UK, Wills of Royal Navy and Royal Marines Personnel, 1786-1882, sourced from ADM 48: Navy Board, Navy Pay Office, and Admiralty, Accountant General’s Department: Seamen’s Wills at TNA, contains 32,361 records.
Most are handwritten onto pre-printed forms. You will usually find name, rank, will date, ship, captain, esecutor and beneficiary on the first page. Be sure to look beyond the first page for other information.