Isomat Exit Blocks

Exit Blocks, or Sheave Boxes, incorporate a sheave, and are used to exit any internal control line (halyards, spinnaker pole lifts, etc.) from a spar where a directional change of 90 to 180 degrees is required. Isomat uses a wide variety of Exit Blocks on their Mast Sections, common ones are listed here. Other Exit Blocks are available for replacement or exact matching purposes. See: Exit Blocks or, depending on the kind of spars you have, See also: Kenyon Exit Blocks, or Z-Spar Exit Blocks. Some Isomat Masts have integral Welded Exit Boxes at the base of the mast for leading internal halyards out of the Mast at Deck level. For Parts for them, See Welded Mast Base Exit Boxes. See also, Jib Boxes for Fractional Rigs.

*Exit Block w/ 1 1/2" Sheave: NGA-25:* *Exit Block w/ 1 1/2" Aluminum Sheave: NGA-25A:* Black Plastic Exit Block assembly has removable 38mm (1 1/2") sheave for line up to 3/8" diameter on 8mm (5/16") SS Sheave Axle. Block measures 4 1/8" long x (maximum) 1 1/16" wide and projects 1" inside of mast. Assembly fits in mast cutout 2 3/4" high x 15/16" wide, and is mounted with (2) #10 (3/16") FH fasteners on 3 3/16" (81mm) hole centers. Sheave is 38mm (1 1/2") diameter x 31/64" wide.
*Aluminum Exit Block w/ 2" Sheave: NGA-26:* *Aluminum Exit Block w/ 2" Alu. Sheave: NGA-26A:* Cast Aluminum Exit Block assembly has removable 10mm (3/8") SS Sheave Axle. Acetyl Sheave (NG1-3) is 50mm (2") OD x 14.5mm (9/16") wide for line up to 1/2" diameter. Block measures 4 1/2" (115mm) long x 1 3/8" (35mm) wide and projects 1 7/16" (36mm) inside of mast. Assembly fits in mast cutout 2 13/16" (72mm) high x 15/16" (24mm) wide, and is mounted with (2) 1/4" (6mm) fasteners on 3 5/8" (92mm) hole centers. Aluminum Sheave version is identical, but with *NG1-3A* Aluminum Sheave. 11
*Aluminum Exit Block w/ 85mm Sheave: NGA-27:* *Aluminum Exit Block w/ 85mm Delrin Sheave: NGA-27D:* Large Cast Aluminum Exit Block assembly has lightweight tubular 22mm (7/8") SS Sheave Axle. Acetyl Sheave (NG2-4) is 85mm (3 3/8") OD x 20mm (3/4") wide for line up to 5/8" diameter. Block measures 6 1/4" (160mm) long x 1 5/8" (41mm) wide and projects 2 7/8" (72mm) inside of mast. Assembly fits in mast cutout 4 1/2" (115mm) high x 1 1/4" (32mm) wide, and is mounted with (2) 1/4" (6mm) fasteners on 5 3/8" (136mm) hole centers. Stronger Delrin Sheave version uses NG2-4D Sheave for heavy-duty applications as on Beneteau First 40.7 and others. 503

*Aluminum Exit Block w/ 60mm Sheave: NGA-29:* Lightweight extruded Aluminum Exit Block assembly has 60mm (2 3/8") Delrin Sheave for line up to 12mm (1/2"). Block measures (maximum) 5 1/8" long x 7/8" wide (129 x 23mm) and projects 1 7/8" (48mm) inside of mast. Assembly fits in mast cutout 3 3/8" high x 7/8" wide (85 x 23mm), and is mounted with (2) 6mm (1/4") fasteners on 118mm (4 5/8") hole centers. As used on Hanse 342 and others.

