WO1981001275A1

WO1981001275A1 - A marine structure

Info

Publication number: WO1981001275A1
Application number: PCT/AU1980/000081
Authority: WO
Inventors: G Eichhorn
Original assignee: G Eichhorn
Priority date: 1979-11-01
Filing date: 1980-10-31
Publication date: 1981-05-14
Also published as: EP0038832A1

Abstract

An offshore marine structure including a central hub section (10), a plurality of buoyant arm units (11) radiating from the tub, each with a plurality of buoyant finger units (12) extending laterally therefrom to define mooring berths and means for anchoring the assembly to a seabed.

Description

A MARINE STRUCTURE THIS INVENTION^' relates to a floating^' marina or like structure.

With increasing affluence and increased leisure- time, hoating as a recreational activity has caused an unprecedented growth in all facets of the boating industry. In addition, a growing consumption of fish and other marine -foodstuffs has caused a significant increase in the number of fishing vessels. It is anticipated. that in the not so distant future, the rising costs of petroleum fuels for road and aerial transport will cause a -reversion to marine transportaion means particularly for- coastal and intercontinental transportation of goods.

In order to accommodate the presently large and ever growing number of marine vessels, suitable moorings must be constructed. For leisure craft mooring facilities generally comprise "swinging" moorings in sheltered bays or estuarine regions or of recent years, due to lack of suitable naturally sheltered areas, marinas may be provided.^' A major difficulty being encountered at present is that convenient marina sites would be preferably located at or near bayside or harbourside city urban areas and in most cases adjacent exclusive residential areas. Local residents actively campaign against the construction of new marinas and generally comprise a more effective lobby than boat owners. Further, and most importantly, effective barriers to the construction of marinas can be found in government and semi-government regulatory bodies, e.g. Environment Protection Authorities, Bay or Harbour Authorities, Local Government, Foreshore Protection Authorities etc.

For commercial marine vessels, berthing facilities require deep water and extensive facilities for servicing, maintenance loading etc. The cost of construction of such facilities and the usually necessary dredging and other maintenance can prevent the construction of such facilities particularly where the useful life of such facilities may be determined by say the expected life of a mining or construction operation.

Generally speaking therefore, the difficulties encountered in obtaining adequate mooring or berthing facilities mitigates against a growth in the boating and shipping industries.

The present invention has been devised with the object of providing mooring or berthing facilities on a floating marina or like structure. It is considered that the structure proposed in accordance with the invention ca alleviate all of the objectionable features of present marina and other berthing facilities and at the same time provide a safe, relatively inexpensive and aesthetically acceptable structure, adaptable to a wide range of purpose in a marine environment.

According to the invention there is provided a marine structure comprising;- a main portion; a plurality of buoyant arm portions connected to said main portion; and means for anchoring the structure to a seabed. Preferably the main portion is located centrally of the structure. Preferably the buoyant arm portions extend radially from said main portion.

Preferably one or more of the buoyant arm portion comprise a plurality of outwardly extending buoyant finger portions to define mooring areas for marine vessels adjace said arm portions.

Preferably, the arm portions comprise a plurality of joined members articulated at predetermined intervals.

Preferably, the arm portions comprise a plurality of members joined by post-tensioned joining means. Preferably, the post-tensioned joining means extends from the main portion to join the articulated members in end to end relationship and said main portion to said articulated members.

Preferably the finger portions are retained in opposed relationship on each side of an arm portion by post- tensioned joining members.

Preferably the main portion, arm portions and finger portions comprise essentially hollow members formed from fibre reinforced concrete, Preferably the arm portions comprise ducts positioned in the region of the geometric centre thereof to locate the post-tensioned joining means. The post- tensioned joining means preferably comprises a post-tensioned cable. Preferably the means for anchoring the structure to the seabed comprises a plurality of anchors connected by an extendable shock absorbing linkage to suitable positions on said structure to permit even load distribution on the structure regardless of tidal conditions and/or direction of waves and prevailing weather.

The present invention has been devised with the general object of providing a marina which is capable of being located offshore, and so overcomes the main present difficulties. With the foregoing and other objects in view, the invention resides broadly, in one embodiment, in a marina including a central hub section, a plurality of bouyant arm units radiating from the hub, each with buoyant finger units extending laterally therefrom to define berths, and means for anchoring the assembly to a seabed.

