Jordan Series Drogue

[Aeolus]

Just looked at the Jordan Series Drogue web site where they recommend dedicated straps bolted to the hull. However they also say:

"A large steel cleat would be acceptable if the deck is thick solid fiberglass and a steel plate is provided underneath."

I guess I need to check how much backing the cleats have.

 

[Fascadale]

The SS strap shown in the earlier photo is about 3.5mm thick.
The strap is bedded on sikaflex
The counter sunk bolts are A4 10s
The hull is about 1 cm thick
There is a spacer made of a bit of nylon chopping board between the backing plate and the hull

I'm not an engineer but this seemed fairly close to what Jordan spec'ed. I live in hope.

I suspect if this "system" fails it will be by ripping out the stern of the boat. Not a nice thought

 

[Independence]

I have set mine up to run from the forward cleats, 1turn around the winch and then through the stern cleats. Have allowed for some stretch!!

 

[ScallywagII]

The SS strap shown in the earlier photo is about 3.5mm thick.
The strap is bedded on sikaflex
The counter sunk bolts are A4 10s
The hull is about 1 cm thick
There is a spacer made of a bit of nylon chopping board between the backing plate and the hull

I'm not an engineer but this seemed fairly close to what Jordan spec'ed. I live in hope.

I suspect if this "system" fails it will be by ripping out the stern of the boat. Not a nice thought

I would agree that this looks rather thin and liable to bend. It seems unlikely but repeated bending could break the strap. Oceanbrake sell straps 10mm thick. OK the loads are less for our smaller craft, but I would think 6 or 8 mm should be the minimum. Clearly the shorter the overhang the better, and the aft through bolt should be as far aft as practicable. The longer the distance between throughbolt and shackle, the easier it is to bend the strap. Certainly the dedicated straps aft is the way to avoid chafe.

Len

 

[helixkimara]

bkts

I think "Scalliwag11" is right. Also countersunk bolts in 3.6mm steel look the job BUT the plate would just rip off them as very little steel is left. Seriously not wanting to be a pain.
I would use a heavy s/steel angle to give some lateral strength and dome head s/s bolts.
Inside, due to the thin s/s plate you are relying in the hull at the bolts location only. If you use a marine ply inner pack between the hull and a heavier s/s backing plate then you can tighten the bolts so that the outside and inside plates grip the hull sides giving you a friction grip as well as bolt shear or damage to hull at the bolt locations. keeping the overhang as short as practical.

I haven't worked any "theoretical" loads out, Just my initial opinion with my engineering head on.

Then again my sons do call me a "perfection-arse"

 

[andlauer]

Loads provided by drogues on the nuts

Drawings should be attached in a word format (readable with the free software "openoffice")
The effort that is opposed to the drogues is the power of the wave that pushes the boat forward. In fact it is linked to the surface opposed to the wave the cross section in case of forward motion, the lateral surface in case of a broach.
The order of magnitude of the efforts is the weight of the boat; In very severe conditions (resistance to the acceleration) it may raise up to several (lest say 2 to be conservative) the weight of the boat. (With a parachute sea anchor It could be much higher as there are some chocks). To limit the chock effect spring should be provided in the way of generous length of expendable rope.

----So just think in tons of loads!----

With the chain plates the load of the drogue is transmitted perpendicularly to the nuts in a very effective way (perpendicular to the nut and the hull). there is no pull out effort.

With the deck cleats the load is partly transmitted in a twist effort that tend to pull out the rear nuts from the deck. It is the worse way to provide an effort on a nut and on the deck. The cleat or the deck may be pulled out.... which might be rather uncomfortable in such conditions.

trust me I'm an Froggy engineering.
Eric

 

[andlauer]

The drawing opfully

I retried to upload a PDF drawing.
Eric

 

[jesterchallenger]

As per the instructions from the JSD site I'd originally intended to bolt on some transom chainplates for my drogue. However, it occurred to me that this makes the first part of retrieval quite difficult - you would have to lean off the back of the boat to get a line around one of the bridles to be able to start winching it in. I envisaged a fair bit of hanging off the transom and trying to tie a rolling hitch with one hand whilst hanging on with the other, in what would still be quite a rough sea. Clutter on the aft deck also made this quite awkward (tiller, pushpit, windvane, water generator etc).

In the end I made up a much longer bridle set, so that each side came through a fairlead on either quarter, round the 43ST winches and then forward via genoa cars to a substantial central cleat on the foredeck. I deemed that the structure holding the winch would be sufficient on its own, with the foredeck cleat as additional backup.

One of the strengths of the JSD is that, unlike a para anchor, it allows forward movement proportional to the loading on it, almost like a giant bungee, which helps mitigate shockloads. Nevertheless, any chainplates used for it needs to be similar in scantlings to the capshroud chainplates of the boat.

 

[oldbilbo]

Recovery is a puzzle.

I'm minded that, in sailing ships before the use of steam windlasses, the anchor cable was an unwieldy hawser often as thick as a man's body which could be bent around massive bits. This was recovered indirectly by means of a continuous-loop 'messenger' hawser, clinched to the anchor cable by means of 'nippers', and which was passed several times around the capstan-winch and hauled in continuously until the cable and anchor came home.

Perhaps this technique could be bent into service for recovery of a JSD warp....

I carry 'ascendeurs' and wonder if I cannot use these somehow as modern 'nippers' onto both the JSD warp AND a continuous-loop 'messenger' line taken around one of the sheet winches.

 

[Pye_End]

I carry 'ascendeurs' and wonder if I cannot use these somehow as modern 'nippers' onto both the JSD warp AND a continuous-loop 'messenger' line taken around one of the sheet winches.

My plan is to use a couple of prussic knots with a lines to a sheet winch, possibly from further forward (genoa track?). It would be fairly slow to start, but time is unlikely to be too much of an issue. Ascenders sound quicker to set up. Wouldn't have thought chafe would be an issue is the line might get deployed a couple of times in its lifetime, if that.

I can't picture the benefit in a continuous line - can you draw a piccie?

 

[jesterchallenger]

Jordan Series Drogue recovery

My braid-on-braid line is 18mm, so they'd need to be big 'ascendeurs'. I didn't know climbers used anything that thick. A rolling hitch is cheaper too!

 

[oldbilbo]

My braid-on-braid line is 18mm, so they'd need to be big 'ascendeurs'. I didn't know climbers used anything that thick. A rolling hitch is cheaper too!

I'll be interested to hear how well you get your rolling hitch to hold, loaded, on streaming-wet braid-on-braid.