I am relatively new to this game, though I have been playing WK games for many years, so i know that ability texts are often subject to errata or other rules, since they always seem to forget a thing or two in the playtest phase... This seems like a simple question. but can you use the HMS London's ability to load off all the treasure from Pirate ships if they are your own pirate ships?

Thanks.

Yes, because the ability does not specify "friendly" or "opposing".

"When touching a Pirate ship, this ship may load as much of that ship's treasure as she can carry."

any ship in the pirate faction is subject to this effect friendly or enemy.

Wizkids listing for HMS London
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Thanks for the information, I appreciate your help.

Since this ability doesn't require one of the four actions it's done as a free action but with a non-London ability ship, is an explore action required to transfer treasure from one friendly ship to another that are touching?

Yep! It does take an explore action to transfer treasure (or crew) ship to ship while at sea.