HMS Speedy: Seakeeping trials, 25 February to 1 March 1982

The results of seakeeping trials carried out on HMS Speedy off the Eddystone Lighthouse (off Plymouth, English Channel, UK) in sea states 4 and 5 are presented. The craft was capable of remaining foilborn throughout, and with the exception of longitudinal acceleration, the motions and accelerations experienced were higher when hullborn. The hydrofoil is concluded to be an extremely stable platform in the foilborn mode. It is capable of operating with 'hands off' under the control of the automatic control system up to and including sea state 4, although manual override is sometimes necessary. In sea state 5 with manual control HMS Speedy can operate with very little loss of speed (usually in excess of 40 knots).