Conference unifix::sailing

    A recent article in Sail or Cruising World discussed a system being
    tested (and patented/marketed I presume) which streams about 200'
    of line aft with small drogues (about 1' diameter) every few feet.
    
    The idea here was to reduce shock loads by spreading the braking
    effect across a couple wave peaks behind you. That way you dont
    get either the speed build up between the boat and drogue one normally
    finds slowing up and speeding down a wave face or the sudden shock
    at the end. I cant do justice to the article (carefully written
    with good examples and illustrations) but will find it and give
    the issue.
    
    I was convinced that it is an excellent hybrid between trailing
    warps and huge chutes.
    
    Walt 

    RE: .1
    
    The article I referred to is in the June 1986 SAIL.  It is authored
    by Don Jordan, sailor and senior lecturer @ MIT.
    
    In the article he describes the problems encountered by a boat trying
    to utilize a Drogue (streamed astern) or Sea Anchor (deployed from
    the bow).  The work simulating boats in breaking and non-breaking
    seas was done at the USCG Academy and partially reported in earlier
    SAIL articles (February 1982, December 1982, September 1984).
    
    Don eventually describes the prototype drogue and fitting requirements
    developed.  For a 30 foot boat it consists of a 20 foot bridle run
    from the transom to 230 feet of 3/4 inch braded nylon line. Five
    inch dacron cones are attached every 20 inches starting at the 100
    foot point to the end.  The end of the line has a shackle to which
    an anchor (any type weighing about 25 or more) is attached. He calls
    this arrangement the SERIES DROGUE.
    
    He expects a followup article on this prototype once at sea tests
    are conducted to fine tune the computer model used to design the
    prototype, and prove the favorable characteristics of the design.
    
    The article is 3 pages. Rather than enter it here, if anyone would
    like the details, and cannot locate the June SAIL, send me a note
    and I will forward a copy of the article.

    Walt

    
    re: .2	 So, for 130ft at 20inch centres it takes 130*12/20 = 78  
    5 inch cones.  Hmmm, there must be an economic source of those around
    somewhere ?   Well, its an even number, so we could use 39 units of
    something that occurs in pairs, or 13 units of something that occurs
    in six packs.   
    
    	Five inch cones ?  
    
		Five inch cones ?  

			Five inch cones ?

    	Aw, I'll find *something*, somewhere.
    
    	Reg
    

    Re: .2
    
    The 5 inch cones are very much like the 2-3' "sea anchors" made
    by Cal-June.  Made from heavy dacron sailcloth with something like
    1" webbing to attach it to the 3/4" line which runs thru each. Don
    Jordan said about 90 of these were apprpriate for a boat displacing
    9,000 to 12,000 pounds.    Not counting the attachment points on
    the hull or the anchor cost, this thing would probably cost $500
    for the above boat (my guess, not Don's).  
    
    Walt

    I just read a book on the subject (Parachute Anchoring System, by
    John Casanova, pub: Chiodi Publishing, Quincy MA., $8.95), and he
    trails a warp of his anchor line and 30' of chain... but the diff
    is that he ties knots in the chain. A real blow would require 5
    knots in the chain, but normally just 3 for the 'standard' storm.
    Also stressed is a swivel between chain/warp.
    Parachute anchoring was the main subject, and they use 28' wide
    'chut, with a boat and 1/2 length rode, and swivel of course (else
    it will twist right up to the boat), and trip line with fender to
    keep parachute from sinking.
    
    One item I forgot to mention... he sails a large multihull, but
    says it works the same on those single hull boats also!

    Can you imagine trying to deploy the multiple drogue anchor in bad
    conditions?  Stowing it without knots and snags sounds like it would
    be quite the art, also.  
    				J

    I just finished reading an article written by Hal Roth back in a
    back issue of Pacific yachting where he said the best place to hang
    a drogue is off the bow of the boat...It is stronger than the stern,
    built to withstand going through the waves better, and will keep
    water out of the cockpit better than if hung from the stern. The
    only potential problem he mentioned was possible damage to the rudder
    when backing into a wave. My question is this, are there as many
    philosophies on this subject as their are people? If seas and
    conditions are such that survival is the primary motivation, what
    would be considered the best course of action? Bare Pole it and
    run with it? Keep a small storm jib up and fight your way through
    it? Hang a drogue from the bow or stern? Some of the above?
    
