Where to attach the sea anchor? - Page 2 - SailNet Community
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post #11 of 52 Old 02-25-2012
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I decided that rather than expose the wrong end of the boat to breaking seas as in using warps or drogues, and then having to constantly be at the wheel that I would go the sea anchor route. I know the CG recommends drogues rather than sea anchors but I just feel more confident that the pointy end should be into the sea when waves get really big and start to break.

Storm Tactics suggests that either port or starboard tack should be chosen as the conditions dictate regarding sea room and likely storm path. The main anchor line should run through the place where it will chafe least. On my boat it is through the standard hefty old fairleads on either side of the bow, about 18" back from the bow roller (which I would NOT trust). The secondary line, run from the stern somewhere and attached to the main line via a snatch block, serves to haul the anchor line aft so that it prevents the boat from tacking.

Alberg 35: With a philosophical flourish Cato throws himself upon his sword; I quietly take to the ship.
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post #12 of 52 Old 02-25-2012
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On a fibreglass hull, I would put a massive U bolt on the outside of the hull, well down on the hull, on the stern quarter, with a massive back up plate and several layers of glass buildup under it, as a sea anchor attachment point.
This makes deployment easy, and totally eliminates chafe, and yawing. It also makes the most comfortable motion at sea, in a gale. I've never had to steer with a stern drogue, in nearly 40 years of cruising. I just lash the helm down, put in the earplugs, and go to sleep. Laying off a stern drogue, drastically reduces load on the rode.
I don't think that, by mooring from the bow, you will succeed in keeping the pointy end into the sea. You are more likely to lay beam on.

Brent Swain, Boat designer, Builder, and author of "Origami Metal Boatbuilding"

Last edited by Brent Swain; 02-25-2012 at 07:49 PM.
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post #13 of 52 Old 02-25-2012
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Holy smoke, snapping a 3/4" line (Samson tensile strength 16,700lbs). Even with a reduction of that for a splice where the heck are you going to attach a bridle (other than Brent's method above) that can handle those loads? When that nylon line snaps I don't want to be anywhere near the cockpit if that's where it's attached, maybe not even anywhere on deck.

John
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post #14 of 52 Old 02-26-2012
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Just wondering with your yacht's configeration whether you need a sea anchor to hove to? When I had my 45ft ketch I found it heaved to really nicely just using the mizzan sail. My memory of the Parleys suggested that they were quiet content to heave to without using the parachute, including some pretty rough weather. Jon Sanders would also heave to in force 10-12 just with using a tripple reefed main. I've also read other accounts of yachts heaving to in really bad conditions without deploying anything.

Make things a whole lot simplier if you do not need to deploy anything over the side.

Ilenart
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post #15 of 52 Old 02-26-2012
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Quote:
Originally Posted by Ilenart View Post
Just wondering with your yacht's configeration whether you need a sea anchor to hove to? When I had my 45ft ketch I found it heaved to really nicely just using the mizzan sail. My memory of the Parleys suggested that they were quiet content to heave to without using the parachute, including some pretty rough weather. Jon Sanders would also heave to in force 10-12 just with using a tripple reefed main. I've also read other accounts of yachts heaving to in really bad conditions without deploying anything.

Make things a whole lot simplier if you do not need to deploy anything over the side.

Ilenart
I have never had to deploy the sea anchor and have been able to heave-to without it. The reason I have one is if I feel there may be the chance of being knocked down or broaching in a really bad approaching storm that is likely to create breaking waves high enough to be dangerous. Guess I've been lucky so far in avoiding being caught in this situation. Would like to hear from folks who have actually used their sea anchor in life-threatening conditions.

Brent, have you never had waves break into your cockpit repeatedly? I have had waves break over the cockpit in moderate conditions and have always thought it would be a really bad idea to put the stern to the sea in really bad conditions.

Alberg 35: With a philosophical flourish Cato throws himself upon his sword; I quietly take to the ship.
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post #16 of 52 Old 02-26-2012
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For those who have NOT purchased Lin & Larry Pardey's Storm Tactics I urge you to do so before venturing offshore. I've read it three times, and I personally, consider it a must read text book for bluewater sailing. I have taken a wave into the cockpit in a powerboat while running in following seas--it wasn't fun standing knee deep in ice-cold water and hoping the cockpit drains would not get the water out fast enough before the next wave hit.

One of the things I initially found difficult was obtaining that magical 50 degree angle to the seas without the boat making forward progress. A relatively small parachute anchor solved the problem when placed upon an adjustable bridle similar to the one used by the Pardeys. One that was achieved the breakdown of the seas that they described in their book appeared to take place. The wind was only about 18 to 20 knots so I was unable to test their heave-to process in horrendous conditions, and to be perfectly honest, I hope I NEVER have to do so. However, if I do, I'm fairly confident that it will work, and work well.

