NG2 Masthead Assembly

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Isomat NG2 Masthead

The NG2 Masthead for Masthead Rigs is commonly used on Isomat NG-51 through NG-105 Mast Sections, and on some Sparcraft Masts. See: NG Mast Sections, and Sparcraft Mast Sections. Fractional Rigs on NG-60 and larger NG Mast Sections use a variety of welded semi-custom Fractional Mastheads, which often use a number of the Components listed below. Smaller NG Mast Sections (and sometimes the NG-51) use the NG1 Masthead. The NG2 Masthead for Masthead Rigs consists of 2 interlocking cast pieces welded to the Mast Section and is easily identified by having 4 Sheaves (or provision for 4 sheaves) side by side, on the forward side. Masthead allows for 2 Main halyards, 2 Jib halyards, and 2 internal Jib/Spinnaker* halyards (using the 2 forward outboard sheaves) for a total of up to 6 halyards. The NG2 Masthead uses up to 6 Sheaves, NG2-3, and (2) Sheave Axles of different lengths. Masthead includes provisions for attachment of Headstay, Backstay, and (2) Upper shrouds using Stemball rigging fittings. Headstay attachment requires use of an NG2 Stemball / Eye Adapter, also commonly used on Backstays for fitting Insulators; Upper shrouds use Swage or Norseman Stemball fittings. Parts for the NG2 Masthead are listed below. Optional Masthead Spinnaker Crane, NG2-2*, for running External Spinnaker Halyards, is recommended for long-distance racing or cruising, and is listed below. Newer Mastheads have screw hole indents.

NG2 Masthead Assembly - Complete: NG2-1AC:

Used on Isomat NG51 through NG105 (& other) Mast Sections, the NG2 Masthead Assembly is suitable for welding into a variety of Mast Sections of similar size (7 1/2" - 11" fore & aft).
Masthead Assembly accommodates six (6) Internal Halyards and includes Sheaves, Axles, Cover Plate w/ screws, and Clevis Pin for topping lift or Triatic Stay attachment using NG2-LP8- Triatic 'Dogbone' Links, below.
Masthead frame consists of 2 interlocking cast pieces that can be assembled at 15", 16", or 17" long (top measurement). Unit is (maximum) 6 3/4" wide, and fits in 5" (125mm) wide slot. Slot can be reduced to 4" (100mm) wide when not using shroud Stemball seats.
Professional installation and welding is required.

NG2 Masthead - Forward Casting only: NG2-1-CF:

Forward Casting only, as used in Isomat NG2-1AC Masthead Assembly, above. Forward casting is (maximum) 6 3/4" wide x 9" long, and weighs 3.35 lbs..

NG2 Masthead - Aft Casting only: NG2-1-CAft:

Aft Casting only, as used in Isomat NG2-1AC Masthead Assembly, above. Unit is (maximum) 6 3/4" wide x 10" long, and weighs 3.25 lbs.. Aft casting is also used alone (without Forward Casting) in Fractional Rigs and is not tapped for Cover Plate screws.

NG2 Masthead Cover Plate: NG2-1:

Cast aluminum Masthead Cover Plate for NG2 standard Masthead. Masthead Cover Plate also provides level surface for mounting Anchor light and has holes and slots for exiting other electrical wires. Unit is 10 1/4" (260mm) long (maximum) x 7 1/8" (180mm) wide and is fastened with two (2) 6mm screws that thread into tapped holes in Masthead: NG2-1S:

NG2 Masthead Spinnaker Crane: NG2-2:

Heavy SS Masthead Spinnaker Crane is designed to attach to standard Isomat NG2 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 (4) 5/16" (8mm) bolts and locknuts. SS Plate is (maximum) 4" long x 5 3/8" wide x 1/4" thick, and projects 1 3/8" forward of the masthead. Mounting requires drilling (4) 5/16" holes (in already cast divots) in the masthead. Unit comes complete with fasteners.

