GB2611879A

GB2611879A - Hand-powered watercraft

Info

Publication number: GB2611879A
Application number: GB2213543.8A
Authority: GB
Inventors: Macfarlane Stephen
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-09-22
Filing date: 2022-09-15
Publication date: 2023-04-19
Also published as: GB202213543D0

Abstract

A hand-powered watercraft 100 comprises two sections 102 and 103 releasably joinable to one another at a joint. The joint comprises a first interlocking face 123 on a first of the sections and a second interlocking face 124 on a second of the sections. The first and second interlocking faces being correspondingly shaped such that they interlock with one another when the first and second sections are joined and are releasable from one another in a release direction. The first and second interlocking faces being shaped such that when joined movement in the release direction alone is allowed. All corners on the first interlocking face and all corners on the second interlocking face are greater than 90 degrees. A method of manufacturing the hand-powered watercraft is also disclosed.

Description

HAND-POWERED WATERCRAFT

Technical Field

The present disclosure relates to a hand-powered watercraft, particularly, but not exclusively, a kayak

Background

Hand-powered watercraft, such as kayaks, stand up paddleboards (SUPs), row boats and others, are often long structures which need to withstand significant loads due to carriage of people and impacts from water, such as waves. Further, they are often transported and launched by hand.

For example, sea-kayakers, sea-kayak guides and their clients are expected to lift and carry heavy and fully loaded single piece sea-kayaks to and from the water. Sea-kayaking often requires carrying kayaks over beaches, rocks, up and down cliffs, as well as often loading above head height, for example onto car roofs. It is recognised that more injuries occur from carrying sea-kayaks, and loading them on and off vehicles or trailers, than paddling them on the sea itself. To reduce the overall weight of a sea-kayak to within UK Health and Safety Executive carrying guidelines, it needs to weigh no more than half that of most sea-kayaks currently in use or production.

Sea-kayaks are usually between 4.5 metres and 5.5 metres long and performance sea-kayaks are often made from 'composite' materials, like fibreglass, and more recently Kevlar and carbon fibre. Current carbon fibre sea-kayaks are formed by laying carbon fibre flat into moulds, one for the deck and one for the hull, and then joining the deck and hull with an additional seam running the length of the sea-kayak either side. However, the weight of the final product is still relatively high as it requires significant amounts of additional material to stiffen the components and to hold the entire structure together.

Single piece composite sea-kayaks usually weigh between 24kg and 30kg. Composite, multi-sectional, sea-kayaks are made by cutting a single piece sea-kayak into three sections, then laminating and sealing in the joints. These are always heavier than the original single piece. Plastic modular sea-kayaks are made by forming the sections of the kayak separately, so that they then fit together using various fixings.

Both multi-sectional composite sea-kayaks and plastic modular sea-kayaks rely upon clips, nuts & bolts, and/or straps or cords for the strength of the joint between sections when in use. This causes any stress or shock loading to be transferred along the kayak through the fittings that are holding the sea-kayak together. Further, the mechanical, multi-part components used to hold the sections together often require tools to assemble and disassemble, are very time consuming, and/or have external clips which are exposed to the elements and at risk of being opened by accident.

Summary

There is provided a hand-powered watercraft comprising: two sections, the sections being releasably joinable to one another at a joint, wherein the joint comprises a first interlocking face on a first of the sections, and a second interlocking face on a second of the sections, the first and second interlocking faces being correspondingly shaped, such that they interlock with one another when the first and second sections are joined, the sections being releasable from one another in a release direction.

The first and second interlocking faces may be shaped to prevent movement of the first section relative to the second section in all but one direction when the first and second sections are joined, said direction being the release direction.

