NZ529293A

NZ529293A - Mounting arrangement, method and component therefor

Info

Publication number: NZ529293A
Application number: NZ529293A
Authority: NZ
Inventors: Antony Brian Hambrook
Original assignee: Alloy Yachts Internat Ltd
Priority date: 2003-10-31
Filing date: 2003-10-31
Publication date: 2005-09-30
Also published as: NL1026850A1; ITTO20040756A1; NL1026850C2

Abstract

A mounting arrangement for attaching a stanchion (2) or railing post of one metal to the body (1) of a vessel, the body being, at least at the location of the stanchion or post, of a second metal, the metals having different galvanic potential. The arrangement comprises: a cavity (16) in the body; a spigot (31) of the one metal, integral with the stanchion or post, or adapted for retaining an end of the stanchion or post, the spigot extending into the cavity, the spigot being smaller the cavity and not contacting the surface of the cavity at any point; and a body of cast-in-place electrically insulating material occupying substantially all of the space within the cavity between the first member and the second member.

Description

<div class="application article clearfix" id="description"> 52 93 NEW ZEALAND PATENTS ACT, 1953 No: 529293 Date: 31 October 2003 COMPLETE SPECIFICATION MOUNTING ARRANGEMENT, METHOD AND COMPONENT THEREFOR We, ALLOY YACHTS INTERNATIONAL LIMITED, a company duly incorporated under the laws of New Zealand of 1 Selwood Road, Henderson, Auckland, New Zealand, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: Intellectual Property Offrce of i\j ^ 1 7 AUG 2004 RECEIVED BACKGROUND TO THE INVENTION Filed of the Invention The present invention relates to mounting arrangements for joining components that would be subject to galvanic corrosion in a marine environment under direct contact, in particular for mounting a stanchion or post to some part of the body of the vessel such as the bulwark, deck or superstructure. In a preferred form the arrangement is particularly suited for mounting stainless steel uprights, such as stanchions, to the vertical sidewall of a side deck bulwark or superstructure of an aluminium alloy hulled vessel. Summary of the Prior Art In the luxury yacht market aluminium alloy construction is preferred for the body of the vessel for its low weight and general corrosion resistance. At the same time, aesthetic considerations lead to the specification of stainless steel fittings, including railing or life line stanchions and pulpits. While aluminium alloys and stainless steel are generally considered corrosion resistant in isolation, when they are electrically connected in the presence of an electrolyte (for example sea water) the aluminium alloy becomes susceptible to galvanic corrosion. The main approaches to avoiding galvanic corrosion include providing a plastic sleeve or washer between the components to electrically isolate the components or to carefully and completely seal one of the components from access to the electrolyte. For example in mounting stainless steel stanchions to the bulwark of an alloy yacht it has been common practice to provide an alloy mounting block extending from the inner vertical side of the bulwark. The mounting block is provided with a vertical threaded hole in its upper face. The bulwark and the mounting block are fully sealed on the outer surfaces by an applied coating preventing electrolyte access to those surfaces. A stainless steel mounting post is screwed into the threaded hole. The mounting post has a shoulder. A sealing washer is sandwiched between the shoulder of the post and the sealed upper surface of the block. This prevents seawater access to the region of the threaded hole. Accordingly, although the aluminium alloy and stainless steel are in electrical contact an electrolyte path cannot occur between bare stainless steel and bare aluminium alloy so long as the protective coating on the aluminium alloy remains intact. In practice maintaining the coating fully intact in a seagoing vessel is difficult due to the loads that can be imposed on the joint. The forces applied to the stanchion can lead to excessive compression or shear loads on the protective coating. This can cause the coating to lift away from the alloy mounting block and crack. This allows penetration of seawater to the aluminium alloy providing the potential for electrolyte pathways between the aluminium alloy and stainless steel. At this point corrosion can begin to occur. SUMMARY OF THE INVENTION It is an object of the present invention to provide a joint or mounting arrangement for connecting a stanchion or post of one metal to a vessel body of another metal, that at least goes some way towards overcoming the above disadvantages. In a first aspect the invention consists in a mounting arrangement for attaching a stanchion or railing post of one metal to the body of a vessel, the body being, at least at the location of the stanchion or post, of a second metal, said metals having different galvanic potential, said arrangement comprising: a cavity in said body, a spigot of said one metal, integral with said stanchion or