GB2474450A

GB2474450A - Dredging apparatus

Info

Publication number: GB2474450A
Application number: GB0917966A
Authority: GB
Inventors: John Simon Blight
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-14
Filing date: 2009-10-14
Publication date: 2011-04-20
Anticipated expiration: 2029-10-14
Also published as: GB0917966D0; GB2474450B

Abstract

The invention relates to a dredging apparatus 1. Apparatus 1 has a sledge 10 with cables 11 attached to the tow vessel X. The sled has one or more one scraper 13,14 projecting from the bottom of the sledge to scrape along a water bed. Mixing means is provided to mix scrapings from the/each blade from the water bed with the adjacent water. The mixing may be provided by water jets 14C, 13C which spray into the scraped material. The mixing device may include a baffle plate 17 with a curved surface to apply a downward force to the device and increase the turbulence in the surrounding water to aid the mixing of material ploughed from the water bed. In use the vessel tows the sledge along the water bed with the/each scraper scraping the water bed with scrapings dissipating into the adjacent water.

Description

Title: Dredging Apparatus The present invention relates to a dredging apparatus.

According to the present invention there is provided a dredging apparatus comprising: a) a sledge with support means to support the sledge under water under a tow vessel b) at least one scraper adapted to project from the bottom of the sledge and having a leading edge to scrape along a water bed, and c) mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water, in use said vessel towing the sledge along the water bed with the or each scraper scraping the water bed with scrapings dissipating into the adjacent water.

Preferably the apparatus further comprises at least one water flow generator to direct at least one jet of water on the scraper to break up scraping from the sea bed.

Preferably a curved baffle is provided adjacent the or each scraper, said baffle creating a downward pressure on the sledge as it is towed. Preferably the curved baffle creates an increase in water flow velocity across the or each scraper which provides at least in part said mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water. Preferably the curved baffle further directs scrapings mixed with water away from the sledge.

The apparatus may comprise at least one water flow generator to direct at least one jet of water on the or each scraper to provide at least in part said mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water. Preferably the or each water flow generator further directs scrapings mixed with water away from the sledge.

Preferably the or each scraper is adjustable in the distance it projects down away from the sledge.

Preferably the or each scraper is adjustable in the angle it projects down away from the sledge.

Preferably the or each scraper is pivoted at a trailing edge to the sledge to adjust the distance it projects down away from the sledge and the angle it projects down away from the sledge.

Preferably the sledge is supported from a vessel by wires.

Preferably the sledge is towed from a front end. The front end may be connected to the bow of a tow vessel.

An embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a perspective view of a sledge, and Figure 2 shows a side view of the sledge towed by a vessel.

Referring to the drawings there is shown a dredging apparatus 1.

Apparatus I has a sledge 10 with support means in the form of a wire cradle I IA to support the sledge under water under a tow vessel "X", and has a towing bridle 1 lB at a sledge front end to tow the sledge from the bow of the tow vessel "X".

Sledge 10 is formed from a rectangular metal frame having four sides 12A,12B,12C,12D. A bracing strut 12E divides the frame into two parts. Side 12A forms a leading edge and side 21C forms a trailing edge.

Two pairs affront and rear scrapers 13,14 andl5,16 are provided. Front and rear scrapers 13,14 have trailing edges pivoted at pivot points 13A,14A between sides 12D and strut 12E. Front and rear scrapers 15,16 have trailing edges pivoted at pivot points 15A,16B between sides 12B and strut 12E. Each scraper 13,14,15,16 is adapted to project from the bottom of the sledge 10 and has a leading edge I 3B, I 4B, I 5B, 1 6B to scrape along a water bed. As each scraper is pivoted, this allows adjustment of the distance the leading edge projects down away from the sledge and the angle it projects down away from the sledge.

A curved baffle 17 is provided adjacent and above each scraper 13,14,15,16. Baffle 17 creates a downward pressure on the sledge 10 as it is towed as shown by the arrow in Figure 2. As baffle 17 is curved, when the sledge is towed, the water pressure above the baffle is high and the pressure below the baffle is low (as shown by the dotted arrows). This creates an increase water flow velocity below the baffle and hence across the scrapers 13,14,15,16 which provides a mixing means to mix scrapings from each scraper from the water bed with the adjacent water.

