Help me to figure out what this film was please

Sorry If I have posted this in the wrong place but there is a movie I watched a long time ago and I have spent a long time trying to figure out what it was.
What I can remember was:
1.It was a pirate movie.
2.It was about a boy who's father was killed by pirates.
3. There was a man who had a telescope kind of thing that had a retractable blade inside of it.

Thanks for any help

Shipwrecked? It's been 25 years since I've seen it, but that's the only one that comes to mind

thanks I'll have a look