post, or adapted for retaining an end of said stanchion or post, said spigot extending into said cavity, said spigot being smaller than said cavity and not contacting the surface of said cavity at any point, and a body of cast-in-place electrically insulating material occupying substantially all of the space within said cavity between said first member and said second member. In a further aspect the invention consists in a vessel including an aluminium alloy body and a plurality of stainless steel posts or stanchions mounted to said body by a mounting arrangement as set forth above. In a further aspect the invention consists in a method of mounting a stanchion or railing post of one metal to a part of a vessel of a different metal comprising the steps of: inserting a spigot, integral with said stanchion or post or adapted for retaining an end of said stanchion or post into a cavity of said vessel, supporting said spigot in an inserted position so as to not contact said vessel, pouring a settable material that is electrically insulating when set into said cavity to surround the inserted portion of said first body and fill the space in said cavity between said first body and said second body, causing said settable material to solidify. In a further aspect the invention consists in a support member for mounting a stanchion or post, said support member including a spigot at one end and an upright member at another end for snugly receiving an end of the stanchion or post, a flow passage extending through said upright member and said spigot, said spigot including keying features to restrain said spigot from withdrawal from a surrounding solid material when installed. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. BRIEF DESCRIPTION OF THE DRAWINGS One preferred form of the present invention will be described with reference to the accompanying drawings. Figure 1 is a cross-sectional side elevation through a mounting arrangement in accordance with the preferred embodiment as assembled, but prior to completion by pouring a casting resin to fill the joint cavity, but shown with the stanchion filled. Figures 2A to 2D illustrate completion of an assembled mounting arrangement by pouring a casting resin to fill the joint cavity. Figure 3 is a cross-section on line AA in Figure 1. DETAILED DESCRIPTION Referring to the figures the present invention has a mounting arrangement between a first body, such as bulwark 1 of a first material and a second body of a second material where one of the materials is susceptible to galvanic corrosion in conjunction with the other material. In the illustrated embodiment the second body is a support member for mounting a further component of the same material. For example, a stanchion 2 is connected with the support member 3. The stanchion 2 and support member 3 are formed from, for example, stainless steel and the bulwark 1 is formed from, for example, an aluminium alloy. The mounting arrangement involves a cavity 16 extending internally from the inner face 18 of bulwark 1. A spigot 31 of support member 3 extends into the cavity 16. As illustrated in Figure 2D a solidified cast resin occupies the space within cavity 16 between the spigot 31 and the inner surface of the cavity wall. The solidified resin supports the spigot 31 away from the inner surface so that there is no electrical contact between them. Accordingly the possibility of galvanic corrosion arising from the mounting of the stanchion to the bulwark is eliminated. In the preferred embodiment illustrated, additional aspects of the invention are evident. These result in particular advantages in completing the mounting arrangement and/or in relation to such a mounting arrangement particularly for mounting an upright such as a stanchion to an upright face such as the face of a bulwark. With particular reference to Figure 1 the bulwark is illustrated in the fashion that is commonly found on iuxury yachts. The bulwark 1 has an inner side member 11, an outer side member 12 and a top cap 13 all of aluminium alloy. These members may be welded or otherwise joined. A fairing compound 15 is typically applied over all of the outer surface of the bulwark and subsequently finished with a marine paint system. A wooden cap 14 is fixed over the top of the bulwark for aesthetic purposes. In the bulwark of the present invention a cavity 16 is formed for the mounting of each upright 2. In the preferred form the cavity 16 has a sidewall member 21 and a bottom wall member 22. The sidewall member 21 is fixed, for example by weld 24, around the perimeter of bottom wall 22 and extends to an opening formed in inner sidewall 11 of the bulwark. The opening end of sidewall 21 is secured to the opening in the bulwark sidewall 11, for example by weld 23. It will be appreciated that the precise form of the cavity and the manner of its manufacture may vary considerably depending on the application of the invention. In relation to the use contemplated by the applicant the described construction is suitable and fabrication from multiple stock pieces is expedient. The cavity sidewall may for