off when you dont want it to come off ....ie with big swings of temperature above and below zero. One way of removing scale is to leave the steel outside over winter and watch it fall off.

 

Link to comment
Share on other sites

I'd like to have a little clarification here. Are we talking shot blasting or grit blasting?

 

Shot blasting removes loose material like millscale by percussion.

Grit blasting removes loose material by abrasion.

Shot blasting peens, (hammers), the surface thus very slightly compressing it in the process and possibly embedding particles of millscale/rust into the surface.

Grit blasting act in a very similar way to a grinding wheel insofar that the sharp grit particles actually cut the surface. Anything poorly attached will be knocked off but on sound metal the grit "picks" at the surface, (individual particles do not have enough energy to do more), but do raise tiny burrs.

So my take on the two processes is that shot blasting tends to smooth the surface, grit blasting roughens it. Given that the surfaces so prepared are to be painted/coated which would the membership rather have?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.