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

[NB DW]

I'm contemplating a new build in the near future.  I've spoken to a few builders in the last few days - some of which seem to have especially decent reputations, two of which use Aintree shells - and asked about the prep done to the hull before 2 pack painting.  All of which advised they do not grit blast shells before applying their 2 pack paint to the hull.

 

I'd always understood from what I'd read that shells must be shotblasted for 2 pack paint to adhere.  They advised otherwise, saying they sand between coats etc etc.

 

What's your thoughts?  Is it a matter of following individual paint manufacturer's guides?

 

I also asked about the source of steel.  With some of the new boats being very competitively priced I'd wondered if savings had been made in terms of the steel quality.  I'm told it's all pretty much sourced from the same place - not China, I cannot remember where now.  Is this right?

 

In fairness to them all, none of them slated or had a bad word to say about their competitors, and one went as far as saying it's hard to buy a 'bad boat' as such, more that you'll end up with the boat equivalent of  a Ford Mondeo if you go for the more competitively priced builder.  Nothing wrong with that at all, it'll be fine, but won't ever been a Lexus etc.

 

And by budget build, I mean just under £50k for a 35ft and just under £55K for a 40ft.

[Alan de Enfield]

4 minutes ago, NB DW said:

And by budget build, I mean just under £50k for a 35ft and just under £55K for a 40ft.

For a fully fitted boat ?

 

That's not a 'Asda' or Sainsbury's' boat, that's an 'Aldi' or 'Poundland' boat.

[NB DW]

Just now, Alan de Enfield said:

For a fully fitted boat ?

 

That's not a 'Asda' or Sainsbury's' boat, that's an 'Aldi' or 'Poundland' boat.

Yep.  That's an Aintree boat.  From one of the Beetle range.  It's a template design with limited customisation  - the layout choices are fixed - which I guess keeps the cost down a lot.  Plenty seem happy enough with them.  And Swan and Bickerstaffe use their shells too, so they can't exactly be that bad.

 

Any thoughts on the questions asked though?

 

 

[Sea Dog]

10 minutes ago, NB DW said:

one went as far as saying it's hard to buy a 'bad boat'

Hmm, there's a bold statement. I wonder if anyone ever has....  

[Alan de Enfield]

1 minute ago, NB DW said:

Any thoughts on the questions asked though?

I think that raw steel needs grit-blasting to remove mill scale. and I think that thickness is more important than the source of the steel.

[NB DW]

3 minutes ago, Sea Dog said:

Hmm, there's a bold statement. I wonder if anyone ever has....  

Actually one builder was shamed, I won't name them, but there's plenty on here which supports what was said.  They weren't on the list of builders to speak to for that reason.

[WotEver]

2 minutes ago, Alan de Enfield said:

I think that raw steel needs grit-blasting to remove mill scale. and I think that thickness is more important than the source of the steel.

I agree. Look at the instructions from the manufacturer of any two-pack paint and see what they state about surface prep.

[NB DW]

Thickness is what appears to be the standard 10, 6, 5, 4 mm.  Swan and Bickerstaffe use Aintree shells.

 

I'd understood the millscale would have to be removed too.  I'm just guessing they potentially don't have the facilities to do it.  One did say they'd be able to if I wanted it but likely to add a chunk of money to the build.

[Guest]

5 minutes ago, NB DW said:

Yep.  That's an Aintree boat.  From one of the Beetle range.  It's a template design with limited customisation  - the layout choices are fixed - which I guess keeps the cost down a lot.  Plenty seem happy enough with them.  And Swan and Bickerstaffe use their shells too, so they can't exactly be that bad.

 

Any thoughts on the questions asked though?

 

 

Bickerstaff boats grit blast Aintree shells before they paint them. Any bare steel will start corroding as soon as its exposed to air, one advantage of grit blasting is that any such corrosion is removed before painting, it also gives a surface better suited to being painted. 

[Alan de Enfield]

1 minute ago, NB DW said:

One did say they'd be able to if I wanted it but likely to add a chunk of money to the build.

If you don't it is false economy, the paint will stick to the scale and when the scale falls off the paint goes with it.

 

Painting 2-pack properly and it will last 7-10 years, paint without proper preparation and you may be re-doing it in 2 years. Which way works out the most expensive  over the life of your ownership ?

[NB DW]

1 minute ago, The Happy Nomad said:

Bickerstaff boats grit blast Aintree shells before they paint them. Any bare steel will start corroding as soon as its exposed to air, one advantage of grit blasting is that any such corrosion is removed before painting, it also gives a surface better suited to being painted. 

Thanks.