Optionally, the first and second interlocking faces may be shaped to provide a load -diverging joint. In this way, loads applied to the joint, for example, during use of the watercraft, is dispersed throughout the joint and the joint has no single points of weakness, thereby making the joint more resistant to the forces applied during use of the watercraft Optionally, all corners on the first interlocking face and all corners on the second interlocking face are greater than 90 degrees. The angles of the corners are measured external to the faces. By utilising large angles, stress applied to the joint is dispersed throughout the joint and the joint has no single points of weakness, thereby making the joint more resistant to the forces applied during use of the watercraft. By contrast, if small angles of less than 90 degrees were used, forces would become concentrated at these corners which become points of weakness in the joint and, ultimately, points of failure. It will be understood that the corners on the interlocking faces do not include corners connecting the interlocking faces to the deck and/or hull. Optionally, all corners on the first interlocking face and all corners on the second interlocking face are less than 270 degrees.

Optionally, a surface area of the first interlocking face is at least 50% greater than a flat area between outer edges of the first interlocking face and a surface area of the second interlocking face is at least 50% greater than a flat area between outer edges of the second interlocking face. This greater surface area means that the interlocking faces have complex shapes which causes any forces applied to the joint to be dispersed over the whole joint and not concentrated on a small number/section of projections. This increases the overall strength of the joint In use, the first and second sections are joined by interlocking the first and second interlocking faces and closing the joint by moving the first section relative to the second section in a direction opposite to the release direction. To separate the sections, the first section is moved in the release direction relative to the second section. It will be understood that the relative movements can be achieved by moving the first section, the second section or both sections.

In this way, the interlocking faces of the sections of the watercraft provide the strength of the joint, rather than point fixings in all but the release direction. This spreads loads applied to the joint across the faces and avoids point loading, thereby resulting in a joint that is less likely to fail.

The joint provided by the first and second interlocking faces ensures that stress, tension, compression and shock loading is transferred from one side of the joint to the other side utilising the fullest area of the surface of the joint and in the most varied directions. The joint does not rely upon point fixings to provide the strength, so avoids point loading.

Instead, the joint uses the shape of the interlocking faces for its strength and disperses any stress or loading throughout the interlocking faces. This utilises dispersed or divergent loading. The use of the interlocking faces means that many of the fixings and other additions to the structure used in current multi-section kayaks are not required, resulting in a more lightweight and easier to use watercraft.

Each section may comprise a portion of a hull of the watercraft and a portion of a deck of the watercraft The first interlocking face may be contiguous with the portion of deck and portion of hull of the first section. The second interlocking face may be contiguous with the portion of deck and portion of hull of the second section. The outer edges of the interlocking faces may meet the deck and hull portions.

Optionally, the first interlocking face comprises a recess and the second interlocking face comprises a protrusion or the second interlocking face comprises a recess and the first interlocking face comprises a protrusion and, when the sections are joined, the recess surrounds the protrusion by more than 180 degrees in a plane normal to the release direction.

The protrusion may be tapered in the release direction. In this way, the surface of the protrusion and the surface of the recess do not slide against one another during release or joining of the sections.

A cross-sectional area of the protrusion in a plane normal to the release direction may decrease along the protrusion in the release direction. The protrusion may comprise a frustum. The protrusion may have a conical portion, which may be truncated.

The first interlocking face may further comprise a first lateral surface and the second interlocking face may comprise a corresponding second lateral surface, wherein the first

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lateral surface and the second lateral surface are configured to contact one another when the sections are joined. The first and second lateral surfaces may be greater than 10, 20 or 45 degrees from the release direction. The first interlocking face may further comprise a third lateral surface and the second interlocking face may comprise a corresponding fourth lateral surface, wherein the third lateral surface and the fourth lateral surface are configured to contact one another when the sections are joined. The third and fourth lateral surfaces may be greater than 101 20 or 45 degrees from the release direction. The first and second lateral surfaces and/or third and fourth surfaces may be planar.

All external surfaces of the each of the interlocking faces may be non-parallel to the release direction. In this way, the two sections can be brought together so all external surfaces of the interlocking faces touch at the same instant. Sliding of parts during assembly and disassembly can be avoided, thereby reducing abrasion of the faces.

In this application, the term non-parallel may require a relative angle of greater than 2 degrees.

