No attempt of any kind must be made at rescuing members of ships sunk, and this includes picking up persons in the water and putting them in lifeboats, righting capsized lifeboats, and handing over food and water. Rescue runs counter to the most primitive demands of warfare for the destruction of enemy ships and crews. Be hard, remember that the enemy has no regard for women and children when he bombs German cities.
Karl DonitzOnly ... from personal experience [can a man] take the necessary measures without a preliminary process of trial and error.
Karl Donitz