On one of the above posts, someone with a 41-foot boat talked of breaking a 3/4-inch bridle and using a 28-foot parachute. First and foremost, 28-feet of parachute seems a bit much for a 41-footer, but I could be wrong. I'm thinking something about half that size would be more than adequate when rigged in conjunction with a stay sail and hove-to. Additionally, I couldn't imagine any winch or cleat on my boat withstanding that much pressure without incurring significant damage to the deck fixtures. I suspect something was not rigged properly, but without being there I surely do not wish to pass judgement.

I sincerely believe the experience of others who were quoted in Storm Tactics is excellent testimony to how effective the Pardey's heave-to technique can be. Each time I read their book I picked up additional tips that I'm sure will be highly beneficial in the future.

All the best,

Gary
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post #17 of 52 Old 02-26-2012
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Quote:
Originally Posted by MedSailor View Post
Even though I've read between 2-300 sailing books by now, I've somehow missed one of the greats: Adlard Coles, "Heavy Weather Sailing." Reading it now and learning a great deal.

Personally I've always thought that, for my boat/crew/situation a parachute sea anchor will be the first line of defense for a survival storm if heaving-to is no longer a viable option.


On S/V Fairhaven, I have a wonderful/awful 8ft long bowsprit, with associated rigging, hanging off the pointy end of the boat. This presents challenges to figuring out the best place to lead a sea anchor from. Ideally I should choose a spot that is immensely strong, has a minimum of chafe, and will hold the boat at a good angle with the rode. See picture below.
I treat my parachute as an anchor through and through. The loads are relative to being anchored. The anchor is lashed on deck, chain stoved, and the rode is passed through the bow roller with chafing leathers at the roller. I have a padeye bedded heavily amidships located just behind the aft lowers for the block which the pennant leads through and makes its way to the winch in the cockpit. The pennant on the winch means I can adjust the boats angle of attack along with the tiller all from the cockpit. getting 50^-60^ off is an art form in ugly conditions


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Originally Posted by MedSailor View Post
I have a bridle set up to the stem (blue arrow) that I use for my main anchor. It's great as it reduces the needed scope and is quite strong as it is attached to the bobstay attachment point. On my rig, the bobstay is the most loaded stay. This seems like a good possibility for leading the sea anchor. It might assist the bow rising over a wave due to it's low aspect, and the fitting is man-enough for the job, but every time I would be nose-down the line might chafe (or bend) on the bobstay and dolphin striker. Also the boat might yaw quite a lot as there is quite a bit of windage (furled headsail) forward of this point.
The line WILL chafe. Being in weather where the sea-anchor is required means usually you will be in it for 24 hours or more. This means regular trips forward to adjust for chafe (the biggest issue). getting your furling headsail off sounds like a fair bit of work but if you are in a mess bad enough to need to get the sea anchor out, you might consider just that (if you cant, wrap your spare halyard over the furled sail to prevent it from unfurling. Paying out enough rode and then using a bridle to pull the boat over 50^ ought to help as well.

Scope, scope, scope. Getting the parachute to ride the crests/troughs in sync with your vessel means minimizing the issues with the bobstay.

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Originally Posted by MedSailor View Post
The Anchor roller I have installed at the end of the sprit (green arrow) is pretty beefy but I have some doubts. It's 3/8 welded aluminum and uses a 5/8"stainless bolt to bolt the roller through the cranz fitting (the collar at the end of the bowsprit where all the rigging is attached) so it is, by way of the bolt, part of the rig. The lead would be free of chafe, except at the roller itself, but I worry it might try and pull the bow down, instead of helping it up as the lower point of attachment might do. Also being part of the rig means it's strong enough, but the way it attaches to that 5/8"bolt makes me worry it could shear off under huge loads.
This should be the same worry then for traditional anchoring? Does the described action happen when you you are lying at traditional anchor with comfortable scope?

Quote:
Originally Posted by MedSailor View Post
Lastly is the red arrow, pointing to the fairlead up forward. This is a bronze fitting through a hefty bulwark in the bow. Since it is part of the hull/deck, I expect it is man enough for the job. It might help hold the bow slightly off center as the fairlead isn't centered. On the other hand if the boat veers the other direction, the anchor lead will be chafing across, and trying to destroy, the bowsprit and it's rigging.

Thoughts?

MedSailor

Bow-on is uncomfortable (for me). When you say "veering" do you mean "tacking" (and in turn are you carrying a strorm tri or bare poles with the anchor) or just rounding and falling off every few mins?

Surfing can be generally managed with the Pardeys method of a control line to the winch, allowing you to find the sweet spot for quartering (and is the way I manage the parachute).

If the boat is yawing/veering whatever you need to get some control over that via the helm, trisail and anchor. quartering is where the comfort and safety is for me...YMMV

s/v Palu | Nantucket Clipper | Hull #3860
"Be Brave - You can't cross a chasm in two small jumps"

Last edited by byr0n; 02-26-2012 at 11:42 AM.
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post #18 of 52 Old 02-26-2012 Thread Starter
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G'day Bry0n, I love your sig.

