GB2243619A

GB2243619A - Mounting a sacrificial anode in the hull of a boat

Info

Publication number: GB2243619A
Application number: GB9105394A
Authority: GB
Inventors: William Newsam
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-05-04
Filing date: 1991-03-14
Publication date: 1991-11-06
Anticipated expiration: 2011-03-14
Also published as: GB9010070D0; GB9105394D0; GB2243619B

Abstract

The anode 32 is removably mounted on a core member 12 which is located within a carrier 6 sealingly mounted in the hull 2 of the boat. The anode may be replaced or inspected without the need to remove the boat from the water or incurring the services of a diver. Recess 36 may be formed in the core 12 and the anode 32 may be withdrawn into the recess. <IMAGE>

Description

CATHODIC PROTECTION FOR BOATS This invention relates to devices for reducing or preventing corrosion of marine vessels due to the galvanic action between parts of dissimilar metals which are exposed to electrolytic sea water. When a substantial proportion of a vessel, or its components, comprises aluminium those parts being a less noble metal are prone to corrosion by this galvanic action.

Engines and gearboxes of stern drive units or outboard motors often have aluminium casings which are operated in sea water, and the galvanic action referred to above is particularly objectionable in those cases.

It is an object of the invention to provide a device for preventing or reducing corrosion due to galvanic action between dissimilar metals in boats, which device may be replaced and/or inspected without removing the craft from the water.

According to the invention there is provided a device for preventing or reducing corrosion due to galvanic action between dissimilar metals in boats comprising a sacrificial anode removably mounted in a carrier which is secured to the hull of a boat.

The anode is preferably arranged to project outwardly from the carrier and is arranged to be capable of being withdrawn from a position outside the carrier to a position within the carrier.

The anode may be mounted on a core member detachably located within a bore in the carrier.

The core member may be axially moveable within the bore in the carrier and may be retained within the bore by a threaded nut. The anode may be axially moveable within the core member and may be attached to that member by means including a threaded rod passing axially through the core member and the anode. The threaded rod may be provided with an electrical connection and the carrier, the core and the nut may be made of a non-conducting material, such as nylon.

The anode may be arranged to project below the hull of a boat into water on which the boat is located and may be formed with a cross-section which is stream-lined. Part of the carrier which projects below the hull of the boat may be formed with a cross-section which is stream-lined.

Other aspects of the invention will become clear from the following description which is given by way of example only with reference to the accompanying drawings in which: Figure 1 is a section view through part of a boat showing a carrier with a sacrificial anode in operative position; Figure 2 is a section view on the line II-II of Figure 1 and Figure 3 is a part section view on the line III 111 of Figure 2.

As seen in the drawings the hull 2 of a boat is provided with a hole 4 in which is located a carrier 6, the carrier being secured in place by means of a suitable adhesive or a fillet of mastic or glass fibre material 8.

The carrier is formed with a bore 10 into which is fitted a core 12. A nut 14 is screwed on to a threaded portion 16 of the carrier 6 and the core is retained within the bore by a lip 17 formed on the nut. O-rings 18 prevent unwanted ingress of water through the bore 10.

The carrier 6, core 12 and nut 14 are made of nylon or other non-conducting plastics material.

A mild steel stem 20, threaded at its lower end 22, is bonded into a bore 24 in the core 12, and a Tee-piece 26 is fixed to the upper end of the stem and carries an electrical connection 28 for wires 30.

A sacrificial anode 32, of zinc is screwed on to the threaded end of the stem 20 and projects into the water below the hull of the boat.

The stem 20 may be formed with a weakened neck portion 34 to ensure that any fracture due to impact will occur at that point.

To reduce or eliminate the turbulence caused by the protruding anode 32 as the boat is driven through the water, the cross-section of the anode may have a streamlined profile e.g. as seen in section in Figure 3.

The carrier 6, as shown in Figures 2 and 3, is formed with a streamlined section 35 in order to divert unwanted debris e.g. weeds from the anode as the boat progresses.

A recess 36 indicated in chain lines, may be formed in the core 12 and the anode 32 may be partially or completely withdrawn into that recess. This, and the previous arrangement are found to be beneficial particularly when racing, when any restrictive influences which may cause turbulence need to be kept to a minimum.

In order to increase the advantages of the use of sacrificial anodes in order to protect the metal components from galvanic action, more than one such anode may be employed, several assemblies of the type shown being located in suitable parts of the hull of the boat.

The method of mounting the anode described above makes it possible to inspect and/or replace it without the necessity of removing the boat from the water, or using a diver.

To remove and replace the anode, the nut 14 is unscrewed and the core 12 is withdrawn vertically. Immediately, a blanking plug is inserted before an undesirable amount of water has managed to enter the boat through the bore 10. The procedure is reversed when the core with a replacement anode 32 is inserted into the bore.

Alternatively, it is possible to replace an entire new assembly comprising a core 12 complete with anode 32 immediately after withdrawal of the original assembly.

Claims

1. A device for preventing or reducing corrosion due to galvanic action between dissimilar metals in boats comprising a sacrificial anode removably mounted in a carrier which is secured to the hull of a boat.

2. A device according to claim 1 wherein the anode is arranged to project outwardly from the carrier.

3. A device according to claims 1 or 2 wherein the anode is arranged to be capable of being with drawn from a position outside the carrier to a position within the carrier.

4. A device according to claims 1, 2 or 3 wherein the anode is mounted on a core member detachably located within a bore in the carrier.

5. A device according to claim 4 wherein the core member is axially moveable within the bore in the carrier.

6. A device according to claim 5 wherein the core member is retained within the bore in the carrier by a threaded nut.

7. A device according to claims 4 or 5 wherein the anode is axially moveable within the core member.

8. A device according to claims 4 - 7 above wherein the means for attaching the anode to the core member includes a threaded rod passing axially through the core member and the anode.

9. A device according to claim 8 wherein the threaded rod is provided with an electrical connection.

10. A device according to claim 6 wherein the carrier, the core and the nut are made of a non-conducting material.

11. A device according to claim 10 wherein the material is nylon.

12. A device according to claims 1 and 2 wherein the anode is arranged to project below the hull of a boat into water on which the boat is located.

13. A device according to any of the above claims wherein the anode is formed with a cross-section which is streamlined.

14. A device according to any of the above claims wherein part of the carrier which projects below the hull of the boat is formed with a cross-section which is streamlined.