Yeah.

It can't happen any more, as JTN said. It didn't appear until quite late in the game, it wasn't long before I could build fighter planes, so I got rid of it with a fighter. My other option was building a city next to it, and building attack ships in that, athough now I think about it, I don't even know if ships can attack from cities. I haven't had the situation arise in Freeciv, that I remember. I played a lot years & years ago, it might have happened then, but in recent years I played Alpha Centauri until I got fed up with a really nasty bug -- transport ships would just vanish with all the units on board. I like to play maps with lots of ocean and the players all on different continents, so it was awful.