[0001] This invention relates to an inflatable boat with a flexible skin defining the bottom
of said boat; a reaction member having a rigid reaction surface overlying said skin;
and inflatable members between said bottom and said reaction surface, each inflatable
member when inflated deforming said skin into a keel.
[0002] Such a boat is known from the document DE-A-1964657, from which the present invention
is distinguished, shows a boat with multiple keels formed by inflatable members. They
are arranged so that the boat rises when at speed. They are orientated in such a way
to tend to direct water flow towards the motor at the rear of the boat.
[0003] There have been other prior proposals relating to the underwater surface of inflatable
boats, and it has also be suggested that for rigid-hull boats multi-keel underwater
surfaces should be provided. Thus in GB-A-1,273,692 there is disclosed a boat hull
provided in a forward section with a twin keel and in a rearward section with a single
keel. The forward twin keels may each be lowerable or raisable to improve riding characteristics
of the hull.
[0004] In GB-A-1,319,072 there is disclosed an inflatable boat in which the shape of the
hull is a function of the hull construction itself of a number of infalatable tubes
which cooperate to provide a generally U-shaped or V-shaped cross-section for the
hull.
[0005] In GB-A-1,362,677 here is disclosed an inflatable boat having inflatable side walls
serving as floatation members, a flexible underwater skin, a rigid deck and between
said skin and deck an inflatable former member along the longitudinal centre-line
of the boat shaping the flexible skin to form a central keel.
[0006] In none of these prior art proposals has it been appreciated or suggested that by
having a boat with a flexible underwater skin and inflatable former members to cause
the undersea surface of the boat to have a multi-keel construction, automatic adaptation
of the planing characteristics of the boat to the load carried in the boat could be
achieved.
[0007] The present invention overcomes these disadvantages by providing a boat having a
keel on each side of the centre line of the boat with a constant-width channel between
the mutually parallel keels centered on the centre line, the channel formed by said
skin being continuous and water-contacting when the members are inflated and the boat
is at rest, the channel also being continuous along the parallel keels when the boat
is planing but variable in its depth in accordance with the loading experienced by
the boat on water so as to adapt the shape of the water-contacting surface to load
conditions.
[0008] The present invention is concerned to form, by inflation, a multi-keel underwater
surface. The proposal uses the flexibility of a fabric skin, stretched over shaped
inflated formers, to allow inherently the adaptation of the shape of the underwater
surface to load conditions being experienced. This gives a self-compensating underwater
surface which retains its good planing performance under all load conditions. The
use of parallel twin inflated formers (preferably separate sacs or tubes) to give
a generally W-section underwater surface is simplest and at the same time yields very
good results. The spacing apart of the parallel formers may be approximately 50% of
the deck width of the boat, when only two keels are present.
[0009] The floor will provide the reaction surface against which the formers act and will
most conveniently be rigid panels extending the whole width of the boat and terminating
under, and being supported by, the inflated buoyancy tubes of the boat.
[0010] Boats thus constructed may be of any appropriate size but especially suitable will
be application of this invention to boats of larger sizes, e.g. 5 metres length upwards,
whether with single or multiple engine installations.
[0011] A particular boat embodying the invention will now be described with reference to
the accompanying drawings wherein:
Figure 1 is a plan view of the forward part of the boat;
Figure 2 is a perspective view of the forward part of the boat;
Figure 3 is a partial, diagrammatic, lateral section;
Figure 4 is a side view and
Figures 5 and 6 show front views of the boat in the water in heavily and lightly loaded
condition respectively.
[0012] The boat 1 has the usual U-shaped inflated buoyancy tube 2 attached to a flexible
fabric floor 3 and a rigid deck 4. The deck 4 is made up of rigid panels extending
the whole width of the flexible fabric floor. A forward panel 5 is adpated to the
shape of the bow of the boat, a removable panel 6 allows for the assembly of the floor
and for access to inflatable keel-formers, and at least one rear panel 7 extends as
far as a transom 8 (Figure 4) which closes off the after end of the boat and to which
(a) power unit(s) can be attached.
[0013] The panel 6 has plates 9 fitting over the adjacent edges of panels 5 and 7 and has
expansion braces 10 boltable to panel 5 and then expansible to tighten the floor in
the boat. The edges of the panels are trapped under the overhang of the inflated buoyancy
tube (Figure 3).
[0014] Between the deck 4 and the floor 3 there are fitted two parallel inflatable tubes
11. Respective inflation valves 12 are accessible through parts 13 in the panel 6.
The tubes 11 are spaced apart by about 50% of the width of the deck 4.
[0015] When the buoyancy tube 2 and the keel-formers 11 are inflated the deck 4 provides
a reaction surface from which the tubes 11 act to press the floor 3 downwardly to
form a W or catamaran section with twin keels 14 separated by a channel 15, 15'. The
panels of the deck 4 are supported by the overhang of the buoyancy tube 2.
