â¢ Position the grinder in a way that the guard provides the maximum protection to the operator from sparks and/or flying debris. â¢ Use caution when grinding in corners because a sudden, sharp movement of the grinder may occur when the wheel strikes the secondary surface.
A boater may not approach within 100 yards of a military vessel; it must slow to minimum speed within 500 yards of any naval vessel. 8 people found this useful.
The limits on how long they can stay underwater are food and supplies. Submarines generally stock a 90-day supply of food, so they can spend three months underwater. The diesel-powered submarines (not now used by the Navy) had a limit of several days submerged.