After final sanding, the yachts had a primer coat, 2 coats of white undercoat, 2 or 3 coats of white gloss depending on whether they were solid or hollow yachts and finally they were lined. Earlier solid yachts and some smaller models of the SY series had coloured hulls.
This sounds like a lot of paint but the paint was heavily thinned down with clear methylated spirits. (Nowadays it is called denatured alcohol)
On the larger SY series solid yachts with the plank lined deck, after the white or cream under coats were applied, the deck was then lined and very thin coats of yacht varnish or heavily thinned out yellow paint were applied over the lining to give the desired finish. Yacht varnish has a yellow tint to it.
** Please note:
In recent years the Humbrol paint formula has been changed several times due to ingredients of the paint being outlawed due to health worries, this meant that the paint was not available for sale in Europe. The ban resulted in hobby shops running out of the paint or totally withdrawing it from sale, you may find that you will not be able to purchase Humbrol paint until it is re-formulated, whether there will be a full range again is predictable and if so may take some time.
Other makes such as Revell and Tamiya are available, if you want the equivalent paint code for Revell, click on the following link.
Here are some of the most used Humbrol gloss paint colours;
22 - White
41 - Ivory
69 - Yellow
18 - Orange
19 - Bright red
20 - Crimson
2 - Emerald
3 - Brunswick green
47 - Sea Blue, 1950s
48 - Mediterranean Blue, 1960s
14 - French Blue, 1970s
15 - Midnight Blue, late 1980s
These are not all of the colours used but are a guide to the most common over the seven decades of production. The later mid-size SY models can have a combination of contrasting colours.
Earlier yachts had a similar shade of colours that can be made by mixing two
or more paints together to lighten or darken as with the Endeavour series which
were off-white so use No. 22 with a small amount of No. 41 to get a closer
match.