Standard Components

The system supplied comprises of the following (see photos alongside):

  • 100 metres of 6mm Dyneema halyard rope line for the fitter to cut to suit for all halyards and strops
  • Four ARK aluminium opening cheek pulley blocks (+ 1 spare) for use on the lower rigging onto the Davit Arms (2 each side)
  • One Set of marine type pulley blocks to mount on the backstay or mast to route the halyards to the windlass (supplied to suit the survey results)
  • One set of shackles and eyebolts and eye nuts (all in 316 stainless steel) to make all required connections to the dinghy lifting points, Davit Arms, Transverse Link, and backstay clamps
  • Two backstay clamps (sized as per the rope diameter of 5 to 10mm as determined by survey)

 

Optional components

(see Price List for costings)

  • Wrap around mast strap/clamp
  • Mast side rivet-on U bolt plate (rivets not supplied)
  • Dinghy transom extension lift point brackets
  • Extra backstay clamps
  • Extra shackles, eyebolts, eyenuts (M8 or M10 thread in 316 S/S)
100 metre reel of Dyneema made for Ark by English Braids. Breaking load rated at 1.9 tonnes.
Barton size 2 ball bearing pulley blocks for Dinghy Derrick
Dinghy Derrick rigging pulleys are anodised cast aluminium with opening cheeks.
Dinghy Derrick selection of 316 stainless steel rigging fixtures
Dinghy Derrick Backstay Clamp

A guide to rigging

Connections:    Each Davit Arm (the 2 short upswept arms from which the dinghy is suspended) is connected to one halyard, working on a 2:1 reduction from the windlass, via  3 connection points

on the Davit Arm boss end                        on the Davit Arm upswept end                  on the Transverse Link end

which collectively tie to the eye of the upper ARK aluminium pulley block.  with a further compensating lower ARK aluminium pulley.

 

Halyard routing:    The line around the upper ARK pulley is tied off at one fixed point high above, then down around the pulley and back up to an upper pulley block on the backstay or mast, and then down to the windlass (or via clutch and extra pulleys leading to the windlass).   This pair of lines runs fully aft of the backstay(s) and hence do not interfere with the sails, topping lift or other lines.  

 

Joining the 2 halyards:  The 2 halyards  may converge to a single point where a double pulley block is mounted (on the mast or on a single backstay) or may rise in near parallel attitude to 2 blocks, one each on a double backstay.

The convergence of the halyards does not result in any significant bending moment on the Davit Arms due to the uppermost ARK aluminium pulley being anchored outboard by the connection to the outer end of the Transverse Link.    However this does require that any single convergent point (i.e. positioning of the backstay clamp) must be at 70% or higher of the mast height to limit excessive angles of convergence.   Again full instructions are given with the kit.

The halyard tie-off point and the pulley block connection maybe any combination of:

  • a shackle onto an ARK backstay clamp
  • a becket on the upper block
  • any mast head fitting able to take the load
  • the masthead plate may have unused holes as in the photo (or drill more)
  • the mast itself has a spare sheave
  • rivet on a side U-bolt plate
  • add a wrap-around mast strap (see Price List)

Sail rig type:      For yachts which have a mast head rig (ie. not a fractional rig, and the head of the mainsail is tight onto the top of the mast) any extra mast fitments should be added immediately below the top plate/face so there is minimal obstruction to the freedom of the sail.  In reality this will have no impact on the sail shape, the head usually streaming aft whatever the remainder of the sail is doing.

 

See the Gallery for a picture of the ARK masthead clamp which is available in different sizes to suit wire ropes of 5, 6, 7, 8, 10mm.

Dinghy Derrick Rigging
Mast head