Isomat NG31 Mast

NG1 Fractional Masthead Cover Plate - Standard: NG1-1F: Cast aluminum Masthead Cover Plate for NG1 Fractional Rig Masthead, standard on NG-31 Masts with Fractional Rigs. Masthead Cover Plate also serves as Sheave separator, provides level surface for mounting Anchor light, and has slots for exiting other electrical wires. Standard Cover Plate is 2 11/16" (maximum) wide x 6 1/4" long (on top) and is fastened with one (1) 6mm screw going through the front of the mast. Note: Older NG1 Fractional Rig Mastheads used different (non-compatible) Cover Plates, See NG1 Fractional Rig Masthead.
NG-31 Masthead Sheave: NG1-3: Factory standard Acetyl Sheave is 50mm (2") OD x 14mm (9/16") wide x 10mm (3/8") ID.
NG-31 Masthead Sheave - Aluminum: NG1-3A: Anodized Aluminum Sheave is 50mm (2") OD x 14mm (9/16") wide x 10mm (3/8") ID, and is much sturdier than the plastic version.
NG-31 Masthead Sheave: NG1-4: Factory standard Acetyl Sheave is 60mm (2 5/16") OD x 14mm (9/16") wide x 10mm (3/8") ID.
NG-31 Masthead Sheave - Aluminum: NG1-4A: 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.
NG-31 Masthead Spinnaker Roller: NG1-5R: Delrin Roller sheave is 18mm (11/16") OD x 14mm (9/16") wide x 10mm (3/8") ID. For use with Internal spinnaker halyards.
NG-31 Masthead Sheave Axle: NG1-6: SS 'Drop-in' Sheave Axle pin is 10mm (3/8") diameter x 40.8mm (<1 5/8") long. Used for all Sheaves and Rollers in all NG1 Mastheads.

NG-31 Mast – Jumper Strut Fittings
*NG1 Jumper Strut Fitting, Single: NG1-25S:* SS Bracket for Single (1) 25mm OD Jumper or Diamond Strut. Welded Bracket has diamond-shaped base that is 110mm (4 5/16") high x 69mm (2 3/4") wide, 30mm OD strut receiver is 72mm (2 7/8") long. 555401

NG-31 Mast – External Halyard Block Attachments
*NG1 Fractional Spinnaker Crane: NG1-39:* SS Spinnaker Crane for attachment of external Spinnaker Halyard Block on Fractionally rigged Masts. Unit fastens to Mast above the Forestay to allow attachment of a Swivel Block for dedicated external Spinnaker halyard (purchase separately). This arrangement eliminates the chafe on the Spinnaker Halyard inherent in any internal halyard design. Formed from 8mm (5/16") SS rod with welded base pads, unit attaches to Mast with (6) 6mm (3/16", #10) screws or rivets. Unit can be bent to fit a variety of Mast Sections. Can also be used for attachment of Spinnaker Pole Lift.
*NG1 Block Attachment Eye: NG1-36:* SS Block Eye fastens to forward face of Mast to allow attachment of Block for Pole Lift, or external Spinnaker halyard (on Fractional Rigs). Unit is 4" high x 2 1/4" wide with 1/2" hole for Block attachment, and attaches to Mast with (4) 1/4" RH screws or rivets. MMS
NG1 Pole Lift / Block Attachment Eye: NG1-34: Fixed Eye for attachment of block for spinnaker pole lift or other items on the front of the mast. Diamond shaped SS pad is curved to fit the front of the Mast and has welded vertical Eye. Unit is 87mm (3 7/16") high x 54mm (2 1/8") wide, and attaches to Mast with (4) 3/16" (5mm) screws or rivets. 8mm Eye is suitable for attachment of any block or shackle.