The release direction may be in an upwards-downwards direction in relation to the hull of the watercraft. In this application upwards, downwards and horizontal are set in relation to the orientation of the hull of the watercraft when floating on calm water. The release direction may also be in a fore-aft direction. The release direction may be 65 degrees from a horizontal direction. The release direction may be in a direction that is not perpendicular to horizontal.

The first and second interlocking faces may be shaped such that a maximum gap between the first and second faces when the first and second sections are joined is less than 3mm, optionally less than 2mm, optionally less than lmm.

The watercraft may further comprise a pin and the second interlocking face may comprise a hole and the first interlocking face may further comprise a hole configured to align with the hole in the second interlocking face when the first and second sections are joined, wherein the pin is movable from a retracted position within the second section or the first section, to an extended position protruding through the hole in the second interlocking face and the hole in the first interlocking face, a length of the pin being in a direction non-parallel to the release direction.

In this way, when it is extended, the pin prevents movement of the joint in the release direction.

The second section and/or the first section may comprise a plurality of pins and the first and second interlocking faces may each comprise a corresponding plurality of holes, each of the holes in the first interlocking face configured to align with a respective hole in the second interlocking face when the first and second sections are joined and the pins each being movable from a retracted position within the second section or the first section, to an extended position protruding through their respective hole in the second interlocking face and protruding through their respective hole in the first interlocking face, a length of each of the pins being in a direction other than the release direction.

There may be at least 2, 3 or 4 pins per joint A width of the or each pin may be 0.2mm less than a width of the corresponding holes in the first and second interlocking faces. Optionally, the pin may have a tapered shape. Optionally, the pin may comprise a material softer than the material of the first and second interlocking faces. In this way, if any abrasion occurs, the pin suffers from abrasion. As the pin is more easily replaced than the interlocking faces, this ensures longevity of the watercraft The pin or each of the pins may comprise an 0-ring, configured to seal the respective hole in the second or first interlocking face when the pin is in the extended position.

The or each hole in the first or second interlocking face may be blind. This means that water cannot enter the first or second section through the hole(s). Alternatively, the or each pin may comprise a second 0-ring, configured to seal the or each hole in the first or second interlocking face.

The pins may be accessible via a hatch or opening in the second section. The hatch may be a deck hatch. The second or first section may further comprise a locking mechanism configurable to lock the or each pin in the extended position. The locking mechanism may be a bayonet mechanism. The pins may have a handle portion inside the second section.

The pins may have a width of at least 10 mm, preferably at least 20mm. The handle portion may have a width of at least 20 mm, preferably at least 40 mm, preferably at least 45mm, for example 47mm. In this way, they can be operated with a wet, cold or gloved hand.

The pin(s) stop the sections from separating along the release direction. The pin(s) are easy, quick and simple to use and require no tools. The interlocking faces of the sections are robust and effective in creating the strength of the joint, and the pin(s) simply retain the joint together in one direction.

As the sections can be assembled and dis-assembled by hand, without requiring tools, this can be done simply and easily on a beach, meaning the watercraft can be carried full, in sections, to and from the water, with assembly and dis-assembly at the water's edge, whilst loaded with equipment.

Each of the sections may be sealed and/or sealable, for example, by the pin(s). In this way, when the sections are joined each section is watertight. This means that the watercraft is less prone to water ingress and even if one of the sections is breached, the others will provide buoyancy to reduce the risk of sinking.

The watercraft may comprise three, four, five, six or more sections. Each of the sections of 25 the watercraft may be joined to one or two adjacent other sections by a joint as described above.

The watercraft may comprise a bow section, a stern section and a centre section. The watercraft may further comprise a fore section configured to join the bow section to the centre section and a rear section configured to join the stern section to the centre section.

The centre section may be a cockpit section. The watercraft may comprise more than one cockpit section, for example in a double-kayak. The watercraft may comprise a joint as described above between each pair of adjacent sections. Each joint may have its own release direction.