example comprise a length of aluminium tube cut off square at either end, or in the case of the preferred embodiment a length of stock bar machined to have an internal profile corresponding with the shape illustrated in Figure 3 along a substantial portion of its length and bored out to a tube of uniform wall thickness in the region adjacent the open end. The profile illustrated in Figure 3 provides a key against rotation of the solidified resin with respect to the cavity and acts in conjunction with the complementary form of the spigot 31. The profile includes a plurality of inwardly extending ribs 40, and in the form illustrated the profile can be machined by drilling four spaced apart passages and a central bore overlapping each of the passages. Alternatively the cavity piece may be formed as a unitary member rather than from a sidewall part and an end plate, for example by machining the internal profile with a blind end, or by manufacture as a single casting. A groove 26 or other surface feature is preferably provided on the inner surface of sidewall 21 to provide a key against withdrawal of the solidified body from the cavity 16 through opening 27. With the cavity 16 oriented with an upright opening it is necessary to stop casting resin flowing out of the cavity 16 when completing the join and prior to solidifying. In the illustrated arrangement a resilient annular seal 4 is provided between the spigot 31 and the sidewall member 21 of the cavity. The sealing member 4 is seated in a groove 39 of the spigot 31. It could be seated in a groove in the sidewall 21 but would be more difficult to retain in position when inserting the spigot into the cavity. Alternatively it may be possible to provide a temporary seal outside the cavity 16 butting against the surface 18 of the bulwark and the outer face of support member 3 for later removal. However this would be more likely to lead to leakage of the casting resin, or damage to the finish of the bulwark. The resilient seal 4 may be of any material compatible with the chosen casting resin. When casting resin is introduced into the cavity 16 to complete the joint, air in the cavity 16, particularly in the upper portion of the cavity above the open end of spigot 31, needs a route of escape from the cavity. To these ends a hole may be provided through the sidewall 21 into the internal space of the bulwark. Or as illustrated by lines 28, a hole may be drilled through the join region between the bulwark and cavity sidewall 21. Alternatively a groove may be provided on the inner surface of cavity 16 adjacent the upper edge of the cavity to bypass the seal 4. The groove should be sufficiently small in dimension that the seal 4 does not compress into it. Alternatively the seal 4 may have a notch or groove, dimensioned so that it does not close entirely upon compression and position. In the preferred form of the invention, as illustrated, the support member 3 is formed such that resin poured into the cavity 16 is introduced through an inside passage in the support member. The support member includes spigot 31 for extending into cavity 16 and a stanchion mounting member 33 extending upright, with a general elbow in between. The mounting member 33 has an bore 34 extending from its upper end. The spigot 31 has a flow passage 37 extending from its open end in cavity 16. The bore 34 extends to meet the passage 37 at the elbow of the support member 3. As will be described below with reference to Figures 2 A to 2D, resin is introduced to the cavity 16 by pouring into the upright bore 34. The resin flows down through bore 34 into flow passage 37, through flow passage 37 into cavity 16 to fill cavity 16. The spigot 31 of support member 3 is preferably provided with surface features or shape to provide a keying effect against withdrawal from the solidified resin locked in cavity 16 and against rotation within the solidified resin. In the preferred form that is illustrated, the spigot includes a hollow cylindrical portion 42 extending into the opening of the cavity for the casting resin to flow through into the cavity. The spigot includes an outwardly open portion 43 extending from the open end of cylindrical portion 42. The outwardly open portion 43 allows resin to flow rapidly and evenly to all areas of the space between the cavity wall and the exterior surface of the spigot. The external profile of the outwardly open portion 43 is complementary to the internal profile of the sidewall of the cavity. It is preferably shaped so that there is a generally uniform separation between the surfaces. In the preferred form the outwardly open portion 43 has outwardly extending ribs 45 spaced to interleave with inwardly extending ribs 40 of the preferred cavity sidewall. The interleaved ribs 40, 45 provide a highly effective key against rotation of the spigot in the cavity, and attempted rotation of the spigot in either direction places the solidified resin in compression in at least some of the enclosed space. Furthermore the substantially uniform and fairly narrow space between the surfaces of the sidewall and the spigot