NG-31 Mast – Jib Boxes & Forestay Attachments Several other varieties of Jib Boxes and Forestay Attachments are used on the NG-31 Mast Section, See Isomat Jib Boxes and Forestay/Staysail Tangs.
*NG1 Jib Box Ass'y w/ Toggle - 8mm Pin: NG1-30A:* *NG1 Jib Box Ass'y w/ Toggle - 10mm Pin: NG1-31A:* *NG1 Jib Box Ass'y w/ Toggle - 12mm Pin: NG1-32A:* Cast aluminum two (2) halyard internal Jib Box Assembly with Forestay Toggle for Fractionally rigged Masts. Accommodates a single Jib halyard below the Toggle and a Spinnaker halyard over the Toggle. Toggle is shielded by contoured nose to minimize chafe on Spinnaker halyard. Assembly uses (2) 60mm (2 5/16") Acetyl Sheaves (NG1-4), on (2) 10mm Axles, (NG1-6S). Sheaves are suitable for use with wire or rope halyards up to 7/16" diameter. Assembly fits in mast cutout 5 5/8" (143mm) high x 1 3/16" (30mm) wide. Internal mounting flange is slightly curved to fit a variety of mast sections. Assembly is designed to fit through the mounting slot and is then fastened from the outside with (1) 6mm machine screw which threads into locknut held in casting (machine screw and locknut included). Stainless Steel Toggle (in various pin sizes) is included. Unit measures (maximum) 6 5/8" long x 1 1/2" wide and projects 2 1/2" (maximum) inside of mast. Suitable for use with a variety of mast sections on boats with forestays up to 1/4" or 7mm diameter. Other Pin sizes (5/16" - 1/2") are available, please specify.
*NG1 Double Jib Box Ass'y w/ Toggle - 8mm Pin: NG1-30DA:* *NG1 Double Jib Box Ass'y w/ Toggle - 10mm Pin: NG1-31DA:* *NG1 Double Jib Box Ass'y w/ Toggle - 12mm Pin: NG1-32DA:* Cast aluminum three (3) halyard internal Jib Box Assembly with Forestay Toggle for Fractionally rigged Masts. As NG1-30A, above, but with two (2) wire Jib halyard Sheaves, NG1-4NS, (5/32" (4mm) maximum) below the Toggle. Other Pin sizes (5/16" - 1/2") are available, please specify.
	NG1 Forestay Toggle w/ 8mm Pin: NG1-30-8T: NG1 Forestay Toggle w/ 10mm Pin: NG1-30-10T: NG1 Forestay Toggle w/ 12mm Pin: NG1-30-12T: SS Toggle only for use with a variety of NG1 Fractional Forestay Attachments. Formed SS Toggle is (minimum) 14mm wide x 4mm thick and 58mm (2 1/4") between Pin centers. Other Pin sizes (5/16" - 1/2") are available, please specify.
	*NG1 Jib Box Sheave: NG1-4:* Factory standard Acetyl Sheave is 60mm (2 5/16") OD x 14mm (9/16") wide x 10mm (3/8") ID. Used in all NG1 cast Jib Box Assemblies.
	NG1 Jib Box Sheave - Aluminum: NG1-4A: 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. Suitable for use in all NG1 cast Jib Box Assemblies.
	*NG1 Jib Box Sheave Axle: NG1-6S:* SS 'Drop-in' Sheave Axle pin is 10mm (3/8") diameter x 22mm (7/8") long. Used for all Sheaves in all NG1 Cast Jib Boxes.
	*NG1 Double Jib Box Narrow SS Sheave: NG1-4NS:* Special Narrow Stainless Steel Sheave is 60mm (2 5/16") OD x 6mm (1/4") wide x 10mm (3/8") ID. Used for Jib sheaves in NG1 Cast Double Jib Box Assembly. SS Sheave is suitable for use with wire halyards up to 5/32" diameter.
	*NG1 Double Jib Box Sheave Washer: NG1-4NSW:* Special Teflon Sheave Washer is 60mm (2 5/16") OD x 10mm (3/8") ID. Used on each side of SS Narrow Jib sheaves in NG1 Cast Double Jib Box Assembly.
	*NG1 Double Jib Box Sheave Separator: NG1-30DS:* Stainless Steel Sheave Separator for use in NG1 Cast Double Jib Box Assembly. SS Plate locks into integral notches in casting between the 2 Jib (lower) sheaves and has a 10mm (3/8") hole for the sheave axle.

NG-31 Mast – Exit Blocks Several varieties of Exit Blocks are used on the NG-31 Mast Section, See Isomat Exit Blocks.

NG-31 Mast – Spreaders The NG-31 Mast Section is commonly (but not always) used with BF-3 Spreaders. Standard Spreader Bases are listed below, for Spreaders, Spreader Parts, and other Spreader Bases, See Isomat Spreaders & Components.

