- 7.1 Mast Construction
- 7.1.1 Construction shall be of wood or aluminum alloy. Wooden masts shall be constructed from mono-specie wood, weighing in excess of 20 lb./cu. ft. (320 kg/cu. m) at 15% moisture content. Aluminum masts shall be constructed from corrosion resistant, marine alloy. (Type 6061, heat treated to T6 condition, or equivalent. is recommended.)
- 7.1.2 The mast shall not be stepped above berth level, i.e., the mast butt shall not be shortened more than 16" (406.4 mm.) from its length if it was stepped on the keel.
- 7.1.3 The mast top shall be tapered for a length of not less than 10' (3.05 m.).
- 7.1.4 The mast shall not rotate and the butt of the mast shall not be moved during a race.
- 7.1.5 Equivalent suitable hardware may be substituted for that on the official plans provided that all standing rigging is per plan, and is attached to the mast with tangs external to the mast or with 'T' bar swage fittings and corresponding keyhole slot hardware. If desired, the lower end of the jumper shroud and the upper end of the lower shroud may be attached to the mast by means of a single tang. Running rigging, including the use of internal halyards, is optional.
- 7.1.6 A fixed stop shall be installed at the masthead to prevent the mainsail from being hoisted above the position as defined by the upper black band and/or the main halyard shall be suitably marked to effect the same results. See Section 7.3.1 for black band location.
- 7.1.7 A fixed stop shall be installed below the gooseneck to prevent the mainsail from being set below the position defined by the lower black band. See Section 7.3.1 for black band location.
- 7.2 Aluminum Mast Weight
Aluminum mast weight includes sail track, spreaders. jumper struts, jumper stays, tangs, sheaves, gooseneck track, and pole track or fittings and main, jib and spinnaker halyards. When weighing masts, halyards shall be in their hoisted position with external tails supported and not weighed. Forestay, backstay and all shrouds are to be removed. Jumper stays are to be installed.
- 7.2.1 Mast weight shall not be less than 94 lb. (42.7 kg).
- 7.2.2 Mast center of gravity shall not be less than 1l'-3" (3.43 m.) above the upper edge of the lower black band.
- 7.2.3 Ballasting of the mast is permitted to achieve the requirements
of Sections 7.2.1 & 7.2.2. Location and amount of ballast
weight shall be recorded on the measurement certificate.
Method to determine weight and center of gravity of mast:
- a. Set up scales (platform type is preferred, or spring
type bathroom style will do) on sawhorses or top
of oil drum.
- b. Lift mast on to scale and maneuver until balance
position is achieved.
- c. Determine difference between scale reading and
required 94 lb. (42.7 kg). If less than 94 lb.,
obtain lead weights (1 lb. fish weights work well)
to make up the difference.
- d. Mark the required center of gravity on the mast;
support the mast at this location with a single
point support.
- e. Place the lead weights at various positions to produce a balanced condition. This is usually at the butt and/or spreader areas.
- f. If mast is in excess of 94 lb., but C. of G. is too low, remove weight from butt area and/or add to top part of mast.
- a. Set up scales (platform type is preferred, or spring
type bathroom style will do) on sawhorses or top
of oil drum.
- 7.3 Mast Dimensions
- 7.3.1 Two (2) 1" (25.4 mm.) black bands, or bands of contrasting color, shall be fixed to indicate the extremities of the mainsail position on the mast. Position of upper edge of lower band shall be 32' 0" +- 1/8" (9.760 m +- 4 mm.) from truck (extreme top of mast). Position of lower edge of upper band shall be 12" +- 1/8" (305 mm. +- 4 mm.) from truck.
- 7.3.2 Spreader centerline position shall be 19' 0" +/- 1/2" (5.80 m +- 13 mm.) from truck.
- 7.3.3 Jumper strut centerline position shall be 7' 9" +/- 1/2" (2.36 m +- 13 mm.) from truck. Where port and starboard jumper struts are at different heights, the average location shall meet this dimension.
- 7.3.4 Intersection of the centerline of the forestay with the forward face of the mast shall be 7' 9-1/2 +/- 1/2" (2.375 +/- 13 mm.) from truck.
- 7.3.5 The genoa halyard block shall be below the mast / forestay intercept.
