Antifolding system to prevent capsizing

[Mika Harju]

Since I heard about DF35 capsize last year I installed an extra backup system to prevent this if the original folding rope breaks down.
This system is quite easy to operate, just open the pulley's quick shackle and fix it to the short harbor pole.
When unfolding the boat you can't forget to put the it back into use.

Drawing for: DF Anti-Folding System (pdf format)

[Mika Harju]

Since I heard about DF35 capsize last year I installed an extra backup system to prevent this if the original folding rope breaks down.
This system is quite easy to operate, just open the pulley's quick shackle and fix it to the short harbor pole.
When unfolding the boat you can't forget to put the it back into use.

Drawing for: DF Anti-Folding System (pdf format)

Updated drawing and few photos:
Please click on any of the photos to see them enlarged!

[Double Horizon]

Mika you are ahead of your time! Your system is better than the bow attachment, geometrically stronger and will not be in the way when picking up a mooring. I have heard a similar geometry is now being used for the DF28 (beneath the net rather than attachment to the bow).

I have decided to do something similar for my 1200, as a "folding preventer".

My implementation for the 1200 will need to be stronger though, so all hardware will be rated 6,000 lb or greater (that is the approximate strength of the stainless bow stays Quorning uses). I plan to use Dyneema single braid with splices and lashings.

The forward eye will be bolted through the stainless hinge plate on the lower aft side of the front hinge, so it will be only a slight angled (almost straight out) pull on the eye-bolt rather than a sideways (shear) pull like you're using. The aft attachment is still not decided, but it will either be to the ama or the lower lip on the outer aft side of the aft beam.

Rather than using the multi-part block I plan to use lashings at the aft end for fine tension adjustment, and the "folding preventer" will be able to be released at the aft end using a spliced-on Wichard trigger snap shackle and to a spliced-in Wichard "quick-link" -- all rated for load. The quick link will be attached to the lashings aft, and the trigger snap shackle will be attached to a long dyneema segment attached forward. The release point will be forward of the aft beam, beneath the gap between net and beam where it is easy to reach. Upon release I will be able move the trigger snap shackle to the aft inboard corner of the net where it can be stowed by attaching to the center hull (either the net attachment point or the aft lifting eye).

I won't have this done until the boat is launched again in Spring, but plan to post pictures. There may be some changes to final design.

[penryj]

Hi Mika,
What is the "short harbour pole". Is this something specific to the 1000? do you use this in addition to the bow attachments or instead of? Could you post more details of the parts you use i.e. length of line, size of blocks etc.
Regards, Penry

[Mika Harju]

Hi Mika,
What is the "short harbour pole". Is this something specific to the 1000? do you use this in addition to the bow attachments or instead of? Could you post more details of the parts you use i.e. length of line, size of blocks etc.
Regards, Penry

Short pole is in use when the DF1000 is folded. It prevents the ama to move up and down with waves.
In my DF there is 8mm Dyneema line, breaking strength 3850kg, size 40 Ronstan blocks and Wichard snap shackles and Wichard M8 U-bolt.

[penryj]

Thanks for the info, Mika
Given that you are essentially replacing the wire stays at the the bows with a synthetic material, I wonder whether anyone has given any thought to using a synthetic alternative to the wire water stays?
I would think it would be a significant weight saving.

[tpaliwoda]

I would not recommend replacing the water stays with synthetic lines, just for the fact that you may not have ever taken an object between the hulls yet, but in the event that you ever do, I am sure you would want to hit it with a solid cable.
Synthetic has it places, like in your rigging. I would not venture to have it as your primary source from keeping your boat from exploding.

[Double Horizon]

I would love to replace the water stays with synthetic, but the attachments are the issue. I would do it if it wasn't for the need to engineer new attachments. Even better would be to find a way to attach a backup (secondary) waterstay in synthetic. It would be like wearing belt and suspenders.

I have struck a steel buoy with a prior boat and have a pretty good idea of the considerable forces involved. (I don't think steel is bullet-proof either. The sudden increase in tensile load from a perpendicular impact force could exceed the limits of a steel stay, and a Dyneema stay is around 40% stronger for equal diameter.). I'm very impressed with the properties of Dyneema and would not hesitate to use it if not for the above concern.