NG-31 Mast – Spreader Bases
*Small Spreader Base for BF3 Spreader - Port: BF3-35P:* *Small Spreader Base for BF3 Spreader - Starboard: BF3-35S:* Unique spreader base design incorporates (2) sockets for use with Stemballs on lower and intermediate shrouds. Cast aluminum bases are welded to the mast and accommodate a variety of spreader angles depending on how the inboard spreader end is cut. BF-3 Spreader is attached with (1) 8mm clevis pin which goes through a plastic bushing to allow for some shock loading. New Bases have hole for 12mm (7/16") OD Spreader Bushing, BF3-31. Base measures 4 1/2" high x (maximum) 3 1/2" long, and projects 3 3/4" out from the Mast. For Spreaders and Spreader Parts, See BF-3 Spreaders & Components.
*Large Spreader Base for BF3 Spreader - Port: BF3-36P:* *Large Spreader Base for BF3 Spreader - Starboard: BF3-36S:* Unique spreader base design incorporates (2) sockets for use with Stemballs on lower and intermediate shrouds. Cast aluminum bases are welded to the mast and accommodate a variety of spreader angles depending on how the inboard spreader end is cut. BF-3 Spreader is attached with (1) 8mm clevis pin which goes through a plastic bushing to allow for some shock loading. New Bases have hole for 12mm (7/16") OD Spreader Bushing, BF3-31. Base measures 4 1/2" high x (maximum) 4 1/4" long, and projects 3 3/4" out from the Mast. For use with NG-31 through NG-70 Mast Sections. For Spreaders and Spreader Parts, See BF-3 Spreaders & Components.
*Bolt-on Spreader Base for BF3 Spreader - Port: BF3-37P:* *Bolt-on Spreader Base for BF3 Spreader - Starboard: BF3-37S:* Identical to BF3-36, above, but attaches to mast with (4) 6mm (1/4" ) rivets, and (1) 10mm (3/8") bolt going through the Mast. For Spreaders and Spreader Parts, See BF-3 Spreaders & Components.

NG-31 Mast – Spinnaker Cars Several varieties of Spinnaker Cars are used on the NG-31 Mast Section, See Isomat Spinnaker Cars.
NG1 Spinnaker Pole Mast Eye: NG1-37: Fixed Eye for attachment of whisker or spinnaker pole on the front of the mast. Used where vertical adjustment of inboard pole end is not required. Diamond shaped SS pad is curved to fit the front of the Mast and has welded horizontal Ring. Unit is 65mm (2 3/16") high x 76mm (3") wide, and attaches to Mast with (4) 1/4" screws or rivets. 8mm Ring has 50mm (2") ID.
NG1 Reaching Strut Mast Eye: NG1-38: Diamond shaped SS Reaching Strut Mast Eye with welded horizontal Ring. Unit is 67mm (2 1/4") high x 85mm (3 1/4") wide, and attaches to the side of the Mast with (4) 1/4" screws or rivets. 8mm Ring has 31mm (1 1/4") ID.

NG-31 Mast – Exit Plates Several varieties of Exit Plates are used on the NG-31 Mast Section, See Isomat Exit Plates.

NG-31 Mast – Cleats Several sizes of Cleats are used on the NG-31 Mast Section, See Isomat Cleats.

NG-31 Mast – Mainsail Gates
NG1 Mainsail Gate & Screw Kit: NG1-9K: Cast aluminum Mainsail Gate fits NG-28 through NG-51 Mast Sections, allowing slides to pass by without falling out. Gate has horizontal slot for Thumbscrew (NGA-10); Gate is 'opened' by loosening Thumbscrew and sliding gate away from Mainsail track. Kit includes Gate casting, NG1-9, and SS Thumbscrew, NGA-10.
	NG1 Mainsail Gate: NG1-9: Cast aluminum Mainsail Gate fits NG-28 through NG-51 Mast Sections. Gate casting is 2 3/8" (60mm) high x 1 7/16" (36mm) wide, with 1/8" (4mm) deep lip. Part is marked 157006.
	NG1 Mainsail Gate Screw: NGA-10: SS Thumbscrew is 4mm diameter with 5/8" (15mm) long thread and has serrated plastic head.
	NG1 Mainsail Gate Screw - All Stainless: NGA-10SS: All Stainless Thumbscrew is 4mm diameter with 5/8" (15mm) long thread and knurled head.
	Mainsail Gate Rivet Nut: NGA-10RN: 4mm Aluminum Rivet Nut is often used to seat NGA-10 Thumbscrews. Rivet Nut is installed in a 6mm (15/64") hole with a special Rivet Nut Tool. Please note that some Masts have been produced with the Mast tapped directly for the Thumbscrew, and do not use this item.
	Mainsail Gate Rivet Nut Tool: NGA-10RNTool: Special Tool for installing 4mm Aluminum Mainsail Gate Rivet Nut includes two (2) Rivet Nuts. Rivet Nut is installed in a 6mm (15/64") hole, Tool requires use of a 7/8" and a 11/16" wrench (not included).

