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Nov. 24th, 2022 10:27 pmBoring stuff:
With the lowers bolted to the bulkhead and attached, pulled out the uppers yesterday. That's a bit more precarious as the top of the mast is pulled mostly downward, at two points, fore and aft. Four or even three well spaced points holds it in column. I attached the upper shrouds weakly to other things while dropping the bronze bar and old stainless uppers at the small town welding shop where the prediction had come true that the machinist had gone huntin', and no one knew when he would be back. With two new lowers, I had spare lowers so the obvious thing to do was see if I could get old lowers in as temporary uppers with even one single bolt through the bulkhead to hold them, and I can, but I had to switch sides. The bolt hole pattern is completely haphazard and different on each, so the zig-zag of the bolt hole pattern wound up being approximately opposite the lowers, so, switching side. Also had to trim metal off the bottom of one, since starboard chainplates are longer and have a whole extra 5th bolt than portside chainplates on account of the placement of the sink and cubby in the head on port. So, upper shrouds are fastened to the old lower chainplates, temporarily.
There are things working for me and against me here. A keel step mast is partially supported by the cabin it goes through. Some people say that absent high winds, you can leave a keel stepped mast completely detached from rigging indefinitely, and there was already the mast-step collapse incident that did something like that but with sails up, but quickly dropped when shrouds started slacking. Against me is only two lowers where four is standard on a cruising rig. Four lowers in an X and four uppers in a + reportedly has enough redundancy that any one shroud or stay can break and the rig will hold together. Sailing on a club Merit 25, a lightly built boat, on a recent visit, there were four lowers, but the aft two lowers attached inline with the mast, to the same place as the upper shrouds, then the other two were forward a bit, so, not quite an X around the base of the mast, leaving the rig ultimately dependent on the backstay for support, but giving some redundancy with the forestay, which, being at a steeper angle, with lateral load from the jib on it, and under more tension to counteract jib sag and maintain windward ability, is more often the one to go. So, pondering adopting that design and adding two more lowers forward of the mast. That would also help reducing "pumping", where the relativelack of mid support in the mast allows it to get in to oscillations. No lowers aft of the mast means the boom can go 90 degrees out on a downwind run, which is a racy thing intentionally done on this rig, and has an added benefit of reducing downwind sailing by the lee range which reduces accidental gybes.
The dinghies on the other hand don't have any backstay, only a forestay and two upper and two lower side shrouds, where the shrouds are well aft of the mass, creating a not-quite-but-close-enough 120 degree separation. The mast flexes like nuts trying to go to wind, which wrecks forestay tension, which makes the jib sag, which limits windward ability, but, most of the time, those three uppers semi-equally spaced do hold the mast up.
One option for keeping the uppers and lowers clear of the boom and having redundancy is dual backstays, so I googled to see if anyone had done that and found out indeed some have, but Brion Toss is mortally opposed to it: http://www.briontoss.com/education/archive/miscapr99.htm . Lack of lowers led aft of the mast (which serve as backup for the backstay on a cruising rig) was not mentioned in there as either a valid or invalid reason to do that. I read Brion Toss' book, _The Complete Rigger's Apprentice_, apparently the go-to for learning rigging as my introduction to this stuff, by the way. One reason against is that there's likely only one tang both backstays attach to at the top, so it's not completely redundant, which while a valid consideration hardly nullifies the idea. That would mean 5 points of support at the top and then either 2 (or if I added 2 more) 4 lowers. In favor of the idea is better support on the windward, load bearing side, and a shallower angle on each, so more of the tension is transferred in to support instead of compression. It would add windage tho. So, two more lowers forward of the mast just to take out that damned pumping and add redundancy with the forestay is probably next on this front. Lowers add a lot less windage aloft than uppers, and the belly of the sail, especially when reefed, is near or below the lowers, so most of the force on the mast is there. Pulling the top of the mast back or pulling the middle forward both have an effect of pulling some of the belly out of a sail, for high wind sailing. That minimizing heeling forces and increases forward power by making it a more slight wing. Moving the already existing two lowers aft could be done later still, then it would be a completely standard sloop rig.
With angles right around 11 degrees, a fairly small component of stay's strength holds the mast in column, and that's the best case, when the forces on the mast are directly opposite the stay, which is not usually the case. More typically, only a component of a component of a stay's strength holds the mast in column.
Since things are maybe stable and supported at the moment, I could try taking the forestay off, I suppose, to have a new one fabricated, but most likely that will be a future project. The age of the chainplates with the lack of redundancy has been stressing me out.
Boatfriend is in limbo after hauling out before his apodment lease starts, so he's out here van camping a few days before slowly crawling up the coast. There's a communal Thanksgiving dinner we both skipped, separately. More sanding on the coaming. Got a China special small battery powered angle grinder that claimed to be compatible with the "12 volt max" Makita drill battery and in fact is. That made short work of chopping one of the old chainplates for my old-lowers-are-now-uppers deal. Trying to limit the number of battery systems across tools while avoiding fancy big high-end tools is challenging.