The bow section may comprise a first interlocking face configured to interlock with a second interlocking face of the fore section. The fore section may further comprise another second interlocking face configured to interlock with a corresponding first interlocking face of the centre section. The centre section may further comprise another first interlocking face configured to interlock with a second interlocking face of the rear section. The rear section may further comprise another second interlocking face configured to interlock with a first interlocking face of the stern section. In this way, the strength of each of the joints in the watercraft is provided by the shapes of the interlocking faces. This arrangement of the sections allows the pins to be provided in the fore and rear sections. The pins may be accessible via a hatch in the fore section and a hatch in the rear section.

The watercraft may comprise a hull and each of the sections of the watercraft may comprise a portion of the hull of the watercraft. The watercraft may further comprise a deck and each of the sections of the watercraft may comprise a portion of the deck of the watercraft.

Each of the sections may comprise a monocoque. This increases the strength of the sections and ultimately the watercraft as the strength of the monocoque material can be utilised fully in the monocoque structure. The combination of the monocoque sections and the interlocking faces of the sections spreads load along the watercraft, thereby increasing the overall strength. The lightweight monocoque material combined with the multi-sectional nature of the watercraft also increases portability of the watercraft.

Each of the sections may comprise a composite, such as carbon fibre, fibreglass, kevlar, aramids and/or organic materials. The composite may comprise hemp, flax, bamboo or another fibre. The composite may comprise a bio-resin, optionally with a bio content of 30%. It will be understood that these materials are examples only, and other composites may be used without departing from the invention.

Each of the monocoques may form a hull part, a deck part and an interlocking face of its respective section.

Each of the sections may comprise a plastic.

The hand-powered watercraft may be a kayak, such as a sea kayak, surf-ski or sit-on kayak, a stand-up paddleboard (SUP), a canoe, a row boat a dragon boat or any other type of hand-powered watercraft. A hand-powered watercraft is any watercraft that is primarily propelled by a user's hands via, for example, an oar or paddle. In this application, hand -powered watercraft includes a watercraft primarily propelled by hand, for example a kayak or row boat, with an auxiliary propulsion means, for example a temporary sail/kite/flippers.

There is further provided a hand-powered watercraft comprising: at least two sections, each of the sections comprising a respective monocoque.

Each of the sections may comprise a composite such as carbon fibre, fibreglass, kevlar, aramids and/or organic materials. The composite may comprise hemp, flax, bamboo or another fibre. The composite may comprise a bio-resin, optionally with a bio content of 30%. It will be understood that these materials are examples only, and other composites may be used without departing from the invention. Carbon fibre may comprise pre-impregnated (Prepreg) carbon fibre. The Prepreg may comprise epoxy resin.

Each of the monocoques may form a hull part and a deck part of its respective section. Each of the monocoques may further comprise an interlocking face of its respective section.

The sections may be bonded together. In this way, the single piece watercraft is considerably stronger and lighter than a traditional single piece of the same size.

The sections may be releasably joinable. The lightweight material combined with the multi-sectional nature of the watercraft also increases portability of the watercraft. Further the use of a monocoque structure increases the strength of the sections and ultimately the watercraft as the strength of the carbon fibre can be utilised fully.

There is further provided a method of manufacture of a hand-powered watercraft, the 5 method comprising: forming a first section comprising a first interlocking face, and forming a second section comprising a second interlocking face, the first and second interlocking faces being correspondingly shaped, such that they interlock with one another when the first and second sections are joined, wherein the first and second interlocking faces are shaped to prevent movement of the sections relative to one another in all but one direction when the first and second sections are joined, said direction being the release direction.

The watercraft may be formed by rotomoulding, 3D printing, and/or autoclaving a composite material.

The sections may comprise plastic or composite. Each of the sections may be formed as a monocoque.

There is further provided a method of manufacture of a hand-powered watercraft formed of at least two separable sections, the method comprising: forming a first section from a first monocoque, and forming a second section from a second monocoque.

There is further provided a computer-readable medium having computer-executable instructions adapted to cause a 3D printer to print a hand-powered watercraft as described above.

The methods and watercrafts described above may be combined in any possible combination. The optional features described above are equally applicable to all of the described methods and watercrafts and are not limited to the particular method/watercraft with which they are described here. The essential features of any of the methods described may be optional features of any other method described.

Further features and advantages of the aspects of the present disclosure will become apparent from the claims and the following description.