AutoReef Fairlead
*AutoReef Fairlead: NGA-65:* SS AutoReef Fairlead is mounted on either side of mast above gooseneck bracket. Acts as fairlead for reef line and stop for sail when reefed with AutoReef (single line) reefing system. Flattened SS ring is welded to diamond shaped SS plate. Ring is 32mm (1 1/4") OD x 16mm (5/8") ID, plate is 65mm (5/8") high x 40mm (1 5/8") wide and is fastened with four (4) 1/4" (6mm) rivets. For details, See: Isomat AutoReef System.

NG-31 Mast - Gooseneck Brackets & Hardware
NG1 Gooseneck Bracket *Ass'y*: NG1-11AC: Cast aluminum Gooseneck Bracket Assembly fits NG-28 through NG-51 Mast Sections. Assembly comes with everything needed to attach directly to New-Style NB-16 or NB-26 Gooseneck Casting. Includes Bracket (NG1-11), Vertical Toggle Pin (NB1-1), Tack Shackle (*NB1-2), Horizontal Gooseneck Cylinder (NB1-3), and Gooseneck Toggle (NB1-4). Bracket is 3 7/8" (98mm) high x 2 3/4" (70mm) wide, and is fastened with four (4) 1/4" (6mm) rivets. For Gooseneck Parts not listed below, See NB-16* or NB-26 Boom Section.
	NG1 Gooseneck/Vang Bracket: NG1-11: Cast aluminum Gooseneck/Vang Bracket fits NG-28 through NG-51 Mast Sections. Bracket is 3 7/8" (98mm) high x 2 3/4" (70mm) wide, and is fastened with four (4) 1/4" (6mm) rivets. Bracket has holes for 12mm (7/16") Vertical Toggle Pin (NB1-1).
	NG1/NB1 Gooseneck/Vang Vertical Toggle Pin: NB1-1: SS Clevis pin is 12mm (7/16") diameter with a 85mm (3 3/8") grip length, and has 8mm (5/16") hole for Shackle attachment. Fits vertically in NG1-11 Gooseneck/Vang Bracket.
	NB1 Tack Shackle: NB1-2: SS Tack Shackle fits through hole in top of vertical gooseneck clevis pin.
	NB1 Horizontal Gooseneck Cylinder: NB1-3: Plastic Cylinder slides through the Gooseneck Casting and the Gooseneck Toggle. Vertical Gooseneck Pin then slides through Mast Bracket, Gooseneck Toggle, and Horizontal Gooseneck Cylinder, in that order. Black plastic cylinder is 1" diameter x 1 1/2" long with hole for 12mm (7/16") pin.
	NB1 Gooseneck Toggle: NB1-4: Plastic Toggle fits in between the ears in the Gooseneck Casting. Horizontal Gooseneck Cylinder then slides through the Gooseneck Casting and the Gooseneck Toggle. All 3 pieces are held together by the Vertical Gooseneck clevis Pin.
NG1 Old-Style Gooseneck Bracket: NG1-11X: Cast aluminum Gooseneck Bracket fits NG-28 through NG-51 Mast Sections. Old-Style NG1 Gooseneck Mast Bracket is cast with horizontal ring for use with Old-Style NB-16 and NB-26 Boom Goosenecks using Plastic Ball Halves and SS Spring Clips (NB1-5 & NB1-6). Bracket is 2 15/16" (75mm) high x 2 3/4" (70mm) wide, and is fastened with four (4) 3/16" (5mm) rivets. Cast horizontal ring is 1 3/4" (45mm) OD x 1" (26mm) ID. This part is no longer available and is shown here for identification only. For Gooseneck Parts used in conjunction with the *NG1-11X* Old-Style Gooseneck Mast Bracket, and for replacement options, See NB-16, or NB-26 Boom – Old-Style Gooseneck Assemblies and Parts.

