Antifoul, Primers, Old Coatings

[WotSandbank]

I am stripping the old coatings off a 32ft Rival (this pics shows the 10 layers - http://www.humbird.co.uk/rivalcoatings/myRivalHullCoatingsReverse.jpg

It isn't epoxied so after much reading I think I won't add an epoxy shield. There are so many views on this but as it is a 35 year old sound and dry hull (survey last year) I don't think I can do a good enough job in outside conditions even later in the year. Also if it ain't broke etc....

I found out from the previous owner that he thinks he used a Blakes Primer with some sort of rubber in it which may be the sparkly purple layers (aluminium flakes).

So my plan is to clean a de-grease the hull. Wash down thoroughly.
2 x coats of Hempel (Blakes) Underwater Primer (this still has the aluminium flakes in it and some sort of rubber base, not epoxy though).
1 x coat Hempel Hard Racing (white) and then
1 x coat Hempel Tiger Extra Dark Blue (self eroding)

This way I can clean the Self eroding each year and the white hard racing will tell me whether I am cleaning too far.

Any major views against this plan I'd be glad to hear it.
I realise this has been extensively covered in many topics but I have added the pic of the original coatings to see if anyone recognises the sparkly purple stuff.

All very much appreciated. I have all the Hempel Data sheets by the way and have also looked closely at International but Primocon doesn't seem to have the 'excellent waterproofing abilities' that Hempel Underwater Primer says it has.

Oh by the way on scraping old antifouling I was nearly at the end of my road when I bought an Andrews Electric scraper from Amazon (£30) - it has changed my life! And it's very non-invasive on the hull. Far less marks if carfeully used. You can use it for 8 hours a day and only have a bit of 'white finger' vibration rather than dead arms! You can even make it to the pub that same day! Interstrip only works if you use about 10 coats of the stuff and even then the mess is horrific. Wear a very good mask and goggle and the electric scraper will do the job. About 3-4 times faster than by hand. Hope this helps any would-be scrapers.

 

[rob2]

I don't want to dampen your enthusiasm, but I doubt you'll get much protection with a single coat! The eroding type of antifouling wears down of its own accord, it doesn't need cleaning - if you scrub it it will just crumble away. Most antifoulings need at least two coats just to make it through a single season. The idea of maybe two coats of hard stuff underneath is sound, though.

Rob.

 

[WotSandbank]

Rob: yes you might be right... on my previous boat I only used one coat per season of Cruiser Uno but there were others underneath so hard to say how much stayed on!

 

[Plevier]

Oh by the way on scraping old antifouling I was nearly at the end of my road when I bought an Andrews Electric scraper from Amazon (£30) - it has changed my life!

That looks a good deal. What do you do about blades, can you get spares? Can you get carbide tipped ones?

I was reckoning on several days with this http://www.amazon.co.uk/Hamilton-Pe...ef=sr_1_2?s=diy&ie=UTF8&qid=1328639931&sr=1-2

Can't help with your queries, sorry!

 

[WotSandbank]

Troubador: Ah the old manual jobbie. I have one like that and yes it is sort of useful but after 8 hours of it you will be crying in your beer. The whole antifoul removal thing seems to need a host of things like a manual scraper, an electric scraper, some Interstrip to help here and there and a good old putty knife with rounded off edges. This is what I bought: http://www.amazon.co.uk/Andrew-Jame...52M2/ref=sr_1_1?ie=UTF8&qid=1328641403&sr=8-1

I am just grinding the edge of the electric scraper blade every now and again but most of the action is the vibration. The angle you offer it up to the hull varies a lot depending on how easy the layers are to remove. Also this scraper doesn't vibrate until it engages with the layer so you can position it quite accurately. Hope this helps.

 

[Pasarell]

Not sure why you are putting 2 coats of primer on unless the spec says you need to. 2 coats would not normally be enough to get any protection but will act as a tie coat for adhesion to the hull. I would be inclined to apply two coats of the eroding antifouling. The point of the hard antifouling layer is to see when you eroding layer has worn through and to act as a backstop and prevent fouling until you can replace the eroding stuff. 1 coat of eroding will be very thin in places and give you only short term protection. Applying a second coat in the first year gives you a decent base to work from and then you probably only need 1 coat in subsequent years

 

[WotSandbank]

Pasarell:
well it's because the previous owner did 2 coats but you may well be right - I will check the specs and have a chat with Hempel. I used to to do 2 coats of self-eroding but found it did nothing extra except cost me twice as much, so I've opted in the past to do a basic scrub in early July and early Sept when the growth seems worse and this was as effective (if not more so) and very easy for me since we have an area at our club where I can do this on a tide.

 

[WotSandbank]

Small Update

I have spoken to a very helpful chap called Keith at Hempel in Wales:

His view is that my plan is fine but suggests I change the White Hard Racing to Black as apparently Black Antifoul (and the darker ones generally) has much more biocode in it as it doesn't need so much paint pigment.

