Spars, Rigging, and Hardware for Sailboats

Rig-Rite, Inc.
Phone: (001) 401-739-1140 -- FAX: (001) 401-739-1149
www.RigRite.com          Ordering/Questions

Isomat/Sparcraft Sheaves & Rollers


Isomat uses a variety of Acetyl (hard plastic) Sheaves in their Mast and Boom applications. Sheaves have a groove for rope or wire. These Sheaves are sufficiently strong to be used with wire halyards, as they are in Europe. Anodized Aluminum Sheaves are manufactured in the U.S., for high load applications and for their greater longevity. The most common Sheaves are listed below, but, as always, there are many "Specials". All Isomat Sheaves run directly on a SS axle. Delrin Sheave Bushings are available for some Sheaves to allow use with smaller diameter axles.
Rollers do not have any groove, and are sometimes used as sheaves in a limited number of low-load applications. Sheaves and Rollers are listed by size, and by common application.

For other Metric Sheaves, See Francespar Sheaves, and Z-Spar Sheaves.
See also: Sheaves Main Page.

Isomat Sheaves & Rollers by Size

Part # OD Width ID Material
NB1-11R, NG1-5R 18mm (11/16") 15mm (5/8") 10mm (3/8") Delrin (Roller)
NB1-20R 22mm (7/8") 15mm (9/16") 10mm Delrin (Roller)
NB2-20R 35mm (1 3/8") 15mm (9/16") 10mm Delrin (Roller)

NB1-10 30mm (1 3/16") 10mm (3/8") 10mm (3/8") Acetyl
NB1-10A 30mm (1 3/16") 10mm (3/8") 10mm Aluminum
NG1-3,  FB2-10 50mm (2") 14.5mm (9/16") 10mm Acetyl
NG1-3A 50mm (2") 14.5mm (9/16") 10mm Aluminum
NG1-4,  NB2-10 60mm (2 5/16") 14.5mm (9/16") 10mm Acetyl
NG1-4A,  NB2-10A 60mm (2 5/16") 14.5mm (9/16") 10mm Aluminum
NG1-4NS 60mm (2 5/16") 6mm (1/4") 10mm Stainless Steel

NG2-3B10 85mm (3 3/8") 15mm (5/8") 10mm Acetyl
NG2-3AB10 85mm (3 3/8") 15mm (5/8") 10mm Aluminum
NG2-3B12 85mm (3 3/8") 15mm (5/8") 12mm (7/16") Acetyl
NG2-3AB12 85mm (3 3/8") 15mm (5/8") 12mm Aluminum
NG2-3 85mm (3 3/8") 15mm (5/8") 22mm (7/8") Acetyl
NG2-3A 85mm (3 3/8") 15mm (5/8") 22mm Aluminum

NG2-4B10 85mm (3 3/8") 20mm (3/4") 10mm Acetyl
NG2-4B12,  FB3-10 85mm (3 3/8") 20mm (3/4") 12mm Acetyl
NG2-4-16 85mm (3 3/8") 20mm (3/4") 16mm (5/8") Acetyl
NG2-4,  NGV2-3 85mm (3 3/8") 20mm (3/4") 22mm Acetyl
NG2-4D 85mm (3 3/8") 20mm (3/4") 22mm Turned Delrin

NG3-3 110mm (4 5/16") 21mm (13/16") 18mm (<3/4") Delrin
NG3-3ABB 110mm (4 5/16") 21mm (13/16") 18mm Alum. Ball-Bearing

Sparcraft Sheaves & Rollers by Size
Sparcraft Spars use all the Sheaves & Rollers listed under Isomat Sheaves, above.
In addition, a wide variety of others are used, common ones are listed here.
Part # OD Width ID Material
NB2-19R 25mm (4 5/16") 21mm (13/16") 18mm (<3/4") Delrin (Roller)

FM0-2S 25mm (1") 10mm (3/8") 8mm Acetyl Black
FB36-10G 27mm (1 1/16") 10mm (3/8") 8mm Acetyl Black
FM1-2S 30mm (1 1/8") 10mm (3/8") 8mm Acetyl Black
FB125-10 37mm (1 1/2") 10mm (3/8") 8mm Acetyl Black
FM0-3 40mm (1 9/16") 10mm (3/8") 8mm Acetyl Black

SM48R13-10 48mm (1 7/8") 13mm (1/2") 10mm Delrin
SM60R15-12 60mm (2 5/16") 15mm (5/8") 12mm Delrin
SM80R15-12 80mm (3 1/8") 15mm (5/8") 12mm Delrin
NG2-3B12 85mm (3 3/8") 21mm (13/16") 12mm Acetyl

Sheaves & Rollers by Application

Mast Sheaves & Rollers

   NG 1 Masthead Part #
11/16" OD (18mm) Forward Roller for Spinnaker Halyard NG1-5R
2" OD (50mm)   Acetyl Sheave, 10mm ID NG1-3
2" OD (50mm) Aluminum Sheave NG1-3A
2 5/16" OD (60mm)   Acetyl Sheave, 10mm ID NG1-4
2 5/16" OD (60mm)   Aluminum Sheave NG1-4A
   NG 2 Masthead
3 3/8" OD (85mm) Acetyl Sheave, 21.5mm (7/8") ID  (6 pieces maximum) NG2-3
3 3/8" OD (85mm) Aluminum Sheave NG2-3A