NG-31 Mast – Winch Pads
NG-31 Side Winch Pad - Clear Anodized: NG31-20: Formed aluminum Bracket fits either side of NG-31 or NG-37 Mast Section. Winch mounting surface on Bracket is 4" (100mm) high x 3 3/4" (95mm) wide. Anodized Bracket fastens to Mast with eight (8) 3/16" (5mm) rivets. 65,37260
NG-31 Aft Winch Pad - Clear Anodized: NG31-21: Formed aluminum Bracket fits aft side of NG-31 Mast Section. Designed to mount under the Boom for use with a Reef line winch. Winch mounting surface on Bracket is 3 7/8" (100mm) high x 3 1/2" (90mm) wide and angles aft approximately 12 degrees to align Winch with Outhaul or Reef lines exiting from Boom. Anodized Bracket fastens to Mast with eight (8) 3/16" (5mm) rivets. 56,180

NG-31 Mast - Vang Brackets & Hardware Brackets are available with Toggles to fit any type of Vang. Isomat Masts were often supplied with an Isovang solid Vang as standard equipment, they are also commonly added to boats originally supplied without one. See: Isomat Isovangs, and Isomat Vang Brackets & Toggles.
NG1 Vang Bail: NG1-15: SS Vang Bail is used on NG-28 and NG-31 Mast Sections for Light-duty applications. Formed SS Bracket has welded 3/16" (5mm) Bail for attachment of line or shackle, Bracket is 2 1/8" (55mm) high x 2 1/4" (58mm) wide, and is fastened with six (6) 3/16" (5mm) rivets.
NG1 Gooseneck/Vang Bracket: NG1-11: Cast aluminum Gooseneck/Vang Bracket fits NG-28 through NG-51 Mast Sections. Bracket is 3 7/8" (98mm) high x 2 3/4" (70mm) wide, and is fastened with four (4) 1/4" (6mm) rivets. Bracket has holes for 12mm (7/16") Vertical Toggle Pin (NB1-1).
NG1/NB1 Gooseneck/Vang Vertical Toggle Pin: NB1-1: SS Clevis pin is 12mm (7/16") diameter with a 85mm (3 3/8") grip length, and has 8mm (5/16") hole for Cotter Ring or Block attachment. Fits vertically in NG1-11 Gooseneck/Vang Bracket.
NG1 Vang Bracket Ass'y w/ Toggle for Rope Vang: NG1-16A: Complete NG1 Vang Bracket Assembly has Toggle with Slot for attachment of shackle for Rope (soft) Vang. Assembly consists of Vang Bracket (NG1-11), Vang Toggle Pin (NB1-1), and NG1-16 Vang Toggle with 3/8" x 7/8" (10mm x 22mm) Slot. Assembly is fastened to Mast with four (4) 1/4" (6mm) rivets or screws. Toggle can be replaced with any listed below for later conversion to a Hard (solid) Vang.
	NG1 SS Vang Toggle w/ Slot for Rope Vang: NG1-16: SS Welded Vang Toggle with Slot for attachment of Block or Shackle fits *NG1-11* Vang Bracket. SS tube is 1 15/16" (50mm) long and is drilled for 12mm Vertical Pin, *NB1-1.* Welded SS Tab has Slot (3/8" x 7/8") suitable for attachment of most any shackle. Heavy-duty Tab is 7mm (.280") thick and projects 2" (50mm) out from tube.
NG1 Vang Bracket Ass'y w/ Toggle for 3/8" (10mm) Pin: NG1-17A-10: NG1 Vang Bracket Ass'y w/ Toggle for 1/2" (12mm) Pin: NG1-17A-12: *NG1 Vang Bracket Ass'y w/ Toggle for 5/8" (16mm) Pin: NG1-17A-16:*
Complete NG1 Vang Bracket Assembly with Toggle for Vang is available in various Pin sizes. Assembly consists of Vang Bracket NG1-11, Vang Toggle Pin NB1-1, and one of the NG1-17 Vang Toggles. Assembly is fastened to Mast with four (4) 1/4" (6mm) rivets or screws. 10mm size is used with the NG1 Isovang. Please Note that all Vang Toggles shown here (and others) are available separately, See Isomat Vang Brackets & Toggles.
*NG1 Vang Bracket Ass'y w/ Toggle for 14mm (9/16") Pin: NG1-18-9A:*
As NG1-17A, above, but with NG1-18-9D Vang Toggle with 14mm (9/16"), and 8mm (5/16") holes. Special for use with Sparcraft Pneuvang.
*NG1 Vang Bracket Ass'y w/ 22mm (7/8") Toggle: NG1-19A:* Complete NG1 Vang Bracket Assembly with Toggle for Vang with 22mm (7/8") Pin. Assembly consists of Vang Bracket (*NG1-11), Vang Toggle Pin (NB1-1), and NG1-19* Vang Toggle with 22mm (7/8") hole. Assembly is fastened to Mast with four (4) 1/4" (6mm) rivets or screws. For use with the NG2 Isovang. Please Note that all Vang Toggles shown here (and others) are available separately, See Isomat Vang Brackets & Toggles.

