proper mast angle and rigging

[jboright]

I have a DS1 and I've recently had a dismasting . My boat was on a mooring, and there was a big blow, I got a call from the harbot master... long story short(er); one of my side-stays parted at the spreader, and the mast fell.

Sad DS1

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It ended up not being as bad as it could have been. The only real damage was a mangled tabernacle hinge and a broken mast step casting. I was able to order a new set of standing rigging, a tabernacle hinge, and a mast step casting from (our hero) Rudy @ D&R Marine. This is where the fun begins. It turns out that my mast isn't a standard DS mast profile, which means that the mast step casting didn't fit, and the standard standing rigging lengths are not a perfect fit. After some work with a hacksaw and a metal file, I was able to get the mast step plug to work for me. I'm now trying to get the standing rigging sorted. I bought the 'upgraded' DS1 standing rigging package from D&R Marine, which includes full-sized turnbuckles for each stay. However, even with the turnbuckles as loose as they will reasonably go, they (in combination) are a bit too short. I first tried adding some length to the forestay (with some spare d-shackels I had lying around) but the result was a mast angle that was leaning too far (I think) aft.

mast angle 1

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I then purchased a couple of stainless steel O-rings and added them to the side stays. This added about an inch to each of the side stays, and the mast angle looks better to me.

Mast angle 2

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So... my questions are as follows;
1. How can I tell if I have the correct mast angle? I'm fairly sure that the PO didn't have the angle quite right... it always felt like it leaned a bit too far aft (but I don't really know that for sure).
2. Is it OK to add extra hardware (o-rings, shackles, etc.) to add some length in the shrouds (or forestay)? Or should I ask Rudy for longer standing rigging? Any idea what the expected working loads are for the shrouds? I see that the o-rings I have now are labeled "4,564 Pounds Breaking Strength", and "300lb. MWL". I haven't checked on the relative strength of other shackle options... but I'm wondering if I could find a captive d-shackle that would be strong enough.
3. Seeing as my old shroud parted at the spreader... I'd like to avoid that scenario in the future. My spreaders are just tubes with a slot cut in at the end, and the shrouds fit in the slot and are trapped there by a wire tie. It seems like an obvious place for wear to happen. Is there something I can or should do to protect the shrouds? Wrap them in tape? or fit them through a plastic sleeve?

spreader 1

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I'll leave it there for now. I'll see if I can figure out how to add some images to this post...

Thanks, all, for maintaining such a great forum!

[GreenLake]

Wow. That's quite the post. Sorry to hear about your dismasting. That can be a bit traumatising but it looks like you are able to recover.

in drafting a reply I'm going to work back to front a bit, jumping on the questions first.

Spreaders: Those are fine as they are. If you replace your stays every other decade, you should not need to worry about coming up with a unique redesign of your very standard spreader configuration. Replacement should be somewhat more frequently the more exposed to saltwater and the more time exposed to variations in loads (like on a mooring vs. dry sailed). Visual inspection doesn't always locate any damage at the connectors / turnbuckles, so replacement "on spec" isn't a bad idea. Definitely the right idea to replace the whole set now (not just the failed one).

Instead of a simple wire loop, on my boat the wire is wrapped a couple of turns around the stay, both above and below the spreader. That cuts down on any movement. I then wrap the connection with self-amalgamating "rigging tape" - the white stuff that you stretch while wrapping and that really bonds to itself. This is more for protecting the sails.

Mast rake: Your mast should lean a few degrees aft. When your boat is floating(!) on its waterline, a weighted line from the mast top should be about 3" aft of the gooseneck. (That value is from memory.) A more accurate measure can be used if your mast has regulation length. In that case, you can measure the distance from transom to mast top (values can be found in the North Sails tuning guide for the DS).

There's another way to confirm you have correct mast rake. Sail the boat, and in moderate winds (moving well, but not hiking) you should need about 3-5 degrees of tiller deflection (pull to windward, or "weather helm") to keep the boat from rounding up, going upwind with sails trimmed correctly. Your boat speed should be around 4 knots for this test, not more. You would be sailing close hauled. At the angle of deflection you need, there should be some "feel" to the tiller, but definitely nothing that would feel forced. (That will come if you sail much faster and in higher winds). More mast rake will make the boat turn upwind more strongly, and vice versa. (See also the diagram and discussion in this post). If your boat doesn't round up, or even falls off, when you let go of the tiller, you are desperately short of the required mast rake.

(Mast in your image looks too straight. But it's impossible to eyeball when out of the water as boats never sit level on the trailer.).

Length of stays: you are getting a new set of stays. Now is the time to make sure they are the correct length. Also make sure that your mast top is at the correct height above the mast step for your boat, especially, if someone installed an aftermarket tabernacle. If you are wondering, it's OK to put a bit of stable support under the base of the compression post, but not OK to add shackles etc. to the stays. (You write you have a non-standard mast profile, can you give us the length above the mast step. And do you have a mast-jack or any other type of mast step (I'm talking about what supports the bottom of the compression post, not the top of it at the tabernacle position).