Rustproofing mild steel fairlead - how ?

[sarabande]

I lost a fairlead in the big storm when the boat was in a marina on the Hamble.

For a variety of reasons I have decided to forego stainless and use mild steel for a brace of new fairleads (with 'bright steel'* for the bitts ) which will come out of the fabrication shop with three coats of agricultural red oxide.

*bright steel is used for parts of ploughs and implements in contact with soil. It does not seem to rust when left wet, but is definitely not as shiny as stainless.

As the boat is on a fore and aft mooring, the inner surface of the fairleads will be in fairly firm contact with the polysteel lines wrapped in fire hose, and I expect some abrasion to take place on the bearing surfaces.


I have three choices to prevent/reduce rusting:

1 galvanising - but that will take extra time, and my experience of having farm stuff done is that the process leaves jagged edges and sharps of zinc. Can these be hammered down to produce smooth surface ?

2 powder coating, and sand it off the surfaces which will be in contact with mooring lines, to prevent heat/pressure melting the plastic coating. I am not too enamoured of this.

3 painting - what is the best paint process, and make of paint, please ? Is e.g. Hammerite as tough as it makes out ?


thanks in advance for advice and suggestions.

 

[MM5AHO]

I run a company doing all of your options (not looking for the work, too far away), but...

painting. Will abrade and as soon as the coating is perforated to steel rust will start and creep under the rest of the coating. All paints are porous, just that some are more porous than others. So eventually, even without a scratch or other perforation, rust will start.
Powdercoating: That's really paint except that it's pigments and resin are carried without a liquid. The end product tends to be harder, so a little more resilient, but same issues apply as for paint. Powder applied coatings (there are many formulations and chemistry available) are also porous.
Galvanizing: Its a molten metal dipping process, so yes there can be surface irregularities, but these are zinc, which is soft so easily "fettled", filed, sanded etc taking car not to go through the coating to the steel. Its an alloy and a coating, so metallurgically bonded to the steel. Downside of galv is that its a sacrificial coating - it is a consumable coating, and the life expectancy is proportional to the thickness and to the environment into which its placed. Yours environment is hostile, so you might only get 10 years life, perhaps more perhaps less. The alloy part of the coating is harder than mild steel, so has higher abrasion resistance than the steel, but that part is pretty thin (perhaps 5-10 microns).

Saying all that, I'd still choose 316 stainless. I don't have any plain carbon steel fittings exposed to the sea or spray, and only steel at all is around the engine. Stainless is the right choice, but if ou must slect from your three listed options, Galvanizing is the least worst option.

 

[rogerthebodger]

I lost a fairlead in the big storm when the boat was in a marina on the Hamble.

For a variety of reasons I have decided to forego stainless and use mild steel for a brace of new fairleads (with 'bright steel'* for the bitts ) which will come out of the fabrication shop with three coats of agricultural red oxide.

*bright steel is used for parts of ploughs and implements in contact with soil. It does not seem to rust when left wet, but is definitely not as shiny as stainless.

As the boat is on a fore and aft mooring, the inner surface of the fairleads will be in fairly firm contact with the polysteel lines wrapped in fire hose, and I expect some abrasion to take place on the bearing surfaces.


I have three choices to prevent/reduce rusting:

1 galvanising - but that will take extra time, and my experience of having farm stuff done is that the process leaves jagged edges and sharps of zinc. Can these be hammered down to produce smooth surface ?

2 powder coating, and sand it off the surfaces which will be in contact with mooring lines, to prevent heat/pressure melting the plastic coating. I am not too enamoured of this.

3 painting - what is the best paint process, and make of paint, please ? Is e.g. Hammerite as tough as it makes out ?


thanks in advance for advice and suggestions.

Galvanising is the only option in my view as painting for powder coating would be chafed away on a fairlead. There is another (other than mine) steel boat in the same marina that has painted mild steel enclosed mooring chock that all the paint has rubbed off from and started to rust.

 

[drakes drum]

You are doing the proverbial into the wind painting mild steel subject to abrasion. The best bet is hot dip galvanising ( not zinc plating!) and if its done competently there shouldnt be any spikes. But you can hammer those down anyway.

The "bright steel" bit is metallurgical nonsense really. All steels other than the purest mild steel are alloyed to some degree and the alloying does affect the rate of corrosion as you see with stainless. But the difference is small until you get to stainless so dont let anyone charge you anything extra for bright steel on the basis that its better corrosion wise.

 

[PotatoNavigator]

Would only cast about £30 to get it gold plated...

 

[rogerthebodger]

You are doing the proverbial into the wind painting mild steel subject to abrasion. The best bet is hot dip galvanising ( not zinc plating!) and if its done competently there shouldnt be any spikes. But you can hammer those down anyway.

The "bright steel" bit is metallurgical nonsense really. All steels other than the purest mild steel are alloyed to some degree and the alloying does affect the rate of corrosion as you see with stainless. But the difference is small until you get to stainless so dont let anyone charge you anything extra for bright steel on the basis that its better corrosion wise.

The real difference between bright mild steel and black mild steel is the black mild steel is generally hot worked when as bright mild steel is cold worked and this the surface finish and as said no reflection on corrosion properties.

