What product would you recommend to use on a cast iron keel after stripping back to bare metal? i.e. some sort of epoxy sealant on the bare metal, before anti-fouling?

Good article here of successful use of Hempels.

abba.org.au/wp-content/uploads/bsk-pdf-manager/130_201904-ABBA-Newsletter-Apr-May-2019.pdf

For International if you go through their guides to get to cast iron keels this is the result;

www.international-yachtpaint.com/en/gb/paint-guides/BW067-how-to-fully-repaint-bare-steel-cast-iron

Good comments here;

www.cruisersforum.com/forums/f55/cast-iron-keel-44847.html

2 pack bare cast iron primer and undercoat products before the afouling will normally give better results than single pack but the latter do a good job at less cost generally.

Whatever you are using preparation is key - if you can grit blast down to a class 2 1/2 surface (near white metal manual.ingal.com.au/03.php) so the whole cast iron is silver with no rust spots etc, then dry and clean well with acetone or the oem cleaner, and quickly get the first coat on before condensation forms, that is the best start.

In the old days cast iron primer was called "black tar epoxy" and would get all over everything if you went within 5m of the keel but if laid on well it worked well. The modern 2 part epoxies should be developments of this and just as good hopefully.

Thanks r13. This is great info. Exactly what I was looking for.

The Northshore 340 I surveyed at Lake Macquarie had breakthrough rust spots on the keel. I had assumed I would need to be grinding back to bare metal, epoxy coating and then re-antifouling. So want to understand the products and process as I am now looking hard for a Northshore 33, 34, 340 Mark I or 340 Mark II.

So am guessing I may need the info in the future.