   NG 3 Masthead
4 5/16" OD (110mm) Delrin 18mm (<3/4") ID  (6 pieces maximum) NG3-3
4 5/16" OD (110mm) Aluminum 18mm (<3/4") ID w/ Torlon Ball-Bearings NG3-3ABB

   FM 0, FM1 Masts
1" OD (25mm) Delrin 8mm (5/16") ID  (FM0 Hinged Mast Step) FM0-2S
1 9/16" OD (40mm) Delrin 8mm (5/16") ID  (Mastheads & FM0 Jib Box) FM0-3
1 1/8" OD (30mm) Delrin 8mm (5/16") ID  (FM1 Hinged Mast Step) FM1-2S

   FM 2 & Larger Mastheads
FM 2 & Larger Mastheads use all the sheaves listed under NG Mastheads, above. In addition, many use a wide variety of Specials, common ones are listed here.  
3 3/8" OD (85mm) Acetyl Sheave 12mm ID NG2-3B12
1 7/8" OD (48mm) Delrin 10mm ID  (FM-135 Masthead) SM48R13-10
2 5/16" OD (60mm)   Delrin 12mm (<1/2") ID  (FM-195, 230 Masthead) SM60R15-12
3 3/16" OD (80mm)   Delrin 12mm (<1/2") ID  (FM-305 Masthead) SM80R15-12

   NG 1 Cast Fractional Jib Box
2 5/16" OD (60mm) Acetyl Sheave, 10mm ID (1 or 2 required) NG1-4
2 5/16" OD (60mm) Aluminum Sheave NG1-4A
2 5/16" OD (60mm) SS Narrow Lower Sheave - 1/4" wide (2 required) NG1-4NS
   NG 2 Cast Fractional Jib Box
3 3/8" OD (85mm) Acetyl 5/8" ID /  3/4" wide NG2-4-16

    NG 1 Welded Mast Base Sheave Box
2 5/16" OD (60mm) Acetyl Sheave NG1-4
2 5/16" OD (60mm) Aluminum Sheave NG1-4A
   NG 2 Welded Mast Base Sheave Box
3 3/8" OD (85mm) Acetyl Sheave 10mm ID NG2-3B10
3 3/8" OD (85mm) Aluminum Sheave 10mm ID NG2-3AB10

Boom Sheaves & Rollers
   NB 16, NB 26 Booms Part #
11/16" OD (18mm) Gooseneck and Outboard Roller (3 forward, 2 aft) NB1-11R
1 3/16" OD (30mm) Acetyl Outhaul Sheave (1 required aft) NB1-10
1 3/16" OD (30mm) Aluminum Outhaul Sheave NB1-10A
7/8" OD (22mm) Delrin (Shuttle Block Roller) NB1-20R
   NB 32, NB 40, NB 55 Booms
2 5/16" OD (60mm) Acetyl Sheave, 10mm ID (all sheaves, 4 in each end) NB2-10   
2 5/16" OD (60mm) Aluminum Sheave NB2-10A
7/8" OD (22mm) Delrin (AutoReef Roller) 10mm ID NB1-20R
1 3/8" OD (35mm) Delrin (AutoReef / Shuttle Block Roller) 10mm ID NB2-20R
   FB 36, FB 60, FB 125 Booms
1 1/16" OD (27mm) Acetyl Sheave, 8mm ID (FB-36 Gooseneck) FB36-10G   
1 1/8" OD (30mm) Acetyl Sheave, 8mm ID (FB-36 Outhaul, 60, 125 GN) FM1-2S
1 1/2" OD (37mm) Acetyl Sheave, 8mm ID (FB-125 Outhaul) FB125-10
1 9/16" OD (40mm) Acetyl Sheave, 8mm ID (FB-60 Outhaul) FM0-3
   FB 220, FB 550 Booms
2" OD (50mm) Acetyl Sheave, 10mm ID (Gooseneck & Outhaul, 4 each) FB2-10   
1" OD (25mm) Delrin (Gooseneck AutoReef Roller) 10mm ID NB2-19R
   FB 810, FB 1700, FB 3400 Booms
3 3/8" OD (85mm) Acetyl Sheave, 12mm ID (Gooseneck & Outhaul, 4 each) FB3-10   
2 3/8" OD (60mm) Delrin (Gooseneck AutoReef Roller) 12mm ID FB3-10S

Isovang Sheaves

   NG 1 Isovang       2" OD (50mm)          Acetyl  (2 per end) NG1-3
   NG 2 Isovang       3 3/8" OD (85mm)    Acetyl - 3/4" wide  (2 per end) NGV2-3
   

Sheave Bushings for NG2 Sheaves
Precision press-fit Delrin Bushings produced by RigRite to reduce the ID of NG2-3 & NG2-4 Sheaves.
 

Part # OD Width ID Isomat Approximation
NG2B-10 22mm (7/8") 15mm (9/16") 10mm    NB1-20R
NG2B-12 22mm (7/8") 15mm (9/16") 12mm    151189
NG2B-10L 22mm (7/8") 20mm (3/4") 10mm    None
NG2B-12L 22mm (7/8") 20mm (3/4") 12mm    None

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