The Mercury Class
by Peter Vinton
History

Gerald Durbin and David Miles designed the Mercury in 1959. Their aim was to design a round bilge boat that could be built from a kit so it included cold moulded bilge panels with plywood topsides and floors. Finished boats and kits were built by Durbin/Miles' own company Plycraft at Clevedon until 1962 when production stopped at boat No. 99, reputably because they found Fireballs, Solos and other chine craft were much cheaper and more profitable to build. A complete boat sold for 212 and a kit for 129. The dimensions were within the International 14 class rules and in the early 60s a Mercury with a larger rig managed a top six place in the International 14 class championships.

The class was sailed competitively in the Bristol area in the 1960's and 70's. By the mid 80's very few were racing and the class was dying out.

An attempt was made in the early 80s to restart the class. A mould was taken from an original boat and a new, fully cold moulded boat was built, No. 101. This boat had a larger jib extending further aft, sheeting to the inboard side of the side tank. Despite exhibiting this boat at the Dinghy Show and other promotion no more were built. Unfortunately the mould warped and was scrapped. No glassfibre hulls have been made.

In the early 1990's Bob Corfield and Keith Glassbrook, based at Bristol Avon SC began to revive the class by tracking down the remaining Mercuries around the country and bringing them back to Saltford near Bristol. This revival resulted in several more competitive years of sailing with the high point being a national championship held at Clevedon in 1997 with 16 boats taking part. However it soon became apparent that racing seriously boats nearly 40 years old was taking its toll. The best of the boats were those that had had an easy life up until then and another five years or so of racing was all that they could stand.

Since then several more boats have succumbed to rot and decay and ended up as firewood. The class has settled back into obscurity with only a few boats still sailing at Saltford. There are now very few remaining in sailing condition although there are still probably a few unknown, unused boats sitting around in garages in the area. The only possibility of the class surviving much longer is to treat the remaining few boats as carefully as possible.

Description

The Mercury is a light 14' long dinghy with a hull shape typical of the late 50s. It has a slightly raked stem leading into a well rockered keel and a high freeboard with flared topsides to give a reasonable beam. The floors have a rise on them all the way aft although they are flat enough for the boat to plane easily. It could easily be described as a larger Firefly or a smaller Albacore. Although it carries a spinnaker the hull does not have firm enough bilges to carry the sail very effectively on a reach. The boat does however sail well and is reasonably competitive on the same handicap as a Wayfarer. Under CVRDA it's rated much faster which is rather difficult to achieve. It's light enough to handle single handed or with a child as crew but responds

best to two adults crewing, particularly in fresher winds.
Construction

The construction of the Mercury is unusual. The floor and topsides are curved from flat panels of plywood, but the bilges are cold moulded. Therefore two seams run from bow to stern on each side where the panels join, with stringers on the inside at each seam. A bulkhead forwards forms a large bow buoyancy tank and tanks also run each side back to a large stern tank. On some boats the stern tank has been removed and the side tanks extended to the transom. Class folklore says that the floor aft is soft, not having the stiffeners that the cockpit floor has, so removing the aft tank allows stiffeners to be extended aft as well. There is a foredeck but no side decks or aft deck. The centreboard case is extended all the way forward to the bulkhead.

The boat is lightly built and, because it was originally built on a mould without any frames, it is difficult to repair without losing the shape. Leaks around the centreboard case are common as expected with old boats but the case can be removed and resealed without great difficulty. Leaks around the hog are also common and are more serious. The final straw when struggling to keep a Mercury alive is when the hog rots, because it's almost impossible to rebuild the boat then. Any leaks around the centreboard case or hog have to be carefully dealt with, because the leak into the boat could be the result of water rotting the hog from the centreboard case outwards. Delamination of the cold moulded bilges can also be a major problem, due to the glues used in construction being well past their useful life. The side tanks are fitted to the stringers, but because the inner panel is fitted outboard of the lower stringer it gets pushed away by the crew when tacking, causing the tanks to leak. This is also a difficult area to repair.

Rig

The mainsail is of fairly low aspect ratio with four battens, the top being full length. . The original jib was very small, sheeting to the aft end of the foredeck. The larger jib extends aft to the shrouds, sheeting to the inner edge of the side tanks just forward of the thwart. The original mast is a very stiff Proctor aluminium mast with short, round section spreaders. The mast is stepped just aft of the fore bulkhead on the top of the centreboard case. If a later, softer mast is used then a mast gate at deck level is needed to control sideways bend. Originally all booms were wooden.

Sails were originally made in cotton, then terylene by J R Williams in the 60s, all characteristically very flat. In the 80s SM in Bristol made several sets, these were made of fairly thin cloth with insufficient reinforcement. In the 80s and 90s Mac Namara made a few very good sets with the larger jib, and Rockalls made a few sets of cheaper cloth to the original dimensions in the 90s. Osen also made a good set with a larger jib in the 90s.

Length 14' (4.27m), Beam 5'10'' (1.78m), Sail Area 111 sq.ft. (original sail area, 10.31 sq.m), weight 207lb. (94kg)