One particular embodiment of the invention is shown, by way of illustrative example only, in the accompanying drawings wherein:

FIG. 1 is a schematic plan view of a floating marina according to the invention, FIG. 2 is a plan view, to larger scale, of a part of the marina,

FIG. 3 is a plan view of a further part of the marina, FIG. 4 is a plan view to further enlarged scale of part of one arm, and several fingers, of the marina, FIG. 5 is a sectional view of part of the arm shown in FIG. 4,

FIG. 6 is a sectional view of part of the main part of the marina,

FIG. 7 is a sectional view of a submersible slip of the marina,

FIG. 8 is a cross-sectional view, to further enlarged scale, of an arm of the marina, and FIG. 9. is a cross-section, to the same scale as

FIG. 8, of a finger of the marina.

The marina shown in the drawings consists essentially of a buoyant central _f main or hub section 10 from which a number of buoyant arms 11 radiate, each havin a number of buoyant fingers 12 extending perpendicularly to both sides. These units may suitably be made principal of glass or steel fibre-reinforced concrete, with decks and certain other surfaces of glass or steel fibre- reinforced concrete. The hub, shown in FIG. 6, is octagonal in plan view and has a base suitably composed of floatation chambers 13. The base is formed with a peripheral deck 14 upon which various compartments 15 are grouped around a central service core 16. Supported on deck 17 may be additional compartments 18 such as observation decks, recreation rooms etc. surrounding the service core which may be extended upwards to support an elevated control room, lookout station or the like (not shown) .

Each of the arms 11 radiating from the hub consist of a series of elongated buoyant box-like structures braced by internal transverse diaphragms 19 and connected end to end to each oth.er, and secured to the hub 10, by longitudinal post-tensioned cables 20.. Service ducts 21 are carried through the arm, supported in part on diaphragms 19. The arm is decked as a walk-rway, and fenders 22 are fitted to its sides. Access hatches 23 are provided. At its outer end, each of the arms 11 is connected perpendicular¬ ly to the middle of an outer arm 24 generally of similar construction to the main arm 11. The fingers 12, which define berths for boats 25, and which extend perpendicularly from each of the main ^'arms 11 and the outer arms 24, are of varying lengths depending on the size of the vessel to be moored, each having a tapering outer section 26 and either one or two parallel- sided sections 27. Each of the sections is of hollow substantially rectangular shape in cross-section and with an internal transverse partition 28. In the majority of cases, two fingers 12 extend in opposite directions from an arm 11 or outer arm 24, and a post-stressed cable 29 in a duct passes centrally through both and the interposed arm 11 or 24. Fenders 30 are provided at the sides and ends of the fingers.

In addition to the arms and fingers, providing berthing facilities for many boats of different sizes, the marina includes other facilities, such as a fueling dock 31, with fuel tanks 32 within the arm 24 and appropriate fuel pumps. Submersible slips 33 are also connected to the hub 10. By part-filling the bottom tanks 34 of each slip with water, the slip is lowered sufficiently for a boat to enter and be chocked in place after which the tanks are emptied by compressed air, causing the slip to rise bringing the enclosed boat above water level.

The marina is anchored in the required location by means of anchor chains and/or cables indicated at 35, connected between brackets 36 under arms 11 and 24 and various other points of the marina and suitable anchorage points 37 on the seabed. In areas of very large tidal differences, the anchor chains or cables may be such that provision is made for the extension and contraction of their effective lengths. For example, a length of heavy ships chain may be connected at one end to a deadweight concrete block and at the other end to a high tensile steel cable attached to a specially reinforced portion of the underneath of the structure. The chains/cables may be arranged to permit tidal movement and a certain amount of lateral movement due to prevailing waves or weather. The anchoring blocks and cables are angularly arranged to permit even loading of the structural components regardless of prevailing conditions. The seabed anchoring points may be permanent i.e. a series of raked piles with a poured concrete pile cap incorporating a chain or cable fixing point or, alternatively, a large dead eight concrete block with a suitable fixing point.

In an alternative embodiment, the anchoring points may be portable, for example a series of interconnected concrete blocks which may be shifted to another location if required. In any event, the invention contemplates a floating marine structure adapted for permanent or temporary positioning- at a suitable location. The structure according to the invention offers many advantages over prior art marine structures in that it is applicable to both deep water and shallow water locations For example, in a region where large tidal variations are found or where silting of a mooring or berthing area necessitates frequent dredging, the structure according to the invention permits such problems to be alleviated by situating the structure in a deep water or clear channel region where a permanent, rigidly positioned structure would not otherwise be possible. The present invention also offers a relatively - 1 -

inexpensive structure which, is capable of withstanding the forces of wave motion and other weather forces. Whereas other marine structures (particularly those positioned in deep water, must be constructed in immense proportions to withstand wave and weather forces, the articulated construction and shock absorbing anchoring means of the present invention permit it to withstand such forces without complex and expensive engineering construction. Depending on the longest known wave length for a particular geographic location, the post-tensioned arm units are arranged in groups, articulated to each other to form beam sections of a length at least twice the known wave length or less than half the known wave length for that location. The articulat¬ ed construction of the arms 11 and 24, the cables 20 permitting a degree of angular movement between the succeeding parts, enables these arms to flex due to wave motion.

