GP14 Sailing Forums Forum Jib Halyard Sheave

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    • #18030

      Hi, I have just obtained my very own GP14. Having had a good look over her today, there are a couple of little jobs need doing one of which is getting and fitting what I think is called a Jib Halyard Sheave. I have had a look online and can’t find anything that I think will fit in the hole in the mast. The length of the hole is approximately 70mm, the widest point is about 15mm and the narrowest point is about 10mm. As you can see there appears to be screw fittings left and right of the hole but the ones I have seen online are top and bottom screw fittings. Any advice would be really appreciated. Ste Lyon.

    • #18032
      Chris Hearn

      Hi, and welcome to the GP14 class!
      I am sure one of the experts in older boats will advise more thoroughly! It appears to be an early wooden mast – all the metal masts I have seen are as you have found online, with mounting holes top and bottom, not on the sides (I guess that keeps the “pull” on the sheave in line with the halyard).
      So the two options that occur to me are a) ask here in the forum and/or in the “Classifieds” sections as a “wanted item”, or b) fit a modern one and fill the current holes!

      Good luck!

      • #18033

        Hi Chris, thanks for the response, the boat is Fibreglass and the mast is actually metal, I will put a post in the wanted section as you suggested, there is another GP14 in our sail club with the same hole and a Halyard Sheave but it looks like it’s been made custom rather than store bought. Will see if anyone else has seen a hole like this, thanks again.

        PS I have added my hull Cert No.29240, can I find out the age of the boat from this? 😉

    • #18036


      I don’t think the Association will be able to cross-reference the builders plate with the  Association registered number and Googling shows the boat builders federation to have  disappeared.  Some old fibreglass boats had another plate with the registered number, this may be near the mast gate, on the centreboard case, or on the aft face of the cockpit (or it might have been removed/fallen off!)

      It looks from the photo as though there are rebates in the sides of the pulley slot.  I have seen sheaves with a stainless strap which slid into the rebates thus transferring the load from the screws to the mast, but it’s a long time ago.  Looking for an old IYE mast may be your best option.

      Good luck,


    • #18057

      This would have had a double inline pulley to take the halyard through the tube and exit into the luff track. You wont find a new one.

      I would suggest – depending on your intended use – that you get a younger Proctor mast with spreaders. This may seem drastic but your boat will perform better, be easier to rig and sail. The IYE masts were nothing more than a wooden mast made of aluminum.

      I can help with a mast if required.

    • #18073
      Oliver Shaw

      This does indeed appear to be an IYE mast.     If you want to stay with this mast you will not find a new replacement fitting,  as they have not been manufactured for many decades;   so unless you are lucky enough to find one second-hand I would suggest buying a modern dinghy sheave box of a different make and do whatever metalwork on the mast is necessary to fit it.   The fitting will not be straightforward,  since you will probably have to bring the halliard down the centre of the mast rather than down the luff track,  and then exit at the bottom;  a significant amount of alteration,  and metalwork.

      However I concur with Chris,  that you might do better to go for a younger metal mast for all the reasons that he states.     And in addition the IYE masts are all now extremely old,  so expect to have problems of corrosion and of cracking,  both of which will erode the structural strength of the mast.     It is at least worth following up Chris’s offer of help with the mast.



    • #18105

      I would agree with comments made by others and would reinforce the warning made by Oliver that corrosion around the jib halyard sheave box is a strong likely risk with an old IYE mast.  While I haven’t had an IYE mast for many years ( at least 25 years ago) the IYE masts I did have in GP 10444 both broke due to corrosion at this point.  Also if I remember correctly the jib halyard in the IYE masts was lead through a tube to come down the sail track at the back of the mast rather than running down the middle of the mast as in modern alloy masts so fitting a new style sheave will as Oliver says involve some difficult metal work and care not to weaken the mast at this critical point.

      If possible replacing the IYE mast with a newer mast would be a good move.

    • #18118
      Oliver Shaw

      As a temporary stop-gap expedient,  since (if you are who I think you are) you are local to myself (indeed a member of the same club),  I can lend you a fully working IYE mast  –  or at least it was fully working last time I used it.

      But that is only a loan,  and only a temporary one;  this mast serves on one of my vintage boats until such time as I get my wooden mast for her sorted out.



    • #18140

      What you describe was the later IYE jib halyard sheave. The initial version had two aluminium plates, with the sheave axle between them, and a large diameter sheave that took the halliard through the mast into the sail groove. The axle would pull through the (soft) aluminium, turning the sheave into a high friction fair lead. The later version, which you have, had two stainless strips that went into slots, or rebates, on either side of an extruded section that was welded into the mast. A stainless pin with shoulders on each side located into the stainless strips to form the axle for the sheave. I can’t remember if the axle was peened over at each side, or if it was just the correct width to fit tightly. It was secured with two self tapping screws through the outer ends of the stainless steel strips which were formed to the mast x-section, so the holes were indeed either side of the sheave, not vertically as with an ordinary sheave box as fitted to the later Proctor masts. I would recommend you try to find some stainless steel strip and make up something similar to the original fitting. I do not recommend cutting out the box section insert welded into the mast!

      I also do not agree with some of the comments about those IYE masts – they were very bendy compared with the wooden mast, and behaved in exactly the same way as the Proctor masts that replaced them. However the quality and design of the mast accessories and fittings were very poor. In particular the very early IYE masts had a welded in tube for the spinnaker halliard, which was an appalling high friction solution. The early masts never used spreaders, nor muscle boxes on the Genoa halliard, so were not subject to the extreme rig tensions in use today.

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