With the lowers bolted to the bulkhead and attached, pulled out the uppers yesterday. That's a bit more precarious as the top of the mast is pulled mostly downward, at two points, fore and aft. Four or even three well spaced points holds it in column. I attached the upper shrouds weakly to other things while dropping the bronze bar and old stainless uppers at the small town welding shop where the prediction had come true that the machinist had gone huntin', and no one knew when he would be back. With two new lowers, I had spare lowers so the obvious thing to do was see if I could get old lowers in as temporary uppers with even one single bolt through the bulkhead to hold them, and I can, but I had to switch sides. The bolt hole pattern is completely haphazard and different on each, so the zig-zag of the bolt hole pattern wound up being approximately opposite the lowers, so, switching side. Also had to trim metal off the bottom of one, since starboard chainplates are longer and have a whole extra 5th bolt than portside chainplates on account of the placement of the sink and cubby in the head on port. So, upper shrouds are fastened to the old lower chainplates, temporarily.
There are things working for me and against me here. A keel step mast is partially supported by the cabin it goes through. Some people say that absent high winds, you can leave a keel stepped mast completely detached from rigging indefinitely, and there was already the mast-step collapse incident that did something like that but with sails up, but quickly dropped when shrouds started slacking. Against me is only two lowers where four is standard on a cruising rig. Four lowers in an X and four uppers in a + reportedly has enough redundancy that any one shroud or stay can break and the rig will hold together. Sailing on a club Merit 25, a lightly built boat, on a recent visit, there were four lowers, but the aft two lowers attached inline with the mast, to the same place as the upper shrouds, then the other two were forward a bit, so, not quite an X around the base of the mast, leaving the rig ultimately dependent on the backstay for support, but giving some redundancy with the forestay, which, being at a steeper angle, with lateral load from the jib on it, and under more tension to counteract jib sag and maintain windward ability, is more often the one to go. So, pondering adopting that design and adding two more lowers forward of the mast. That would also help reducing "pumping", where the relativelack of mid support in the mast allows it to get in to oscillations. No lowers aft of the mast means the boom can go 90 degrees out on a downwind run, which is a racy thing intentionally done on this rig, and has an added benefit of reducing downwind sailing by the lee range which reduces accidental gybes.
The dinghies on the other hand don't have any backstay, only a forestay and two upper and two lower side shrouds, where the shrouds are well aft of the mass, creating a not-quite-but-close-enough 120 degree separation. The mast flexes like nuts trying to go to wind, which wrecks forestay tension, which makes the jib sag, which limits windward ability, but, most of the time, those three uppers semi-equally spaced do hold the mast up.
One option for keeping the uppers and lowers clear of the boom and having redundancy is dual backstays, so I googled to see if anyone had done that and found out indeed some have, but Brion Toss is mortally opposed to it: http://www.briontoss.com/education/archive/miscapr99.htm . Lack of lowers led aft of the mast (which serve as backup for the backstay on a cruising rig) was not mentioned in there as either a valid or invalid reason to do that. I read Brion Toss' book, _The Complete Rigger's Apprentice_, apparently the go-to for learning rigging as my introduction to this stuff, by the way. One reason against is that there's likely only one tang both backstays attach to at the top, so it's not completely redundant, which while a valid consideration hardly nullifies the idea. That would mean 5 points of support at the top and then either 2 (or if I added 2 more) 4 lowers. In favor of the idea is better support on the windward, load bearing side, and a shallower angle on each, so more of the tension is transferred in to support instead of compression. It would add windage tho. So, two more lowers forward of the mast just to take out that damned pumping and add redundancy with the forestay is probably next on this front. Lowers add a lot less windage aloft than uppers, and the belly of the sail, especially when reefed, is near or below the lowers, so most of the force on the mast is there. Pulling the top of the mast back or pulling the middle forward both have an effect of pulling some of the belly out of a sail, for high wind sailing. That minimizing heeling forces and increases forward power by making it a more slight wing. Moving the already existing two lowers aft could be done later still, then it would be a completely standard sloop rig.
With angles right around 11 degrees, a fairly small component of stay's strength holds the mast in column, and that's the best case, when the forces on the mast are directly opposite the stay, which is not usually the case. More typically, only a component of a component of a stay's strength holds the mast in column.
Since things are maybe stable and supported at the moment, I could try taking the forestay off, I suppose, to have a new one fabricated, but most likely that will be a future project. The age of the chainplates with the lack of redundancy has been stressing me out.
Boatfriend is in limbo after hauling out before his apodment lease starts, so he's out here van camping a few days before slowly crawling up the coast. There's a communal Thanksgiving dinner we both skipped, separately. More sanding on the coaming. Got a China special small battery powered angle grinder that claimed to be compatible with the "12 volt max" Makita drill battery and in fact is. That made short work of chopping one of the old chainplates for my old-lowers-are-now-uppers deal. Trying to limit the number of battery systems across tools while avoiding fancy big high-end tools is challenging.