[0016] As can be seen in Figures 5 and 6 the inherent characteristics of a flexible floor
3 supported by spaced inflated keel-formers is to adapt its conformation to the load
being experienced. Greater load deepens the channel between the two keels 14 (15'
as against 15). This gives good planing characteristics under any load conditions,
something which is difficult to achieve for most flexible-bottom inflatable boats.
1. An inflatable boat with:
a flexible skin (3) defining the bottom of said boat;
a reaction member (4) having a rigid reaction surface overlying said skin (3); and
inflatable members (11) between said bottom and said reaction surface, each inflatable
member (11) when inflated deforming said skin into a keel (14) characterised in that
there is a said keel (14) on each side of the centre line of the boat with a constant-width
channel (15, 15') between the mutually parallel keels centred on the centre line,
the channel formed by said skin being continuous and water-contacting when the members
are inflated and the boat is at rest, the channels also being continuous along the
parallel keels when the boat is planing but variable in its depth in accordance with
the loading experienced by the boat on water so as to adapt the shape of the water-contacting
surface to load conditions.
2. An inflatable boat according to claim 1 wherein the reaction member (4) consists
of a rigid deck (6) overlying the flexible skin (3).
3. An inflatable boat according to claim 1 or claim 2, wherein the inflatable members
are two parallel tubes (11) which on inflation give a twin-keel boat with only one
keel (14) on each side of the centreline of the boat.
4. An inflatable boat according to claim 3 wherein the parallel tubes (11) are spaced
apart by a distance equal to about half the width of the reaction member ( 14).
1. Schlauchboot mit einer den Boden des Bootes bildenden flexiblen Haut (3), einem
Widerlagerteil (4), das eine die Haut (3) überdeckende starre Widerlagerfläche aufweist,
und mit zwischen dem Boden und der Widerlagerfläche angeordneten aufblasbaren Teilen
(11), wobei jedes aufblasbare Teil (11) im aufgeblasenen Zustand die Haut (3) zur
Bildung eines Kiels (14) (verformt, dadurch gekennzeichnet, daß auf jeder Seite der
Mittellinie des Bootes ein Kiel (14) angeordnet ist und zwischen den beiden parallelen
Kielen eine Rinne (15, 15') von konstanter Breite zur Mittellinie mittig angeordnet
ist, wobei die von der Haut (3) gebildete Rinne durchgehend und wasserbenetzt ist,
wenn die Teile (11) aufgeblasen sind und das Boot stillsteht, und wobei die Rinne
längs der parallelen Kiele (14) auch dann durchgehend ist, wenn das Boot gleitet,
aber in ihrer Tiefe in Abhängigkeit von der Beladung des auf dem Wasser befindlichen
Bootes veränderlich ist, um die Form der wasserbenetzten Oberfläche an den Beladungszustand
anzupassen.
2. Schlauchboot nach Anspruch 1, dadurch gekennzeichnet, daß der Widerlagerteil (4)
aus einem die flexible Haut (3) überdeckenden starren Deck (6) besteht.
3. Schlauchboot nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die aufblasbaren
Teile zwei parallele Schläuche (11) sind, die beim Aufblasen ein Doppelkielboot mit
nur einem Kiel (14) auf jeder Seite der Mittellinie des Bootes ergeben.
4. Schlauchboot nach Anspruch 3, dadurch gekennzeichnet, daß die parallelen Schläuche
(11) in einem Abstand angeordnet sind, der ungefähr der halben Breite des Widerlagerteils
(14) entspricht.
1. Un bateau gonflable avec:
une peau flexible (3) définissant le fond dudit bateau;
un élément de réaction (4) ayant une surface de réaction rigide surmontant ladite
peau (3); et
des éléments gonflables (11) entre ledit fond et ladite surface de réaction, chaque
élément gonflable (11), lorsqu'il est gonflé, déformant ladite peau en une quille
(14), caractérisé en ce qu'il y a une dite quille (14) de chaque côté de l'axe du
bateau, avec un canal d'écoulement de largeur constante (15, 15') entre les quilles
mutuellement parallèles, centré sur ledit axe, le canal formé par ladite peau étant
continu et étant en contact avec l'eau lorsque les éléments sont gonflés et que le
bateau est au repos, le canal étant également continu le long des quilles parallèles
lorsque le bateau part au planing, mais étant variable en profondeur, selon la charge
subie par le bateau sur l'eau, de manière à adapter la forme de la surface en contact
avec l'eau aux conditions de charge.
2. Un bateau gonflable selon la revendication 1, dans lequel l'élément de réaction
(4) consiste en un plancher rigide (6) surmontant la peau flexible (3).
3. Un bateau gonflable selon la revendication 1 ou la revendication 2, dans lequel
les éléments gonflables sont deux tubes parallèles (11) qui, lorsqu'ils sont gonflés,
donnent un bateau à quilles jumelles, avec seulement une quille (14) de chaque côté
de l'axe du bateau.
4. Un bateau gonflable selon la revendication 3 dans lequel les tubes parallèles (11)
sont espacés d'une distance égale à peu près à la moitié de la largeur de l'élément
de réaction (4).