Primer for anti-fouling?

[m1taylor]

Hi, I have just completed scraping off all the old anti-fouling paint on my boat. The paint was multi-layered and brittle and so getting back to the gel was not too bad - just lots of labour. My question is - what constitutes a good primer for anti-fouling? Should I put on a coat of epoxy first for exta protection and if so, what sort and best place to get it? And for filling any scratches and minor gauges that inevitably arise from scraping?

 

[kandoma]

Tar epoxy gives a good "primer" for a new start. Myself, I would check the hull for the moisterlevel first. If its still ok, I would aply several layers of West System Epoxy.
First one layer epoxy, then fill in the holes with epoxy filler and then several layers of epoxy with aluminium flakes and then on top tar epoxy. If you are using epoxy as last layer, you should not paint directly on it without sanding it.
Use a brush instead of rollers. Saves you a lot of money. With two good brushes, you can do all the boat. Dip the brush after 15 minutes in a glas with Aceton. Take the other brush out, clean with a rag and go on and change to the other, as soon as the epoxy starts to get hard. The rollers are costing a fortune and are good only for a short time.

I do not understand, why new boats are not protected against osmosis. I was in a similar situation as you. I scraped down the one layer of antifouling put on by the boatbuilder and due to lazyness I did not protect the bottom from the start with epoxy. I couple of years later.... its all history now.

Please be aware, that any epoxy product can cause serious health problems.

Peter

 

[andyroo]

Definitely epoxy. Not sure how many coats of epoxy you have on the hull but I would recommend 4-5 coats from the gelcoat up. It is clearly a matter of person choice, but I would recommend blakes epoxy. I know atleast one boat yard which swears by this stuff and will not use anything else for love nor money.

 

[oldsaltoz]

G'day Mark,

Built 1971, I suspect this has been treated at some time, worth checking prior to recoating with epoxy.

If not treated, sand and fill with minor imperfections with closed cell micro-balloons mixed with epoxy resin, wash with fresh water and rub with a kitchen plastic scourer till water no longer forms beads, this will remove the residue left by the curing process.

After sanding apply epoxy with an epoxy roller (West System have them) and tip off with a long bristle 2 inch brush at once, keep a white cotton rag and some Acetone handy to wipe the brush every 5 mins or so. Clean the roller and brush about every 15 minutes. Best applied by two persons, one to roll on an area about a roller width wide, starting at the water line and down to the centreline or keel, the second person tips this off with the brush and the first person applies the next strip at the same time, this keeps the edge wet and reduces drag on the finish. Do the keel and rudder after the hull.

When you have completed the first lap, check the previously applied epoxy, if it is very tacky you can apply the next coat and sane a lot of sanding, apply 3 or 4 coats.

If the resin cures to the point that you can not make a mark with your thumb nail, then let it cure for 24 hours, wash and scour as above, then dry and give it light sand just to remove the shine, a 125 grit will be ok.

After all coats have been applied and cured, wash and scour as above, sand as above and apply an epoxy primer coat prior to antifouling.

Mix about 2 cups of resin at a time and only use shallow containers to avoid heat build up, a box of latex rubber cloves will save your skin. Make sure you have a good respirator when sanding, not a paper mask please.

I hope this helps.

Andavagoodweekend.........

 

[m1taylor]

Hi,

thanks for that - i have looked up Blakes Epoxy and it comes out as a staggering £73 for 2.5 litres (cream or grey colour). I presume this is the stuff you are talking about?