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Johnson 18 Specifications

Jn18 Specs

A dingey sportboat sailing community

This page list the lengths and dimensions of equipment and rigging on a Johnson 18. Please visit the Johnson 18 Google Group if there is a missing metric you require, or if you know one that you think should be added.
If you're interested in the process of rigging a Johnson 18, take a look at our Videos page to see an instructional video from White Bear Boatworks on initial rigging.

Specifications

Length Over All (LOA)18'5.54m
LWL16'7"
Beam (width) 6' 7"2.03m
Weight ~480 lbs~218kg
Sail Area- Mainsail 127.7 sq ft
Sail Area- Jib 56.6 sq ft
Sail Area- Spinnaker 256 sq ft
Draft (depth) 5" centerboard up4' 6" centerboard down
Mast Length23'7.08m
DesignerRodger Martin
Year Introduced 1994


Hull

  • The hull, deck, backbone, bow sprit, tiller, rudder, centerboard, mast, and boom, shall conform to the building specifications and shall only be manufactured from the Class approved molds by licensed builders established by the copyright holder (Johnson Boat Works, Inc.). Hardware and rigging shall conform to the official plans, no exception unless stated herein.
      • 3.0.1 A yacht's hull, deck, backbone, hardware placement, bow sprit, mast, boom, tiller, centerboard, and rudder, shall not be altered. Sanding is prohibited on hull, deck, centerboard, and rudder, except when repair of superficial damage is required. (Sep 10, 1995) Fairing of centerboard and rudder trailing edge seam is allowed.
      • 3.0.2 The location, design, and sizes of hardware fixed to the hull, deck, backbone, centerboard, rudder, tiller, bow sprit, mast, and boom shall not be altered. (Sep 10, 1995) Jib sheet cam cleats and mainsheet cam cleats may be moved or removed.
      • 3.0.3 Altering hull and deck construction by coring, drilling out, rebuilding, replacement of materials, grinding, or sanding through surface laminations, or any other practice which reduces weight, improves moment of inertia, or changes standard shapes or structural characteristics is prohibited. Reshaping or fairing of hull profiles or contours is prohibited.
      • 3.0.4 The tiller extension may be of any material and of any length.
    • 3.1 Weight The dry weight of the yacht as raced shall not be less the 218 kgs (479.6 lbs). The dry weight shall include: mast, boom, bow sprit, rudder, tiller, centerboard, jib, all standing and running rigging. An optional compass may also be included as part of the dry weight. Lead corrector weight(s) shall be positioned at a distance of no less than 2616 mm and shall not exceed 3016 mm from the transom. The corrector weight(s) shall be thru-bolted to the sidewall of the cockpit. . The corrector weight(s) shall not exceed a distance of 300 mm from the topside of the mini deck.