Brief Description of Drawings

Embodiments of the present disclosure will now be described by way of example only, with reference to the following diagrams, in which:-Fig. 1 is a perspective view of a multi-sectional sea-kayak where the sections are joined; Fig. 2 is a perspective view of the multi-sectional se-kayak of Fig. 1 where the sections are separated; Fig. 3 is a perspective, sectional view of a released joint between two sections of the multi-sectional kayak of Fig. 1; Fig. 4 is a perspective, sectional view of the joint Fig. 3 in the joined configuration; Fig. 5 is a perspective view of a first interlocking face of a section of the sea-kayak of Fig. 1; Fig. 6 is a perspective view of a second interlocking face of a section of the sea-kayak of Fig. 1.

Detailed Description

A number of embodiments of the disclosure are described subsequently.

Fig. 1 shows a multi-sectional sea-kayak 100 having five sections 101-105. The sections include a stern section 101, a rear section 102, a centre section 103, a fore section 104 and a bow section 105. The sea-kayak includes a seat 106, hatches 107 to 112, rudder 113. The centre section 103 is a cockpit section.

The sections 101-105 are releasably joinable to one another. At each joint between adjacent sections, one of the adjacent sections has a first interlocking face and the other adjacent section has a second interlocking face, the first and second interlocking faces being correspondingly shaped, such that they interlock with one another when the first and second sections are joined. For example, the stern section 101 has a first interlocking face 121 and the adjacent rear section 102 has a corresponding second interlocking face 122. The rear section 102 further has another second interlocking face 123 which corresponds to first interlocking face 124 on the cockpit section 103. The cockpit section 103 further has another first interlocking face 125 which corresponds to second interlocking face 126 on fore section 104. The fore section 104 further has another second interlocking face 127 which corresponds to first interlocking face 128 on bow section 105.

The sea-kayak 100 has four joints: a stern-rear joint formed by faces 121 and 122, a rear-cockpit joint formed by faces 123 and 124, a cockpit-fore joint formed by faces 125 and 126, 20 and a fore-bow joint formed by faces 127 and 128.

The first and second interlocking faces 121 to 128 may be shaped to prevent movement of the sections relative to their corresponding faces in all but one direction when the first and second sections are joined, said direction being the release direction.

Interlocking faces 122, 124, 125 and 127 each have at least one recess and corresponding interlocking faces 121, 123, 126 and 128 each have at least one protrusion. The recesses each surround their respective protrusion by more than 180 degrees in a plane normal to the release direction when the sections are joined as shown in Fig. 1.

As can be seen more clearly in Figs. 3.4. 5 and 6 which shows part of the joint between the rear section and the cockpit section, the protrusions, for example 123P, are tapered along their length in the release direction of their respective joint. In this way, the surface of the protrusion and the surface of the recess do not need to slide against one another during release or joining of the sections. The protrusions have adjacent stem portions which attach the protrusion to a slanted surface of the interface. In other embodiments, the stem may not be present and the recess may surround the protrusion by 360 degrees in a plane normal to the release direction for at least some of its length.

The details of the joint will now be described in relation to Figs. 3, 4, 5 and 6 and the joint comprising interlocking faces 123 and 124. The same descriptions apply to the other joints and interlocking faces of the kayak.

Interlocking faces 122, 124, 125 and 127 further comprise a first lateral surface, such as 123L1, and interlocking faces 121, 123, 126 and 128 each comprise a corresponding second lateral surface, such as 124L2, the first and second lateral surfaces being greater than 45 degrees from the release direction. Interlocking faces 122, 124, 125 and 127 further comprise a third lateral surface, such as 123L3 and the second interlocking face may comprise a corresponding fourth lateral surface, such as 124L4 the third and fourth lateral surfaces being greater than 45 degrees from the release direction. The first and second lateral surfaces and/or third and fourth surfaces are planar.

All external surfaces of the each of the interlocking faces are non-parallel to the release direction of their respective joint In this way, the sections can be brought together so all external surfaces of a joint touch at the same instant. Sliding of parts during assembly and disassembly can be avoided, thereby reducing abrasion of the faces.

