GB2464768A

GB2464768A - Boat with a pivoting hydrofoil arrangement

Info

Publication number: GB2464768A
Application number: GB0819957A
Authority: GB
Inventors: Gareth Roberts
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-10-31
Filing date: 2008-10-31
Publication date: 2010-05-05
Also published as: GB0819957D0

Abstract

A boat 1 comprising conventional hulls is provided with a pivoting hydrofoil arrangement 2. The sailor is able to transfer his weight from the hulls of the boat and onto a connecting rod 7 of the hydrofoil arrangement, significantly reducing the weight carried by the hulls and in turn reducing the drag of the hulls. Unlike a conventional foiling boat, the hulls are still in the water retaining the desirable stability characteristics of a conventional boat so that no complicated control mechanisms are required. The foils 6 of the hydrofoil section may be positioned perpendicular to a vertical section 5 of the hydrofoil arrangement, or may be angled upwardly when in a rest position.

Description

SEMI-FOILING BOAT

Field of the Invention

This invention relates to a semi-foiling boat. In particular, the invention relates to a semi-foiling beach catamaran, but it is also applicable to various other boat configurations both sail and powered where th weight of the crew of the boat makes up a significant portion of the total weight of the boat.

Background of the Invention

One problem with a conventional boat is that the drag of the hull in the water increases as the speed increases. Some boats get around this by planing.

However many boats cannot plane as they are limited by their hull shape or power to weight ratio.

Some high speed boats such as beach catarnarans use hulls that are too long and thin to promote early planing. Consequently they cannot reach the veiy high speeds attainable by some modern monohulls as a result of the reduced drag associated with planing.

Some monohulls have fitted horizontal foils or wings in order to make the boat "fly", the weight of the boat and crew is supported by the lift generated by the foil in water in much the same way as the lift from an aircraft wing supports the weight of the aircraft. This is often referred to as "foiling" or "hydro foiling". The problem with this technology is one of control of the boats stability, they are difficult to sail for the average sailor and require complicated control mechanisms.

The present invention seeks to overcome these problems.

I

Summary of the Invention

According to one aspect of the present invention, there is provided a boat comprising conventional catamaran hulls, with the addition of a pivoting horizontal hydrofoil, or T-foil. The sailor is able to transfer his weight off the boat and onto the T-foil. This significantly reduces the weight cathed by the hulls and in turn reduces drag of the hulls and may promote early planing.

Unlike a conventional foiling boat the hulls are still in the water retaining the desirable stability characteristics of a conventional boat so that no complicated control mechanisms are required.

An example of the invention will now be described with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 is an isometric view of a boat according to the invention configured for use, the sails and motors are omitted for clarity.

Figure 2 is a front view of the boat showing the horizontal foil.

Figure 3 is a side view of a boat showing the T shaped foil in the resting position.

Figure 4 is a side view of a boat showing the T shaped foil pivoted into the "flying" position, the sailors weight is positioned between the pivot and the T-foil to distribute the weight between the boat and the T foil.

Figure 5 is a side view of a boat showing the T shaped foil pivoted into the "flying" position, the sailors weight is positioned behind the T-foil so his weight is being supported mostly by the T-foil.

Figure 6 is an isometric view of a boat fitted with angled foils.

Figure 7 is a front view of the boat with angled foil.

Detailed Description

Referring to figures 1 & 2 a conventional catamaran 1 is shown with a T-foil aerofoil 2 attached via a pivot 3. In this example the T-foil 2 is attached to the front beam 4 but could be attached anywhere on the boat structure. The T-foil 2 comprises of a vertical section 5 which could be aerofoil shaped attached to a horizontal aerofoil 6. The horizontal foil 6 is designed to provide the vertical lift. The T-foil 2 is connected to tl pivot 3 via a connecting rod 7 which could also act as a seat.

Referring to figure 3, when the boat is at rest the T-foil 2 sinks under its own weight allowing the front or nose of the horizontal foil 6 to be angled upwards. As the boat begins to move water will flow past the horizontal foil 6 in the direction shown by the anow 8 and the force of the water acting on the horizontal foil 6 at this inclination will begin to generate lift 9 in the same way as an aeroplane wing.

Referring to figure 4, with the boat 1 moving the lift 9 on the horizontal foil 6 will cause the T-foil 2 to pivot and lift until it reaches a position of equilibrium where the weight on the T-foil 10 and the lift on the horizontal foil 9 are balanced out. If the sailor sits on the connecting rod 7 the his weight is transferred from the boat 1 to the T-foil 2. The reduced weight on the boat 1 reduces the drag of the boat and the boat will travel faster. The sailor is able to move his weight for and aft on the connecting rod 7. If the sailor sits close to the pivot or allows his legs to support some of his weight then the boat hulls will carly more of the sailors weight and it will behave more like a conventional sailboat. If the sailor sits closer to the T-foil 2 and does not let his legs support his weight then more of his weight will be supported by the T-foil and the boat will increase in speed.

Referring to figure 5, the sailor has shifted his weight 10 behind the T-foil 2, in this instance the T-foil will support all of the sailors weight and some of the boats weight affectively reducing the displacement of the boat.

Referring to figures 6, the boat 1 may also be configured with an angled foil 11, in this instance the lower flying foil is not horizontal but is divided into two separate angled foils 12 & 13. This shape of foil is advantages when used on a sailboat as the foil automatically counteracts the heeling moment of the boat.

Referring to figure 7, as the boat heels over the foil which is more horizontal 12 generates a larger lift 14 and the foil which is less horizontal 13 generates less lift 15. The resulting moment tends to counteract the heeling moment of the boat and help to prevent it from capsizing.

Claims

Claims 1. A boat comprising conventional hulls, with the addition of a pivoting hydrofoil which enables the crew to transfer its weight off the boat and onto the hydrofoil reducing the weight carried by the hulls and in turn reducing the drag created by the hulls.
2. A boat as in claim 1 where the hulls are still in the water retaining the desirable stability characteristics of a conventional boat so that no complicated control mechanisms are required.
3. A boat as in claims 1 & 2 where the hydrofoil is allowed to pivot thus varying the amount of lift provided by the hydrofoil. 0)C cjC