[Steve B.]

I love that stuff, but you can cut it easily with a knife.

Imagine what you would experience if you sailed over anything with enough of an edge to act as a knife. Almost any metal with lots of rust or nasty edges could instantly leave you with NO waterstay. You might not even feel an impact !

For that application, I'll stick with s.s.

BTW, here in the Pacific NorthWET, I am still sailing on my original waterstays from 1995. Swages and wire look fine. All the rain keeps the salt out.

[Double Horizon]

I doubt you could encounter a rough edge that would cut Dyneema without you knowing about it. Yes it could be cut by something, and your hull could be holed too. Although Dyneema does cut easily with a sharp edge, it is THE most abrasion-resistant synthetic. Practical Sailor did a rope test recently and one of the tests was to press a piece of tensioned rope against the drum of a belt sander at a controlled tension and pressure. Dyneema came out on top, and the photo showed it was barely affected. It's tougher than Kevlar.

[gminkovsky]

Steve,
How often do you replace backstays and forestay? 15 years sounds like very long time for waterstays! I look at the wire and fittings regularly too. But I was under impression that SS can fail without warning. So the precaution is to change SS rigging at predetermined intervals. I am very concerned about salt doing its work inside the fitting where you can't see anything.

Quorning recommends 5 year year interval for waterstays and 10 year interval for standing rigging. I believe someone had a forstay failure at 9 years.

George

[Steve B.]

I go over the whole rig at least once a year.
Last year I pulled the mast to replace the conduit and VHF cable as well as move the radar to the mast.
I checked every fitting and swage very carefully. No problems found at all.

A few years ago, I replaced the bearings in the upper swivel of the forestay.

A couple of years ago, I pulled all the waterstay chainplates, cleaned and polished them. No cracks or corrosion found there either.
I did however, find salt intrusion through the bolt holes to the inside of the boat due to improper bedding of the chainplates.

Rain, although depressing, is a good thing for the rig.

Steve B.

[tpaliwoda]

Larry,
If you really want to use synthetic on the waterstay's, I can hook you up with someone that can make that happen. You can contact John at Colligo. He does all my custom work for me. They specialize in synthetic rigging. A couple of years ago he wanted to outfit my entire boat with synthetic, but I passed on the offer.

There is no question that synthetic can handle the loads as waterstay's, But I still like the comfort factor that the SS waterstay's provide.

Ted

[Double Horizon]

Thanks Ted -- I know about Colligo. I have several years to go with my present waterstays, but I will consider them when ready. Dynex Dux would be the way to go for that application, if I don't stay with stainless.

[EarthBM]

I must say, after reading that SS waterstays are to be replaced every 5 years and must come from Quorning, the first thought to cross my mind was Spectra or Dyneema. Other than cutting though, both of them stretch over time, so there would need to be a mechanism to adjust their length. I assume they are load-bearing.

Back to Mika's original post -- do I understand it right that this system is meant to do what the bow attachment wires do (I think those can and should go synthetic, by the way)?

[Mika Harju]

Mika's original post -- do I understand it right that this system is meant to do what the bow attachment wires do (I think those can and should go synthetic, by the way)?

Yes, DF1000 does not have those bow attachments and these are engineered to be a better solution to prevent the amas folding in if everything else goes wrong.

[Double Horizon]

Larry,
If you really want to use synthetic on the waterstay's, I can hook you up with someone that can make that happen. You can contact John at Colligo. He does all my custom work for me. They specialize in synthetic rigging. A couple of years ago he wanted to outfit my entire boat with synthetic, but I passed on the offer.

There is no question that synthetic can handle the loads as waterstay's, But I still like the comfort factor that the SS waterstay's provide.

Ted

Spoke with Colligo and sent some photos of the end fittings on my 1200. I asked him about rigging some kind of backup using Dynex Dux so I could have a redundant system with standard steel stays as primary, and Dux as a backup "failsafe". We figured the main hull attachment could be customized easily with a replacement chainplate and agreed the challenge was the outer end attachment and that something would need to be engineered. Neither of us have that kind of idle talent lying around the bench free of charge so we agreed to shelve the idea for now.