Metal parts underwater are subjected to two basic types of corrosion: galvanic corrosion and stray current corrosion. Both can harm your boat, propeller, and motor if not correctly monitored and avoided.
According to Flags Unlimited, the significance of the flag's colors is this: The Blue represents the officer and the courage they find deep inside when faced with insurmountable odds. The Black background was designed as a constant reminder of our fallen brother and sister officers.
The picture the stars created in the field of blue was strictly symbolic, however. The Congressional resolution establishing a flag of 13 red and white stripes and 13 stars in a field of blue did not establish HOW the stars should be arranged, or even how many points each star would have. For this reason the earliest United States flags had a variety of designs.