The qualifications and competencies you need to sail in the UK depend greatly on the type of sailing you plan to do, the vessel you'll be operating, and whether you'll sail in domestic or international waters. Here is a more detailed breakdown:

Recreational Sailing (Dinghies, Yachts, Motorboats):

If you're sailing recreationally, there's no legal requirement in the UK to hold a specific qualification. However, it's highly recommended to have some level of training for the safety of yourself and others. The Royal Yachting Association (RYA) offers a wide variety of courses suitable for beginners and more experienced sailors alike. For example, you could start with the RYA Level 1 Start Sailing Course, which provides a short introduction to the sport of sailing. It covers the basics, such as boat parts, rigging, and sailing in all directions, emphasising understanding safety onboard. As you progress, you could consider courses such as the RYA Day Skipper Course, which is designed for aspiring skippers with some yachting experience and basic navigation and sailing skills. This course covers preparation for sea, deck work, navigation, pilotage, meteorology, road rules, maintenance and repair work, engines, and more.

Commercial Sailing:

If you plan to work commercially as a sailor or skipper, you'll require professional qualifications. The Merchant Navy Training Board (MNTB) oversees the training of officers and crew for the Merchant Navy. The qualifications you need will depend on your role on the ship.For example, to work as a deck officer, you'll need to complete an officer of the watch (OOW) navigation and radar course, along with other requirements. The Maritime and Coastguard Agency (MCA) provides certification for commercial sailors, with requirements varying depending on the size of the vessel and the distance from the coast.

International Sailing: 

If you plan to sail in international waters, you may need an International Certificate of Competence (ICC). This certificate is proof of your competence for the operation of a pleasure craft. The RYA can issue the ICC to British citizens and residents. The ICC assessment is a check of competence, it is not a teaching session. Therefore, if you are not sure of your ability it would be wise to undertake some training before you book your ICC assessment. This could be done through taking an RYA course, or through personal practice.

Inland Waterways:

 If you're planning to navigate the UK's inland waterways, such as canals and rivers, you may need a different set of qualifications. The RYA Inland Waterways Helmsman's Course is one such course, covering all the basic knowledge you need for navigating the inland waterways. In addition to qualifications, it's important to remember that safety equipment, insurance, and boat maintenance are all critical aspects of sailing. Always check the latest guidance from the RYA and other relevant bodies before setting sail. Staying updated with weather forecasts and maritime safety information is also a crucial part of being a responsible sailor.