Offshore 31 Stem Roller/Forestay Fitting
Submitted by Andy Laurence

Preamble: The original Cheoy Lee fitting was poorly designed. For US$30.- you can build yourself a much more robust fitting – just need a big hammer, a strong vice, drill, and an angle grinder for cutting and polishing – no welding required.  
Note:  all images are thumbnails and can be clicked for full images

     Potential for failure: The previous owner of Triton had the fitting weld-repaired at the end of 1995 when cracks were noticed at the join between the centre forestay/tack web and the base. The repair was carried out by grinding back the crack using an angle grinder, and arc welding in sufficient amount to make the join secure again. There was so much weld material put on, it was no longer possible to fit the bow rollers. No post weld heat-treatment was done.

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    Actual failure: It did not fail at the weld! Instead a new crack appeared in the web at the line of the roller-pin hole and 2nd tack attachment holes until the fitting was literally hanging by a thread, and I was so lucky not to lose the mast. The weld repair may have caused some serious weakness about 1" away from the weld itself.

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    Construction of this fitting is poor enough in the first place. I was astonished to see the tang running down the bow was barely attached to the base of the fitting.

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    The forestay/tack web is welded to the upper side of the base (with no lateral support) – the tang is welded to the base on the lower side. If all is well it would still be poor design.

   Construction of a new fitting: Based on discussion with a Naval Architect and observation of other bow fittings, it is clear that the tang should be connected in one piece both to the bow and the forestay. I wanted to do this fitting myself and am a poor welder, so I decided the whole arrangement should have no welds. The tack fitting must accommodate the tang for the forestay, and also needed to be connected outboard on a short tang and inboard via the thro’ bolt to the tang. For strength it should be a channel section. The channel could serve as the inboard arms for the rollers. The tack fitting would therefore have to be on top of the base portion. The base, a larger channel, carrying the outboard arms for the rollers, being trapped between the tack fitting and the bow would not require additional strength against being pulled upwards. Sizes for these can be easily figured out using cardboard templates.

Main components made simply from grade 304 stainless plate:
1.1 Tang 6mm thick x about 2" wide x about 14" long
1.2 Tack 5mm thick, cut and bent to form a channel section and a short tang front and back, formed from a piece of plate about 12" square
1.3 Base 5 mm thick, cut and bent from a piece of plate about 12" x 14"
Other components
2.1 Pin for the tack – the old roller shaft cut shorter
2.2 Shaft for the rollers – ˝" dia stainless bar
2.3 Pin for the pulpit – cut and recycled from the old fitting. (Had I been able to predict my existing pulpit would be destroyed during typhoon York, I would have left this item off, and had a four leg pulpit made.)

   The forestay connects directly on the tang (1.1) which has three bolts and one screw into the bow.

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    The Tack fitting (1.2) was the most difficult to make, with short front tang, rear tang and centre channel section. All I had was a vice and a large hammer. It is secured by a thro’ bolt on the front and rear tangs and two machine screws tapped into the base. These two screws were mainly for holding the assembly together while marking the final profiles and drilling the roller shaft holes.

    The inner arms for the rollers need to be bent inwards and the outer bent outwards a little to reduce chafe. This was done last

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ALaurence.jpg (19879 bytes)Boat-  "Triton" - 67  Offshore 31
OWNERS - Andy Laurence
Click Here for Andy's Website with links to Hong Kong Yachts Clubs plus a Hong Kong Harbor Cam.   Click Here   for the Hebe Haven Yacht Club, where Andy, Werner and Nigel are members
E-Mail Andy The prettiest sailing vessel in Sai Kung says Andy.  

Andy has submitted many of the brochures on Cheoy Lee models that have made this website what it is.  Thanks Andy - james....

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