Could someone help me describe the attached coat of arms in proper heraldic terms. It's from about or before the 1600's and the description of colours was lost when the book (very old, written in Latin and on vellum) was stolen. It's a Sinclair/St Clair coat of arms but one that no-one has seen before. Any help in getting it's heraldic description correct would be very gratefully appreciated.

The four quarters contain two galleons for Caithness and two for Orkney, or so we believe.

Many thanks
Meg