At a recent sailboat race, while milling around waiting for the start, the windward stay parted in rather moderate winds.
After the initial shock, we immediately deployed the motor to motor home. With the situation stable, we checked for damage: the keel-stepped mast was bent, but the shroud seemed intact. Closer inspection revealed that the pin had failed, because the fork terminal had been installed next to the chain plate instead of straddling it. (The overlong clevis pin that was used had made that mistake possible).
The fork was bent, but not cracked, so I pried it open and with a spare pin that I keep on my keychain, we decided to see if we could reattach the shroud.
My DS1 has a mast jack, so we lowered the mast, and despite the bend in the mast, were able to attach the shroud and raise the mast. With the shrouds defining the distance between chainplates and hounds, the mast was forced back into position, although the bend must have set up a slight curve and most of all asymmetric tension.
Unfortunately the maneuver took some time, and we had motored away for a fair distance, so we didn't make it back to the starting line in time, but this being a fun regatta, we simply followed the fleet around the marks in generally light winds for a bit before retiring. We did not really notice any effects of the bent mast while sailing, but when trying to take it down, the bend made it difficult to handle. It didn't help that the ground was inclined sideways a bit in the same direction. In short, the mast was leaning over so far that we needed one person to counteract the sideways lean while the other person took it down.
Repairs were needed.
First, I used the occasion to upgrade to 1/8" stays from D&R Marine. Because I have the mast jack, the stays are normally fixed length. So I got the ones with the simple adjusters, which should be fine for a one-time rig trim, but can be locked with the locknut after that.
Second, I needed to figure out how to go about straightening a mast. By sighting along the sail slot I determined that there was a bend roughly at the partners (that is where the mast exits the deck), but that a second bend had occurred near the gooseneck. I confirmed the location of the bend with a straightedge. I measured the bend, crudely, and the deflection seemed to be a bit less than a full mast diameter at the mast foot. (Meaning, if the mast foot was held true, the mast tip was deflected several mast diameters because of the longer lever arm given where the bend was).
I took all shrouds, halyards, spreaders and jumper struts off the mast and laid it across an old tire, put a 2cu ft bag of bark across the tip and stood on the other end. While the mast would give, the deflection would all be elastic and it sprang back.
After a bit of this, I discovered that if I stood closer and closer to the end, there was a point where had just enough leverage given my weight to decrease the bend in the mast. This worked best at the upper bend, which, being further from the foot, gave me a better lever arm.
I repeated the exercise moving the tire along the mast to try to straighten different locations.
At the end of the day, it looked like progress, but a significant bend remained. Perhaps 1/2 mast diameter sideways deflection at the short end.
The next day, I repeated the effort with a helper acting as a spotter and adding a bit of weight on the long end, to keep it from flexing as much. Mostly because that flexing would limit the range of deflection for the short end (it would hit the ground, before it was fully deflected).
With that optimization we quickly took out almost all the bend near gooseneck, but for the bend near the partners the lever arm proved too short. Turns out, cat litter is an essential ingredient in this kind of operation. I had two 40# boxes of it sitting around, so I did some weight lifting while balancing on the very bottom tip of the mast. (Glad there aren't any pictures of this ).
That did the trick, and now we are down to a very slight deflection of between 1/2 and 1 mast diameter sideways deflection at the *long* end, or between 1/8 and 1/4" at the short end.
My inclination at this point, and after conferring with some local sailors, is to leave well-enough alone and try to raise the mast and trim the rig. Having been straightened, the mast isn't quite as strong as it used to be, however, most of the bend isn't in a location where failure due to buckling is a primary concern - where the mast goes through the deck, it is held in position, after all. Whether the slight asymmetry will show itself sailing the boat, I don't know. I doubt it, in fact, both from our initial experience and because the boats aren't fully symmetric in the first place. Just my luck if the two effects add up, though.
The first key to the success of the operation so far appears to be the use of soft yet firm support at the location of the bend. An old tire was the ticket, but by the second day, it started to get crushed, so I stuffed a partial bag of bark on the inside. The other key was to find a way to just apply enough force to start the bend. By slowly shifting my weight I had good control over the bending force, and I could actually feel when the mast "gave". Being able to work on the short end made everything quite simple, because a simple bag of bark could serve as a counter weight. In the reverse case, I would have had to wedge the short end under something really heavy, like a car and to find ways to cushion it from any hard spots.
I had to take the diamond stays and jumper struts off, as otherwise I couldn't lay flat the mast on its side. I'm planning to keep them off, because too many people recommend just that. Which, of course, means I won't have a perfect before and after comparison. Too bad .
Finally, why did I have overlong pins in the first place? Turns out that the fork terminals on my stays were drilled for a size pin that's smaller than the pins used on the DS chainplates, and a slightly odd size it is, as it's less than 3/16". (The standard pin size is 1/4"). In fact, to get spares, I had to locate the same rigger that a previous owner had used to order replacement stays and he rummaged on his work bench and measured each pin, and finally located just enough so I would have some spares, but not enough so I could replace all the overlong pins that the PO had used.