A group of boats is a fleet.
A flotilla
A group of boats is usually referred to as a convoy. If they are a medical group of boats it is normally called a Medical Convoy.
a fleet
They would also call them boats.
The Red Ensign is the national flag flown on British non-military boats and ships. The White Ensign is flown on military vessels.
They are actually called 'u-boats', and they were employed by the german military.
A flotilla.
Boatwright ; one who makes boats .
The military does not mount 8 guage shotguns on boats. Sometimes shotguns are CARRIED aboard boats, but those are 12 gauge. Afraid you have been given some bad information.
We can call them as Boat Builders.
a boatwright