*SS Exit Block w/ 40mm Sheave: NGA-31-40:* Lightweight Investment Cast SS Cage-style Exit Block assembly has removable 40mm (1 9/16") Delrin Sheave for line up to 8mm (5/16"). Block measures (maximum) 4 5/8" long x 7/8" wide (118 x 23mm) and projects 1 3/8" (36mm) inside of mast. Assembly fits in mast cutout 2 1/4" high x 3/4" wide (57 x 19mm), and is mounted with (2) 3/16" (5mm) fasteners on 3 3/4" (95mm) hole centers. Replacement Sheave is SM40R12-10.
*SS Exit Block w/ 60mm Sheave: NGA-31-60:* Lightweight Investment Cast SS Cage-style Exit Block assembly has removable 60mm (2 3/8") Delrin Sheave for line up to 12mm (7/16"). Block measures (maximum) 6 1/2" long x 1 1/8" wide (165 x 29mm) and projects 2 3/8" (60mm) inside of mast. Assembly fits in mast cutout 3 1/4" high x 1 1/16" wide (82 x 27mm), and is mounted with (2) 1/4" (6mm) fasteners on 5 3/8" (136mm) hole centers. Replacement Sheave is SM60R16-12.
	*Exit Block Clamp for Carbon Mast: NGA-31-60CS:* Investment Cast SS Clamp Set for use with 60 and 85mm SS Exit Blocks on Carbon Masts. Units slide onto integral Exit Block Tabs, allowing Blocks to be attached without stress on the Mast wall. Clamp Set (2 pieces) are threaded for 6mm screws (included).
*SS Exit Block w/ 85mm Sheave: NGA-31-85:* Lightweight Investment Cast SS Cage-style Exit Block assembly has removable 85mm (3 3/8") Delrin Sheave for line up to 14mm (9/16"). Block measures (maximum) 7 3/4" long x 1 5/16" wide (196 x 34mm) and projects 3 3/8" (84mm) inside of mast. Assembly fits in mast cutout 4 1/4" high x 1 3/16" wide (108 x 30mm), and is mounted with (2) 1/4" (6mm) fasteners on 6 3/8" (162mm) hole centers. Replacement Sheave is SM85R18-14.
	*Exit Block Clamp for Carbon Mast: NGA-31-60CS:* Investment Cast SS Clamp Set for use with 60 and 85mm SS Exit Blocks on Carbon Masts. Units slide onto integral Exit Block Tabs, allowing Blocks to be attached without stress on the Mast wall. Clamp Set (2 pieces) are threaded for 6mm screws (included).
*SS Exit Block w/ 110mm Sheave: NGA-31-110:* Lightweight Investment Cast SS Cage-style Exit Block assembly has removable 110mm (4 5/16") Delrin Sheave for line up to 16mm (5/8"). Block measures (maximum) 9 5/8" long x 1 5/8" wide (245 x 42mm) and projects 4 1/4" (109mm) inside of mast. Assembly fits in mast cutout 5 1/4" high x 1 7/16" wide (133 x 36mm), and is mounted with (2) 5/16" (8mm) fasteners on 8" (203mm) hole centers. Replacement Sheave is SM110R21-18.
	*Exit Block Clamp Set for Carbon Masts: NGA-31-110CS:* Investment Cast SS Clamp Set for use with 110 and 130mm SS Exit Blocks on Carbon Masts. Units slide onto integral Exit Block Tabs, allowing Blocks to be attached without stress on the Mast wall. Clamp Set (2 pieces) are threaded for 8mm screws (included).
*SS Exit Block w/ 130mm Sheave: NGA-31-130:* Lightweight Investment Cast SS Cage-style Exit Block assembly has removable 130mm (5 1/8") Delrin Sheave for line up to 18mm (5/16"). Block measures (maximum) 10 1/2" long x 1 3/4" wide (265 x 46mm) and projects 5 1/8" (131mm) inside of mast. Assembly fits in mast cutout 5 7/8" high x 1 5/8" wide (149 x 42mm), and is mounted with (2) 5/16" (8mm) fasteners on 8 5/8" (220mm) hole centers. Replacement Sheave is SM130R25-20.
	*Exit Block Clamp Set for Carbon Masts: NGA-31-110CS:* Investment Cast SS Clamp Set for use with 110 and 130mm SS Exit Blocks on Carbon Masts. Units slide onto integral Exit Block Tabs, allowing Blocks to be attached without stress on the Mast wall. Clamp Set (2 pieces) are threaded for 8mm screws (included).

Your cart

Spars, Rigging, and Hardware for Sailboats