There should not be any water intrusion as the trunk enclosing the dagger is isolated from the interior of the hull. Any opening in the raising and lowering mechanisms are likely above the waterline. It may take some unusual force to break off a dagger board so my only concern regarding safety would be to inspect the trunk for any damage. As far as sailing you loose your ability to point when going up wind. The boat is no longer in production and the manufacturer is out of business. I would suggest you contact a Neptune 24 group forum as they may help locating a new dagger board and give tips on the installation. A poorly performing boat will quickly become a source of frustration.