In some cases it it is less about bending the mast and more about ensuring as little drift in the head sail luff as possible. Sight the luff some time while underway to see what I'm talking about. Hardening on the back stay will reduce the curve, flatten the head sail and allow the boat to point a little better with a little less heal.
The 37+ came with a split backstay and I'm a huge fan. Sitting at the helm is much more comfortable since the backstay isn't riding in the back of your head. Boarding via a swim ladder or platform is much easier too. On the 37+ (from what I can tell) the transom attachments are not particularly robust. 1/4 inch worth of fiberglass layup? ish? I've seen on other boats where the backstay chainplate is simply bolted to the surface of the reverse transom. This seems to be very effective and easily manufactured DIY. If it were me I would attempt to determine the thickness of the transom layup near the outboard areas as compared to the center. Assuming they are equal, using some 3/32nd SS bar stock from McMaster Carr I would make my chain plates ~1.5 inch wide and 18 inches long. I'd use 3 3/8th SS machine screws spaced about 4 inches from one another and pre-bend the tang a few degrees off the transom. I would align the chainplates to approximately the angle of the split portion of the backstay. Corrosion-Resistant 316 Stainless Steel Strip, 0.09" Thick https://www.mcmaster.com/9090K8 Split back stays afford a number of different types of tensioners. The type which seems the best value while staying effective is the type with rollers which pull down on the intersection of the split section. Hydraulics are nice since they provide a pressure gage but alternative measuring devices can be engineered. http://www.bartonmarine.com/tech-info-Block-Systems-8-1-Split-backstay.asp https://www.defender.com/product.jsp?name=c.s.-johnson-split-backstay-cars&path=-1|118|2358491|2358500&id=4474057 Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Thu, Aug 13, 2020, 20:49 Charlie Nelson via CnC-List < cnc-list@cnc-list.com> wrote: > My 1995 36 XL was delivered with a hydraulic backstay which I have used > regularly with one trip to the local hydraulic shop to replace the seals > (~$250). Of course, the stern steps were likely designed to withstand the > loading this can produce--if not it was over-designed since I have never > had an issue with its attachment to the hull. > > I think it is an elegant solution compared to the blocks and tackle > necessary to rig a mechanically adjustable backstay. > > If I were to add such a backstay and uncertain of the strength of an > attachment point, I would simply spread the load with a SS single or > Y-shaped bar attached to the stern with a solid and relatively large > backing plate to which the SS bar is through bolted. The plate could be > starboard of sufficient thickness (at least 1/2") or some solid wood (I > like red oak) whose area is such to generously spread the load. > > Keep in mind that the load is not perpendicular to the stern but pretty > close to tangential and depending on your mast cross section, it should > bend with only about 1000-2000 lbs of gauge pressure. OTOH if your mast is > 'telephone pole' like, you aren't going to bend it anyway in which case I > would 'forgetaboutit'. > > Charlie Nelson > Water Phantom > C&C 36 XL/kcb > > > > > > > -----Original Message----- > From: Wade Glew via CnC-List <cnc-list@cnc-list.com> > To: cnc-list@cnc-list.com > Cc: Wade Glew <wadeg...@gmail.com> > Sent: Thu, Aug 13, 2020 5:27 pm > Subject: Stus-List C&C 33 MK II backstay > > Dear Listers, > > As many of you know, the 33 MK II has a single rod backstay which > terminates approximately in the centre of the reverse transom. I don't > have a hydraulic backstay tensioner. Instead there is a small (perhaps 6") > diameter wheel in the backstay which can be turned by hand (rather > laboriously) to tighten or loosen the backstay (which is quite impossible > when the sails are loaded). I'm not really a racer (and hydraulics are > expensive) so have pondered the wisdom of swaging a fitting on the rod > backstay and converting it to a split backstay with a Johnson car and > blocks to have a manual tensioning system. This would increase somewhat > the angle of the backstay and present the issue of finding spots on the > hull or deck to anchor the backstay that would have sufficient strength. > I have no idea if this would drastically alter the dynamics of the sail > plan or the boat altogether. I also don't know where on the hull might > have sufficient strength to support the backstay attachment. Is this a bad > idea? > Would anyone have any thoughts? Many thanks ...... > > Wade > Oh Boy 33 MK II > Lake of the Woods > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
