The “Brave” class of FPB’S were to finally demonstrate the viability and success of using gas turbines as main machinery for fast surface craft and from the early trials with HMS Grey Goose, through to the “Bold” experiments etc, the “Braves” proved to be the epitome of ‘wet hulled’ FPB design.
Long before HMS Brave Swordsman was completed it was realised that these were going to prove to be expensive craft to build. Messrs Vosper Ltd therefore planned, as a private venture, a two-turbine version but using well tried and ‘traditional’ building methods.
Using the high Chine and deep ‘V’ sections, as incorporated in the “Brave’s”, but being rather ‘softer and deeper’ in the forward sections. Using glued ‘all timber’ construction making full use of laminated plywood techniques etc to a considerable extent; the cost of the Hull construction for “Ferocity” was kept down to a minimum. Although still quite expensive, as a prototype, the ‘initial costs’ were considered as favouring the then current production methods used at Messrs Vosper Ltd while being much cheaper to repair than the composite material construction employed in the building of the “Brave” Hulls.
The use of two, as opposed to three, Proteus Gas Turbines allowed a much narrower Beam while the up rated engines (from 3500bhp max to 4250bhp max) promised to give similar performance with comparative armament profiles. The designed length of “Ferocity”, as against the “Braves”, was also shortened as the 3.3inch gun, under development (and originally fitted to “Bold Pioneer”), was eventually cancelled.
Other major changes from the “Brave” class were the introduction of two small diesel engines for cruising and manoeuvring. Gas turbine’s inherent high consumption at low power outputs made this change favourable as it increased the operating range to 2000 miles. Two Mathway-Daimler diesel engines, with a continuous rating of 150bhp each, were connected to the two main prop shafts via the V drive-reduction gearboxes. “Ferocity” retained the two Rover Gas Turbines for electrical power generation.
The much-reduced Beam however proved to be too narrow and a revised figure was quickly calculated for the first export model ordered by the then- German Federal Navy. This craft, (Pfeil. P6193), was ordered alongside an export modified “Brave” (Strahl. P6194), that craft using similar building techniques and materials as used in “Ferocity”.
(Both of these craft were eventually transferred to the Royal Hellenic Navy in 1967 after first being refitted by the then incorporated Vosper\Thornycroft Companies).