BuiltWithNOF

Roger Strube        Roger H Strube, MD

THE UNIQUE SAIL CONTROLS OF THE DRAGON

I designed the systems that control the Dragon’s Wings so that she could be sailed single or short handed.  It has always been my feeling that all boats are one or two person conveyances.  A vessel that is too complicated or to large to be managed by one or two people will not be used very often.  It is a big plus to have the room and facilities to allow guests to cruise comfortably for a weekend or, for really close friends a week or so but the boat and it’s systems must be manageable by one or two people.

My goal was to minimize the number of control lines in the cockpit while allowing ease of sail trim adjustment with minimal effort.  With the notable exception of the Nonsuch Unimaran most vessels with this primary goal can’t get out of their own way under sail.  The Dragon has rod rigging and a rotating mast similar to all high performance beach cats.  Millennium Dragon was designed with an air draft of 62’ so that during nasty off shore conditions she could travel from port to port on the Intracostal Waterway.  She carries a large square top main sail (approximately 600 sq. ft.) with full battens.  The sail is stored in the “rain gutter” boom between the “side curtains” held up by Lazy Jacks.  The main has a 2:1 halyard and is hoisted (usually hand over hand) with assist of a Lewmar #44 electric winch located at the helm station.  The main halyard passes through two Lewmar Rope Clutches, one at the spar and the other near the Lewmar Electric Winch.  The tack is lashed to the mast just above the goose neck.  The main has two reef points and a Cunningham grommet.  Once the main sail is hoisted luff tension is controlled using a 4:1 block and tackle Cunningham.  This control line is lead down to the deck then turn through a large high strength turning block back to the port side of the cockpit at the helm station.  A Lewmar Rope Clutch secures its position near the electric winch.

A hydraulic out haul cylinder provides the other elements of main sail shape control, leach tension and draft.  A master hydraulic pump is located for ergonomic control by the helmsmen.  This pump pressurizes the system that controls out haul tension and mast rotation.  The out haul is composed of several elements.  The entire system is mounted on a big boat deck track bolted inside the gutter boom at the aft end.  The 2” hydraulic cylinder is fixed at the forward end of this track.  The ram is fixed to a heavy duty car that slides on the track actuated by the hydraulic system.  This car carries a custom fabricated stainless steel fixture for the attachment of two lines.  One line is the main clew tether.  The other is the out haul trim block control.  A big boat Harken cheek block is located at the aft end of the track at the aft end of the boom.  A sliding big boat trim block is located between the aft Harken cheek and the custom SS fixture attached to the hydraulic cylinder ram.  The trim point line runs from the fixture to the Harken cheek block turning 180 degrees and running back to the big boat sliding block.  As the hydraulic ram pulls the SS slide and fixture forward the trim line pulls the out haul trim car/block aft.  At the same time the main clew tether runs from the SS fixture through the big boat trim car/block turning about 120 degrees and up to the main sail clew.  When the system is pressurized the main sail clew is pulled aft and down as the tether shortens and trim point moves aft.  Opening the hydraulic valve releases the pressure and the leach tension is released causing the top 1/3 of the square top main to twist off and loose power.  This loss of power in the upper 1/3 of the main more than makes up for any increase in power cause by the increased draft.  Sounds complicated?  It really is quite simple.  Close the valves and pump the handle and the main flattens and leach tightens.  Open the valve and the leach loosens and the square top twists off.         

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The Cunningham and hydraulic system described above control the shape of the mainsail.  The large square top and full battens provide an extremely efficient and powerful main but a significant portion of this power could be reduced if a non-rotation mast had been fitted.  Most non-rotating sail boat masts disturb the air flow across the low pressure side of the sail casting a “wind shadow” of up to 20 percent of the leading edge (luff).  A tier drop rotating mast reduces this loss of power significantly.  Small beach cats sometimes use a SS yoke pinned to the mast and swinging under the goose neck and boom.  A line, sometimes with a small block and tackle is used to limit the rotation of the mast relative to the boom.  Larger racing trimarans and catamarans use a torque strut protruding either fore or aft of the base of the mast and controlled by block and tackle to port and starboard.  This controls mast rotation relative to the position of the vessel, not the boom or sail.  It works but requires more crew, more attention and more lines on deck.  Both these systems have problems with the forces generated at the goose neck where some sort of universal joint is located a little aft of the sail track.  All the force of a loaded mainsail are carried through this goose neck which at times, especially while tacking, causes a violent slamming full lock to lock rotation of the mast from side to side until the tack is completed.  I wanted an easier way to control mast rotation and maintain a relatively constant angle between the mast and the boom.  The rotation controls had to be between the mast and the boom.  

