172
479
480
481
489
477
493
478
Small Boat Furling 
Components: Underdeck
Underdeck Furlers
Small Boat underdeck furling units are ideal for sportboats and 
daysailers from 4.8 - 9 m (16 - 30'). The drum is located beneath 
the deck, lowering the tack height for maximized sail area. The 
single through-deck ball joint provides a low-profile, nearly watertight 
system that aligns the spool to the headstay. Like all Small Boat 
furlers, the underdeck furler is for furling only, not reefing.
An optional hoistable ball bearing halyard swivel can be installed on 
the headstay so the sail can be raised or lowered without removing 
the headstay. See page 162. 
Tack Adapter Tangs
Stainless steel tack adapter tangs are used to adapt clevis pin 
diameters on headstays to the standard clevis pin size that comes on 
the Harken unit. A third hole accepts lashing to adjust jib luff tension.
UNDERDECK FURLERS
Deck
Belowdeck
Turnbuckle eye on stationary bracket 
attaches to an underdeck chainplate.
Fairlead feeds line onto the spool.
Stationary  
bracket
Spherical joint
Spool pivots to align with load.
TACK ADAPTER TANGS
Components (if ordering separately)
*Includes drum and upper swivel. Does not include hoistable swivel.
Furlers
Tack Adapter Tangs
Upper 
swivel 
Part No.
Hoistable 
swivel 
Part No.
Drum
Part No.
Weight
Fits 
furler
Upper swivel
Hoistable swivel
Drum
oz
g
oz
g
oz
g
164
464
477L
2.6
74
2.9
82
24
680
477
207
465
493L
9.2
261
8.9
252
42.6
1201
493
478U
482
478L
15
431
16.8
477
81
2296
478
Part
No.
 Description
Tang-hole to tang-
hole length
Upper pin
Ø
Lower  pin
Ø
Max luff 
wire Ø
Clevis pin
Ø
Weight
 Maximum
working load
Fits furler
in
mm
in
mm
in
mm
in
mm
in
mm
oz
g
lb
kg
 479  4 mm tack adapter tang 
 1 1/2 
 38 
 5/16 
 8 
 7/16 
 11 
 5/32 
 4 
 5/16 
 7.9 
 5.2 
 147 
 3000 
 1361 
 478 
 480  5 mm tack adapter tang 
 1 1/2 
 38 
 3/8 
 10 
 7/16 
 11 
 3/16 
 5 
 3/8 
 9.5 
 5.2 
 147 
 3000 
 1361 
 478 
 481  6 mm tack adapter tang 
 1 1/2 
 38 
 7/16 
 11 
 7/16 
 11 
 1/4 
 6 
 7/16 
 11.1 
 5.2 
 147 
 3000 
 1361 
 478 
 489  8 mm tack adapter tang 
 1 3/8 
 35 
 5/16 
 8 
 5/16 
 8 
 5/32 
 4 
 5/16 
 7.9 
 3.2 
 91 
 2000 
 907 
 493 
Part
No.
Description
Pin-to-pin
length
Drum
Ø
Line Ø
Jaw
width
Max luff 
wire Ø
Clevis pin
Ø
Weight
 Maximum
working load
Min
Max
in
mm
in
mm
in
mm
in
mm
in
mm
in
mm
in
mm
oz
g
lb
kg
 477  Underdeck furler/small* 
 6 1/8 
 156 
 3 1/8 
 79 
 1/8 
 3 
 5/32 
 4 
 5/16 
 8 
 1/8 
 3 
 1/4 
 6.4 
 23.3 
 661 
 950 
 431 
 493  Underdeck furler/medium* 
 7 3/8 
 188 
 4 
 102 
 5/32 
 4 
 3/16 
 5 
 3/8 
 10 
 3/16 
 5 
 5/16  7.9 
 50.5  1433 
 2000 
 907 
 478  Underdeck furler/large* 
 10 7/32 
 260 
 5 
 127 
 3/16 
 5 
 1/4 
 6 
 1/2 
 12 
 1/4 
 6 
 7/16  11.1 
 96 
 2721 
 3000 
 1361 

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