I set to this evening with the intention of getting the hull under the waterline ready for the tie-coat but two things have prevented me from achieving this. The first is physical. In order to remove the partially degraded brass strip from the bottom of the keel I have to stands on a step and then rest my upper body on the hull to be able to reach the keel. In doing this the muscles in my lower torso are held tight. After and hour and a half of this my stomach muscles hurt too much to continue so I have to stop. The second reason is shown below.
This is the slot in the keel through which the centre plate protrudes. It seems to have an insert made of something non-metallic, bakelite perhaps, and I will need to be very careful in removing the old bottom paint from this so that I do not damage it. The white stripes are the epoxy coating that the prior owner put onto the bull before paining it with CopperBot where the brass band had been fitted and the grey and blue outer bits are the bottom paint that has to be removed. The centre section, the insert, has bottom paint on it but the material from which it is made is black or dark grey and difficult to distinguish from the paint, hence the care needed to remove it. One layer of this bottom paint flakes off and has to be removed before the tie-coat is applied
Apart from that the keel is not looking too bad. I still have to remove the brass strips from the two bilge keels or runners or whatever they are called and then scrape the hull back to the copper layer. At that point the hull needs to be sanded before the tie-coat can be applied.