 

[Adamastor]

Hot dip galvanising is the best bet. It self-heals against dings and scratches and the interface between steel and zinc is easy to mind where, say, ropes wear through the galvanising. If it worked on old barges there's no reason it wouldn't work in your case, especially if you prime and paint the non-wearing parts for cosmetic effect. Wrought iron would be my choice for ferrous fittings to ensure a proper working look, but then you'd be using things like Stockholm Tar and navy rustproofing- chip, paint, paint again; repeat weekly!

 

[cpedw]

Would paint be practical if the wear spot was reinforced with something like this in stainless or this in Kevlar?

I have successfully used the stainless version to protect GRP where a roller reefing line rubs.

Derek

 

[Adamastor]

Would paint be practical if the wear spot was reinforced with something like this in stainless or this in Kevlar?

I have successfully used the stainless version to protect GRP where a roller reefing line rubs.

Derek

I like your thinking! The old idea of using wrought iron whelps on sampson-posts and Andersen winches with their "power rib" smacks of the same thinking. You could fashion SS wear ribs and TIG weld them into the fairlead just where the line changes angle, or you could machine-screw some SS half-round onto the wear points.
Rogershaw will be rubbing his hands in glee at this point, imagining that I'm thinking about boating again! ;-)

 

[Big-Bang1]

http://www.frost.co.uk/automotive-p...ack-two-component-coating-us-quart-946ml.html

I have used this on all sorts of projects from my Land Rover Chassis to the flukes on an old fishermans anchor and I can't recommend it highly enough! Goes on great, lasts for ever and really is as hard as nails!

 

[rogerthebodger]

Wrought iron would be my choice for ferrous fittings to ensure a proper working look,

Neal

Where can you get true Wrought Iron these days. True I does not rust in the same way as steel but It may only be available in billet form, if at all. and would need to be be forged into the required shape, Fabrication is not easy as conventional welding not really possible.

What are you doing these days not with Vetus I hear.

 

[rogerthebodger]

<Quote Originally Posted by cpedw

Would paint be practical if the wear spot was reinforced with something like this in stainless or this in Kevlar?

I have successfully used the stainless version to protect GRP where a roller reefing line rubs.

Derek
>
Read more at http://www.ybw.com/forums/showthrea...g-mild-steel-fairlead-how#ebkJEt7kWYX4YVpk.99
I like your thinking! The old idea of using wrought iron whelps on sampson-posts and Andersen winches with their "power rib" smacks of the same thinking. You could fashion SS wear ribs and TIG weld them into the fairlead just where the line changes angle, or you could machine-screw some SS half-round onto the wear points.
Rogershaw will be rubbing his hands in glee at this point, imagining that I'm thinking about boating again! ;-)

That's how the inside bearing of my mild steel chainplates are done to prevent any rust. The hole that the rigging toggle pin passes through is lined with a stainless steel tube welded with stainless rods to the side of the mild steel chain plate.

My fairleads and bollards are stainless steel any way.

 

[PCUK]

How about epoxy coating? Better abrasion resistance than paint, and just as easy to apply!

 

[rogerthebodger]

How about epoxy coating? Better abrasion resistance than paint, and just as easy to apply!

But does tend to crack on corners as the rust spots on my side deck at the corners where the deck meets the cabin sides and where my toe rails bolt on.

It does tent to chip unless you use something like epoxy tar that I used below the waterline which is black and does look nice topsides.

 

[sarabande]

I bow to the experts' opinions


The fairleads will be galvanised after all. The fabrication shop gets agricultural stuff done at around £40/tonne, so for about £3 for the fairleads, painting and all its preparation time and wear problems does not bear thinking about.


thanks everyone for the interchange of ideas and experience.

 

[MM5AHO]

I bow to the experts' opinions


The fairleads will be galvanised after all. The fabrication shop gets agricultural stuff done at around £40/tonne, so for about £3 for the fairleads, painting and all its preparation time and wear problems does not bear thinking about.


thanks everyone for the interchange of ideas and experience.

£40/tonne? Surely that'd be £400/tonne.
If its really that cheap, let me know and we'll subcontract all our work to that place!

 

[sarabande]

that was a quotation from the foreman on the shop floor who is working on the fairleads. I did not think to check his figures, but they do use the Crediton people a lot for structural and functional steelwork.


I'll find out

 

[PCUK]

But does tend to crack on corners as the rust spots on my side deck at the corners where the deck meets the cabin sides and where my toe rails bolt on.

It does tent to chip unless you use something like epoxy tar that I used below the waterline which is black and does look nice topsides.

Good point Roger, but I was thinking of nicely rounded corners along the edges.

 

[rogerthebodger]

Good point Roger, but I was thinking of nicely rounded corners along the edges.

The problem also tends to be differential expansion between the epoxy and the steel causing the epoxy to crack.

Of cause worse in my location than yours.

 

[DownWest]

Bit late, but hot dip galvanizing is the only answer to the OP. Around here it costs € 2 /kilo of metal. Wrought iron is a nightmare to work with. I have restored a few big gates from the 1860s. Not easy.