Attaching Sea Anchor on larger multihull

[nfbr]

When I bought my cat (61ft, daggerboard) it came with a large parchute sea anchor. 25 yrs old. Never used.

So, if I wanted to use it, I've been trying to figure out how to rig and deploy it. Probably why it was never used.

Keeping in mind I have a bowsprit, so opportunities to tangle are endless.

Anyway, lets say it's a big storm, I'm tired and don't want to use a drogue, but face it head on to get some sleep. And we can argue the stupidity of that seperately (Drogue device database).

The books I find are very dated, and seem to not use a bridle. Instead they rig the sea anchor line to one hull and use a pulley to pull it across.
That won't work on my boat. Padeyes are too far down on nose of hulls.

So I have gotten as far as the below:

Attaching

Attach an extra long (2.5 times beam) nylon bridle to anchor padeyes on front of bow, possibly using dyneema soft shackles. Bridle having a spliced eye in the middle.

Now the next question is how to attach the anchor rode to the bridle, and how to do so in a manner that could be adjusted for chafe or length.

And how to do an adjustment using the windlass, which goes across the crossbeam, which we don't want to overload.

How do you setup a bridle with a sea anchor, and make it adjustable.

Thanks
Paul

[Tin Tin]

You might find this useful
https://www.para-anchor.com/faq.zac.html

[nfbr]

Originally Posted by Tin Tin

You might find this useful
https://www.para-anchor.com/faq.zac.html

That's an example of what doesn't seem right.

The rode and bridle are both pretty well fixed, with little opportunity to adjust.
Maybe once long enough (600ft) adjustment doesn't matter

Also no way to inspect bridle attachment for chafe once deployed by bringing things in a bit.

I suspect there is a smarter way.

[Tupaia]

Originally Posted by nfbr

That's an example of what doesn't seem right.

The rode and bridle are both pretty well fixed, with little opportunity to adjust.
Maybe once long enough (600ft) adjustment doesn't matter

Also no way to inspect bridle attachment for chafe once deployed by bringing things in a bit.

I suspect there is a smarter way.

Ignoring the fact that the loads may exceed your ability to adjust it anyway. If you are in conditions that require deployment the last thing you want to be doing is adjusting it perched on the bow. Make sure there is chafe protection before deploying in earnest.

[Slainte1]

pass anchor rode thro a turning block on one bow back to a winch.
From block on the other bow pass line with a snatch block on the outer end and clip over the anchor rode and run the other end to a winch. As you slowly let out each line in turn to form a bridle which can be adjusted from winches

[Montanan]

Configure chaffless hardpoints on each bow as is equipped on the Exit Only catamaran.

Scroll down on the webpage linked below to see the custom chainplate.

Blue Water Catamaran - Exit Only Sails Offshore Around The World.Â* Captain Dave - Privilege 39

Copied the relevant description:

SEA ANCHOR CHAINPLATES

I've heard some experts say that the forces generated by the pull of a parachute sea anchor will pull your cleats right out of the deck. If you attach the parachute bridle to the cross beam of your catamaran, it will pull the crossbeam out of the bow.

I created my own answer to this objection. If you examine these pictures, you will see the parachute sea anchor chainplates that I put on my bows for use during storms, and I also sometimes use them at anchor in harbors if a major storm is headed my way. They create a chafe free way to attach a bridle to Exit Only.

These chainplates are twenty-five inches long on deck and consist of six millimeter thick stainless steel. On the underside of the deck is the same size of stainless plate, but it is only twenty inches long. Large bolts go through the deck and through both chainplates, and there is nearly zero chance that these chainplates will ever move. If they move, it's because both bows will have been pulled off the boat.

Welded down both sides of the chainplate and sticking out in front of it is a stainless steel bail that is about as thick as my finger. The part of the bail that sticks out in front of the bow is where I attach my parachute bridle using d-shackles that I wire closed after the bridle is in place. The bridle has large stainless steel thimbles on it so there is no chafe on the arms of the bridle where they are shackled to the bails.

[Wallaby]

Please excuse my ignorance. Why would you use a parachute, with its problems of impact loading on the bow, and not a Jordan series drogue at the stern where there appears to be far more strength in the hulls?

[Mike Banks]

I agree with Montanan. The forces generated by a sea anchor from a vessel surging backwards in a storm and coming up against the sea-anchor's rode can be extreme.

For that reason I would only ever deploy a large sea anchor if there was limited sea room.