The most elegant solution was to use the hydraulic system to control mast rotation as well as out haul main sail clew position.  The mast rotation control system consists of tracks on each side of the boom near the goose neck.  One inch hydraulic cylinders are fixed to the aft end of the tracks.  Their rams are attached to cars forward of them on the track.  A bent armature (SS arm) is attached to the cars on each side of the boom.  The other ends of these arms are attached to the sides of the mast just behind the mid point.  As one cylinder pushes, the other pulls.  The result is a hydraulically controlled rotation.  When tacking the Dragon the rotator valve is released and the mast is free to rotate with the wind however the speed of rotation is dampened by the shock absorber effect of the hydraulic cylinders.  Once on the other tack, the port/starboard selector valve is rotated and the pressure valve closed.  The hand pump provides pressure to the system and the mast is over rotated into the wind.

The excessive forces generated through a gooseneck fitting located aft of the mast are also eliminated in this design as the boom is fitted to and concentrically articulates with the same thick wall aluminum pipe used to fabricate the mast rotation deck fitting.  This four foot aluminum alloy pipe is fixed internally at the base of the mast with several bulkheads/baffles.  An aperture cut into the aft edge of the mast provides access to this pipe for the goose neck fitting.  The goose neck rotates concentrically with the mast allowing the boom to travel from side to side without generating the usual goose neck forces.  The second axis of rotation (boom up and down) is facilitated by a half inch SS bolt connecting the mast element of the fixture with the boom.  This bolt also fixes the yoke/sheave that is the center element of the 4:1 Cunningham system and provides the pin/shaft for the two plastic sheaves running the reef lines down to the deck.  This attachment moves very little as there is essentially no up/down movement of the boom.       

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This design also eliminates the need for a boom vang and mainsheet.  Because of its width a catamaran accommodates a long traveler.  Because of the speed a fast, well sailed cat will always have the apparent wind on or a little ahead of the beam.  Because of the size of this vessel I was able to mount the traveler on top of the bimini at the aft end of the cockpit.  Because the traveler is 24 feet long and because the hydraulic out haul allows control of mainsail twist, there is no need for a main sheet.  Because the boom is lashed to the traveler cars there is no need for a boom vang.  The boom rotates on the same axis as the mast and swings from port to starboard on cars attached to a big boat Harken traveler track rolled to a 19’ radius.  Traveler control lines (4:1 ratio) are used port and starboard.  These lines dead end on the end of the boom (at a through bolted back up plate used for the internal, aft, Harken out haul turning cheek block).  A stacked double sheave Harkin big boat traveler fitting is used at each end of the track.  The traveler lines run from the dead end at the boom (with swivel fitting) to the lower end sheave back to the boom/traveler car blocks, back to the upper end sheave and back to the boom turning block ahead of the traveler yoke.  From there the lines run under the boom to the goose neck fitting where they turn down to the deck blocks at the base of the mast.  From there they run aft to the port side of the cockpit near the electric winch at the helm station.  The traveler provides the angle of attack to the wind.

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The outboard (aft) jiffy reef lines (2:1) run from dead ends inside the rain gutter boom up through the large reef grommets and down to turning blocks on the opposite side.  From there the lines turn forward and travel to the mast inside the boom.  The goose neck fitting contains two sheaves that turn these lines down to the deck.  These sheaves use the horizontal 1/2” bolt that attaches the boom to the goose neck fitting and the Cunningham yoke to the goose neck fitting.  After making this 90 degree turn down the reef lines run through deck mounted blocks at the base of the mast and run aft turning into the starboard side of the cockpit.  The screecher and spinnaker halyards are also lead through turning blocks back to the starboard side of the cockpit.  All halyards run through Lewmar Rope Clutches mounted to the mast to prevent overloading of the mast/deck rotation bearing.  The forward reef line is controlled at the mast using a Lewmar Rope Clutch.

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The Profurl roller furling jib clew leads to one of two through bolted sail tracks on the bridge deck.  I use the outer track for easier cruising.  The jib sheets run from the jib clew through the adjustable car back to mechanical Lewmar #44 winches on each side of the bridge deck.  The winches are self tailing.  The big boat roller cars are controlled using slide adjustment lines that run from the car/block to a turning block at the end of the sail track.  The line then turns 180 degrees and runs aft back to the cockpit through smaller Lewmar Rope Clutches.  This provides fore/aft adjustment of the trim point.  The clue may be barber hauled in or out by rigging temporary snatch blocks on the inner track car or side deck screecher track car.  The roller furler drum control line runs from the drum to the starboard side of the bow where it turns 90 degrees through a double cheek block and runs aft along the starboard deck through fair leads mounted on the stanchions.  At the position of the traveler/bimini mount a double cheek block turns the line 90 degrees toward the #44 electric Lewmar winch mounted on the middle of the aft cross beam (back of the cockpit).  Between the cheek block and the winch the control line passes through a small Lewmar Rope Clutch.  In light weather the sail is simply rolled up by hand.  In heavier air the electric winch is used.

