The ‘True Frigate’ 1748-1778 Part II

This highly detailed model of the Lowestoffe, launched in 1761, represents Sir Thomas Slade’s final thoughts on the 12pdr 32-gun frigate. The hull form was developed from that of a French prize, the more upright stem and sternpost being obvious features, but the midship section is more difficult to appreciate in a photograph. The French employed a characteristic transverse shape with sharp angles at the ends of the floors and around the load waterline, combined with excessive tumblehome (the curving in of the topsides), but it is notable that the British avoided the extreme versions of this ‘two-turn bilge’, preferring more rounded versions with less tumblehome. In Lowestoffe Slade produced a very fast ship, but she was only a slight improvement over his already excellent Niger class.

Continuity and Conservatism, 1771-1778

Slade died in 1771 leaving an impressive body of work – outstanding frigates, continuously improved 74s and the immortal Victory, the finest First Rate of the century – but, more significantly, a daunting reputation. Sir John Henslow, one of his followers and himself a Surveyor in the 1790s, summed up the view among his contemporaries: ‘My late very esteemed friend and patron, Sir Thomas Slade, he was truly a great man in the line he took, such a one I believe never went before him, and if I am not too partial, I may venture to say will hardly follow him.’ His successors certainly trod softly in the shadow of the great man.

Cruiser building had lapsed with the peace of 1763, but the threat of war with Spain in 1770 prompted a small programme of frigate construction. Alongside a few additions to Slade’s 32-gun Lowestoffe and 28-gun Mermaid classes, the new Surveyor, John Williams, produced his own designs for both rates. These set the precedent for his very conservative approach, although this was underpinned by the general satisfaction with existing dimensions, proportions and specifications. His resulting Amazon class 32s and Enterprize class 28s were almost clones of the earlier Niger and Unicorn classes, except that relatively minor changes to the lines of both classes actually degraded their performance under sail.

As tensions with Britain’s north American colonists escalated into rebellion, the Admiralty’s response was considered: six more 28s to Williams’ Enterprize design were ordered in 1776 and a further nine over the next two years, but no 32s. Instead, there was an apparently surprising return to the two-decker 44, built to a design derived from Slade’s Phoenix via a slightly modified one-off, the Roebuck of 1769. This was not a failure of belief in the frigate form, but a conscious response to the requirements of ‘littoral warfare’ as it is called these days. The colonies had no navy to speak of, and 28s could deal with the largest privateers, but the amphibious and shore bombardment missions characteristic of this war required ships of relatively shallow draught but heavy batteries – with 18pdrs on the lower deck, the 44s fulfilled this need perfectly, and nineteen of them were built during the conflict.

STRUCTURE: French and British

As a shipbuilding material, wood suffered from two major drawbacks of its organic nature: it was only available in limited dimensions, and it was subject to natural decay over time. These two factors determined the way wooden vessels were built. Ships were necessarily made up of many relatively small pieces, which placed great importance on the way they were put together – the methods of fastening – and the quality of those individual parts. The structural design was essentially a transverse system whose principal strength members were the large athwartship timbers loosely known as frames. Relatively speaking, wooden ships were longitudinally weak and therefore vulnerable to stresses set up by the action of wind and wave on the hull, which because of its fine ends possessed far less buoyancy fore and aft than amidships. This led to a condition known as ‘hogging’ in which the hull arched upwards, ‘breaking the sheer’ in the contemporary expression, opening up seams and forcing out the caulking that made the hull watertight. The gradual loosening of the hull’s integrity let in water, accelerated decay and degraded the performance of the ship itself.

Minimising this problem was a major concern for shipwrights, and there were various approaches open to them: increasing the scantlings (a term that encompassed both the breadth and thickness of the timbers); employing more elaborate fastenings; or optimising the hull design for greater strength. The first, which generally meant more substantial frames with less space between them, resulted in heavier and therefore slower hulls, so was not entirely appropriate for frigates (although British ships were generally more heavily built than those of their enemies). The second was something to which the British paid special attention, so that beam-ends, for example, were secured by both hanging and lodging knees, and ever more complex schemes of fastening were applied throughout the structure; this was costly in both labour and materials, but in the British view repaid by more durable hulls. The third was more subtle, in that the British preference for shorter, deeper hulls naturally endowed them with greater girder strength, despite the downside of potentially slower speed.

That these were conscious policies is evident from a comparison with French practice, which was dramatically but consistently different. French frigates were longer, shallower and often more fine-lined, so at full load might displace about 25 per cent less than a British ship of similar burthen (a ‘tonnage’ calculated from the length, breadth and depth, known as Builder’s Measurement or bm for short). They were also more lightly built (typically, hull weight was about 48 per cent of full load displacement, or about 5 per cent less than for a comparable British frigate), largely because the frame timbers were of slighter scantling with more space between them. Associated with light timbering was a more limited scheme of fastening, particularly the absence of many of the knees, riders and other structural reinforcements common in British practice; this contributed to a lighter hull but one that was less rigid.

The many French prizes in Royal Navy service made these differences very obvious to the shipwrights charged with their upkeep, whose surveys and reports were usually critical – French frigates spent more time in dockyard hands, so cost more to maintain, and enjoyed shorter operational lives. In truth, they were never intended for the kind of hard usage to which the British subjected them – there was, for example, no French strategic requirement for allweather, year-round blockade duty – so they were a rather different kind of ship. Put crudely, French frigates were predators, designed to go to sea on limited, well-defined missions, able to run down intended targets and escape on their chosen point of sailing from more powerful opponents. Their light construction served this role as consciously as their hull form.

When scrutinised carefully, the ways various navies built their ships reveals as much about their tactical and strategic priorities as the way they were designed.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.