Profurl MK1 In-Boom Furling System — Installation Manual

Components

• Luff profiles articulated on the aft face of the mast: one 0.60 m feeder profile (1) with the feeder (3), plus 2 meters luff profiles (2); the top one is re-cut to the luff length.
• Connectors/articulations (4) held by set screws (9), on articulation brackets (5) fixed with 2 slide screws (7), washer (33) and locknut (8). Caution: articulation brackets (5) have a stainless steel pin; end brackets (6) have Nylon flanges (55) – do not mix them up.
• Sheave box (11) for the main halyard at the top of the profiles, on 2 end brackets (6).
• Gooseneck (12) on 2 slide screws with 2 plates (13), cambered and riveted with conical head pop rivets (14).
• Boom profile (15) delivered in 4 or 5 meters, mandrel (16) on bearings (17 and 18), drum boom end fitting (22) with drum (21); furling line supplied.
• 2 adjustable mainsheet bails (25) (more optional); boomvang (27) on its own mast attachment (56) with articulation eye (49), boomvang hound (28).
• Ball bearing block (52) and furling line (51) to the cockpit, and a boom brake.

Before You Start

• Not for wooden masts, or aluminium masts with a track added by screws, rivets or glue. Carbon masts: not recommended, special skills required.
• Check the mast for severe corrosion.
• The boom is heavier than a conventional boom: no uncontrolled gybes. Winch in traveller and mainsheet, turn, release gradually; a tackle as boom preventer is better still.
• The boom brake supplied must be used and adjusted at all times – and released completely each time you operate the system.
• Warranty: 3 years on parts and materials from date of purchase (original owner).

Tools & Preparation

• Measuring tape, drill and bits, hacksaw (new fine blade), file, plastic hammer, 13 mm and 19 mm wrenches, torque wrench (1daN/m), Allen keys (supplied), 2 clamps with 300 mm opening, pop rivet gun for 5 mm stainless steel rivets, a large sheet of paper with true 90° corners.
• The gooseneck and boomvang plates are 8 mm thick aluminium: bend them with a hydraulic or mechanical press, then fit with the clamps.
• On a standing mast: bosun's chair and short 8 or 10 mm ropes.
• Remove the original gooseneck, cleats, winches and anything stopping the forward boom end rotating; do not reuse the original vang fitting; remove the original feeder. Slide screw width may be reduced to suit the track.

Gooseneck & Luff Profiles

1. Line «C» at the lower edge of the original boom. Vang angle at least 30° to mast and boom – fit the gooseneck higher if needed. Vang pin-to-pin: 1400 mm open / 1305 mm closed.
2. Line «B» 364mm (1' 2 21/64") above «C» = top edge of the gooseneck plates (13).
3. Slide screws: two to the mast foot for the vang attachment, four for the upper end brackets (6), two per articulation bracket (taped above the track entrance), 2 for the gooseneck.
4. Gooseneck at 1 to 1.5 daN/m. Camber the plates, screw them to the gooseneck, drill Ø 5 mm and countersink so the conical rivet heads sit flush: at least 12 pop rivets (14) per plate. Nylon washer 29a on the vertical pin; temporarily fit the articulation (10) with washers 29/30, low nut (31) and Nylock (30a).
5. Assemble the profiles on the ground from the feeder profile; the Nylon bushing collars (57) of every connector point to the bottom of the column. Leave the last 2 meter profile off. Hoist with the topping lift, pulling from the bottom to keep it straight; seat the feeder profile in the articulation (10).
6. Articulation brackets: stainless pin pointing up into the connector bushing, washers (33) and locknuts (8) at 1 to 1,5 daN/m. Sheave box on the end brackets with at least 20 mm clearance to the backstay(s); mark line «A».
7. Measure «A» to «D» and cut the last profile to it. Very flexible mast or fractional rig: cut at «A» to «D» minus 15 mm and leave the 15 mm as play. Insert the sheave box bar, refit, tighten the 4 slide screws and set screws (9).

