Drogue attachment to cleats or chainplates?

[OrangeCrush]

I'm considering a Jordan Series Drogue on my Shannon 38 and wondering if I need to install chainplates or if my aft cleats will suffice. The deck is very thick there and the cleats have backing plates. Jordan's website says that strong cleats are good option, but I would need to fashion a bridle to distribute the load and run it cleanly past the davits/tubing.

Chainplates would no doubt be stronger and better positioned but I would really rather not install them if I can avoid it.

Anyone gone through a similar thought process?

[robert sailor]

The downside of cleats is that you have to lead the bridle through fairleads and this would be a major chafe situation. The loads are quite high on these systems and by adding separate chain plates you can install shackles with a metal thimble in the back spliced eye which almost removes the chance of chafe. Personally i think in more moderate conditions you might get by with your plan but if you get into survival conditions, which is why you bought the device, chain plates are the way to go.

[Mycroft]

Proper chainplates would be easy to install on the sides of your stern. Sign up for the ebooks on https://www.morganscloud.com/ The amount of information on drogue installation, not to mention all the other topics, is phenomenal! John's boat, s/v Morgan's Cloud, has the same stern design as yours, so you can see how he did it.

[deluxe68]

I was considering buying a series drogue, but their web site states I would need attachment points rated at 16,000 pounds. I could not find cleats rated even 1/2 of that unless they were sized for a 100 foot boat.

[Southern Star]

That’s why you should install chainplates extended past the transom off the topsides. Mine were custom fabricated and bolt through the hull/deck joint. As I recall, Jordan posted specs for chainplates relative to the size of the drogue.

Brad

[FlightPlan]

I would get two healthy snatch blocks and attach a to the cleat with a dynema strop. Use a bridle, and make a fair lead to the spinnaker winches.

[thinwater]

Originally Posted by deluxe68

I was considering buying a series drogue, but their web site states I would need attachment points rated at 16,000 pounds. I could not find cleats rated even 1/2 of that unless they were sized for a 100 foot boat.

Details, please. I can't remember seeing cleats rated for load at all.

A Boat US study from the 90s suggested that most cleats were matched in strength to the line they are rated for. In other words, 16,000 pounds means 5/8-inch polyester rope, or 10-inch cleats. They would also need a good backing, but that is not crazy big at all. About $100 each.

[thinwater]

Originally Posted by FlightPlan

I would get two healthy snatch blocks and attach a to the cleat with a dynema strop. Use a bridle, and make a fair lead to the spinnaker winches.

The WLL of the winches is probably 1/4 to 1/3 the Jordan recommendation. This is based both on the manufacture rating and studies of fastener strength. He may rip the winches off. I've seen winches come off with just sheeting loads. Using them for mooring is not recommended by any vendor.

I agree that an adjustable bridle is a good idea in merely bad weather when using a speed limiting drogue or for emergency steering (I've done both), but that is not what the OP is asking about.

[Paul L]

Why would say the 6 bolts on a winch base be less strong than the 4 in a cleat? Even if they were one size smaller.
I see possibly damaging the winch with the excessive pull, especially if you tied the line with pressure on the pawls, but it seems like it should be a pretty strong structual base.

[CarlF]

Shannons are overbuilt, but that coaming may not have a particularly thick laminate. It's not really structural. And are the cleats bronze? How about the fasteners? The cleats are not wide enough apart to give the boat good directional stability. And finally, as mentioned, a lot of things are nearby to chafe.

I'd put a fitting down near the hull-to-deck joint, which is probably over an 1" of glass. Stainless steel or titanium fasteners (which are surprisingly cheap). G10 backing. I think the suggestion of using a dyneema strop is a good one. Less likely to melt or chafe where it touches the fitting. I think I also remember someone (maybe Dashew?) made a whole Jordan Drogue out of dyneema to make it lighter.

[thinwater]

Originally Posted by Paul L

Why would say the 6 bolts on a winch base be less strong than the 4 in a cleat? Even if they were one size smaller.
I see possibly damaging the winch with the excessive pull, especially if you tied the line with pressure on the pawls, but it seems like it should be a pretty strong structual base.

Pull out an engineering book and do the math. It is all about the leverage. A cleat take the load less than an inch from the deck. A winch will take the load 4-6 times higher, thus experiencing 4-6 times more up lift ont he fasteners. The fasteners are typical the same size. Finally, remember that the fasteners on the winch are not all well positioned to share the load; only the 2 to windward are doing any real work as the winch begins to pry off the deck. With the winch, all 4 are in shear. Bottom line: the cleat can be MUCH stronger. Heck, a climbing bolt hanger, no larger than a 50 cent piece and held by a single 3/8" bolt, is stronger than a typical winch. It's all about the design and leverage.

I've seen winches pull out of the deck from sheet loads. It's not that rare. And sheet loads are 4-6 times less.

Just go through the math. Ask a winch manufacture. The data is on the web site.

[Paul L]

Thinwater
What's your opinion on the loads that Jordan lists vs practice? Are they close?

[kmacdonald]

To experience the loads that Jordan designed for would require hurricane force winds and HUGE BREAKING WAVES. No one in their right mind would ever experience that. We just don't get blindsided by hurricanes anymore-----they are forecast long in advance. About a fourth of the worst case loads should be fine, if not overkill. From what I've read, most of the time the drogues are used for riding out gales and storms in comfort and not survival situations. You should be able to avoid sailing in survival situations with little effort.

[estarzinger]

Originally Posted by thinwater

winches . . . . Using them for mooring is not recommended by any vendor.

mmmm . . . .true . . . .but out in the real world they are very very commonly used for shore ties and med moors. We pretty much always used they for that, and for our drogues, and never experienced any winch damage (in like 15 years of usage).

[deluxe68]

Originally Posted by thinwater

Details, please. I can't remember seeing cleats rated for load at all.

A Boat US study from the 90s suggested that most cleats were matched in strength to the line they are rated for. In other words, 16,000 pounds means 5/8-inch polyester rope, or 10-inch cleats. They would also need a good backing, but that is not crazy big at all. About $100 each.

Cleats : BoatUS Foundation