reduces any risk of overheating during exothermic solidification of the resin in those critical areas. The cylindrical portion 42 preferably terminates with an outwardly extending lip 47. With the spigot in place in the cavity, the outwardly extending lip 47 is substantially adjacent groove 26 in the cavity sidewall. The lip 47 provides keying against withdrawal of the spigot from the solidified resin. For mounting of the stanchion 2, the upright member 33 is preferably formed to fit closely within the internal bore of the hollow stanchion. A shoulder 35 is provided to locate the open end of the stanchion. The upright member 33 has a hole 39 which can be aligned with a hole 9 in stanchion 2. A set screw 8 may then secure the stanchion 2 to upright member 33. The upright member 33 preferably includes an elongate portion that extends for a substantial distance into the stanchion so that the stanchion is supported against bending at two well spaced locations, the first location being at the shoulder 35 and the second location being at the end 49 of the elongate portion 48. This reduces the magnitude of the local forces exerted on the stanchion tube. Preferably the first location 55 and the second location 49 of the elongate portion 48 each include one or more grooves 50 accommodating resilient seals 51. The resilient seals may comprise an O-ring of any suitable resilient material. The resilient annular seals allow for minor discrepancies in casting of the support member 3 and any minor discrepancies in the sizing of the stainless steel stanchion tube. This is only one possible arrangement for securing the stanchion 2 to the support member 3, and other possibilities will suggest themselves.to persons skilled in the art. Following assembly, it may be preferred to fill the annular space, at the opening 27 of the cavity, that remains in front of the seal member 4. In that case a bead 29 of adhesive sealant may be applied into this annular space. The method of completing the joint will be described with reference to Figures 2A to 2D. Referring to Figure 2A the support member 3 is fitted to the bulwark 1 with spigot 31 extending into cavity 16. The sealing member 4 is preferably a tight fit within the cavity 16 and provides substantial support for the position of the support member 3. The completed joint will be extremely rigid so accurate positioning and orientation of the support member 3 is necessary. Accordingly, an assembly jig (not illustrated) to align and hold the support member 3 relative to the bulwark 1 may be desirable. Persons skilled in the art will appreciate many ways in which such a support jig may be formed and applied. The support jig may be maintained in position until an appropriate setting time for the casting resin has elapsed. Referring to Figure 2B casting resin 5 is poured into the upright wall 34 of the support member 3 and pools within the cavity 16 and within the flow passage 37 of the support member 3. The casting resin fills the cavity, flowing to completely occupy the space. Pouring of resin is maintained until the resin reaches a level, as illustrated by dash line 7 in Figure 2C above the uppermost point of the cavity. Remaining air in the cavity escapes through the provided vent passage, for example passage 28. Preferably the intended finish level 7 is above the uppermost level of the cavity 16, but below the uppermost point of the vent hole 28. The joint is then allowed to sit for a period corresponding to at least the setting time of the resin. Subsequently any assembly jig can be removed, and final finishing of the bulwark and stanchion can be completed. An adhesive sealant 29 may be applied if desired. The stanchion post 2 may be fitted over the upright member 33 with the securing holes align and the two may be locked together by set screw 8. The wooden cap rail 14 may be fitted to the upper surface of the bulwark 1. The completed construction is illustrated in Figure 2D. The solidified body of resin 10 locks the support member 3 rigidly in position. Yet there is no electrical connection between the support member 3 and the aluminium bulwark 1. Accordingly even if a sealing protective coating of the bulwark 1 is damaged there will be no galvanic corrosion resulting from the proximate connection of the two dissimilar metals. The joint is rigid in all directions and against rotation. The resin used in completing the joint may be any suitable casting resin. The most important characteristic is no shrinkage during hardening. A 4 to 1 (resin to hardener ratio) Epoxy resin with a powered silica filler has been found satisfactory. For example the second member, including the spigot and the upright member may preferably be manufactured by casting, but could be machined from stock. The member may be unitary or formed of multiple components. It may for example be stainless steel. It may -9- incorporate a mounted fitting, such as a stanchion, or may mount the fitting. The cavity may be provided as a fabricated well in, or welded into, the upright wall. The upright wall and cavity may, for example, be aluminium. - 10- </div>