 

To be honest, I didn't ask Bickerstaff too many detailed questions as within the first 30 seconds I found out they don't build the size of boat I'm looking for which was a shame.  They were really helpful in general though and spent a while chatting despite knowing they couldn't help me further with a build.

2 minutes ago, Alan de Enfield said:

If you don't it is false economy, the paint will stick to the scale and when the scale falls off the paint goes with it.

 

Painting 2-pack properly and it will last 7-10 years, paint without proper preparation and you may be re-doing it in 2 years. Which way works out the most expensive  over the life of your ownership ?

 

I agree and would probably pay the extra.  I'm not too fussed about cabin sides/roof etc, just the hull.

[Guest]

Just now, NB DW said:

Thanks.

 

To be honest, I didn't ask Bickerstaff too many detailed questions as within the first 30 seconds I found out they don't build the size of boat I'm looking for which was a shame.  They were really helpful in general though and spent a while chatting despite knowing they couldn't help me further with a build.

I think they just do 57 feet to a fairly std. internal fit out which like the beetle helps keep costs and therefore price down.

[NB DW]

Just now, The Happy Nomad said:

I think they just do 57 feet to a fairly std. internal fit out which like the beetle helps keep costs and therefore price down.

That's right, just 57 ft but didn't ask any further questions about design etc so as not to waste their time.

 

Evidentily there's some negativity towards Aintree boats from the above comments.  I had a 25ft and never had a problem with it, and the fit out appeared decent enough.  I've no issue with a template design if that's the reason costs are kept down.

[WotEver]

3 minutes ago, NB DW said:

Evidentily there's some negativity towards Aintree boats from the above comments.

I didn't see that anywhere?  They are what they are and make no pretensions about their 'heritage'.

[NB DW]

Just now, WotEver said:

I didn't see that anywhere?  They are what they are and make no pretensions about their 'heritage'.

I'm not sure likening them to the boating equivalent of Poundland is exactly positivity, is it?

 

Their heritage is ex Skater Marine.

[WotEver]

37 minutes ago, NB DW said:

I also asked about the source of steel.  With some of the new boats being very competitively priced I'd wondered if savings had been made in terms of the steel quality.  I'm told it's all pretty much sourced from the same place - not China, I cannot remember where now.  Is this right?

Yes, that's right, and even if it does come from China it will still comply to the same specs as if it came from Sheffield.

Just now, NB DW said:

I'm not sure likening them to the boating equivalent of Poundland is exactly positivity, is it?

That was said about the price - nobody had even mentioned Aintree when that comment was made.

[NB DW]

1 minute ago, WotEver said:

Yes, that's right, and even if it does come from China it will still comply to the same specs as if it came from Sheffield.

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

[system 4-50]

Isn't it possible to remove the millscale by other methods than gritblasting?  My boat was very bright steel when being assembled but was not (I think) grit blasted.  The 2 pack has not fallen off in 10 years.

[matty40s]

The reason for gritblasting is to remove millscale. 

If you dont do this, the first coat of  blacking/two pack or anything else will not adhere properly and be coming off in sheets within months.  I have seen many boats from some builders with this problem

If you follow the normal 2 year blacking regime, this will mean you have lots of rust already established when it comes to the first docking.

Decent hull manufacturers DO gritblast before coating.....especially if 2 packing or applying zinc based solutions.

[Bee]

Others will know more than me but whenever I have been in boatyards in France and Holland the steel that is being used always seems to be pre primed and prepared. I honestly do not know if it is ready shotblasted or if it is just painted but when I was more involved with narrowboats they were just fabricated from plain plate, is this still the usual practice I wonder.

[ditchcrawler]

Don't some builders buy in blasted and primed steel sheets

 

Like what Bee said

Edited June 9, 2020 by ditchcrawler

[Bee]

2 minutes ago, ditchcrawler said:

Don't some builders buy in blasted and primed steel sheets

 

Like what Bee said

Wot he said!

 

[David Mack]

Some of the better shell builders use steel plate which has alreay been shotblasted and primed by the steel supplier. After fabrication they only have to grind down and prime the welds and adjacent areas affected by the welding heat.

[Guest]

1 hour ago, NB DW said:

That's right, just 57 ft but didn't ask any further questions about design etc so as not to waste their time.

 

Evidentily there's some negativity towards Aintree boats from the above comments.  I had a 25ft and never had a problem with it, and the fit out appeared decent enough.  I've no issue with a template design if that's the reason costs are kept down.

I see no negativity.

 

Aintree build a decent shell. Of course they may not impress the purists, traditionalists or folk with shed loads of money to spend but they are fine.

[NB DW]

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...