Each of the release directions of the respective joints of kayak 100 is in an upwards or downwards direction in relation to the hull of the watercraft. The release direction may be 65 degrees from a horizontal direction.

At each joint, the interlocking faces are shaped such that a maximum gap between the first and second faces when the first and second sections are joined is less than 3mm.

Each of the joints further comprises at least one pin 129 and a corresponding hole 130, 131 in each interlocking face of the joint. The holes 130, 131 align with each other when the sections 102 and 103 are joined. The pin 129 is movable from a retracted position shown in Fig. 3 within the section 102, to an extended position shown in Fig. 4 where the pin 129 protrudes through the hole 130 in the interlocking face 123 and through the hole 131 in the interlocking face 124. The length of the pin is in a direction non-parallel to the release direction. When the pin 129 is extended as in Fig. 4, the pin prevents movement of the joint in the release direction.

The section 102 may comprise a plurality of pins and the interlocking faces 123, 124 may each comprise a corresponding plurality of holes, each of the holes in the first interlocking face configured to align with a respective hole in the second interlocking face when the first and second sections are joined and the pins each being movable from a retracted position within the second section, to an extended position protruding through their respective hole in the second interlocking face and protruding through their respective hole in the first interlocking face, a length of each of the pins being in a direction other than the release direction.

The pin 129 is narrower than holes 130 and 131 by 0.2mm. The pin 129 has an 0-ring (not shown) configured to seal hole 130 in the interlocking face 123 when the pin is in the extended position. The hole 131 in interlocking face 124 is blind so that water cannot enter the first section through the hole 131.

The pin 129 is accessible via hatch 109 in the section 102. Pins in other joints of the kayak are accessible via hatches 108 and 111. The hatches 107 to 112 are deck hatches.

The section 102 further comprises a bayonet locking mechanism 132 configurable to lock the or each pin in the extended position.

Sections 101, 103 and 105 are sealed and sections 102 and 104 are sealable by the pins. In this way, when the sections are joined each section is watertight.

Each of the sections 101 to 105 of the watercraft comprises a portion of the deck of the watercraft and a portion of the hull of the watercraft. Each of the sections is formed of a carbon fibre monocoque. Each of the carbon fibre monocoques form the hull portion, the deck portion and the interlocking face(s) of its respective section.

A method of manufacture of the kayak of Figs. 1 to 6 will now be described. The method involves forming each of sections 101 to 105 comprising interlocking faces 121 to 128, wherein each of the sections 101 to 105 is formed by a respective monocoque.

The monocoques are each formed of carbon fibre by laying prepreg carbon fibre in a respective mould and autoclaving the carbon fibre to form the monocoque.

Although particular embodiments of the disclosure have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The 15 aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims.

It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the scope of the invention as defined by the claims. For example, in other embodiments, the kayak may be formed of other composite materials, and/or by other manufacturing methods such as 3D printing. In other embodiments, the kayak may be formed of plastic. The same principles may be applied to other watercraft such as other types of kayak, a stand-up paddleboard (SUP), a canoe, a row boat, surf-ski, dragon boat or any other type of hand-powered watercraft.