The Dragon carries a screecher at the end of an 8’ bow sprit.  This is a thick walled SS pipe with a locking pin at the forward cross beam and water stays at forward (roller furler) end.  The water stays travel from the bow weldment to each bow just above the water line.  These water stays are 5/16 SS stranded wire with pressed end fittings.  The screecher is raised using a 2:1 halyard that exits the starboard side of the mast and runs through a Rope Clutch prior to reaching the deck plate turning block below.  The halyard then turns toward the cockpit to reach a winch for final luff tension adjustment.  Once up and adjusted for tension the Rope Clutch on the mast is engaged taking the additional downward pressure off the mast rotation bearing.  The screecher Profurl drum is attached to the end of the bowsprit.  The roller furler drum control line runs from the drum to the starboard side of the bow where it turns 30 degrees through a double cheek block and runs aft along the starboard deck through fair leads mounted on the stanchions.  At the position of the traveler/bimini mount a double cheek block turns the line 90 degrees toward the #44 electric Lewmar winch mounted on the middle of the aft cross beam (back of the cockpit).  Between the cheek block and the winch the control line passes through a small Lewmar Rope Clutch.  In light weather the sail is simply rolled up by hand.  In heavier air the electric winch is used.  When deployed the sail is trimmed to adjustable sliding big boat cars on heavy duty tracks located on deck amidships at the toe rail.  The sheet then travels aft to a large double turning block near the deck attachment point of the overhead traveler.  The sheet then turn 90 degrees inboard to Lewmar #44 self tailing winches located on the port and starboard back rests at the side of the cockpit.

Millennium Dragon also carries an asymmetrical spinnaker.  This sail uses a single part halyard that exits the mast on the starboard side, runs through a Rope Clutch, down to the deck then back to the cockpit.  As this sail is hoisted in a sock winching is never needed but this lead makes assistance from the cockpit possible.  The tack for this asymmetrical sail is attached to a bridle that runs from bow to bow through large Lewmar blocks.  The bridle line is secured to one of the two available deck cleats at the bow.  The sheet for the spinnaker uses the same deck track/block used by the screecher when it is flown.  The sheet then travels aft to a large double turning block near the deck attachment point of the overhead traveler.  The sheet then turn 90 degrees inboard to Lewmar #44 self tailing winches located on the port and starboard back rests at the side of the cockpit.

There are large self bailing deck stowage lockers forward adjacent to the fore deck trampolines.  These lockers are used to store the sails when they are not in use.

Additional pictures with some additional comments may be reviewed by clicking on the film strip below.  Other sections of this site cover other topics.  The next section on “Sailing the Dragon” explains how the gear described above has propelled this vessel to a maximum speed of 17.9 knots.

Garmin GPS Speed Documentation

Helm Station Electric Lewmar Winch

Navtec Outhaul And Mast Rotation

Navtec Pump And Operating Valves

Navtec Pump And Selector Valve

0

1

2

3

4

Goose Neck & Cuningham

Goose Neck Cunningham

Boom Goose Neck & Cunningham

Boom Goose Neck Cunningham

Boom Goose neck

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6

7

8

9

Spar Goose Neck Rotation Connect

Spar Boom Hydraulics

Boom Goose Neck & Mast Hydraulics

Out Haul Hydraulic

Out Haul Hydraulic

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11

12

13

14

Out haul Turning Block

Rig Goose Neck Hydraulics

Radar Arch Bimini & Traveler

Traveler & Bimini

Traveler Outboard Ladder Support

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Traveler 25 feet Beam To Beam

Traveler Cars Lashed To Boom

Traveler Mounting Assembly and Radar Arch

Traveler Port Side

Traveler & Reef Lines

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Goose Neck Looking Up

Goose Neck Detail

Base of Mast

Spar Goose Neck

Detail Mast Base

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Rig Sail Controls

Starboard Cabin Deck

Starboard Jib Winch

Starboard Rope Clutch Position

Port Cabin Deck

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Helm Station Controls

Aft Cross Beam Electric Winch

Aft Cross Beam View to Port

Traveler Outboard Ladder Support

Port Bimini/Traveler Supports

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Do you like what you see so far?  Now that you have an idea about how the sails are controlled for single or short handed sailing, take a look at the “Sailing the Dragon” section to understand how these tools are applied.

Do you want to contact me to get additional information?  I may be reached at the following locations:

Captain Roger H Strube
2560 Rio Palermo Ct
Punta Gorda, FL 33950
Home Phone:      941.639.6232
Cell Phone:         941.661.4579

Web Site:      www.wingsailor.com
E-mail #1:     wingsailorflorida@yahoo.com
E-mail #2:     rogerstrube@embarqmail.com

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