- 7.3.6 The spinnaker halyard fittings shall be arranged so the lead to the spinnaker head is not be more than 1" (25.4 mm.) higher than the extension of the forestay to the mast and no more than 3" (76.2 mm.) from the leading edge of the mast.
- 7.3.7 Mast/Sheerline intercept shall be 34' 9-1/2" +/- 1/4" (10.611 m +- 7 mm) from truck. (This mark may be a screw. copper tack. for wooden masts; or a center punch, file mark for aluminum masts.) Locate this mark on the rear centerline of mast.
- 7.3.8 Vertical position of mast, as installed in the boat, shall meet the following. The mast/sheerline intercept mark shall be within +- 1/2" (13 mm.) of a string which has been drawn tight between port and starboard sheerlines at back of Bulkhead #2. The sheerline is the external deck edge at side. An alternate method of locating the vertical position of the mast is as follows: Lay a straight beam transversely across the boat along the aft edge of Bulkhead #2. Measure down to the sheerlines, port and starboard, and average the two readings. This average reading will be the distance from the center of the beam down through the mast hole in the deck to the mast/sheerline intercept mark. Measure from the beam to the mast step and use these values to calculate the length of mast below the mast/sheerline intercept mark.
- 7.3.9 Spinnaker pole attachment to front face of mast shall be 4' 3-3/4" (1.315 m) maximum above upper edge of lower 1" (25.4 mm.) black band.
- 7.4 Mast Section measurements
- 7.4.1 Except for existing wood masts measured before 15 August 1972. mast sections shall be as per plan, with a tolerance of - 0" + 5/8" (15.9 mm.).
- 7.4.2 At deck and spreaders: 3-1/4" x 4-l/4" (82.6 mm x l08 mm.) minimum. Corner radii: 1-5/8" (41.2 mm.) maximum.
- 7.4.3 At jumpers - 2-15/16" wide x 3-11/16". minimum. (74.6 mm. x 94 mm.). Corner radii: 1-1/2" (38 mm.) maximum.
- 7.4.4 At upper black band - 1-3/4" (44.4 mm.) x 2-1/8" (54 mm.) minimum.
- 7.5 Spreaders
- 7.5.1 Construction shall be of wood or corrosion resistant metal. Aluminum alloy is recommended.
- 7.5.2 Spreaders shall he positioned in accordance with 7.3.2 and shall be solidly affixed to the mast. For maximum strength, the spreaders may be angled upwards length-wise from the mast attachment point. Swinging spreaders are not permitted.
- 7.5.3 Distance tip to tip (and shroud to shroud) shall be 55-1/4" (1.403 m.) minimum to 57-1/4" (1.454 m.) maximum with spreaders positioned in accordance with 7.5.2.
- 7.5.4 Wooden spreaders shall be constructed of solid wood and sized according to the plans (except that the length may be reduced to minimum as per 7.5.3.
- 7.5.5 Wooden spreaders shall be installed with the fore and aft width at right angles to the mast length, i.e., the spreaders may not be aligned with the heeled, close-hauled relative wind direction.
- 7.5.6 Wooden spreader edges may be rounded to a 1/2" (12.7 mm.) radius at the inner end decreasing linearly to a 3/8" (9.5 mm.) radius at the outer end. Streamlining or tapering in the fore and aft direction is not permitted.
- 7.5.7 Cross-section of wooden spreaders at mast shall be 4-1/4" (108 mm.) x 1"(25.4 mm.) minimum at mast.
- 7.5.8 Metal spreaders shall be untapered round tube of not less than 1-1/4 (31.7 mm.) OD.
- 7.6 Jumper Struts
- 7.6.1 Construction shall be of wood or corrosion resistant metal.
- 7.6.2 Jumper struts shall be positioned in accordance with 7.3.3, and shall be solidly affixed to the mast.
- 7.6.3 Length of struts from face of mast to strut tip shall be 18" (457.2 mm) minimum and 20" (508 mm.) maximum.
- 7.6.4 The cross tie between struts is preferred but shall be optional.
- 7.6.5 The angle between the struts shall be 85 to 95 degrees.
