Sea Anchor versus drogue for multihull

[Sail Houston]

I was really looking forward to joining and contributing to this community. I'm very surprised at the caustic welcome. Pretty off-putting to be honest. Worse then g-captain and that is saying something. I do wish you all the best and hope everyone remains safe on the water.

[thinwater]

Originally Posted by Sail Houston

I was really looking forward to joining and contributing to this community. I'm very surprised at the caustic welcome. Pretty off-putting to be honest. Worse then g-captain and that is saying something. I do wish you all the best and hope everyone remains safe on the water.

I thought I was respectful, but you persisted in providing obfuscated non-answers delivered with a condescending attitude. Perhaps they were intended to be teasers, hinting at advanced knowledge, but it seems no one accepted it that way. At least some of the contributors are engineers and understand wave theory perfectly well. I do.

I'm sure if you provided a few pictures and diagrams you could amaze folks. Until then they are simply unsatisfied with the explanation because too much is hidden behind the veil of mystery. Parts of it seem rational, but too much flies in the face of convention, and when that happens, extraordinary proof is required.

Just sayin' that's the reaction you saw.

[boom23]

Originally Posted by Sail Houston

I was really looking forward to joining and contributing to this community. I'm very surprised at the caustic welcome. Pretty off-putting to be honest. Worse then g-captain and that is saying something. I do wish you all the best and hope everyone remains safe on the water.

There are a lot of "experts" in this forum... On the Internet, it is hard to differentiate a real expert from an armchair expert. So, some people tend to be skeptical while others try to disprove you. But, many are listening trying to learn. Please do not let some comments discourage you from voicing your opinion.

[StuM]

Originally Posted by thinwater

I'm sure if you provided a few pictures and diagrams you could amaze folks. Until then they are simply unsatisfied with the explanation because too much is hidden behind the veil of mystery. Parts of it seem rational, but too much flies in the face of convention, and when that happens, extraordinary proof is required.

It's not so much the flying in the face of convention that got me going, it was the irrational parts and flying in the face of basic physics.

Especially when we suddenly get cruising displacement hulls transforming into semi-displacement/planing hulls to illustrate how dragging a drogue actually makes you (not just allows you to) go faster.

[Mike Banks]

Drogues and sea anchors are used by me for different reasons. I use a sea anchor to keep a quarter to a sea when drifting slowly backwards in uncomfortable conditions or when needing a rest, and it is deployed over the bow quarter in my case and retrieved using the anchor windlass when the majority of the strain is absent. This can be achieved by slowly motoring forward a little at a time--and when the float line can be retrieved with a boat hook, the parachute itself can be dragged aboard.

I only ever used it in moderate seas--never in a severe storm--but I would use it in the same way if confronted with an emergency--a bridle between bow fairleads and a fairlead half way down the length of the vessel, adjusted so that the breaking seas are taken on the quarter rather than sweeping down the deck. Where the nylon rode passes through the fairleads, split heavy duty polythene pipe is fitted over the rope and tied on, preventing chafe which is a problem with nylon because of its elasticity.

I use a drogue of tyres or if I have anything more elaborate over the stern, using a bridle through the stern fairleads and snubbed on horn cleats with the loose ends near my mainsail winches, which allow the stern to be adjusted in relation to the bridle by first taking the tension on the line using a tarbuck hitch on a lanyard then to the winch.

A drogue used the way I do allows the vessel to continue forwards with the seas and winds coming towards the stern. Not good near a lee shore--and certainly I do not use either sea anchor or drogues with any sail set.

Then again--I have not survived a hurricane or cyclone in open water--just used them to get the idea of HOW to use them in case I ever needed to deploy either in a real emergency, or just to stop the vessel surfing down waves. Nylon rodes pre-spliced with loops at the ends and at half-boat length from the vessel end allows for some safer handling.

Nylon must always be shielded against abrasion. Ideally any loops need to have thimbals. Tuffnel thimbals are OK

Caution for anyone using this equipment for the first time. It is incredibly powerful the strain that comes in the rodes, and under no circumstances should one try to pay out or release any rode under tension without first securing it by an alternative fixation and taking up the strain--or it will drag you overboard faster than one can imagine.

Trying to retrieve a deployed drogue or sea anchor requires a windlass or winches. It is not possible to do it manually and it is dangerous to try. Because I use muine with floats, if I ever had to jettison one, I could possibly recover it later using the Man Overboard coordinates from the plotter.

You CAN handle them under tension--nut only after you have secured them to a winch or windlass and taken the strain off the cleats, and then only to pull them inwards first.

Once you have secured the lanyard, you can then put the rode around the winch, take up the strain again, remove the lanyard and slowly pay out the rode.

I use 20mm diameter nylon because of its great tensile strength and elasticity--but those same properties can make it dangerous. Any rope in tension can be a hazard. Elastic ones seem to have their own stored energy--

One needs to practice using this equipment before having to rely on it in an emergency. Lots of sea room is required.

[Octopus]

Originally Posted by Mike Banks

Drogues and sea anchors are used by me for different reasons...

Great post Mike, really helpful and informative. I had never thought of adjusting the bridle of a sea anchor to take the seas on the quarter.

Chris

[fxykty]

Originally Posted by StuM

It's not so much the flying in the face of convention that got me going, it was the irrational parts and flying in the face of basic physics.

Especially when we suddenly get cruising displacement hulls transforming into semi-displacement/planing hulls to illustrate how dragging a drogue actually makes you (not just allows you to) go faster.

Thank the <Lord> (insert your favourite deity here) that I’m not the only one totally confused by what SH is proposing with such condescending obfuscation, while telling us it’s just basic physics and a different way of using a magical kind of drogue that enables the boat to go faster. Just one relevant picture would be worth a thousand posts.

In any case, why limit the use of this drogue to regular sailing? Gee, racers have been missing out and I’m sure there’s nothing in any race rules that prevents you making your boat faster by towing something.

SH, if you’re for real you will man up and show us clearly what you mean. Up till now all you’ve done is wave your hands. Of course we’re skeptical.

Specifically, what design of drogue?

What size?

How is it (are they) deployed?

What design of kite?

How is it deployed?

What happens when breaking waves blow the boat’s wave form to hell?

What happens when cross seas slow the boat down and knock it off its wave?

[Sail Houston]

I didn't forget about you guys I was doing a delivery and just got back. I'm working on putting some solid information together as well as some historical information on how others in the past have used increase waveform to go faster on a sailing vessel.

In the meantime check out this link. The page is very detailed and gives some great information on how most of you will use a drogue, the forces involved and some of the theory on how to set up.

Analysis & Lessons Learned: Drogues | Victor Shane's Drag Device Data Base

This link in the first half is based on slowing the boat down the second half starts in on some of the theory on how what they are calling a medium speed drogue works.

This link talks about the benefits of using a drogue to steer with under different conditions.

http://bermudarace.com/wp-content/up...t-a-Rudder.pdf

check back in soon. Cheers

[PapaLulu]

Aside from the SH trolling, I have appreciated the input thus far. There is a lot of detail provided in other sea anchor and drogue threads though haven’t found as much on catamaran use until this discussion. Victor Shane’s db has probably been reviewed by all of the contributors here. What has been very useful is understanding contributors’ detailed procedures in testing, drilling and actual deployment and recovery of both drogues and sea anchors, especially as they may differ on catamarans. The discussions centering on the specific conditions for deployment of drogue vs. sea anchor have also been useful, so much appreciated. In regards to catamaran-specific detail, I hope useful contributions to this discussion can continue.