Markings on old clinker dinghy

[dur]

A friend is working on an old 12 foot clinker dinghy. Stripping layers of old paint has revealed the following markings stamped on the stem and on the transom:
x;9;an arrow, point up;53;CH (where the H is smaller and superscript). Each of these elements is above the next so the markings are in a column.
A plate inside the dinghy is marked: Swamp Test;9;53;12-12-63

The planking is mahogany. The hog has a slot for a dagger board and the keel is wider in this area though not slotted - quite possibly it has been replaced at some time. There are some bronze loops on the inwhale which could have been for shrouds.

Can anyone shed any light on these markings and the possible origin of the boat? Could it be naval with CH for Chatham? Any thoughts very gratefully received.

 

[cliffordpope]

I don't know who else did swamp tests, but I remember an old RNSA 14 foot dinghy in our school sailing club had a plate saying it had been swamp tested.
The wording always amused me - I imagined a boatload of sailors paddling through a crocodile-infested swamp in the Everglades.

 

[Ifraser]

Don't know about the letters and numbers but the up arrow is know as the "pussers arrow" and indicates she was once owned by the navy....Iain

 

[dur]

Thanks guys. Looks like navy then. I'll keep digging.