    I'd sure be interested in learning your views and your reasoning
    behind them. Thanks!
    
    Robert

    The choice of Bow or Stern is usually based on the whether you are
    'riding it out' or trying to make way to a specific destination.
    In the former case you are likely dealing with severe sea state
    or some form of disablement and would want to be bow on the weather.
    In the latter case and with a following sea, you would use the
    drogue over the stern to help control yawing. If making way to
    weather, the usefulness of a drogue escapes me. 
    
    It is especially useful if you have a drogue which can be partially
    "spilled" by its trip line. This gives you finer control of the
    drogue's drag and thus the interaction with your vessel.
    
    Jerry
    

Roth may well be right, but .....

A very substantial sea anchor would be required to hold the bow of a 
boat into the wind and sea in storm conditions. The loads on the sea 
anchor rode would be tremendous (an article reporting on sea anchor 
testing reported rode loads approaching 18 000 pounds [!] for an anchor 
suitable for a 32' boat if I recall correctly). I cannot imagine how to
deploy a sea anchor and rode safely from a wildly pitching foredeck.
Frankly, I wouldn't even attempt it. 

Most published recent opinion seems to be that the best strategy is to 
run before the wind and seas at a speed that gives good control without 
risk of broaching. If the crew is large, the helmsperson can be relieved 
frequently and the boat can probably be sailed very fast safely (as the 
Whitbread racers are wont to do). If the crew is small, it is probably 
better to tow a drogue to reduce boat speed to 3 to 5 knots. This will 
give adequate steering control without unduly fatiguing the helmsperson 
(who may have to steer for hours on end). The rode loads for a drogue
(eg, a Galerider) are probably much lower than for a sea anchor. Of 
course, sailing downwind means risking a wave slamming into the cockpit. 
The usual hatch weatherboards aren't all that strong, and heavily 
reinforced weatherboards and a strong latch on the sliding hatch are a 
good idea. In the BOC races, everyone ran downwind without drogues and 
let the autopilot steer, I gather. Must have been, er, interesting.

Years ago we were sailing downwind well out in the Gulf of Maine in a
C&C 26 in a big wind and sea (not all that big, but big for the C&C 26)
towing a dinghy. The dinghy swamped about 0300, instantly becoming a
quite effective drogue. The boat speed dropped to about 2 knots, and
virtually no steering at all was required to maintain course downwind.
Before the dinghy swamped, maintaining course was difficult and tiring.
Some hours later, the wind dropped and the seas calmed a bit. Bailing
out the dinghy was difficult, exhausting, and not very safe. (Ever
since, we've been extremely reluctant to tow a dinghy.) 

RE: .7,

Boy, there's alot of discussion about this topic, and not much clear 
agreement!  However, a few things I've noticed which may be relevant to 
your view of things:

1)  A drogue and a sea anchor are different things.  The former is 
designed to slow you down -- towed from astern, it is supposed keep your 
bow leading, thus reducing the risk of a broach and subsequent rollover.
The latter is designed to hold you as motionless in the water as possible, 
from the bow.  The tether length is *critical*, as the sea anchor (the 
most effective kind are ruggedized parachutes 10'+ in diameter) *must* 
ride in water moving the same way the boat is, which mean exactly in the 
same position in a wave, two or more waves apart.  If this sound tricky, 
it is (so everyone says).  Wave periods, lengths, and heights all change 
throughout a storm, and affect each other as well, so this implies that 
accurate assessment and constant adjustment are required.

