In 1755, having risen to be a mate, Cook joined the Royal Navy, and after four years' service was, on the recommendation of Sir Hugh Palliser, his commander, appointed master successively of the sloop Grampus, of the Garland and of the Solebay, in the last of which he served in the St. Lawrence.
Tap Bolt vs Cap Screw. What is the difference between a tap bolt and a cap screw? A tap bolt is (typically) a fully threaded hex bolt, while a cap screw is (typically) a hex head bolt that will be installed by turning the head of the bolt (screw) instead of tightening it with a nut.
UNF (Unified Fine) is the same as UNC except that for each size of bolt, the number of threads per inch is higher, so the thread is finer. UNEF (Unified Extra Fine) is the same as UNF except that the number of threads per inch is even higher for each fastener size. UNF and UNEF fasteners are generally available only from industrial fastener suppliers. 4UN, 6UN, 8UN, 12UN, 16UN, 20UN, 28UN, and 32UN are thread series in which the number before the UN indicates the number of threads per inch.