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‘MUSTANG’ A NATIONAL 12 IN G.R.P.

Author unknown

For a variety of reasons more people are finding it increasingly difficult to find time to carry out essential maintenance on their craft or to keep them in the condition they would like them to be; perhaps it is due to the fact that they now sail twelve months of the year or it may be through sheer pressure of work. This situation, coupled with the other advantages of G.R.P. such as integral construction no sprung planks or leaking buoyancy tanks, super fine external finish, self colour through­out and lower costs, prompted Graham Rabbitt to design, and Don Woof to build, the first G.R.P. National 12 dinghy.

When approaching the problem of design, their first consideration was that she should not be extreme in any direction: she should have good sea qualities coupled with a good tacking. They also felt that there was a need for a slightly greater displacement to carry a crew of 20 to 23 stone rather than the more common 18-20 stone.

The hull lines are therefore as fine as the rise of floor measurement will allow, sweeping back to a maximum W.L. beam of 3 ft. 10 in. at 7 ft. 6 in. from the stem. The sections flare out to a smooth curve to give a maximum beam of 5 ft. 9 in. over the skin and 6 ft. over the rubbing strip. These smooth sections coupled with good freeboard allow the boat to be heeled to advantage in light air with a consequent reduction in wetted area. A moderate rocker is used with a long clean run to the transom.

Trials so far would seem to indicate that the designer’s and builder’s aims have been achieved. Mustang planes very early in a level attitude and is completely stable. She has no vices and feels completely under control at all times. Under light wind conditions she has shown the ability to ghost along due to the low wetted area, while in the rougher stuff she really comes into her own and is well able to carry her sail. Many helmsmen have commented on the cleanness of her wake and the complete absence of any fussiness.

On the construction side it was felt that this being a Restricted Class it would be wrong to offer an all G.R.P. boat. The inclusion of a G.R.P. deck would limit the scope of the owner as to any changes he might wish to make in the layout or the position of fittings; in any case it would have made it difficult for the builders to offer shells for home completion.

G.R.P. is used where it is most advantageous, i.e. hull, centreboard case and buoyancy tanks, while the deck structure thwarts and capping strips are in timber. The result is a dinghy of pleasing appearance incorporating all the advantages of G.R.P. construction yet retaining the flexibility of layout that will appeal to ‘Twelve’ owners.

In the past one of the difficulties when using G.R.P. was the problem of obtaining adequate stiffness without excessive weight. This has been overcome by using a sandwich construction based on end grain balsa giving an extremely rigid structure, light but robust.

Two versions are available with the same external lines but having different buoyancy layouts, both have transom flaps. The Mark I has two tanks, one three-quarter height forward giving some 400 lbs. and one horse shoe shaped tank aft giving access to the flaps and support to the floor, the total lift is in the region of 660 lbs. The Mark II has the same forward tank but the aft tank is reduced in height and two long quarter tanks run forward in the turn of the bilge giving some 100 lbs. each and a total buoyancy of 800 lbs. The forward top face of these quarter tanks is used to secure the side benches and provide a broad platform for the jib fairleads. Both variants now have dished transoms with wide side decks of the modern type having deep returns to their inside faces. Cold moulded rolled side decks are available as an optional extra.

Prices: 

Complete Dinghy £295 ex sails. Bare Shells, Mark I £135: Mark II £145. There are many optional extras, e.g. Mast Bend Control, Adjustable Jib Fairleads, G.R.P. Centre Board and Rudder Blade.

Full details may be obtained from the builder, Donald A. Woof.

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