How to treat rust on galvanised rubbing strake

westernman

westernman

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I have a galvanised rubbing strake around my boat which is rusting badly.
Which product would be the best to treat this to stop the rust?

I had a look here, but have no idea how to choose between the different products:-

http://www.frost.co.uk/automotive-rust-products.html

Initially I thought Zinga might be the best for the job - but I was put off by the surface preparation requirements - about the only preparation that is going to happen realistically is a light brush with a wire brush and maybe brushing on some kind of solvent while I lean over the side of the boat.

What do you experts suggest?
 
I work on the Scillonian ferry, and any rust found is either wire brushed off or removed with a needle gun, and then treated with Vactan rust converter.

It is overpainted with primer and a top-coat.

I have also used it on my bilge keels with an overcoating of antifoul.

From reading, if you have a clean surface, you could spray it with Zingard from MGDuff.
 
Wire brush, apply rust converter and leave as per makers instructions.

The rust converter may leave small grit like bits, a light sant will remove them but may expose some raw steel, so apply a coat of zinc the top cot as usual.

Good luck and fair winds. :)
 
philip_stevens said:
I work on the Scillonian ferry, and any rust found is either wire brushed off or removed with a needle gun, and then treated with Vactan rust converter.

It is overpainted with primer and a top-coat.
Click to expand...

I was going to say something similar based on my experiences looking after Stavros, but I guess that Michael doesn't want his rubbing strake painted (not much good as a rubbing strake then).

Pete
 
prv said:
I was going to say something similar based on my experiences looking after Stavros, but I guess that Michael doesn't want his rubbing strake painted (not much good as a rubbing strake then).

Pete
Click to expand...

Instead of the paint, he could overspray it with Zingard (faq's). The information given on the MGDuff site states that in independent tests, it is as good as, if not better than, hot dipped galvanising.


btw, I've got a spray tin to do my prop this season. Let's see if it keeps the barnacles off!!
 
michaelchapman said:
I have a galvanised rubbing strake around my boat which is rusting badly.
Which product would be the best to treat this to stop the rust?

I had a look here, but have no idea how to choose between the different products:-

http://www.frost.co.uk/automotive-rust-products.html

Initially I thought Zinga might be the best for the job - but I was put off by the surface preparation requirements - about the only preparation that is going to happen realistically is a light brush with a wire brush and maybe brushing on some kind of solvent while I lean over the side of the boat.

What do you experts suggest?
Click to expand...

I recommend FE123 from rust.co.uk

It does not need washing off and works well on my steel ketch. I overpaint with the same company's epoxy paint and they also sell a zinc loaded epoxy as well.

Ian
 
I am coming to the conclusion that may be something like the Vectran rust converter overcoated with Zinga will do the trick.

Some of the rust is behind the strake - so preparation is going to be limited to letting the rust converter trickle through.

The rubbing strakes don't get rubbed too much now (I am much better at reversing into berths now). Just the fenders from time to time will rub against the rubbing strake.
 
michaelchapman said:
The rubbing strakes don't get rubbed too much now (I am much better at reversing into berths now). Just the fenders from time to time will rub against the rubbing strake.
Click to expand...

Not making full use of the asset you have, then :D

In a Swedish boat with brass-bound rubbing strakes projecting well out from the hull, we once forced our way into a too-narrow box-berth by motoring full ahead and squeezing the piles outwards to let us through :)

Pete
 
michaelchapman said:
I am coming to the conclusion that may be something like the Vectran rust converter overcoated with Zinga will do the trick.

Some of the rust is behind the strake - so preparation is going to be limited to letting the rust converter trickle through.

The rubbing strakes don't get rubbed too much now (I am much better at reversing into berths now). Just the fenders from time to time will rub against the rubbing strake.
Click to expand...
I don't think you can use Zinga on top of a rust convertor. I think it stops the galvanic action.
 
Ocean Safari said:
I don't think you can use Zinga on top of a rust convertor. I think it stops the galvanic action.
Click to expand...
That was my understanding too - I'm pretty sure it has to be applied to clean white steel for maximum protection, as it works by forming a chemical bond with the steel's surface. It's not just a paint covering.
 
philip_stevens said:
Instead of the paint, he could overspray it with Zingard (faq's). The information given on the MGDuff site states that in independent tests, it is as good as, if not better than, hot dipped galvanising.


btw, I've got a spray tin to do my prop this season. Let's see if it keeps the barnacles off!!
Click to expand...

I stand corrected.

from the MGDuff site-
"In order to obtain cathodic protection, an electric contact is required between Zingard and its substrate.
Therefore the substrate must be clean and rough. That is the main rule.
It is very important to keep the following working order in mind :
1. eliminating all dirt, grease, oil and salts
2. total removal of all old paint, rust and mill scale
3. roughening
4. dedusting or rinsing"
 
michaelchapman said:
The age of the boat I guess - which is about 13 years now.
Click to expand...

Then the obvious thing to do is get another 13 years by getting them re-galvanized.

All zinc rich paints are paints whatever they might claim about being "cold galvanizing" etc.
They don't metallurgically bond to the steel, they don't lay down pure zinc to be a sacrifical anode, and they don't conduct electricity as well as galvanizing does, so they can't protect in the same way.
Paint is fine as a barrier protection - right up to the time it gets perforated.

And what does a rubbing strake do? it Rubs.
 
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