A list of equipment that is useful on a boat is long, but I think that a good skipper should always carry these 5 essential pieces of equipment:
The most important tool that every skipper should have is a multitool with pliers and a sharp knife. Forget about cheap Chinese knockoffs, for the boat you need the best and that’s a proper Leatherman.
It’s amazing how many things you can fix temporarily on a boat with a good tape. Gorilla Tape is the biggest, strongest, toughest thing ever to happen to tape.
On a boat there is always something that need lubricating, or another thing that got stuck and the solution is WD-40. It protects metal from rust and corrosion, penetrates stuck parts, displaces moisture and lubricates almost anything. It even removes grease, grime and more from most surfaces.
A good headlamp is a must for night navigation. The RAW Pro is a waterproof, light weight, high power white and red beam head torch. Engineered specifically to excel in the harsh marine environment, you can rely on it in any situation.
A reliable lighter is a must on a boat, weather you need it to light a stove, or burn an end of a rope. Silva Helios Storm Lighter is windproof, waterproof and with very high temperature flame.