Some one time friends of mine in an Oro sat out a storm using a sea anchor for two days. In that time they moved over forty nautical miles, some of it caused by ocean currents, the rest by dragging a sea anchor. They deployed it from the bow using chain bridles.

So--you need plenty of sea room. The more the better. If there is plenty of ocean downwind, then the series drogue is a better option than a sea anchor--it is less strain on crew and vessel and it is a softer ride.

However, if you MUST deploy a LARGE sea anchor, you have to think of it as an immovable object. That means you have to have some sort of spring between it and the vessel. Most will opt for a long length of heavy nylon twist-laid rope, at least two hundred metres of it because nylon has a good stretch factor, and provided that splices have many tucks, can be spliced to stainless or galvanized thimbles without too much trouble.

I do not recommend bringing nylon through fairleads UNLESS they are roller-gated. I have done it, but where I did so I encased the nylon in a plastic sleeve designed to protect the rope from chafe.

I like to splice loops into my nylon lines and rig those loops with thimbles. One splices in a length of nylon with the ends of the loop facing the direction of the sea anchor or bollard--whatever is mooring the vessel. Splice in one end ahead of the other--that makes a stronger splice and smaller diameter than a cat's paw loop. It is an old sailing-ship man's ploy seldom seen these days, but it makes a good way of setting the quarter of a vessel into a seaway, or of runnning a bridle, (I like to use chains to the vessel for my bridles if using a sea anchor on a nylon rode. Chains sag and do not flick up out of the water easily, do not chafe, and take a moused shackle without any problems. They are quickly rigged, and if the main part of the chain is enclosed in a plastic hose, will not scratch paintwork.)

Water-cooled nylon, not rubbing on anything, does not fail unless its breaking load or splicing factor is exceeded.

Having said all this--I never used my sea anchor in earnest either. I deployed it from time to time for practice--but I always managed most unpleasant weather with a conical drogue made up of three or four vehicle tyres of different sizes spliced together and towed like a cone--which tyres when separated also served me as fenders.

The only thing one has to be concerned with when using a drogue from the stern, is your rudders. They are subjected to a lot of strain as seas rush past them from the wrong direction--if the drogue is being towed. It is a good idea to lash the helm midships and just let the vessel run--if you have a clear run of course.

Which brings me to something so obvious one ought not to need to say it--but as soon as a serious storm is forecast, abandon your course if necessary, and get your vessel into such a position that it has as much sea room as possible. More vessels run ashore in storms than are ever sunk by storm driven waves in deep water.

[Montanan]

Originally Posted by Wallaby

Please excuse my ignorance. Why would you use a parachute, with its problems of impact loading on the bow, and not a Jordan series drogue at the stern where there appears to be far more strength in the hulls?

Primarily so as to have the bow take the force of breaking waves and to ease the rise of the vessel over the waves; also windage is less from the bow then the wind blowing on the stern of a catamaran, hence the pull on the rode will be much less.

[sierramerkur]

One might respond to this thread: "Never, Never Never, use lifesaving equiptment beyond 5-10 years or it's expiration date--except for training." Take the parachute sea anchor out and get in some good wind. Pretend you've been rolled 360 by a rouge wave in a storm. Now what? Imagine the bridle, etc... is decayed beyond imagination. Now what? You're 1000 miles from rescue in any direction. Your rudder is smashed, you've been demasted. You deploy your parachute sea anchor and it fails. Now what? Your No. 1 job as captain of your boat is knowing what to do when disaster occurs. What else/How else can you deploy other equiptment on you boat to use as a sea anchor. You have a hole in the side of your boat big enough to put your foot through. Now what? Disaster does occur & most often when planning/experience fails. Become an expert. A Ph.D dude I know did a study on disasters/Accidental deaths. Disasters occur because of #1 Failure to plan & lack of training &/or experience. Usually, a minumum of three cues are missed which normally would have prevented the disasterous event.

[nfbr]

Originally Posted by Montanan

Configure chaffless hardpoints on each bow as is equipped on the Exit Only catamaran.

Scroll down on the webpage linked below to see the custom chainplate.

Blue Water Catamaran - Exit Only Sails Offshore Around The World.Â* Captain Dave - Privilege 39

Copied the relevant description:

SEA ANCHOR CHAINPLATES

I've heard some experts say that the forces generated by the pull of a parachute sea anchor will pull your cleats right out of the deck. If you attach the parachute bridle to the cross beam of your catamaran, it will pull the crossbeam out of the bow.