Claims

<div class="application article clearfix printTableText" id="claims"> CLAIMS:

1. A mounting arrangement for attaching a stanchion or railing post of one metal to the body of a vessel, the body being, at least at the location of the stanchion or post, of a second 5 metal, said metals having different galvanic potential, said arrangement comprising: a cavity in said body, a spigot of said one metal, integral with said stanchion or post, or adapted for retaining an end of said stanchion or post, said spigot extending into said cavity, said spigot being smaller than said cavity and not contacting the surface of said cavity at any point, and 10 a body of cast-in-place electrically insulating material occupying substantially all of ^ the space within said cavity between said first member and said second member.

2. A mounting arrangement as claimed in claim 1 wherein the shape or form of said cavity is such that a rigid body conforming to the shape of said cavity within said cavity cannot 15 be withdrawn without deformation or fracture.

3. A mounting arrangement as claimed in either claim 1 or claim 2 wherein said cavity extends laterally into said body and said arrangement includes a non-conductive seal member adjacent the opening of said cavity, bridging between the cavity surface and the surface of said 20 spigot.

4. A mounting arrangement as claimed in claim 3 including a vent opening to an uppermost point of said cavity, through said body or said seal. 25

5. A mounting arrangement as claimed in any one of claims 1 to 4 wherein the surface of said cavity includes keying features to restrain said body of insulating material from rotation in said cavity. 30

6. A mounting arrangement as claimed in any one of claims 1 to 5 wherein the surface of said cavity includes keying features to restrain said body of insulating material from withdrawal from said cavity. -11 -

7. A mounting arrangement as claimed in any one of claims 1 to 6 wherein said spigot includes keying features to restrain said spigot from rotation relative to said body of insulating material. 5

8. A mounting arrangement as claimed in any one of claims 1 to 7 wherein said spigot includes keying features to restrain said spigot from withdrawal from said body of insulating material.

9. A mounting arrangement as claimed in any one of claims 1 to 8 wherein said spigot 10 includes a fluid flow passage into said cavity.

10. A mounting arrangement as claimed in any one of claims 1 to 9 wherein an upright member extends from said spigot for receiving an upright such as a stanchion. 15

11. A mounting arrangement as claimed in claim 10 wherein said upright member includes at least a pair of spaced apart load points, with an annular resilient member protruding from the surface of the upright member at each said load point.

12. A mounting arrangement as claimed in any one of claims 1 to 11 wherein said flow 20 passage extends through said upright member and through said spigot, to be able to receive a casting material through said upright member and deliver it into said cavity.

13. A mounting arrangement as claimed in either claim 7 or claim 8 wherein said keying features on said spigot include a plurality of elongate ribs at the open end of said spigot. 25

14. A mounting arrangement as claimed in claim 13 wherein said cavity includes a plurality of elongate ribs, arranged such that with said spigot in said cavity said ribs of said spigot and said ribs of said cavity are interleaved. 30

15. A vessel including an aluminium alloy body and a plurality of stainless steel posts or stanchions mounted to said body by a mounting arrangement as claimed in any one of claims 1 to 14. - 12-

16. A method of mounting a stanchion or railing post of one metal to a part of a vessel of a different metal comprising the steps of: inserting a spigot, integral with said stanchion or post or adapted for retaining an end of said stanchion or post into a cavity of said vessel, supporting said spigot in an inserted position so as to not contact said vessel, pouring a settable material that is electrically insulating when set into said cavity to surround the inserted portion of said first body and fill the space in said cavity between said first body and said second body, causing said settable material to solidify.

17. A method as claimed in claim 16 wherein said spigot includes a flow passage therethrough and said method includes the step of pouring said settable material into said flow passage. 15

18. A method as claimed in either claim 16 or claim 17 wherein said spigot is part of a stanchion mounting member, and said method includes steps of: aligning said stanchion mounting member to a prespecified orientation prior to solidification of said resin, and after solidification of said resin, fitting a stanchion post to said stanchion mounting 20 member. 10

19. A mounting arrangement mounting a stanchion to a bulwark, said mounting arrangement being substantially as herein described with reference to and as illustrated by the accompanying drawings.

20. A method of mounting a stanchion to a bulwark, said method being substantially as herein described with reference to and as illustrated by the accompanying drawings.

21. A support member for mounting a stanchion or post, said support member including a 30 spigot at one end and an upright member at another end for snugly receiving an end of the stanchion or post, a flow passage extending through said upright member and said spigot, said spigot including keying features to restrain said spigot from withdrawal from a surrounding solid material when installed. -13-

22. A support member as claimed in claim 21 wherein said spigot includes keying features to restrain said spigot from rotation relative to said body of insulating material.

23. A support member as claimed in either claim 21 or claim 22 wherein said upright 5 member includes at least a pair of spaced apart load points, with an annular resilient member protruding from the surface of the upright member at each said load point.

24. A support member as claimed in any one of claims 21 to 23 wherein said keying features on said spigot include a plurality of elongate ribs at the open end of said spigot.

25. A support member substantially as herein described with reference to and as illustrated in Figure 1. DATED THIS HAY OF ftoQp5* 20°^ A] PARK PER agents' for the applicant </div>