With the traditional double-ended lifeboat now replaced by fast lifeboats at every one of the Institution's stations RNLI Naval Architect Keith Thatcher takes a look at two of the classes which dominated the Institution's carriage-launch fleet for many years.

Both were the product of the innovative R. A. OakleyTo many people the word lifeboat will always conjure up a picture of a long, low craft, pointed at both ends with the crew, open to the elements, crouching behind a small protective screen. Alas, times are changing and with the last Mersey now on station at Aldeburgh (see THE LIFEBOAT Winter 1993/94) the age of the traditional boat has passed.

From the days of the Original lifeboats have always been pointed at both ends, or 'double-ended'. Relying for propulsion on muscle power and wind, having a pointed stern helped the coxswain remain in control when negotiating big following seas.

Even when engines took the place of oars the tradition was maintained as being the best design for the job.

It was only with the advent of faster boats and semi-planing hulls that things had to change. We have already looked at the development of these faster boats, from the Waveney through to the Arun and Tyne, but many consider the modern selfrighting lifeboat to have originated from the ideas of one man, the Institution's naval architect R.A. Oakley.

Self-righting Following the Second World War lifeboat designs fell into two distinct groups, the large slipway launched Watson and Barnett class boats and the smaller carriage-launched Liverpool and Self-Righting classes. None of the larger boats, nor the Liverpool, would self-right but relied on having very good, upright stability which allowed them to be rolled well beyond 90° before capsizing. Only the 35ft 6in Self-Righter had the ability to save itself but, because of low upright stability, it was not well liked.

None of the smaller boats offered much crew protection and lifeboatmen felt that their chances of survival if thrown into the sea, especially in winter, were not great. Having a self-righting boat was almost irrelevant under the circumstances.

The Oakley 37 changed all that. By employing a combination of offset buoyancy and an opposing offset weight R.A. Oakley developed a boat which had excellent upright stability whilst still II having the ability to self-right from any angle. (Model tests carried out using models of the Liverpool, the best small boat then in service, and the Oakley 37 showed a resistance to capsize of the new design significantly betterthan the Liverpool.) Since the majority of the smaller boats were, and still are, launched from a carriage off an open beach, overall weight was a problem. To keep the boat as light as possible and still provide a good solid working platform when afloat, a self-flooding and emptying water ballast tank was fitted into the bottom. This added 1 1 /4 tons of weight where it could do the most good. This water ballast also formed the righting weight. The actual method of righting is described and shown in the sketches. It will be noticed, however, that the Oakley 37 always rights the same way. If capsized to starboard she turns through 360°, if to port through only 180°.

Re-design The first Oakley 37 (ON 942) entered service at Scarborough in 1958 and despite a number of changes, continued in service until 1993, surely something of a record. She was followed in fairly quick succession by a total of 26 Oakley 37's, the last being built in 1971. All maintained the traditional lifeboat profile - open cockpit for crew and survivors, end boxes and small engine casing.

In 1972 it was decided to re-design the boat with a larger superstructure to provide self-righting without resorting to the water ballast system, and to offer more crew comfort in the form of a wheelhouse. With the hull lengthened Bin at the bow thisnew boat was named the Bother class. The greatest obvious difference in the profile is the long, almost full length watertight casing which stretches from the fore buoyancy chamber to the aft end of the engine room and, for the first time in a small boat, provided a watertight dry survivor cabin. The wheelhouse was fitted with a buoyant roof to aid righting but was still open at the rear. This would eventually be enclosed by a clear plastic screen and, as part of the design, there was a radar scanner fitted, something not available when the Oakley 37 was built.

In 1982 it was decided to provide the Oakley 37 with more modern crew protection (they were all open cockpit with just a small windscreen to keep the spray off). As boathouse height is a prime consideration for any carriage boat, there could be no fixed structure above the existing casing top. A folding wheelhouse was therefore designed and fitted to a trial boat. It was an instant success and soon the whole fleet had been converted.

The change made the Oakley slightly resemble the Bother but there was one major difference.

Under continued pressure from their crews the Oakley had eventually been fitted with radar on a tripod mast at the forwardend of the engine casing. This was designed to hinge forward into the survivor cockpit but the need to manhandle the structure severely limited the size of scanner it could carry. The new lightweight, and predominantly plywood, wheelhouse could not take the weight of a folding radar bracket on the roof, as on the Bother, so the radar had to remain in its original position.

And so they remained until the end, the concept of the design basically unchanged and just as effective in the 1990s as they had been in 1958. It was only because the quest for more speed, and the Institution's commitment to an all fast lifeboat fleet by the end of 1993 that the Oakley and Bother had to go. In all, 40 Oakleys and Bothers were built and it is a fitting tribute to the genius of the design that a boat which was conceived in the immediate post war resurgence in lifeboat building should survive as the last of its type over 40 years later.

Principal Dimensions Length overall Beam Draft Displacement Weight (ex ballast) Speed Bange Engines Number built Introduced Last built Last withdrawn 37ft Oakley 37ft Oin 11ft6in 3ft 4in 1 2 tons 9.12 tons 8 knots 180 miles 2 x 43hp Perkins (later 52hp Ford Porbeagle) diesels 26 1958 1971 1993 37ft Rother 37ft 6in 11 tiffin 3ft 6in 13 tons - 8 knots 180 miles 2 x 52hp Ford/ Thorneycroft diesels 14 1972 1982 1993The valves controlling the entry of water into the righting tank were arranged to operate at about 110° from the upright, as at this angle the boat has already capsized. When capsizing to starboard, the water starts to flow into the righting tank on the port side at about 110°. This transfer of weight, aided by a loss of buoyancy in a flooding compartment built into the port side of the engine room casing, produces a list in the upsidedown condition and this, coupled with the righting moments of the design, rights the boat - her port side emerging first.

When capsizing to port the transfer of water operates in the same way, and the boat returns to upright - her port side again emerging first.