Claims

CLAIMS1. A hand-powered watercraft comprising: two sections, the sections being releasably joinable to one another at a joint, wherein the joint comprises a first interlocking face on a first of the sections, and a second interlocking face on a second of the sections, the first and second interlocking faces being correspondingly shaped, such that they interlock with one another when the first and second sections are joined, the sections being releasable from one another in a release direction, wherein the first and second interlocking faces are shaped to prevent movement of the first section relative to the second section in all but one direction when the first and second sections are joined, said direction being the release direction, and wherein all corners on the first interlocking face and all corners on the second interlocking face are greater than 90 degrees.
2) A hand-powered watercraft according to claim 1, wherein a surface area of the first interlocking face is at least 50% greater than a flat area between outer edges of the first interlocking face and a surface area of the second interlocking face is at least 50% greater than a flat area between outer edges of the second interlocking face.
3) A hand-powered watercraft according to claim 1 or 2, wherein the first interlocking face comprises a recess and the second interlocking face comprises a protrusion or the second interlocking face comprises a recess and the first interlocking face comprises a protrusion and, when the sections are joined, the recess surrounds the protrusion by more than 180 degrees in a plane normal to the release direction.
4) A hand-powered watercraft according to any preceding claim, wherein the protrusion is tapered in the release direction.
5) A hand-powered watercraft according to any preceding claim, wherein the first interlocking face comprises a first lateral surface and the second interlocking face comprises a corresponding second lateral surface, the first lateral surface and the second lateral surfaces configured to contact one another when the sections are joined.
6) A hand-powered watercraft according to any preceding claim, wherein all external surfaces of each of the interlocking faces are non-parallel to the release direction.
7) A hand-powered watercraft according to any preceding claim, wherein the first and second interlocking faces are shaped such that a maximum gap between the first and second faces when the first and second sections are joined is less than 3mm.
8) A hand-powered watercraft according to any preceding claim, the watercraft further comprising: a pin, a hole in the first interlocking face, and a hole in the second interlocking face, configured to align with the hole in the first interlocking face when the first and second sections are joined, wherein the pin is movable from a retracted position within the first section or the second section, to an extended position protruding through the hole in the first interlocking face and the hole in the second interlocking face, a length of the pin being in a direction other than the release direction.
9) A hand-powered watercraft according to claim 8, wherein a width of the pin is 0.2mm less than a width of each of the holes in the first and second interlocking faces.
10) A hand-powered watercraft according to claim 8 or claim 9 wherein the pin is accessible via a hatch or opening in the second section.
11) A hand-powered watercraft according to any of claims 8 to 10, wherein the first or second section further comprises a locking mechanism configurable to lock the or each pin in the extended position.
12) A hand-powered watercraft according to any preceding claim, wherein each of the sections are sealed or sealable.
13) A hand-powered watercraft according to any preceding claim, the watercraft comprising: three or more sections, wherein each of the sections of the watercraft is releasably joinable to one or two other sections of the watercraft, and a joint as defined in claim 1 between each pair of adjacent sections.
14) A hand-powered watercraft according to any preceding claim, wherein the watercraft comprises a hull and each of the sections of the watercraft comprises a portion of the hull of the watercraft.
15) A hand-powered watercraft according to any preceding claim, wherein each of the 15 sections comprises a monocoque.
16) A hand-powered watercraft according to any preceding claim, wherein each of the sections comprises a composite.
17) A hand-powered watercraft according to any preceding claim, wherein the hand-powered watercraft is a kayak, such as a sea kayak, surf-ski or sit-on kayak, a stand-up paddleboard (SUP), a canoe, a row boat" a dragon boat.
18) A method of manufacture of a hand-powered watercraft, the method comprising: forming a first section comprising a first interlocking face, and forming a second section comprising a second interlocking face, the first and second interlocking faces being correspondingly shaped, such that they interlock with one another when the first and second sections are joined, the sections being releasable from one another in a release direction wherein the first and second interlocking faces are shaped to prevent movement of the sections relative to one another in all but one direction when the first and second sections are joined, said direction being the release direction, and wherein all corners on the first interlocking face and all corners on the second interlocking face are greater than 90 degrees.
19) A method according to claim 18, wherein a surface area of the first interlocking face is at least 50% greater than a flat area between outer edges of the first interlocking face and a surface area of the second interlocking face is at least 50% greater than a flat area between outer edges of the second interlocking face.
20) A method according to claim 18 or 19, wherein the watercraft is formed by rotomoulding, 3D printing or autoclaving a composite material.
21) A method according to claim 18 or 19, wherein the sections comprise plastic or composite.
22) A method according to claim 18 or 19, wherein each of the sections is formed as a monocoque.
23) A method according to claim 22, wherein each of the sections comprise carbon fibre.
24) A computer-readable medium having computer-executable instructions adapted to cause a 3D printer to print a hand-powered watercraft according to any of claims 1 to 17.