Boom & Mandrel

• Case 1: same overall length as the original boom. Case 2: use the over-length to lengthen the boom (helm balance may change; check backstay clearance). Delivered pre-assembled in over-length.
• If the full length is used, the rear end fitting is only fitted temporarily for shipping: follow § III 9 c as if the boom had been cut.
• Remove the rear end fitting (23), pull the mandrel out under control (keep washer 20), square the cut with a paper wrap, cut and file.
• Cut the mandrel by exactly the same amount (example: 312 mm off the boom = 312 mm off the mandrel), at the rear only – never the drum end.
• Refit bearing (18) and holder (19); tap M6 (6mm) opposite the grooves at 25 mm (1") from the cut end and fit screw (38). If the mandrel is a little short, loosen (38), push it forward, pull the holder out until washer (20) touches, retighten.
• Turn the boom upside down and fit the gooseneck articulation (10) to the drum boom end fitting with pin (34) and split pin (35) before inserting the mandrel.
• Drill Ø 5mm through the rear end fitting holes and fit the flat head pop rivets (24).
• Hoist the boom level while pulling it aft; slide the articulation bar into the feeder profile and the stainless pin into the gooseneck; Nylon washer (29a), stainless washer (29), low aspect locknut (31) and Nylock (30a) with a 19 mm wrench, plastic cap on. Never drop or raise the boom more than 15° from horizontal.

Vang, Mainsheet & Lines

• Vang ideally at 45°, never under 30°. Attachment (56) on the two slide screws at the mast foot; plates cambered, countersunk Ø 5 mm, at least 12 pop rivets (14) per plate; stickers (33) over the rivet heads, on both gooseneck and vang plates.
• Articulation eye (49): Nylon washer (29), washers (30 and 29a), locknuts (31 and 30a). Pin the vang to the eye and hound (28); release the topping lift.
• Mainsheet bails (25) set with the set screws underneath; move them as far aft as possible with a deck mainsheet ahead of the hatch; stopper knot in the mainsheet so the boom cannot hit the aft shrouds.
• Ball bearing block (supplied) at the starboard mast foot, line into the middle of the drum at 90°, knot hidden in the drum shaft. Turn the mandrel towards port (seen from above) to load the drum – the line exits to starboard.
• Lead the halyard aft through another ball bearing block; check the mast exit for chafe. Few blocks, large sheaves, small deviation angles.

Fitting the Sail

1. Foot track ends filed smooth at the cut end; sail to Profurl specification; vang angle set (§ VI).
2. Mandrel tracks facing up; battens out.
3. Tack slide (48), flat part aft, into the tack webbing (locked ahead of the two plastic cylinders); webbing and slide into the port side foot track, then the foot bolt rope; pull forward.
4. Clew slide (49) into the clew webbing and into the mandrel groove; lock the flat of the tack slide in the machining of the groove and pull the sail aft.
5. Clew pin (50), ring up, into the foot track ends; lash the clew webbing to the ring and tension the foot.
6. Battens in, halyard on. Back off the port side knob (46) about 3 turns; feed the "continuous" port luff tape between the bronze rollers (40) and hoist a few centimetres by hand.
7. Slide the starboard "head" luff tape into the starboard groove – its entry is just above the feeder (3), at connector level.

Feeder & Vang Angle

• Roller gap: port knob (46) fully hand-tight (not over-tight); release screw (63); turn the starboard plastic screw (41) with the adjustment tool (67) until the luff tape is pinched, back off about ¼ turn, lock (63) again.
• Re-inserting the bolt rope: open knob (46) a few turns, feed between the rollers into the port track, close the knob by hand; the starboard tape goes directly into the starboard track above the feeder.
• Vang angle (no wind, head to wind): hoist with normal halyard tension, free the hound (28), mainsheet slack, let the boom hang, retighten.
• Luff tape rolls too far aft → boom angles up a little more. Too far forward → boom angles down a little more.