Do all ships have the same rate of movement on the campaign map, or does this vary by ship type similar to how arty move slower than cav on the map?

I tried experimenting with this recently and got some weird results, though I probably just didn't spend enough time with it. It seems that ships get less movement points the turn they are created in, but that's all I can find out for sure. Othertimes, it seems like all ships move the same on the campaign map. (E.g, Heavy 1st Rates move as quickly as sloops?)

If I wanted to create a medium sized fleet to patrol the trade theaters -- (the fleet would need to move fast on the campaign map) -- what would it be best to compose it of? Or if everything moves at the same rate, should this consideration be based purely on economics & likely adversaries?