Submersible impact test hammer

A submersible impact test hammer, comprising:

• a resilient tip;
• an output shaft connected to the resilient tip such that it transmits a force to the resilient tip;
• an end closure;
• a pressure housing attached to the end closure such that the two enclose a watertight volume;
• a sealing bearing that supports the output shaft to the end closure and allows relative movement while preventing leakage into the watertight volume;
• a slug;
• solenoid coils;
• slug shaft bolts supported by the end closure and perpendicular to its interior surface;
• linear bearings that slidably mount the slug to the slug shaft bolts;
• and
• a spring between the slug and the output shaft;
• wherein current through the solenoid coils creates an attractive magnetic force between the slug and the end closure accelerating the slug toward the end closure, and
• wherein impact of the slug against the output shaft creates a force pulse which is transmitted to the resilient tip and then to a test object.