The Cape Dory Board

Thinking of installing an electric bilge pump. I had the idea to attach the pump outlet to the sink drain which is nearby, using a plastic connector. Do I need some kind of backflow preventer? Also trying to replace my impeller. It seems to be located just below the fan belt pulley. No screws just h...

Can anyone help?

I just purchased a Cape Dory 25D.

Absolutely love the boat.

I am unable to pump out the waste holding tank, due to a seized screw cap any suggestions ?

Thank You !