I created my own answer to this objection. If you examine these pictures, you will see the parachute sea anchor chainplates that I put on my bows for use during storms, and I also sometimes use them at anchor in harbors if a major storm is headed my way. They create a chafe free way to attach a bridle to Exit Only.

These chainplates are twenty-five inches long on deck and consist of six millimeter thick stainless steel. On the underside of the deck is the same size of stainless plate, but it is only twenty inches long. Large bolts go through the deck and through both chainplates, and there is nearly zero chance that these chainplates will ever move. If they move, it's because both bows will have been pulled off the boat.

Welded down both sides of the chainplate and sticking out in front of it is a stainless steel bail that is about as thick as my finger. The part of the bail that sticks out in front of the bow is where I attach my parachute bridle using d-shackles that I wire closed after the bridle is in place. The bridle has large stainless steel thimbles on it so there is no chafe on the arms of the bridle where they are shackled to the bails.

Kindof what i have now (mine are vertical and on the front, but similarly reinforced)

I would love to know how he rigs the bridle and parachute rode to the bails.

The pulley block idea I have seen, but the forces on that are really weird / do my head in a little. Makes loads on bows uneven. Must remember high school vectors.

[Tupaia]

Originally Posted by Wallaby

Please excuse my ignorance. Why would you use a parachute, with its problems of impact loading on the bow, and not a Jordan series drogue at the stern where there appears to be far more strength in the hulls?

A drogue allows you to slow down in open ocean a parachute enables you to stop something you would want to do if there was something in the way ahead like Australia for example. Both have their place depending on the circumstances.

[Montanan]

Originally Posted by nfbr

Kindof what i have now (mine are vertical and on the front, but similarly reinforced)

I would love to know how he rigs the bridle and parachute rode to the bails.

The pulley block idea I have seen, but the forces on that are really weird / do my head in a little. Makes loads on bows uneven. Must remember high school vectors.

I believe he just uses standard bridles connected by the D shackles to the bails with no difference in length of the legs of the bridle, i.e. standard Y and even pull on the bows. He uses this chaff free connection also for anchoring / mooring when a storm is brewing so as to not have to worry about the bridle chaffing through on fairleads or cleats.

I believe he chose to deploy a sea anchor on a couple of occasions, but he also chose to deploy "boat brakes" / a speed limiting drogue off of his stern linked to winches mounted on the stern to slow his boat from surfing too fast down the face of waves when running with them.

A pulley block would seem to induce chaffing where the rode is tied off, but does offer the potential to align the boat directionally which depending on sea state and wind direction may avail a more favorable riding of the elevator of steep passing swells. Albeit definitely unequalizing the load on each leg of the bridle and where the bridles are connected to the vessel.

Reference his remarks about the infrequency of dealing with harsh wind events and the construction and use of an Abbott Drogue.

MULTIHULL VIDEOS FROM AROUND THE WORLD.Â* SURVIVING THE SAVAGE SEAS. ABBOTT DROGUE

Snipet:

"SURVIVING THE SAVAGE SEAS

Once upon a time there was a small catamaran named Exit Only. Although it wasn't a large yacht, it was big enough to sail the seven seas - the reason was simple. Ninety-five percent of the time the seas were small and the winds were light. In fact, in an eleven year voyage around the world, Exit Only never saw winds in excess of fifty knots while on passage, and only three or four times saw winds up to forty knots.

That's the way it is for most boats who sail in temperate latitudes at the correct time of year. People who sail for pleasure, rather than necessity or racing, rarely find themselves caught out in a gale. Nevertheless, sometimes mother nature throws you a curve and you get caught in a storm, and that's exactly what happened to us as we ventured out into the Atlantic from Gibraltar.

[Sos]

Originally Posted by nfbr

Kindof what i have now (mine are vertical and on the front, but similarly reinforced)

I would love to know how he rigs the bridle and parachute rode to the bails.

The pulley block idea I have seen, but the forces on that are really weird / do my head in a little. Makes loads on bows uneven. Must remember high school vectors.

I agree about the pulley block - I don't think it will work because it can move up and down one bridle leg. I would also like to know how to attach the bridle to the sea anchor rode. For my anchor I have a bridle that is spliced into a single leg with a chain hook. I guess you could use something similar and use a rolling hitch to attach it but not sure I would trust just a knot??

[Rucksta]

Ring and dog bone

Ring is spliced into the bridle.
A bite in the warp goes through the ring
Dog bone goes through the bite.

Adjustable, retrievable, inspectable and works either end for drogues.