S.o.s. My Old Ship Is Sinking. Oxid/Fungus/Rust?

his looks like a stain from a hinge - many hinges have a glue which goes yellow over time from oxidation. I don't think there's anything you can do about it - but it's pretty common.

Mind you, your forum name made me look carefully at the stamp - and it DOES look as if it is sinking at the front! Never noticed that before, and I have this stamp - which (as with nearly all Spanish stamps of this period) is beautifully engraved. Given the amount of bulk at the stern of the boat, it definitely looks wrong . . . Any sailing ship experts out there?

Looks like a Spanish Caravel,
2 square rigged sails and a lateen,
common with high stern deck, or poop
to watch crew, sails and navigation.
Probably drawn a little awry on the stamp.

Im no boat man, but just what I have seen in movies of ships, the boat could be rolling over a wave. Some times a boat would run down the wave and the front plow into the next wave. Probably depends on length of ship and boyancy.

Bad luck on the stamp maybe you can find a better one to replace it with.

Yes, and because the vessel has a lot of sails hoisted the plowing in would be more noticeable, especially when empty of cargo (looks like it) or having cargo distributed unevenly.

your spot or stain its so circular leads me to think something non stamp friendly was dripped on by accident.

I know some fungus grow in a circle pattern, but this looks more like a drip.