|Most ships crests are available on the net in full colour. If you look at the
period photographs of various ships, and especially Royal Navy, you will see the
crest just under the bridge.
To reproduce this in 1:700 to enhance your build, and give it something extra, download the image, which is usually small anyway, and then have it reduced on a colour photocopier, my sample is 25%, and then 50%, until the size is proportional.
The final image is cut out with a scalpel, and then glued to the superstructure as per your photograph, and there it is.