GB2095634A

GB2095634A - Fairing anti-stacking rings

Info

Publication number: GB2095634A
Application number: GB8110083A
Authority: GB
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1981-03-31
Filing date: 1981-03-31
Publication date: 1982-10-06
Also published as: GB2095634B

Abstract

A demountable design of fairing anti-stacking ring for clamping to underwater towed cable is made in two halves 1, 2 secured together with locking strips 3, 4. <IMAGE>

Description

SPECIFICATION Fairing anti-stacking rings This invention relates to fairing anti-stacking rings for underwater towed cable.

It has been the practice to place fairings around cable that is to be towed underwater in order to streamline it and thus reduce the drag. These fairings are made in quite short lengths compared with the total length of towed cable. They should be free to rotate about the cable so that they can align themselves with the direction of water flow; but they should be prevented from unlimited movement in the axial direction, for otherwise the drag of the water would pull them down to the bottom of the cable where the forces would be liable to be high enough to prevent the lower fairings from rotating and might even be high enough to cause them to collapse under the loading. For this reason anti-stacking rings are fitted to the cable at intervals along its length, and these rings are designed to prevent fairings from sliding over them from one side to the other.

For further information about the use of fairings reference may be made for instance to the paper entitled "Predicting the Equilibrium Depth of a Body Towed by a Faired Cable" by P. J. Wingham and N. R. Keshavan appearing in Ocean Engineering, Volume 5 at pages 1 5 to 35 (Pergamon Press 1978).

Hitherto anti-stacking rings have been unitary annular structures that have been slipped on to one end of the cable and moved along to their required locations before being crimped in position to secure them firmly to the cable. This method of fixing the rings is somewhat iaborious, but a more significant problem is presented when, for some reason or other, it is found desirable to replace a particular anti-stacking ring on a length of cable with a new ring.

According to the present invention there is provided a demountable fairing anti-stacking ring for clamping to underwater towed cable which ring is made in two halves secured together by a pair of releasable locking strips engaging the ends of said two halves.

Figure 1 is an exploded perspective view of a first design of demountable fairing anti-stacking ring, and Figure 2 is a similar view of an alternative design of demountable ring.

Referring to Figure 1, a fairing anti-stacking ring is formed in two C-shaped cross-section halves 1 and 2 which in use are clamped around the cable and secured with a pair of locking strips 3 and 4.

Typically these pieces are made of stainless steel.

The locking strips have the general configuration of a buckle, each having a pair of slots 5 which engage over co-operating lugs 6 on the ends of the ring halves 1 and 2. These lugs 6 are defined by channels 7 formed in the ends of the ring halves to a depth substantially equal to the thickness of the locking strips so that when the strips are fitted to the ring halves they co-operate to provide a substantially uninterrupted smooth flush outer surface for the ring. The two outer faces 8 of the pair of slots 5 of each locking strip, and the corresponding sides of the lugs, may be slightly undercut so that, when the locking strips are engaged over the lugs, the forcing apart of the two ring halves makes each pair of opposed lugs co-operate to act as a wedge restraining the locking strip from being accidentally dislodged.

In the alternative design of fairing anti-stacking ring depicted in Figure 2 two ring halves 11 and 12 are secured with a pair of locking strips 13 and 14. Each locking strip has a pair of heads 1 5 linked by a web 1 6 providing the locking strip with a substantially I-shaped cross-section. The cooperating ends of the ring halves are bifurcated to accommodate the locking strip heads and terminate with inwardly directed flanges 1 7. The faces 1 8 on these flanges, and the corresponding faces 1 9 on the heads of the locking strips and engaged in the ends of the ring halves each pair of opposed flanges 1 7 co-operate to act as a wedge restraining the locking strip from being accidentally dislodged.

The thickness of each locking strip is equal to that of each ring half so that they co-operate to provide a substantially uninterrupted smooth flush outer surface for the completed fairing antistacking ring.

Before such anti-stacking rings of Figure 1 or 2 are fitted to a cable a length of elastomeric material such as a synthetic rubber is preferably wrapped around the cable at the point of attachment to provide a resilient bedding for the ring. Alternatively pieces of such elastomeric material may be secured with adhesive to the inside of the ring halves.

1. A demountable fairing anti-stacking ring for clamping to underwater towed cable which ring is made in two halves secured together by a pair of releasable locking strips engaging the ends of said two halves.

2. A fairing anti-stacking ring as claimed in claim 1, wherein the locking strips engage the ring halves in a self-wedging manner such that the application of force tending to separate the two halves of the ring produces a force tending to hold the locking strips in position thereby preventing the ring halves from separation.

