STEEL HULLS with Composite Superstructure / Topsides

You are mixing a few concepts here which would take a few pages to address properly. Cold forming techniques, lattice dislocation, hot working decarburisation (and recarburisation). You don't need papers to prove these things happen they are metallurgy 101. decarburisation doesn't produce porosity in the lattice since the carbon atoms fit within it anyway.....remember maybe? But it's all baloney regarding any significant water holding capacity and is a very long way from water dripping out of steel when heated and it's exactly what I said before

Now you appear to be agreeing albeit with some difficulty

Again you are showing your lack of understanding here. All metals have a polycrystaline lattice structure that's what defines metals. And perhaps you should look up as to where in the lattice the carbon atoms fit in the iron lattice to produce steel. They fit within the lattice in spaces no water molecule could ever hope to go.

How you read it is up to you, I assure you what I'm trying to do is put some clarity in this. Otherwise someone else will be quoting you in turn if it is not corrected. And it would be nice if the forum was not a source of disinformation.

There are some great guides to coating steel and they work, manufacturers stand behind their products and apart from restrictions on dew point and air temp and humidity it is never required that you heat steel to get a really well adhering protective coating.

 

Interesting post from both of you guys, and you both preseved a technical argument to your postings.

Bottom line, it appears we need to really clean our steel very well before applying the protective coating. And that was the info I was seeking to suggest to the many naysayers that steel hulls are just too much upkeep. I think there is ssubstantial documentation that with reasonable preparation, and the use of some good proven coating, steel hulls do NOT have to be the nusance they have in many cases in the past.

I did find that comment on the moisture holding capability of the polureas interesting. It might make me shy away from those materials at this time?

Lets get back to alternative ways to construct that 'frameless (for lack of a better word)" steel hull I have in mind. How might it be 'framed out' with 'adhesively applied' reinforcements rather than just welded on ones??

 

Ha ha guys thanks for starting my day.
Galvanized piece go in an acid bath then
go directly in melted zinc.
Do you honestly think you need to heat it
before you paint it?
Heat treat pieces go into a oven and brought
Ramped up to temp by procedure.
By no means, never to get the water out.
Ha Ha

 

Warming steel prior to primer coating to remove any moisture or humidity is a sound practise if its at all doable.

We always place gas fired blowers inside a steel or aluminium hull prior to painting during winter or anytime it has rained if we are prepping to remove trapped surface moisture and reduce humidity below.

 

My company customers were major
Oil and marine companies. We fabricated millions of tons
of all types of carbons and alloys. I had a metallurgist on staff.
Not one spec ever mentioned heating before paint.
I have seen some crazy things but not that.
I built the stuff that could level towns.

 

The humidity of the climate in which we work is an important factor. Corrosion of steel found in a inland continent rubbish dump is markedly different to that found in an island like NZ

 

Warming stops dew forming when there is a high air humidity but it's impractical for large projects.
There are good surface tolerant epoxies that will absorb some surface moisture that is present on application. In Australia Wattyl make a very good epoxy primer that can be applied on low temp damp steel.

In low temps you use a low temp part B and can apply the paint down to 4 degrees C surface temp. And these are systems the paint manufacturer will guarantee on a ship.

Epoxies really have made steel a low maintenance material in salt water. But inside and on decks as I said before hot zinc spray and then epoxy is the delux protection scheme.

 

And just where do you think Mike (and myself) live?

Look, your welder was probably heating with oxy-propane. That's what I use. You get a lot of H20 formation from the burn process. If the steel is cool enough, some of this condenses from vapour to liquid water.

BUT IT'S NOT COMING OUT OF THE STEEL!!!

You've been told in enough detail that this doesn't happen and why. Now it looks like you want to keep arguing just to avoid admitting you're in error. That sort of behaviour is pointless and annoying.

Brian, I had my plate blasted to bare metal then primed before it went anywhere near getting used. All of it including the flat bar for frames and stringers. I'm using Jotun 2 pack epoxy primers, 605 I think it is, on the outside and in the bilges. Easy to work, long pot life, 1:1 mix so easy to get the proportions right, not all that expensive ($100 for 4 litres roughly). Seems very tough and sticks very well to bare steel, primed steel and very lightly rusted steel. I'm quite happy with it.

PDW

 

I've got one of those Metco zinc wire feed spray guns. Never used it, never will. I didn't like the cost of the consumables. If you want it, it's yours.

PDW

 

For 12yrs I owned/operated bespoke engineering company Architectural Ironworks in SE Qld before selling to a large company.
We designed and manufactured metalwork products for many of Qld iconic projects plus super yacht and work boat equipment.

After trying many products to get a quality finish with longevity on exterior ironwork the best performer was zinc spray recoated with 2pak epoxy to seal the zinc. Hot dip gal was okay but difficult to get epoxy to bond without lots of pre labour that even then sometimes failed, powder coating never successful even with dry runs to degassing the galv the PC would still blister.

We used the zinc spray/epoxy finish on all external metalwork installations on projects listed below plus many more that 15yrs later are still corrosion free.

Brisbane Treasury Casino and restaurants stage 1 development plus stages 2 & 3 interior upgrades
Brisbane Customs House refurbishment project (Heritage & Conservation project Qld University)
Brisbane Conrad Hotel
Marriott Hotel Brisbane
Jupiter’s Casino Gold Coast
Cairns Casino Cairns
Sheraton Mirage Resort restaurants French antique ironwork fitout - Gold Coast
Versace Resort Gold Coast
Crown Towers Hotel Gold Coast
Watermark Hotel Gold Coast
Tuscany Village Sunnybank Hills Brisbane
Kevin Seymour CEO Watpak Construction – Riverside Brisbane Penthouse
Kingfisher Bay Resort Stradbroke Is – landscape installations
BCC projects - Paddington and inner city streetscape metalwork (bronze and s/steel sculpture, seating, railings and bike racks.

 

Sp 6 blast. With carbs zinc 11 is a good coating

 

Everyone knows everything is bigger in Texas, even the BS

 

What was the zinc spray process - the Metco one using a wire feed gun and a ton of oxy/acetylene, or some other (perhaps more modern) process?

As I said elsewhere I acquired a Metco gun with the thought of doing this myself, but I got over it. If there is a better way of doing it, I'd like to know just in case I decide to build another boat.

PDW

 

repeat.. PLEASE , back to the original subject matter

HPR25 comes highly recommended for attachments to metal surfaces, alum and steel. Its a toughened epoxy product rather than methacrylate like Plexas??

 

Protruded Fiberglass Beams

....a consideration?