The curved baffle 17 further directs scrapings mixed with water upwards and away from the sledge.

A water flow generator in the form of a hydraulic or electric water pump 18 delivers water under pressure to spray bars 13C,14C,15C,16C. Spray bars 13C,14C,15C,16C direct at least one jet of water on the scrapers 13,14,15,16 to break up scrapings from the water bed.

In use vessel "X" tows the sledge 10 along the water bed with each scraper scraping the water bed with scrapings dissipating into the adjacent water. Sledge 10 can be adjusted in height using winches on the vessel so that it lies just on the water bed. As water flows over baffle 17, the baffle 17 creates a downward pressure on sledge 10 so pushing it against the water bed.

Depending on the nature of the water bed, so that angle and distance the scrapers project below the sledge 10 can be adjusted. For example if the water bed is a loose silt the scrapers can be adjusted so that there is a large distance between the leading edge of each scraper, and each pass of the sledge across the water bed will remove much silt. If however water bed is dense clay, the scrapers can be adjusted so that there is a small distance between the leading edge of each scraper, and each pass of the sledge across the water bed will remove only a thin layer of clay. Also the front scrapers 13,15 can be set to remove a first depth of water bed, and the second scrapers 14,16 a second depth of water bed.

As the sledge scrapers scrape the water bed, the spray bars 1 3C, 1 4C, 1 5C, I 6C direct at least one jet of water on the scrapers 13,14,15,16 to break up scrapings from the water bed into smaller particles. These particles are mixed by the higher velocity flow of water under baffle 17 to put them in suspension in the ambient water. Once in suspension, tidal or river flow of water will take the particles away from the dredging site.

Although not shown, a water flow generator (such as provided by water pump 18) may be used in addition to direct at least one jet of water on the or each scraper to provide at least in part the mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water, and also direct scrapings mixed with water away from the sledge 10. The water flow generator may be used as an alternative to baffle 17 or in combination with baffle 17.

The invention may take a form different to that specifically described above.

Further modifications will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims

CLAIMS1. A dredging apparatus comprising: a) a sledge with support means to support the sledge under water under a tow vessel b) at least one scraper adapted to project from the bottom of the sledge and having a leading edge to scrape along a water bed, and c) mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water, in use said vessel towing the sledge along the water bed with the or each scraper scraping the water bed with scrapings dissipating into the adjacent water.
2. A dredging apparatus according to claim 1, wherein the apparatus further comprises at least one water flow generator to direct at least one jet of water on the scraper to break up scraping from the sea bed.
3. A dredging apparatus according to claim I or 2, wherein a curved baffle is provided adjacent the or each scraper, said baffle creating a downward pressure on the sledge as ills towed.
4. A dredging apparatus according to claim 3, wherein the curved baffle creates an increase in water flow velocity across the or each scraper which provides at least in part said mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water.
5. A dredging apparatus according to claim 3 or 4, wherein the curved baffle further directs scrapings mixed with water away from the sledge.
6. A dredging apparatus according to any preceding claim, further comprising at least one water flow generator to direct at least one jet of water on the or each scraper to provide at least in part said mixing means to mix scrapings from the or each scraper from the water bed with the adjacent water.
7. A dredging apparatus according to claim 6, wherein the or each water flow generator further directs scrapings mixed with water away from the sledge.
8. A dredging apparatus according to any preceding claim, wherein the or each scraper is adjustable in the distance it projects down away from the sledge.
9. A dredging apparatus according to any preceding claim, wherein the or each scraper is adjustable in the angle it projects down away from the sledge.
10. A dredging apparatus according to claim 8 and 9, wherein the or each scraper is pivoted at a trailing edge to the sledge to adjust the distance it projects down away from the sledge and the angle it projects down away from the sledge.
11. A dredging apparatus according to any preceding claim, wherein the sledge is supported from a vessei by wires.
12. A dredging apparatus according to any preceding claim, wherein the sledge is towed from a front end.
13. A dredging apparatus according to any preceding claim, wherein the front end may be connected to the bow of a tow vessel.
14. A dredging apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.