Ships – Boats – boat component – or attachment – Sectional
Patent
1996-12-20
1998-10-27
Swinehart, Ed L.
Ships
Boats, boat component, or attachment
Sectional
114 61, B63B 704
Patent
active
058265333
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a twin-hulled boat designed to be propelled by an outboard motor intended primarily as a work-boat for diving, fishing, fish-farming etc., and of the "Flat-Top" type used in the Florida Everglades for example, with the decks of the two hulls and the top of the central bridge-section arranged to be flush, giving a large area of clear deck, whilst normal catamarans, designed for sailing, have deep "V" hulls to give a good grip on the water. In contrast, Rogers (EP 0 353 901) describes a demountable sailing catamaran comprising two flat-bottomed planing hulls joined by a metal support frame with fabric stretched across it. This resembles the system used in most small sailing catamarans, in which there are two horizontal struts between the hulls at bow and stern, with fabric stretched between them, but in Rogers' design, the ends of the struts are bent downwards and fasten in vertical hull sockets.
In Rogers' design and others (e.g. Bachley, U.S. Pat. No. 3,303,520), the gap between the hulls is considerably wider than the hulls themselves. This is advantageous in a sailing catamaran, since it makes the vessel very resistant to heeling, so that the mast remains vertical and the sails function more efficiently; and also in a motorised catamaran, as increasing the space between the hulls increases the deck area. On the other hand, this wide spacing greatly increases the strain upon the hull fixings. In the Rogers design, the metal frame, being with fabric, can flex to relieve the stress. In Bachley's design, the integrity of the vessel is secured by using rigid boards across the vessel which act as cross-members as well as forming the front and back coamings of the cockpit. Both of these methods have limitations. Rogers' method does not allow the possibility of a rigid deck, while Bachley's design limits the free deck areas and requires heavy and cumbersome components. Neither of these methods is suitable for larger craft.
According to the present invention, there is provided a twin-hulled boat comprising two parallel, relatively narrow and relatively long hulls and a central, rigid bridge section, with each hull having a bow section and a stern section, and with bottoms of the hulls flat and parallel to the bridge section both transversely and longitudinally, apart from the bow sections, characterised in that the beam ratio of hull/bridge section/hull is 30%/40%/30% approximately.
The long water-lines, relatively narrow hulls and a central bridge section that is in effect only slightly wider than the hulls themselves give the boat in accordance with the invention low resistance and a high maximum speed when functioning on displacement, while the large flat areas give a low planing speed. As a result, such a boat requires about half the engine power of a conventional boat for equivalent performance. Furthermore, the long, narrow planing areas allow water to escape to the sides, reducing slamming in a sea; they also allow such a boat to avoid the inefficient bows-up attitude adopted by many conventional planing hulls. Finally, the long hulls give good directional stability and consequently such a boat is very easy to steer.
Further and preferred features of the invention are as follows. The hulls are flat topped, and the bridge section is flush with the hull tops, to form a single flat deck area. The flat bottom extends from the base of the stern section forwards for approximately 58% of the overall length of the boat. After approximately 58% of the overall length of the boat, the bottom is formed into a "V" of approximately 143.degree. for approximately 23% of the overall length of the boat to meet the bow section. The boat is readily separable into three parts, being the two hulls and the central rigid bridge section with engine attached, for land transport. Separation is total, with the three parts being three individual elements. Alternatively, separation may be relative, with the two hulls remaining hinged to the bridge section and being hingeable to a land transportation position.
REFERENCES:
patent: Re24618 (1959-03-01), Rosenberg et al.
patent: 2975747 (1961-03-01), Opie
patent: 3045263 (1962-07-01), Blachly
patent: 3114157 (1963-12-01), Stockmann
patent: 3203014 (1965-08-01), Krueger
patent: 3426716 (1969-02-01), Hackworth
patent: 4295236 (1981-10-01), Upchurch
patent: 4303033 (1981-12-01), King
Clancy John George
Stangroom James Edward
Silky Limited
Swinehart Ed L.
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