Isomat NB55 Boom

NG2 Gooseneck Bracket: NG2-11: Cast aluminum Gooseneck Mast Bracket for use with NB-32, NB-40, and NB-55 new-style Gooseneck Assemblies. Bracket for NG-51 through NG-86 Mast Sections is 4 3/4" (120mm) high x 3 1/2" (90mm) wide, and is fastened with eight (8) 1/4" (6mm) rivets. Bracket has 22mm (7/8") hole at top and 8mm (5/16") hole on bottom side, for use with any of the NB2-1 Vertical Gooseneck Toggle Pins. Though actually a Mast Component, this item is also listed here for your convenience.
NB-55 Gooseneck Assembly Complete: NB55-1AC: Cast aluminum Gooseneck Assembly incorporates provisions for internal outhaul and 3 internal reef lines. Internal lines run over delrin sheaves, and down past lever action cams. Cams can be removed to allow lines to go straight down to the deck. Includes Vertical Gooseneck Toggle Pin with reef hooks, and tack shackle. For use with Isomat Gooseneck Mast Bracket (NG2-11), which has 7/8" hole at top and 5/16" hole on bottom side. Parts for NB-55 Gooseneck Assembly.
NB-55 Gooseneck Assembly: NB55-1A: As *NB55-1AC, above, but with sheaves, cams, and axles only. Does not* include Vertical Gooseneck Toggle Pin with reef hooks, and tack shackle. Parts for NB-55 Gooseneck Assembly.
	NB-55 Gooseneck Casting: NB55-1: Replacement Casting only, for any of the NB-55 Gooseneck Assemblies listed above.
	NB2 Boom Sheave: NB2-10: Acetyl Sheave is 60mm (2 5/16") OD x 14mm (9/16") wide x 10mm (3/8") ID, and fits in upper (aft) slot in Gooseneck Casting.
	NB2 Boom Sheave - Aluminum: NB2-10A: Anodized Aluminum Sheave is 60mm (2 5/16") OD x 14mm (9/16") wide x 10mm (3/8") ID, and is much sturdier than the plastic version.

*Spar Cleat – 6 3/8": NGC-6:* Cast Aluminum Cleat is 160mm (6 3/8") long. Other Cleats have also been used on this boom section, and are listed separately. Other Isomat Cleats.
Exit Plate – Large Snap-in: NG2-7: Large Black plastic Snap-in Exit Plate eliminates line chafe, and accommodates a maximum of 5/8" line. Exit Plate measures 4 1/2" x 1 5/16" (115mm x 34mm), and installs in cut-out 1" x 4 1/4" (26mm x 112mm). Other Exit Plates have also been used on this boom section, and are listed separately. Other Isomat Exit Plates.
AutoReef Internal Shuttle Block: NB2-20: Cast aluminum Shuttle Block incorporates 2 Delrin Roller sheaves. Used in AutoReef single line reefing systems.

NB2 Boom Bail Assembly: NB2-15A: SS Articulating Boom Bail fits in integral slot in underside of NB-32, NB-40, NB-55, and other boom sections with an underside boom bail slot that is 31mm wide x 4.5mm deep. Bail is made from 10mm rod. Formed plate is 3.2mm thick and measures 4 3/4" (120mm) long x 1 3/16" (30mm) wide. Fastens with (2) 1/4" (6mm) rivets.
	NB2 Boom Bail: NB2-15R: SS formed rod bail only, as used in NB2 Boom Bail Assembly NB2-15A, above. Bail is made from 10mm (3/8") rod, and is 2 3/4" (70mm) long x (maximum) 1 15/16" (50mm) high.
	NB2 Boom Bail Plate: NB2-15BP: SS formed plate only, as used in NB2 Boom Bail Assembly NB2-15A, above. Plate is 3.2mm thick and measures 4 3/4" (120mm) long x 1 3/16" (30mm) wide. Fastens with (2) 1/4" (6mm) rivets.
NB2 Boom Bail Assembly - Heavy-duty: NB2-15AW: As NB2-15A (above), but Bail is reinforced with a welded crossbar. This heavy-duty option prevents the bail from compressing in extreme circumstances and is used primarily on larger boats.
	NB2 Heavy-duty Boom Bail: NB2-15RW: SS formed rod Bail only, reinforced with a welded crossbar, as used in NB2 Heavy-duty Boom Bail Assembly NB2-15AW, above. Bail is made from 10mm (3/8") rod, and is 2 3/4" (70mm) long x (maximum) 1 15/16" (50mm) high.
*NB2 Boom Vang Attachment Lug - 14mm (9/16"): NB2-16S-14:* SS Boom Vang Attachment Lug is used for attachment of Solid (hard) Vang Struts. Fits in integral slot in underside of NB-32, NB-40, NB-55, and other boom sections with an underside boom bail slot that is 31mm wide x 4.5mm deep. Slide plate (2.5mm) is 5 3/4" long, and is welded to 5mm (3/16") thick Triangle with 14mm (9/16") hole. Slides into track and fastens with (4) 1/4" (6mm) rivets. Fits NG1 Isovang.
*NB2 Boom Vang Attachment Lug - 16mm (5/8"): NB2-16S-16:* SS Boom Vang Attachment Lug is used for attachment of Solid (hard) Vang Struts. Fits in integral slot in underside of NB-32, NB-40, NB-55, and other boom sections with an underside boom bail slot that is 31mm wide x 4.5mm deep. Slide plate (3mm) is 6 1/2" long, and is welded to 5mm (3/16") thick Triangle with 16mm (5/8") hole. Slides into track and fastens with (4) 1/4" (6mm) rivets.
*NB2 Boom Vang Attachment Lug - 22mm (7/8"): NB2-16L-22:* SS Boom Vang Attachment Lug is used for attachment of Solid (hard) Vang Struts. Fits in integral slot in underside of NB-32, NB-40, NB-55, and other boom sections with an underside boom bail slot that is 31mm wide x 4.5mm deep. Slide plate (3.2mm) is 8" long, and is welded to 6mm (1/4") thick Triangle with 22mm (7/8") hole. Slides into track and fastens with (4) 1/4" (6mm) rivets. Fits NG2 Isovang.