NG-31 Mast - Welded Mast Base Exit Boxes Some Isomat Masts have Welded Exit Boxes at the base of the mast for leading internal halyards out of the Mast at Deck level, rather than higher on the mast using standard Exit Plates. Halyards exit the Mast angled aft, toward the cockpit, eliminating the need for any additional hardware at the base of the Mast. Welded Exit Boxes are especially common on Cruising Yachts. The NG-31 Mast Section would normally use NG1 Welded Exit Boxes, See Welded Mast Base Exit Boxes.

NG-31 Mast - Deck Collars, Mast Boots & Hardware
NG-31 Mast Boot: NG31-15B: Heavy molded Black Rubber Boot for use with NG-28, 31, and NG-37 Mast sections. Lower side of Boot fits over all standard Deck Collars, stepped upper side is trimmed to fit Mast section.
NG-31 White Mast Boot - Special for 5-Bail Deck Collar: NG31-15B-10:
Deluxe Hard molded White PVC Mast Boot to fit NG-31 Mast Section and 5-Bail Deck Collar, NG28-10, below. White PVC Mast Boot is 8 1/4" long x 5 5/8" wide x 2 3/4" high. As used on O'Day 28 and others.
NG-31 Mast Boot Clamp: NG31-16M: All Stainless Steel Clamp for use with Mast Boot on NG-31 Mast.
NG-31 Deck Collar Boot Clamp: NG31-16D: All Stainless Steel Clamp is suitable for use with Mast Boots on all NG-31 Deck Collars.
NG-31 Mast Collar Wedge Kit: NG31-17WK: Kit includes 2 Small (*NGA-18) and 4 Large (NGA-19*) Rubber Mast Collar Wedges for use with NG-31 Mast in all NG-31 Deck Collars.
*Mast Collar Wedge – Small Rubber: NGA-18:* Heavy Extruded Rubber Wedge for use with Isomat and other Masts. Small stepped Rubber Wedge is used to support the mast as it passes through the Deck Collar. Wedge is 2 3/4" (70mm) long x 1 1/8" (28mm) wide, and is 15/16" (24mm) thick at the top tapering to 3/8" (10mm) thick at the bottom. NG-31 Deck Collars require 2 Small Mast Wedges (NG1-18).
*Mast Collar Wedge – Large Rubber: NGA-19:* Heavy Extruded Rubber Wedge for use with Isomat and other Masts. Large stepped Rubber Wedge is used to support the mast as it passes through the Deck Collar. Wedge is 2 3/4" (70mm) long x 1 1/8" (28mm) wide, and is 1 3/16" (30mm) thick at the top tapering to 11/16" (18mm) thick at the bottom. NG-31 Deck Collars require 4 Large Mast Wedges (*NG1-19*).

