HELP ME FIND AN OLD GAME. PLEASE!

Alright guys, I'm finally gonna cave. I have spare money that I intended to use on GOG.com. I NEED to know if I can find this. I've been looking for this particular game for about six years now, and I have no leads other than my own memory. I've never even gotten close before.

It's a business simulation game, taking place in a seafaring setting with caravels and shit. You'd go between island nations and help them grow, or maybe even build them, I can't remember. It had 16-Bit graphics similar to Age of Empires, but not as photo-realistic. I've looked at the popular ones like Tradewinds and I can confirm that none of the boat-sims on Wikipedia are the one.

At the beginning of the game you'd choose one of four flags to fly on your ship. I remember them (at least two) looking something like this:



I know there was a yellow flag in the game. The red/white may not be the correct colour (in fact, the yellow one may have been the checkered flag). There could have been a blue flag but I don't remember. The game may have had a white HUD, and was in an isometric perspective.

Sadly that's all I remember. It's one of the big lost gams in my life. Please help! SAVE ME!