Bobbin solution
As the British planned for the amphibious invasion of Normandy, particular interest was taken regarding the special problems involved with beach landings. According to Nigel Duncan in his book
79th Armoured Division – Hobo's Funnies, “One unique challenge was the issue of the soil composition at the planned British assault beaches. Reconnaissance... determined that soft blue clay was in abundance... and that it would likely impede trafficability.” IWM photo (1944).
And so it was feared that the tracked vehicles would not be able travel across the soft clay once on the beaches of Normandy, thereby impeding the advance of the Allied troops. The problem was assigned to the 79th Armoured Division, commanded by General Percy Hobart, which designed equipment and vehicles for special battle situations. They were able to quickly solve the problem with the mat-layer and bobbin (also called carpet-layer) which became known as one of
Hobart's Funnies. An earlier type had been used at Dieppe but the new version was more sophisticated and would be used on the newly developed Churchill AVRE which was equipped with with brackets to enable the attachment of various equipment.
Design of the AVRE mat-layer with bobbin
The bobbin attachment consisted of a steel frame with two arms, which carried a canvas mat wound on a large bobbin. Attached to the front of an AVRE, it was able to lay a roadway over otherwise non-traversible soils or barbed wire, by spooling out a 10 foot mat. The process was set in motion using a light charge which caused the mat to drop in front of the tank and unroll while the AVRE proceeded over it. Initially the mats made were made of hessian (burlap or gunny) and could be reinforced with chespaling (the use of small saplings).
These AVREs would carry a crew of 5 and were armed with a Petard 290 mm spigot mortar as well as one 7.92 mm Besa machine gun. Once beyond the problem soil, the AVRE could remove the carpet-laying frame with bobbin, and carry on with its roll of giving transport protection and breaching enemy defenses.
The AVRE
bobbin proved successful, with the main difficulty being durability of the mat they laid, which could only be used a temporary roadway. Reinforced or steel versions of matting were eventually used.