Cockle Mk. II Canoe

Despite intentions for a pilot model to be tested by the Special Service Brigade, this plan does not come to fruition. The beam size of this design indicates it is different from the 4.6-meter Mk. II canoe. Following the staff meeting on March 9^th, 1942, Hasler communicates the requirements to Hussey, who arranges a meeting between Goatley, now consulting for Saro Laminated Woodwork Ltd on the Isle of Wight. This partnership, previously undocumented, contributes to developing the canoe used in the Frankton Raid on Bordeaux Harbour, primarily designed by Goatley.

Further developments occur at a meeting at Combined Operations Headquarters on March 9^th, 1942, after which Hasler sends a copy of the staff requirements to Goatley on March 30^th, 1942. While the requirements mention a needed length near 5 metres, Goatley’s document suggests a new maximum length of about 5.2 metres. Other specifications include passage through a 72 centimetres hatch with sufficient clearance, a foldable gunwale outside the chine, and a reduced cockpit size with the potential for an all-fabric deck. The CODC has already approved Goatley’s design, facilitating a smoother progression with fewer bureaucratic delays. An immediate order for six canoes is placed with Saro’s, under contract number C.P. BSF/36052/42 dated April 21^st, 1942.

This order specifies delivery instructions and anticipates the deployment of these canoes across various naval units. The urgency of production is evident, with Saro’s preparing to produce the first pilot canoe by the end of April 1942. Throughout this process, various technical and design adjustments are discussed and implemented to optimize the performance and utility of the canoes, highlighting the collaborative and dynamic nature of this pivotal wartime development.

Specifications Cockle Mk. II Canoe

The Cockle Mk. II canoe is a fully decked, two-man craft, expertly crafted to navigate turbulent waters while carrying two men and approximately 68 kilograms of equipment. It stretches about 4.9 meters in length, with a beam of 72.5 centimeters, and a depth of 30 centimeters, which collapses to just 15 centimeters for ease of transport and storage, weighing around 40 kilograms. The width of the canoe is specifically designed to fit through a submarine’s forward torpedo hatch.

Constructed with a flat wooden bottom made from 3.2 millimeters thick plywood, the canoe is also equipped with shallow bilge keels that facilitate dragging across varied terrains such as mud, sand, or shingle, even when fully loaded. Its sides are made from either canvas or rubberized fabric, and the deck is constructed from 3.2 millimeters plywood reinforced by rigid wooden gunwales. The collapsible design of the Mk. II allows the sides to fold down, enabling the deck to lie flat on the bottom. When erected, the deck is supported by eight hinged struts.

The central cockpit of the canoe is sheathed in waterproof fabric, designed for quick disengagement to facilitate rapid escapes, such as after capsizing. Elastic seals at the bottom of the men’s jackets create an almost watertight joint around the cockpit’s edge, essential for maintaining integrity in rough water conditions where waves may wash over the deck. Navigation is enhanced with the inclusion of a magnetic compass, and the crew employs double paddles, which are jointed in the middle to increase versatility. Steering is coordinated through paddle strokes and supported by a variety of hand signals for silent communication.

In challenging sea conditions, teamwork becomes crucial to maintaining balance and managing the canoe’s buoyancy. In the event of capsizing, swift action is necessary to right the canoe without allowing it to fill with water, a demanding task that highlights the importance of precise cooperation and physical fitness.

Each unit was priced at £160, with a total of 876 units produced.

Submarine Handling

The Cockle Canoe is designed for use onboard a submarine, although moving it around in the tight quarters is a delicate operation with a significant risk of damaging the canoe due to the tight fit. Getting the canoe in and out of a submarine is a well known practice. It involves lowering it down or up the forward torpedo hatch, a shaft of very narrow diameter inclined at about 45 degrees.

The greater challenge, however, lies in developing a method to launch the canoes from the submarine in the open sea. Once launched, these canoes can handle quite rough conditions, but the initial stage of separating from the submarine is crucial. Previous operations in the calmer Mediterranean involved lowering empty canoes from the submarine’s casing into the water. The canoes were then moved to the forward hydroplanes, serving as a makeshift platform, from which the men would enter and receive their stores.

This method is unsuitable for the rougher conditions of the Atlantic, especially given the heavy cargo that needs loading into the canoes. The risk of the canoes being swamped before the crew can secure themselves is too high. Hasler, therefore, proposes a new approach: hoisting each canoe out over the side, fully loaded with its crew inside and the cockpit covers secured. This method would prevent swamping and leave only the risk of capsizing.

During the preparations for Operation Frankton in 1942, Major Hasler of the Royal Marine Boom Patrol Detachment devises a special sling for this purpose, made of two wooden spreaders linked by two broad, heavy webbing strips with a wire lifting strop attached to each spreader. The canoe, initially loaded only with cargo at the ends, is placed onto this sling spread out on the submarine’s casing. After loading the remaining cargo bags, the crew enters and secures the cockpit covers. The canoe is then hoisted over the side, floating off the webbing once it hits the water and quickly pushed clear of the sling.

To facilitate this, the staff of the 3^rd Flotilla (the unit that was providing submarine support for Operation Frankton) engineered a simple yet effective hoisting mechanism by clamping a steel girder to the underside of the submarine’s gun muzzle. This girder, extended well beyond the muzzle like a bayonet, is equipped with a rope tackle for lifting. Controlled by the gun’s aiming mechanisms, the girder can be maneuvered as needed. This setup does not hinder the gun’s operation in emergencies and proves crucial in enabling the launch of canoes in open waters, although it demands significant practice from both the canoeists and the crew operating the hoisting gear, especially when contending with sea swell.

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