NG-31 Deck Collar � 5 Bail Type: NG28-10: Cast Aluminum Deck Collar for use with NG-28, NG-31, & NG-37 Mast Sections. Deck Collar has provisions for 5 bails NG1-20, for attachment of a soft Boom Vang and up to 4 standard blocks. Cast Deck Collar is 9 7/8" (251mm) long x 8 1/2" (217mm) wide, and fastens to deck with (4) 1/4" (6mm) screws. Maximum inside dimensions 7 9/16" x 4 15/16".
NG1 Deck Collar Bail: NG1-20: SS Formed Bail is used for attachment of blocks and lines. Fits in integral slots in NG28-10 Deck Collar. Bails are installed from underside of Deck Collar Casting; Deck Collar must be removed to install Bails. Bail is made from 8mm (5/16") rod, and is 2 1/16" (53mm) long x (maximum) 1" (25mm) high.
NG-31 Deck Collar – New Style: NG28-12: Cast Aluminum Deck Collar for use with NG-28, NG-31, NG-37 & other Mast Sections. Deck Collar has provisions for 12 new-style Mast Base Block Studs and a SS Bail, NG2-20, for attachment of a soft Boom Vang. Nut slots on underside of casting and 12mm holes allow for attachment of NG1 or NG2 threaded Block Studs, and/or Mast Base Turning Blocks, NGA-40 or NGA-41, without unfastening Deck Collar. Includes four (4) provisions for deck tie-down turnbuckles, and slots for (2) NGA-18 and (4) NGA-19 Mast Wedges. Cast Deck Collar is 10 7/8" (276mm) long x 9 3/8" (238mm) wide, and fastens to deck with (4) 1/4" (6mm) Screws. Maximum inside dimensions 7 9/16" x 4 15/16".
NG2 Deck Collar Bail: NG2-20: SS Formed Bail is used for attachment of Boom Vang, and fits in integral slot in aft side of Deck Collars. Bail is installed from underside of Deck Collar Casting; Deck Collar must be removed to install Bail. Bail is made from 10mm (3/8") rod, and is 2 3/4" (70mm) long x (maximum) 1 15/16" (50mm) high.

NG-31 Mast - Mast Steps
NG-31 Mast Step – Single Bail Type: NG31-1: Small Cast Aluminum Mast Step for use with NG-31 Mast Section. Mast Step has provisions for a single bail, NG1-20, for attachment of a soft Boom Vang. Cast Mast Step is 8" (202mm) long x 4 3/4" (120mm) wide, and fastens to deck or keel with (4) 1/4" (6mm) FH Screws. 138
NG-31 Mast Step – 5 Bail Type: NG31-2: Cast Aluminum Mast Step for use with NG-31 Mast Section. Mast Step has provisions for 5 bails, NG1-20, for attachment of a soft Boom Vang and up to 4 standard blocks. Cast Mast Step is 8 5/8" (220mm) long x 6 1/4" (160mm) wide, and fastens to deck or keel with (4) 1/4" (6mm) FH Screws on 7 3/8" (190mm) (fore & aft) x 5 1/8" (130mm) (athwartships) centers. 147
NG1 Mast Step Bail: NG1-20: SS Formed Bail is used for attachment of blocks and lines. Fits in integral slots in NG31-1 and NG31-2 Mast Steps. Bails are installed from underside of Mast Step Casting, Mast Step must be removed to install Bails. Bail is made from 8mm (5/16") rod, and is 2 1/16" (53mm) long x (maximum) 1" (25mm) high.
NG-31 Mast Step – New Style: NG31-5: Cast Aluminum Mast Step for use with NG-31 and NG-37 Mast Sections. Mast Step has provisions for 8 new-style Mast Base Block Studs and a SS Bail, NG2-20, for attachment of a soft Boom Vang. Nut slots on underside of casting and 12mm holes allow for attachment of NG1 or NG2 threaded Block Studs, and/or Mast Base Turning Blocks, NGA-40 or NGA-41, without unfastening Mast Step. Cast Mast Step is 9 1/8" (230mm) long x 7 3/8" (190mm) wide, and fastens to deck or keel with (4) 1/4" (6mm) FH Screws on 7 3/16" (182mm) (fore & aft) x 4 5/16" (110mm) (athwartships) centers. Unit is marked 556178 or 3603140803.
NG2 Mast Step Bail: NG2-20: SS Formed Bail is used for attachment of Boom Vang. Fits in integral slot in aft side of New-Style Mast Steps. Bail is installed from underside of Mast Step Casting, Mast Step must be removed to install Bail. Bail is made from 10mm (3/8") rod, and is 2 3/4" (70mm) long x (maximum) 1 15/16" (50mm) high.
NG-31 Hinged Mast Step Ass'y: NG31-3A: Cast Aluminum Hinged Mast Step Assembly for use with NG-31 Mast Section. Base Plate attaches to Deck with (4) 1/4" (6mm) FH screws, Mast Step Insert casting attaches to mast and hinges on 10mm (3/8") Pin (included), which slides through Base Plate and Insert Casting. Includes Mast Step Bail, NG1-20, for attachment of boom vang.
	NG-31 Hinged Mast Step Insert Casting: NG31-3B: Insert Casting only, used in Hinged Mast Step Assembly, NG31-3A, above. Cast Aluminum Insert slides into, and fastens to NG-31 Mast Section with 1/4" (6mm) screws or rivets, and hinges on 10mm (3/8") hinge Pin in Base Plate. Insert Casting is 8 1/2" long x 4 3/4" wide and has slot for Mast Step Bail, NG1-20, for attachment of boom vang.
	NG-31 Hinged Mast Step Base Plate: NG28-3D: Base Plate only, used in NG28-3A and NG31-3A Hinged Mast Step Assemblies. Cast Aluminum Base Plate is 8 3/8" (212mm) long x 6 1/2" (165mm) wide and has (3) 8mm (5/16") holes on each side for attachment of shackles for blocks and halyards. Unit attaches to Deck with (4) 1/4" (6mm) FH screws on 7 1/16" (180mm) (fore & aft) x 4 7/8" (125mm) (athwartships) centers, and has hole for 10mm (3/8") hinge Pin. 28

