Antifoul or blacking

[955matt]

Hi,

 

I wonder if you might be able to give us some advice. We have recently bought our first boat a 1978 12m Dutch steel cruiser. We live in France and the boat will be used on the french rivers and canals. When we had it surveyed the hull paint was in poor condition so we have taken it back to bare steel. We have purchased a 2 pack epoxy Jotun jotamastic 90 and vinygaurd 87 and we’re going to antifoul over the top. But have seen several people talking about blacking instead if it’s not in salt water. Has any one got any advice as we have no experience in either.

 

Many Thanks 

Edited March 21 by 955matt

[Athy]

Welcome to the forum.

To the best of my knowledge, most steel boats (including ours) are blacked every few years. I don't know if antifoul can also be used, but someone with more knowledge than me is bound to be along shortly. We do have members with considerable experience of the French waterways, so feel free to ask any further questions which you may have.

   If you repaint the upper part of the hull I hope you don't lose that charming panda picture.

[Tony Brooks]

All our river cruiser hire boats were antifouled with fresh water antifouling, but they were wooden or GRP. I suspect the antifouling we used may now be banned because it worked by leaching poisons into the water. I would be reluctant to use a copper based antifouling steel (or aluminium) because it may cause galvanic corrosion of the steel. In any case, you should see if there are any by-laws about what can or can not be used in the area that you cruise.

 

Maybe ask on the Barge Association forum.

 

Although the photo looks like bad prep, I do wonder if it is antifouled with a copper based product, causing it to react with the steel.

 

Edited to add: it might be better to stick with the two pack. If you put bitumen blacking on top, it may well need grit blasting to remove it before redoing the bitumen with two pack.

 

Just been Googling - it seems vinygaurd 87  is a primer for WOOD.

 

I would try to avoid overcoating with a product from a different manufacturer. It is probably best to stick with one manufacturer's system products, just in case there is some kind of reaction.

Edited March 21 by Tony Brooks

[LadyG]

I've used SML paint company for their advice, and also they do some kits which are handy, and save money.

 

My steel narrowboat was originally two pack epoxy and it lasted twenty years!! Not recommended to leave it, but it indicates the protection you can get if hull is prepared properly. I recoated with a Jotamastic on the advice of SML paints.

I would not use blacking.

So, you need to find out what is allowed in the way of antifoul if you go down that route, but looks like a two day prep job before you need to apply any coating. If you can get to bare clean steel you may need a primer, perhaps a rust remover, Vactan and Fertan are often mentioned on here, but again, you need to have the right product. Preparation requires fastidious attention to detail, check the data sheets, the dew point and the ambient temperature.

PS from experience, I would try to clean and polish the rest of the hull rather than painting it, lots of amazing products on the market, but be careful with any chemicals, and be patient.

I am not sure about which anodes you will need, this could also be the the reason for the corrosion.

Edited March 21 by LadyG

[955matt]

5 hours ago, Tony Brooks said:

All our river cruiser hire boats were antifouled with fresh water antifouling, but they were wooden or GRP. I suspect the antifouling we used may now be banned because it worked by leaching poisons into the water. I would be reluctant to use a copper based antifouling steel (or aluminium) because it may cause galvanic corrosion of the steel. In any case, you should see if there are any by-laws about what can or can not be used in the area that you cruise.

 

Maybe ask on the Barge Association forum.

 

Although the photo looks like bad prep, I do wonder if it is antifouled with a copper based product, causing it to react with the steel.

 

Edited to add: it might be better to stick with the two pack. If you put bitumen blacking on top, it may well need grit blasting to remove it before redoing the bitumen with two pack.

 

Just been Googling - it seems vinygaurd 87  is a primer for WOOD.

 

I would try to avoid overcoating with a product from a different manufacturer. It is probably best to stick with one manufacturer's system products, just in case there is some kind of reaction.

sorry my mistake it’s silvergrey 88 which was recommended by SML , which also recommended SML CU-PRO antifoul so I think we will stick to there recommendations 

[955matt]

Just another quick question, is there away to tell if you have zinc or magnesium anodes 

 

Thanks

 

[Tony Brooks]

Chip or cut a small bit off and hold it in a gas flame (use tongs or old pliers). If it flairs it is magnesium, if it just melts it is zinc.

They are marked when new, but once they start eroding the letters will disappear.

 

When in salt water, magnesium usually produce strings of bubbles - as I found when berthed in Liverpool docks.

 

Where did the previous owners keep it? The anode I can see does not look too badly eroded, so if it was in salt water I would bet they are zinc, however, a zinc anode will only erode slowly, if at all, in fresh water.

[Bee]

Stick to the Jotun, two or three coats is good. 4 is better, Dont put any 'blacking' over it (tar based bituminous stuff is banned nearly everywhere now anyway)  Anti fouling might be a good idea, I know our boat has a thick layer of mussels on it and  quite likely a few buckets of barnacles too, these things are widespread especially in Holland and Belgium where the water can be brackish. If you are mooring or travelling there then you will pick them up and they are little sods to scrape off. 

[blackrose]

9 hours ago, Tony Brooks said:

 

Just been Googling - it seems vinygaurd 87  is a primer for WOOD.

 

 

Vinyguard is for steel too, very similar to International Interdeck, underwater steel primer and tie layer. However it's a single part paint and has no place in combination with Jotamastic 90 two part epoxy.

 

3 hours ago, 955matt said:

sorry my mistake it’s silvergrey 88 which was recommended by SML , l 

 

SML have made a mistake. Vinyguard should not be used to prime steel that's being epoxied. The epoxy is its own primer and if correctly applied will last far longer than vinyguard.

Edited March 21 by blackrose

[MartynG]

On 21/03/2023 at 15:47, 955matt said:

Just another quick question, is there away to tell if you have zinc or magnesium anodes 

 

Thanks

 

If they are zinc and the boat is in fresh water the anodes will not have eroded and may have developed a passive coatig.

If in doubt change the anodes.

Is the brown marking fouling or rust ?

If it is rust it seems the previous paint below the waterline  has failed . 

I would expect antifoul rather than blacking on this type of boat but perhaps the law in France regarding suitable products needs to be understood.

Coppercoat is the best antifoul although expensive to apply it should  last a decade. 

https://coppercoat.com/coppercoat-leisure-antifoul-applications/#coppercoat-leisure-image-gallery

 

.

[955matt]

Hi,

 

yes the brown is rust , so have stripped the hull to bare steel to start again. Jotun jotamastic 90 and then vinygaurd 87 and finally CU pro antifoul.

 

I’ll check the anodes and replace if required.