Lets talk loads:

I would have thought that parachute loads would be the same as anchoring loads but everything I read is contrary to that. Not sure exactly why that's the case as both are loads created by wind and waves while laying to an anchor..... best guess I have as to why the para-loads are higher is that I normally try and drop the regular anchor far far away from 40' breaking waves.

In any case, all the research, tank testing etc seem to think that the parachute loads will be 10-15% of displacement and will likely reach up to 60-70% of the boat's total displacement. The US coast guard's drogue tests are a good source of info for this.

As far as the pardey bridle, it does sound like the solution to the uncomfortable pitching, rolling, and yawing, that most report from laying to a bow-only parachute anchor. I'm quite concerned about Adlard Coles's assertion that the bridle will take the heavier load of the two lines and may well be too high to be effective at all with larger boats. I know from my climbing days that if you make a bridle of lines with an angle of greater than 120deg you INCREASE the load on each arm of the bridle over what it would have been without.

I suppose the best option for me might be to arrange the parachute anchor in such a way that I don't NEED the bridle for it to function (ie to keep it away from bowsprit gear) but arrange a massive bridle that I can use anyway. If it breaks it breaks.

Yes Fairhaven does tack and sail at anchor due to all the windage up front. She did this without a furler, but more so now. At anchor I keep her head to wind by keeping the mizzen up. Pretty sure the mizzen would die a quick death if used to keep me head to wind.

All that windage up front, and fairhaven's willingness to tack at anchor, may be leveraged to keep her bow off the wind without a bridle. I'll have to experiment with my rope rode and anchor setup next time I'm out. I'll set the anchor from the nose, from the stem, and I'll try setting it from a fairlead. Perhaps there's a rudder setting that will keep me "hove to" to an anchor.


Does anyone think attaching a line at the stem fitting at the water line is a good idea?

Also I agree with the comments that for a boat like mine I may not need the chute at all. Heaving to will definately be first, second, and third line of defense. Ideally though I'd like the chute option for if the mizzen gets blown up, or if heaving to just isn't an option for some reason. Nice to have options yaknow

MedSailor

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post #19 of 52 Old 02-26-2012
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Agree absolutely that many options for each situation need to be known and available, meaning equipment ready and knowledge to use it. The size of the chute is important according to manufacturers. I believe they are supposed to "give" a bit so that undue stress is not put on hardware. It seems that this slippage would also tend to counter the tendency to swing around the anchor. With 2-300' of 3/4" line, there is also a much greater horizontal scope from anchor to boat than you would ever have on a regular anchor. Also, backing the jib as done sometimes when heaving-to will keep the bow from getting on the other side of the wind. I really think that once a balance has been achieved and the boat is in its own slick that minor adjustments will be all that is necessary along with adjusting lines for chafe every few hours.

Unfortunately none of this stuff can really be practiced. I, for one am not going out in a tropical storm to test the gear! You can know the mechanics and know precisely what procedures to follow but there is no substitute for the real thing. As has been demonstrated with every procedure, there are almost always unforeseen surprises.

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post #20 of 52 Old 02-26-2012
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Quote:
Originally Posted by smurphny View Post

Storm Tactics suggests that either port or starboard tack should be chosen as the conditions dictate regarding sea room and likely storm path. The main anchor line should run through the place where it will chafe least. On my boat it is through the standard hefty old fairleads on either side of the bow, about 18" back from the bow roller (which I would NOT trust). The secondary line, run from the stern somewhere and attached to the main line via a snatch block, serves to haul the anchor line aft so that it prevents the boat from tacking.
If I ever run into Larry Pardey, I'm gonna ask him how they get a snatch block to work in such an application...

After reading of his suggestion to use a snatch block years ago, I decided to give it a whirl with a similar style anchor bridle, which I often use in open roadstead anchorages in places like the Bahamas, in order to keep the boat head-to whatever swell might be wrapping around into the anchorage... The pic shows such a bridle deployed in the anchorage in Baracoa, Cuba - a very rolly anchorage, which would be miserable in prevailing conditions without using a bridle...



Using the snatch block as per the Pardey's suggestion, I found it impossible to maintain a steady angle, as the snatch block kept wanting to "ride" one way or the other along the anchor rode, and thus changing the length of the two "legs" of the bridle... As ineffective as it was in such relatively benign conditions, I cannot imagine it being anything more than worthless while attempting to lie to a parachute, offshore, in a blow... Perhaps it somehow works fine with a Bristol Channel Cutter, but I'm certainly missing the necessary magic to make it work with a boat such as mine...

IMHO, the midships bridle line must be attached to the main road at a point that will remain fixed, and then by controlling the length of the secondary line running to a cockpit winch, one maintains/adjusts the angle of the boat to the seas... At least, that's the only way I've ever managed to get it to work reliably...

As to the use of a parachute in general, I'd be curious to know what Mr. Adlard Coles' impression would have been, had he lived long enough to ever have had experience with a Series Drogue... I'm guessing he might have been favorably impressed... Most everyone who has used one appears to be, including Peter Bruce, who has edited the current editions of HEAVY WEATHER SAILING, in the wake of Mr. Coles' passing...
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