*NG2 Masthead Sheave, 85mm: NG2-3:* Factory standard Acetyl Sheave is 85mm (3 3/8") x 15mm (5/8") wide x 22mm (7/8") ID, with Rope Groove for up to 1/2" line. For Heavy-duty applications, use the aluminum version NG2-3A, below.
	NG2 Masthead Sheave, 85mm Aluminum: NG2-3A: Anodized Aluminum Sheave is 85mm (3 3/8") x 15mm (5/8") wide x 22mm (7/8") ID has Rope Groove for up to 1/2" line, and is much sturdier than the plastic version.
*NG2 Long (Forward) Masthead Sheave Axle: NG2-6L:* Long SS 'Drop-in' Tubular Masthead Sheave Axle is 22mm (7/8") OD x 81mm (3 1/4") long. Hollow Axle fits in Forward side of NG2 Masthead and supports 4 Jib/Spinnaker Halyard Sheaves (NG2-3 or *NG2-3A*).
*NG2 Short (Aft) Masthead Sheave Axle: NG2-6S:* Short SS 'Drop-in' Tubular Masthead Sheave Axle is 22mm (7/8") OD x 46mm (1 3/4") long. Hollow Axle fits in Aft side of NG2 Masthead and supports 2 Main Halyard Sheaves (NG2-3 or *NG2-3A*).
*NG2 Masthead Clevis Pin - 8mm: NG2-6P:* SS Clevis Pin is used on the aft side of NG2 Masthead for attachment of topping lift, lazy jacks, or other items. This item is not standard on all masts and your Masthead may not have a hole drilled for this Pin, but, if not drilled, hole position is marked by an indent. Masthead can be easily drilled to add this item if required. Clevis Pin is 8mm (5/16") diameter with a 52mm (2 1/16") grip length. CPM8-52

NG2 Stemball Cup Washer - 34x20mm: NG2-CW20:

Standard NG2 Stemball Cup Washer is used with swage and mechanical Stemballs in NG2 Mastheads, Spreader Bases, some Stemball Backing Shells, and in other applications. Type 316 SS Cup Washer is 34mm (>1 5/16") OD x 20mm (>3/4") ID x 11.5mm (7/16") high. For use with 5/16", 3/8", 8mm, and 10mm Standard Swage Stemballs, and 5/8" threaded Stemballs.

NG2 Stemball Cup Washer - 34x22mm: NG2-CW22:

Large NG2 Stemball Cup Washer is used with swage and mechanical Stemballs in NG2 Mastheads, Spreader Bases, some Stemball Backing Shells, and in other applications. Type 316 SS Cup Washer is 34mm (>1 5/16") OD x 22mm (7/8") ID x 9mm high. For use with 7/16", 1/2", 11mm, and 12mm Standard Swage Stemballs, and 3/4" threaded Stemballs. os

NG2 Stemball / Eye Adapters

NG2 Stemball / Eye Adapter for 1/2" (12mm) Pin: NG2-SBE-8:

NG2 Stemball / Eye Adapter for 5/8" (16mm) Pin: NG2-SBE-10:

NG2 Stemball / Eye Adapter for 3/4" (19mm) Pin: NG2-SBE-12:

SS NG2 Stemball / Eye Adapters have a 34mm (<1 3/8") head diameter. Length from base of Stemball to Pin center is 4 5/8" (117mm) on 1/2" size, 5 5/8" (143mm) on 5/8" size, and 5 7/8" (148mm) on 3/4" size.
A variety of other NG2 Stemball / Eye Adapters are available with or without a Toggle, See: NG2 Stemball / Eye Adapters.

Swage Stemballs for Imperial Wire

Swage Stemball for 5/16" Wire: RS-SB-10M8:
Swage Stemball for 3/8" Wire: RS-SB-12:
Swage Stemball for 7/16" Wire: RS-SB-14M11:
Standard NG2 Stemball Swage is used with Imperial (US Standard) 1x19 wire and appropriate Stemball Cups in NG2 Mastheads, Spreader Bases, some Stemball Backing Shells, and in other applications.

Swage Stemballs for Metric Wire

Swage Stemball for 8mm Wire: RS-SB-10M8:
Swage Stemball for 10mm Wire: RS-SB-M10:
Swage Stemball for 11mm Wire: RS-SB-14M11:
Standard NG2 Stemball Swage is used with Metric 1x19 wire and appropriate Stemball Cups in NG2 Mastheads, Spreader Bases, some Stemball Backing Shells, and in other applications.

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