I also told him my rudder is non-gelcoated (bare fibreglass) so he suggested using Light Primer (2 pack epoxy coating) on the rudder and then using 'my planned system'. I'm drilling a small hole in the base of the rudder to let any excess water out and then re-sealing it with solventless epoxy filler. I will add some sealant to the tope of the rudder where the stock enters the rudder as a precaution.

Oh he mentioned putting 2 coats of Hard Racing on the keel for extra protection so I'll do that. But no need for 2 coats of Underwater Primer.

Maybe... job done (in theory). Now I need to finish this pint and get back to scraping!

 

[WotSandbank]

Small update

I have almost stripped the hull complete now. The electric stripper did a good job but Interstrip does help a lot - I found 16 hours was the optimum time to leave it on (this is for approx 10 layers of antifoulings and primers).

BUT I have had varying suggestions about whether to even bother with primers. Some, including a GRP specialist, suggested I just put on 2 coats of eroding - straight onto the gel coat - or one coat of Interpseed Ultra. I don't want a build up each year so I wonder if Interstrip will take off Hard antifoul each year?

The opinion of some is that older boats that are wintered ashore should 'breathe' to dry out and best to get antifoul off if at all poss and don't bother with Primers. Even more folk suggested not bothering with epoxy shield as this will seal in moisture.

No easy answer but any pro's out there who can shed any light?

Many thanks

 

[Kilifi]

International interstrip

Hi all I have been reading about the antifoul remover and what a con. I spent a lot of money on this and it barely touched the paint. I don't see how company's can get away with selling this. I should have read up on what people thought of it before I bought a can. I'm thinking of going down the soda blast root now if I can get a good deal. Failing that I will be sanding down. I want to go back to gel coat and start again. Why because it's not been done for the past ten years so as Im converting from petrol to diesel and reupholstering I thought I might as well do the bottom as well.

 

[WotSandbank]

Hi all I have been reading about the antifoul remover and what a con. I spent a lot of money on this and it barely touched the paint. I don't see how company's can get away with selling this. I should have read up on what people thought of it before I bought a can. I'm thinking of going down the soda blast root now if I can get a good deal. Failing that I will be sanding down. I want to go back to gel coat and start again. Why because it's not been done for the past ten years so as Im converting from petrol to diesel and reupholstering I thought I might as well do the bottom as well.

Yes the Interstrip is a bit odd but it does work like this:
you can paint it on (as thick as you can by the way) and leave for about 15 mins. Then scrape off using a pro scraper and this will remove a layer or two. Then repeat and repeat till you or down to the GRP. Expensive way to do it mind you, as the Interstrip ain't cheap! When you have scraped as much off as poss use thinners no.3 to clean the area scraped to see what you have left.

Alternatively you can scrape by hand or use the electric scraper to get most of the top layers off and then use the interstrip at the end.

To get my 32ft hull back to GRP:
1) I used the electric scraper (I found that you need to develop about 4 different ways of using it and differing angles depending on the angle you are to the hull)
2) Then I used a hose and the hand scraper along with some wet and dry blocks of 60grit - sometimes the scraper did well, sometimes the sand blocks did well. I didn't sand to the GRP too much at this stage, more to get the stubborn primers off.
3) Then I used Interstrip on the very thin remains of the primers (there were various ones). Scraped off the Interstrip and cleand the areas with Thinners no.3. I found doing about a 3ft x 3ft area at a time the best thing. Also keeping 2 areas not joined to each other on the go - so whilst one is being affected by the intersrip you are painting the interstrip onto the next area.
4) Then I lightly sanded over all with 320 grade.
5) Then I washed the hull with water and allowed to dry and painted on the antifoul. I am not bothering with primers so I can remove it all again easily should I wish to.

Hope this helps. (I might have considered professionals though had I know how long it would take me!)

 

[WotSandbank]

Small update no.3

In the end I went for VC Offshore with teflon from International. It was expensive for 2 litres but did almost 2 coats - it's very thin but dries to a 'teflon saucepan' finish so I will update on whether this was good or not. I'm expecting barnacles to try some easier hull to stick onto!

As I've said before I have a drying mooring in soft mud and I'm expecting the VC to stay on.

I think you could probably put 10 years worth of VC on before any significant build up! But I intend to see what interstrip does next winter. Happy Sailing to everyone.

 

[jwilson]

I don't want to dampen your enthusiasm, but I doubt you'll get much protection with a single coat! The eroding type of antifouling wears down of its own accord, it doesn't need cleaning - if you scrub it it will just crumble away. Most antifoulings need at least two coats just to make it through a single season. The idea of maybe two coats of hard stuff underneath is sound, though.

Rob.

]
I have used one thin coat a year for 5 years, with one extra thin coat around the waterline, self eroding (seajet 033) and it works well yet it still builds up so sand wet a bit each year.

I'm sure the "two coats" instructions from the antifoul makers are from the accounts department.

 

[WotSandbank]

heh heh - you could be right!