3. A fairing anti-stacking ring as claimed in claim 1 or 2, wherein each end of each ring half is provided with a radially projecting rib which engages a co-operating slot in the associated locking strip.

4. A fairing anti-stacking ring as claimed in claim 1 or 2, wherein each end of each ring half is bifurcated and engages round a co-operating head formed in the associated locking strip.

5. A fairing anti-stacking ring as claimed in any preceding claim wherein the ring halves and locking strips co-operate to provide a substantially uninterrupted smooth flush outer surface for the ring.

6. A fairing anti-stacking ring substantially as

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fairing anti-stacking rings This invention relates to fairing anti-stacking rings for underwater towed cable. It has been the practice to place fairings around cable that is to be towed underwater in order to streamline it and thus reduce the drag. These fairings are made in quite short lengths compared with the total length of towed cable. They should be free to rotate about the cable so that they can align themselves with the direction of water flow; but they should be prevented from unlimited movement in the axial direction, for otherwise the drag of the water would pull them down to the bottom of the cable where the forces would be liable to be high enough to prevent the lower fairings from rotating and might even be high enough to cause them to collapse under the loading. For this reason anti-stacking rings are fitted to the cable at intervals along its length, and these rings are designed to prevent fairings from sliding over them from one side to the other. For further information about the use of fairings reference may be made for instance to the paper entitled "Predicting the Equilibrium Depth of a Body Towed by a Faired Cable" by P. J. Wingham and N. R. Keshavan appearing in Ocean Engineering, Volume 5 at pages 1 5 to 35 (Pergamon Press 1978). Hitherto anti-stacking rings have been unitary annular structures that have been slipped on to one end of the cable and moved along to their required locations before being crimped in position to secure them firmly to the cable. This method of fixing the rings is somewhat iaborious, but a more significant problem is presented when, for some reason or other, it is found desirable to replace a particular anti-stacking ring on a length of cable with a new ring. According to the present invention there is provided a demountable fairing anti-stacking ring for clamping to underwater towed cable which ring is made in two halves secured together by a pair of releasable locking strips engaging the ends of said two halves. Figure 1 is an exploded perspective view of a first design of demountable fairing anti-stacking ring, and Figure 2 is a similar view of an alternative design of demountable ring. Referring to Figure 1, a fairing anti-stacking ring is formed in two C-shaped cross-section halves 1 and 2 which in use are clamped around the cable and secured with a pair of locking strips 3 and 4. Typically these pieces are made of stainless steel. The locking strips have the general configuration of a buckle, each having a pair of slots 5 which engage over co-operating lugs 6 on the ends of the ring halves 1 and 2. These lugs 6 are defined by channels 7 formed in the ends of the ring halves to a depth substantially equal to the thickness of the locking strips so that when the strips are fitted to the ring halves they co-operate to provide a substantially uninterrupted smooth flush outer surface for the ring. The two outer faces 8 of the pair of slots 5 of each locking strip, and the corresponding sides of the lugs, may be slightly undercut so that, when the locking strips are engaged over the lugs, the forcing apart of the two ring halves makes each pair of opposed lugs co-operate to act as a wedge restraining the locking strip from being accidentally dislodged. In the alternative design of fairing anti-stacking ring depicted in Figure 2 two ring halves 11 and 12 are secured with a pair of locking strips 13 and 14. Each locking strip has a pair of heads 1 5 linked by a web 1 6 providing the locking strip with a substantially I-shaped cross-section. The cooperating ends of the ring halves are bifurcated to accommodate the locking strip heads and terminate with inwardly directed flanges 1 7. The faces 1 8 on these flanges, and the corresponding faces 1 9 on the heads of the locking strips and engaged in the ends of the ring halves each pair of opposed flanges 1 7 co-operate to act as a wedge restraining the locking strip from being accidentally dislodged. The thickness of each locking strip is equal to that of each ring half so that they co-operate to provide a substantially uninterrupted smooth flush outer surface for the completed fairing antistacking ring. Before such anti-stacking rings of Figure 1 or 2 are fitted to a cable a length of elastomeric material such as a synthetic rubber is preferably wrapped around the cable at the point of attachment to provide a resilient bedding for the ring. Alternatively pieces of such elastomeric material may be secured with adhesive to the inside of the ring halves. CLAIMS

6. A fairing anti-stacking ring substantially as hereinbefore described with reference to Figures 1 and 2 or to Figures 3 and 4 of the accompanying drawings.

7. A cable having clamped there around at spaced intervals a plurality of fairing anti-stacking rings as claimed in any preceding claim.