- 7.6.6 Wooden jumper struts shall be installed with their fore and aft width at right angles to the mast length. Their cross-section at mast shall be 1-7/8" (47.6 mm.) x 1" (25.4 mm.) minimum.
- 7.6.7 Corner radii of wooden struts shall be 1/2" (12.7 mm.) maximum at inner end decreasing linearly to 3/8"(9.52 mm.) maximum at outer end. i.e.; edges may be square or up to a full round but streamlining or tapering in the fore and aft direction is not permitted.
- 7.6.8 Metal jumper struts shall be untapered round tube of 1.0" (25.4 mm.) minimum diameter.
- 7.7 Boom
- 7.7.1 Material may be of wood or aluminum alloy as specified in Section 7.1.1.
- 7.7.2. Vertical depth (overall external dimension) shall not exceed the overall width of the narrowest cross section by more than 60% at any point along the boom.
- 7.7.3 An upright "T" boom section which conforms with the above dimensions is permitted.
- 7.7.4 Provisions for fastening the foot of the mainsail to the boom shall be so arranged that the sail foot describes a straight line along the fore-aft axis of the boom. A grooved boom which retains the mainsail foot bolt rope is recommended.
- 7.7.5 Roller reefing is permissible.
- 7.7.6 A 1" (25.4 mm.) wide black band, or band of contrasting color, shall be fixed to indicate the aft extremity of the mainsail on the boom. The forward edge of the black band shall be 13' (3.962 m.) aft of the fair extension of the aft face of the mast sail track. For masts with internal sail tracks, the aft face of the sail track is the aft face of the mast. A fixed stop shall be installed to prevent extension of the sail beyond the forward edge of the black band.
- 7.8 Spinnaker Pole
- 7.8.1 Construction material and cross-section dimensions are optional. Material may be wood or aluminum alloy as recommended in Section 7.1.1.
- 7.8.2 The overall length of the spinnaker pole, including fittings, shall be not more than 2896 mm or 9' 6"
- 7.8.3 The spinnaker pole attachment to the mast shall be positioned in accordance with 7.3.9.
- 7.9 Other Spars
No other spars are permitted. However, the spinnaker pole may be used from its normal point of attachment on the mast to the clew of the genoa or working jib provided it is carried on the opposite side from the main boom.
- 8.0 RIGGING
- 8.1 Standing rigging shall be of wire rope of diameter and strength not less than specified below.
- 8.2 Shrouds
Adjustment shall be by turnbuckle only located above the deck. Position, number and length shall be as indicated in the plans except for the optional addition of one set of forward lower shrouds. See Section 4.2.2 for the location of the chain plates.
- 8.2.1 Forward lower shrouds - No minimum, no maximum. (5/32" (4 mm) recommended)
- 8.2.2 Upper shrouds - Minimum dia. 5/32" (4 mm.), no maximum.
- 8.2.3 After lower shrouds - Minimum dia. 5/32" (4 mm.), no maximum
- 8.3 Jumper Strut Stays
- 8.3.1 Minimum diameter 1/8" (3.2 mm.), no maximum.
- 8.3.2 Shall be affixed according to plan except that the lower ends may be extended to connect with the corresponding after lower shroud tang on the sides of the mast at the spreaders.
- 8.3.3 Adjustment shall be by tumbuckle only located above the spreaders.
- 8.4 Forestay
- 8.4.1 Minimum diameter 1/8" (3.2 mm.), no maximum.
- 8.4.2 Adjustment shall be by turnbuckle only located above the deck.
- 8.4.3 May be located aft of the bow extreme to comply with "J" measurements.
- 8.5 Backstay
- 8.5.1 Minimum diameter 1/8" (3.2 mm.), no maximum.
- 8.5.2 Backstay may be tightened by optional means up to a maximum of twelve (12) inches (304.8 mm.) after the owner has established a desired fore and aft position of the mast; provided that the means of adjustment incorporates a "fail-safe" device to assure the integrity of the rig.
- 8.6 Running Rigging
- 8.6.1 Running rigging may be sized, led and located at the owner's option provided that, in doing so, access to and use of cruising facilities and entrance to the cabin through the companion way is not restricted.
- 8.6.2 Sheeting arrangements for the mainsail are optional. The barney post may be omitted in favor of travelers or other devices.
