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I would like to replace my original single backstay with a split backstay. Any advice would be appreciated. Some specific questions though:
1 - can I attach the ends of the split backstay to the loops that are built into the back of the toerail - they seem a convenient location.
2 - I know the boat has a stiff, not a bendy mast, but is there a problem using the backstay adjuster to adjust the forestay tension on this boat (within reasonable limits of course).
Thanks
Greg Tokarz
Nepenthe Mk1 #75
Hi Greg. I am currently in the process of redoing the chainplates for the split backstay on my MK III. A previous owner had mounted them to U-Bolts fastened through the lazarette deck (the flat section between the coaming and the teak caprail on the stern). Believe me, this is NOT a structurally sound practice!
C&C used to sell a conversion kit for installing split backstays onto MK I, II and III 27's. This kit consisted of 2 large, angled V-Bolts (like U-Bolts, but with pointed tips) and 2 aluminum castings, each about 6 inches long, which were intended to replace the outer six inches of the teak stern caprail at each end, beside the stern corner castings. These aluminum pieces are important because simply putting the V-Bolts through the teak would allow them to work under load, crushing the teak and loosening the fastenings. Suitable angled V-Bolts are available from Blue Wave Rigging Products, which are imported by Transat Marine / Western Marine here in Canada. Your local chandler should be able to order them from Transat. If not, please contact me and I can probably help out.
The aluminum castings might still be available from South Shore Yachts, but I am manufacturing my own from plain aluminum stock. My former C&C 25 had its split backstay anchored to the stern corner castings and on the 27 Mk IV, C&C redesigned the stern corner castings and used them to anchor the split backstay. However, the redesigned castings have considerably more material in them then our original corner castings. As well, the attachment portion was along the line of the transom and was carefully angled to be in line with the angle of the backstay. My concern about anchoring to your existing corner castings is that not only are they lighter than the ones on the Mk IV, but that the tension created by the split backstay will be out of alignment with the casting material, putting lateral stress on the castings in a direction in which they are not reinforced. This may cause them to crack and fail.
I use my backstay to adjust my forestay tension all of the time. Obviously, masts as sturdy as ours are not inclined to bend, but by pulling the masthead aft we can straighten out the forestay while it is under load. This works well on the several C&C 27's which are in our racing fleet here at the Bronte Harbour Yacht Club.
Good luck with your rigging changes! My e-mail is available through the "Fleet" page here on the C&C 27 website.
Marcus,
Carriden (Hull #847)
[Let's wait until the lake turns liquid again and your stick is up, then perhaps you can give us some photos, Marcus. (Don't you love squeezing in back there?) - Admin]
Last edited by (2007-03-12 08:38:08)
Marcus. Thanks for the useful information. I will probably try to assemble the pieces for mounting the split backstay sometime in the summer. I'll contact you if I have trouble getting the materials from the chandlery. This may be accelerated if I continue to ding my head on the single backstay. Greg
I would very much like to do this conversion as well. I have '76 Mark III that seems quite similar to many of the Mark IV's. The castings at the stern of the MKIV at our club are identical to the ones on my boat. Did all MK IV's come with the beefed up castings? Anyone know if some of the MK III's had them as well. Maybe this would be a great addition to the Black Arts section with some photographs of the above and below deck details on a correctly done conversion?
Marcus - Extremely interested and will do the project this month on my Mk III. Looking for your opinion.
1. Would you strictly go with "V" bolts or would the "Oval" ones work if they were properly secured with backers, as you have mentioned.
2. How far up the back stay are you going to attach your "tri-plate"?
As noted above, your work would make for an intesting read in the, "Black Arts". Would love to see your work in pics.<IMG src="http://www.cc27association.com/f3/toast/emoticons/icon_smile.gif" border=0>
Dean M Baldwin
Morgan "D"
Mark III - Hull 516
Halifax, N.S.
Dean M Baldwin
Morgan "D"
Mark III - Hull 516
North Sydney, N.S.
Offline
Okay, this thread seems to be of interest to a number of people. As I progress with mounting the new chainplates, I will document the process in photographs, along with measurements. If David agrees to their usefulness, then hopefully he will post them in the Black Arts section. I will supplement this information with some observations on various ways of rigging the tensioning tackle, based on my experiments over the last couple of seasons.
Dean, based on observation of other boats as well as my own, the semi-circular U-Bolts will work. However, you do want the upper body of the bolt, above the stopper plate, to be angled more or less in line with the angle of the backstay. It is the lateral forces which fatigue and overstress a fitting like this. Although the backstay tension may eventually bend the bolt into line, I would rather know that it came from the manufacturer already shaped and tested.
Regards, Marcus from Carriden
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