In constructing a marine structure according to the invention, anchoring points are first placed in pre- determined positions on a seabed. The main or hub portion may be conveniently prefabricated on shore and towed or otherwise transported to the selected site and anchored by chain/cable to at least one of the anchoring points. Pre¬ fabricated arm portions may then be towed or transported to the site and connected to the main portion and each adjacent arm portion by cables which are then post-tensioned. Articulated joints are provided in the arm portions at pre¬ determined positions to suit local wave length constraints. Finger portions are fitted to the arm portions as herein- before described.

Service conduits such as electricity, water, fuel, communications, etc. are then positioned in suitable ducts within the arms and fingers prior to the formation of a glass fibre or steel fibre reinforced concrete capping slab over each articulated structural component. A service core

O PI comprising say, a fuel distribution area, offices, restaurant, toilet facilities, shops etc. may then be formed in situ on the hub portion or constructed from pre fabricated portions. It will be readily apparent to a skilled addresse that a marine structure in accordance with the invention may be modified to suit many different applications withou departing from the spirit and scope of the invention. For example, a suitably modified form of the invention may provide an offshore base for a fishing fleet. Such a base may be assembled on site at the commencement of a fishing season and then disassembled and removed to another location at the end of the season. The base may provide bulk storage facilities for fresh water, fuel etc., freezing facilities for the catch, accommodation and recreational facilities for fishing crews etc. In a remot location such a structure would be self-sufficient in powe generation etc. and may include solar generators for heat and electricity. A similar structure may have a strategic signific ance in providing either permanent or temporary facilities for surveillance operations or berthing facilities for amphibious aircraft, helicopters, transport vessels or naval vessels adjacent a theatre of military operations. in a non-remote location adjacent a shoreline etc suitably modified forms of the invention may comprise conventional marina facilities for pleasurecraft, hotel or motel type accommodation, entertainment facilities such as theatres, gambling casinos etc. Such a structure would include environmentally acceptable features including a sewerage treatment plant or a waste holding tank to avoid water pollution within the area. The structure may be completely remote from the shoreline and self-sufficient in terms of services provided or alternatively it may be linked to the shore by an access gangway or an umbilicus providing connection to essential services such as fresh water, sewerage and electric power. In one embodiment of the invention storage cell units comprising portion of the arm units may be readily detachable therefrom and adapted to be transported e.g. by towing to the structure to provide replenished fuel, water and like storage units or to replace filled waste receptacle units.

Claims

CLAIMS :

1. A marine structure comprising:- a main portion; a plurality of buoyant arm portions connected to said main portion; and means for anchoring the structure to a seabed.

2. A marine structure as claimed in claim 1 wherein the main portion is located centrally of the structure.

3. A marine structure as claimed in claim 1 or clai wherein the buoyant arm portions extend radially from sai main portion.

4. A marine structure as claimed in any preceding claim wherein one or more of said buoyant arm portions comprise a plurality of outwardly extending buoyant finge portions to define mooring areas for marine vessels adjac said arm portions.

5. A marine structure as claimed in any preceding claim wherein the arm portions comprise a plurality of members joined by post-tensioned joining means.

6. A marine structure as claimed in any preceding claim wherein the arm portions comprise a plurality of joined members articulated at predetermined intervals.

7. A marine structure as claimed in claim 6 wherein the post-tensioned joining means extends from said main portion to join the articulated members in end to end relationship and said main portion to said articulated members.

8. A marine structure as claimed in any one of claims 4-7 wherein the finger portions are retained in opposed relationship on each side of said arm portion by post-tensioned joining members.

9. A marine structure as claimed in any preceding claim wherein said portions comprise essentially hollow members formed from reinforced concrete.

10. A marine structure as claimed in any preceding

OMP claim wherein the arm portions comprise ducts positioned in the region of the geometric centre thereof to locate the post-tensioned joining means.

11. A marine structure as claimed in any one of claims 5-10 wherein the post-tensioned joining means comprises a post-tensioned cable,

12. A marine structure as claimed in any preceding claim wherein the means for anchoring the structure to the seabed comprises a plurality of anchors connected by an extendable shock absorbing linkage to suitable positions on said structure to permit even load distribution on the structure regardless of tidal conditions and/or direction of waves and prevailing weather.