The Isomat NG-31 Mast Section has been replaced by the IM-180 Mast Section. Except for the integral Spinnaker Track, the Sections are identical, and all parts (except for Spinnaker Cars) are interchangeable. For complete Mast Assemblies, contact us with details.
NG-31 Mast Components
Masthead Parts Jumper Strut Fittings Block Attachments & Fractional Cranes Jib Boxes & Forestay Attachments Exit Blocks Spreaders Spreader Bases Spinnaker Cars Exit Plates	Cleats Mainsail Gate Gooseneck Brackets Winch Pads Vang Brackets & Hardware Mast Base Halyard Exit Boxes Deck Collars, Mast Boots & Hardware Mast Steps Mast Base Halyard Turning Blocks

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Spars, Rigging, and Hardware for Sailboats


NG-31 Mast – Masthead Parts NG-31 Masts commonly use one of Two varieties of NG1 Mastheads – one for Masthead Rigs and one for Fractional Rigs. NG1 Masthead Rig Masthead is a single casting welded into the Mast Section and is easily identified by having only 2 Sheaves (or provision for only 2 sheaves) side by side, on the forward side. Masthead includes provisions for Headstay, Backstay, and (2) upper shrouds using Stemball fittings. Sheave Axles are the same in all NG1 Mastheads, but fit in various Axle slots using combinations of up to 3 different size Sheaves and Rollers depending upon application. For Details, See: NG1 Masthead Assembly. NG1 Fractional Rig Masthead is a single casting welded into the Mast Section which includes provisions for Backstay and (2) upper shrouds using Stemball fittings. NG1 Fractional Rig Masthead uses a single Sheave Axle (NG1-6) and (2) 60mm Sheaves (*NG1-4). For Details, See: NG1 Fractional Masthead Assembly.*
NG1 Masthead Cover Plate: NG1-1: Cast aluminum Masthead Cover Plate for NG1 Masthead, standard on NG-31 Masts with Masthead Rigs. NG1 (Masthead Rig) Mastheads are easily identified by having only 2 sheaves (or provision for only 2 sheaves) on the forward side. Masthead Cover Plate also serves as Sheave separator, provides level surface for mounting Anchor light, and has slots for exiting other electrical wires. Unit is 10" (255mm) long (maximum) x 2 3/4" (70mm) wide, and is fastened with two (2) 4mm screws, NG1-1S.
NG1 Masthead Spinnaker Crane: NG1-2: Heavy SS Masthead Spinnaker Crane is designed to attach to standard Isomat NG1 Masthead Rig Masthead. Crane allows for off-center attachment of one or two standard swivel blocks for external spinnaker halyards, See Spinnaker Halyard Blocks. This method of running spinnaker halyards has less friction and eliminates the chafe on halyards that is inherent in the standard internal halyard design – it is the only choice for long-distance racing or cruising. Halyards can be led internally; running from the swivel block to an entrance 5-8 feet down from the masthead, but this method does add a potential chafe spot. Attaches with (2) 1/4" bolts and locknuts, and (2) 4mm (5/32") screws that go into the threaded holes for the masthead Cover Plate screws. SS Plate is (maximum) 3 7/8" long x 4 3/8" wide x 3/16" thick, and projects 2" forward of the masthead. Mounting requires drilling (2) 1/4" holes in the masthead. Unit comes complete with fasteners. Masthead crane will not fit Fractional Mastheads.