1651 Programme Group

The 1651 Programme of the Council of State of the Commonwealth of England provided for the building of a group of ten new vessels, with the estimates presented to Parliament on 29 May 1651 providing for "one ship and nine frigates".

The projected nine frigates comprised five Fourth rates and four Fifth rates. The Fourth Rates had already been authorised earlier in the year, to consist of three vessels of 410 tons each (the Laurel, Sapphire and Bristol, at a cost of £6.10.0d^{[Note 1]} per ton), to carry 34 guns each, and two larger of 600 tons (the Ruby and Diamond, at a cost of £7.10.0d^{[Note 2]} per ton), to carry 40 guns each. All except the Sapphire (which was built by contract) were constructed in the state dockyards.

The Fifth rates had also been authorised and were all to be built by contact. They were all named on 18 June 1651 as Pearl, Mermaid, Primrose and Nightingale.They were of 286 tons, and each was established with 22 guns and 100 men.

The "one ship" was the Second rate Antelope ordered on 8 August 1651 to be built by Master Shipwright Christopher Pett at Woolwich, originally to carry 40 guns and to be 110 ft keel length, 32 ft breadth and 18 ft depth in hold (thus intended to have a burthen of 59914⁄94 bm tons); on 1 October the Council agreed to a request from its own Admiralty Committee that Pett be allowed to build his frigate "to his own dimensions", and also that she may carry 50 guns. In fact, when the ship was completed she measured 120 ft keel by 36 ft breadth by 14 ft depth in hold (thus having a burthen of 82788⁄94 bm tons), and was fitted with 56 guns.

Finally, the Admiralty Committee issued an Order on 5 December 1651 to also build three small vessels "to ply among the sands and flats to prevent pirates". These three were the Drake, Merlin and Martin, which were of varying dimensions and tonnage, but were all built in the state dockyards and established as Sixth rate vessels to carry 14 guns and 90 men apiece.