can i make the boat appears in 2 places, like, in the island X so the player can go to the island Y, make missions there, and then i put another boat on island Y to he comeback to island X, i am talking about 2 boats, not a boat and a ship. Is this possible? is yes, how?

The boat will stay wherever its parked, so you can do missions on island Y and still use the same one to return to X
there's no need for a second boat

but if i put a boat on island X to the player go to island Y and a boat on island Y to the player go to island Z, is that possible?

Depending on how you build the map you could still use the same boat for all 3.
If you insist on having multiple boats you could make an event page boat that when activated had a controlled move route.
Or even an event that changed the actor graphic to a boat, though you'd need to import the image of a boat yourself and fiddle about with the tiles passability. This would allow you to free roam though, as opposed to the move route one

thanks for your help!

...This macjonny fellow is either a bot or a buffoon.

It was a bot.

why was it posting then o_O. is it banned now? or?

I banned it and deleted its posts.

Closing this now that it's solved.