Isomat Isovang Isomat's Isovang is a tubular Hard (solid) Vang with integral sheaves and line that is Spring cushioned for Boom support. Commonly supplied with new boats, it is also a favorite addition to older boats with Isomat Spars. See: Isomat Isovangs. For Isomat Mast-mounted Brackets and Toggles to fit any Vang, See: Isomat Vang Brackets & Toggles.

*NB-55 Outhaul Car: NB2-18AS:* SS Outhaul Car Assembly is 92mm (3 5/8") long. Car rides on 4 Delrin wheels and features a 12mm (7/16") clew attachment pin and a 10mm (3/8") pin for attachment of the outhaul pennant.
	NB-55 Outhaul Car Wheel - Delrin: NB2-18WDS: Delrin Wheel for NB-55 Outhaul Car is 19mm (3/4") OD x 7mm (1/4") wide x 10mm (3/8") ID.
	NB-55 Outhaul Car Wheel - Stainless: NB2-18WSS: SS Wheel for NB-55 Outhaul Car is 19mm (3/4") OD x 7mm (1/4") wide x 10mm (3/8") ID. *
	NB-55 Outhaul Car Axle: NB2-18XS: SS Outhaul Car Axle is 10mm (3/8") OD x 19mm (3/4") long.

NB-55 Outhaul Assembly Complete: NB55-2A: Cast aluminum Outhaul Assembly incorporates provisions for internal outhaul and 3 internal reef lines. Sheaves and sheave axle slide in from the aft side simultaneously, and are held in place by the outhaul and/or reef lines. Rib on aft upper side allows for topping lift attachment.
	NB-55 Outhaul Casting: NB55-2: Replacement Casting only, for the NB-55 Outhaul Assembly.
	NB2 Boom Sheave: NB2-10: Acetyl Sheave is 60mm (2 5/16") OD x 14mm (9/16") wide x 10mm (3/8") ID.
	NB2 Boom Sheave - Aluminum: NB2-10A: Anodized Aluminum Sheave is 60mm (2 5/16") OD x 14mm (9/16") wide x 10mm (3/8") ID, and is much sturdier than the plastic version.
	Sheave Axle for NB-55 Outhaul: NB2-13: SS 'Drop-in' Sheave Axle pin is 10mm (3/8") diameter x 79mm (3 1/8") long.
NB-55 Outhaul End Plug: NB55-2EP: Black Plastic End Plug covers opening in back end of NB55-2 Outhaul Casting. New 'Bird Nest Buster' snaps into place, blocking the hole, but is easily removable for access to lines. If you've ever had a nesting problem, here's the solution.

Isomat NB-55 Boom Section Measurements (OD): 7" x 5 1/8" (180mm x 130mm) Wall Thickness: .140" Weight/ft.: 3.72 lbs. Weight/M: 5.55 kg Moments of inertia: Ixx = 20.42", Iyy = 6.97" Circumference: 20 7/8" (530mm) Alloy: 6061-T6 Sail slides: 1/2" round slugs (A018, A118) or 1/2" boltrope Standard Boom Lengths: 15'9" (4800mm) Common Boom usage: Beneteau First 38S, 435S, 456, 456S; Catalina 42; Condor 40; CS 40; CSY 50; Formosa 53; Freedom 35, 36; Hunter 45; Idylle 15.5; Island Packet 44; Jeanneau OD35; Kirie Feeling 13.50R; Mason 53K (main) Northwind 47; Pearson 39; Sirena 44; Tayana 42, 52, 55; Vagabond 52K (main); Whitby 42K (main);

Isomat NB-55 Boom Section Isomat NB-55 Boom Section is stocked in 15'9" lengths fully anodized. Sections can be ordered bare (unmachined), or cut to shorter lengths with or without milling for other components. Painted finishes and other lengths are available on special order. If you require a complete Boom Assembly, you can select from components below and contact us with specifications. If you require components not listed below please contact us with details. All NB-55 Boom Ends have provisions for 4 internal lines.

NB-55 Boom Components Although no other components have changed, the NB-55 Boom has been produced with 2 Different Gooseneck Arrangements. New-Style Goosenecks are listed below; Old-Style Goosenecks are listed separately. Old-Style NB-55 Gooseneck Assemblies and Parts.

Spars, Rigging, and Hardware for Sailboats