2) Another key element is your boat:  condition and design.  Some vessels 
run downwind in much heavier conditions than others.  Some bury their bows 
easily, others don't.  Etc, etc, etc.  Also, your boat's own response may 
change drastically as the wind goes from 60 kts up to 85 kts -- the forces 
in that case far more than double!

3) What can the skipper and crew handle?  Maybe they're best off with an 
"ultimate" strategy long before things reach and "ultimate" state.  
Vice-versa, too:  Some skippers have the skill to handle what a boat can't 
by herself, though they're a rare (and courageous) breed.

J.

    re. .10
    
    Can one look at a boat and get a general impression of how she may
    handle in a storm? By design, I take it you mean more than just
    the shape of her transom, beam, and length, but the interaction
    of all of the above plus weight ,etc. Is this correct? If so, does
    this mean that certain sailboat designs lend themselves better to
    one method of storm handling over another? For example, having a
    canoe stern like whats on a Valiant or Pacific Seacraft Crealock
    designed boat would give me less willies about dragging a drogue
    than say a stern designed to increase waterline that looks like
    a shovel waiting to scoop a following wave into the cockpit. Do
    factors like these really come into play, or am I way off base?

RE: .11,

It's only my opinion, but I think you're on the right track.  Canoe sterns 
and double-enders present less for a wave to pick up and jostle around, so 
one might find that running downwind in breaking seas was less traumatic 
than doing so in a fat-transomed boat (particularly a lightweight one.)

Displacement is another factor.  Lighter boats can lift with the seas more 
readily, but then are often more likely to get pushed off course.  And 
their motion is usually acknowledged to be much less comfortable than 
heavy displacement vessels.  Crew fatigue seems to be a common a reason 
for changing the storm strategy from running to heaving-to or lying-to, 
moreso than just reaching the vessel's limits.

Long keels typically give greater directional stability, which may make 
steering downwind easier, but then again, a well-designed shorter keel may 
give the maneuverability needed to avoid the worst breakers.  Discussion 
on keel depth has also appeared in these notes.  

Rudder design is also important, for two main reasons.  First, how much 
control can you maintain?  This depends on balance, gearing, size, etc.  
Second, how strong is the rudder, especially the shaft?  Lying-to can 
result in shock loads which will stretch the sea anchor rode enough to 
violently slam the boat backwards -- can the rudder take it, especially if 
caught offcenter to the motion?

Today, people no longer equate seaworthiness with heavy displacement 
(which is one of the reasons Westsail went out of business. ;-])
The current wisdom is best embodied in BOC designs, and with the
understanding that they are designed for extreme racing, one can learn a 
great deal from following the progress of their design.  I also think the 
Deerfoot series pretty much reflects the same approach -- moderately light 
displacement, beam/length ratios of 3.5 or more, canoe-type hulls,
moderate fin keels, huge balanced rudders that won't break out or cavitate
at surfing speeds, low inboard rigs, etc.

J.

moved by moderator

================================================================================
           <<< MSCSSE::SYS$SYSDEVICE:[NOTES$LIBRARY]SAILING.NOTE;1 >>>
                                  -< Sailing >-
================================================================================
Note 1169.0                      SERIES DROGUES                       No replies
ENGLES::GARDINER "Architects-R-Us"                   17 lines   4-APR-1989 13:44
--------------------------------------------------------------------------------

    I have just received a copy of a study by the Department of
    Transportation on the "Investigation of the use Drogues to improve
    the Safety of Sailing Yachts".  It describes a new form of Drogue
    called a "Series Drogue" consisting of a large number (90 to 200)
    of 5" diameter cones attached to a long (250') of line with a 35# 
    weight on the end.  The study concludes that this type of drogue,
    when deployed from the stern, is a major improvement over anything
    else available.
    
    If you would like a copy of the study, send me mail and I ship you
    a copy.  It costs $15.95 from the National Technical Information
    Service (NTIS).
    
    Happy sailing,
    Jeff
    
    

    Sounds plausible.  Did it say what the cones are made of?
    
    Rick,