Running Rigging

  • Spinnaker Halyard:
    • synthetic rope
      • 47 feet (14.3256 meters)
        • why not make it 48 feet? (14.6304 meters)
      • 0.236220472 inch (6mm) minimum diameter
  • Main halyard: 
    • Synthetic rope
      • 26 feet  (7.9248 meters)
      •  0.236220472 inch (6mm) minimum diameter
    • Stainless Steel Wire
      • UNKNOWN LENGTH
      • 7x19
      •  0.118110236 in (3mm) minimum diameter from shackle to locking device(?)
  • Boom Vang (kicking Strap)
    • synthetic rope
      • UNKNOWN LENGTH
      • 0.157480315 in (4mm) minimum diameter
    • power ratio not greater than 12:1
  • Mainsail outhaul
    • stainless steel wire
      • UNKNOWN LENGTH
      • 7x19
      •  0.118110236 in (3mm) minimum diameter
    • Synthetic rope
      • 15 feet
      •  0.236220472 in (6mm) minimum diameter
    • power ratio no greater than 3:1
  • Main Sheet Traveler Control
    • synthetic rope
      • UNKNOWN LENGTH
      •  0.236220472 in (6mm) minimum diameter
    • power ratio no greater than 3:1
  • Main Sheet
    • Synthetic rope
      • UNKNOWN LENGTH
      • 0.354330709 in (9mm) minimum diameter
    • power ratio no greater than 4:1
  • Jib sheets:
    • Synthetic rope
      • 15 feet each for separate port and starboard (4.57200 meters)
      • 35 feet for a continuous port-starboard sheet (10.66800 meters)
      • 8mm minimum diameter
    • power ratio no less than 2:1
  • Spinnaker sheets
    • synthetic rope
      • UNKNOWN LENGTH
      •  0.236220472 in (6mm) minimum diameter
  • Spinnaker tack line
    • synthetic rope
      • UNKNOWN LENGTH
      •  0.31496063 in (8mm) minimum diameter
  • Jib furling Line
    • synthetic rope
      • UNKNOWN LENGTH
      •  0.118110236 in (3mm) minimum diameter
  • Bow Sprit Line (pole out)
    • synthetic rope
      • UNKNOWN LENGTH
      •  0.31496063 in (8mm) minimum diameter
    • power ratio equal to 2:1
  • Rudder Downhaul Line
    • synthetic rope
      • UNKNOWN LENGTH
      •  0.196850394 in (5mm) minimum diameter
  • Cunningham:
    • 28 feet (8.5344 meters)

Standing Rigging

  • Mast
    • Stays
      • Forestay
        • non-adjustable
        • 3mm
        • furling drum 64mm tall
        • furling swivel 64mm tall
      • Shrouds
        • 3mm
        • 2 upper
        • 2 lower
    • Boom
      • Black band
        • 25mm wide
        • <= 2591mm from mast
    • Spreaders
    • Black bands
      • 25mm wide
      • <= 6248mm apart
  • Pole
    • 1219mm extended

  • 4.0 Mast The mast shall conform to the building specifications and be supplied by the copyright holder. The mast shall not be altered in any way and shall be replaced only by the copyright holder.
      • 4.0.1 The mast standing rigging shall only consist of two upper shrouds and two lower shrouds. The standing rigging shall only be of stainless steel multi-strand wire and shall not be less than 3 mm in diameter. The forestay pennant shall conform to building specifications and be supplied by the copyright holder.
      • 4.0.2 The forestay shall be non-adjustable. The furling drum shall have a distance of 64 mm from the centerline of the bottom pin to the centerline of the top pin. The furling swivel shall have a distance of 64 mm from the centerline of the bottom pin to the centerline of the top pin.
      • 4.0.3 Standing rigging attachment points on the mast and deck shall not be altered or relocated.
      • 4.0.4 Black band shall be a minimum weight of 25 mm and shall encircle the mast. The distance from the upper edge of the lower band (at standard boom height) to the lower edge of the upper band shall not exceed 6248 mm.
    • 4.1 Spreaders The standard spreader bracket shall not be modified by alteration of the spreader sweep angle.
      • 4.1.2 The length of the axis of the spreader from the bearing point of the upper shroud to the surface of the mast shall be 700 mm + or - 5 mm.
      • 4.1.3 The spreaders shall be fixed on the upper shrouds so that they will be perpendicular to the mast.
    • 4.2 Boom The boom shall conform to building specifications and be supplied by the copyright holder. The boom shall not be altered in any way and shall be replaced only by the copyright holder.
      • 4.2.1 A black band of a minimum weight of 25 mm shall encircle the boom. the forward edge of the band shall not exceed 2591 mm from the aft surface of the mast when the boom is held perpendicular to the mast and on the centerline of the boat.
    • 4.3 Bow Sprit The distance from the intersection of the forward surface hull with the axis of the bow sprit to the forward surface of the bow sprit shall not exceed 1219 mm. The bow sprit shall be retracted so that it is at least even with the most forward part of the hull when the asymmetrical spinnaker is not flying.

Sails

  • 5.0 Sails General
    • 5.1 Only one mainsail, one jib, and one asymmetrical spinnaker shall be on board while racing. Only one set of sails shall be measured in at Johnson 18 Class Association sanctioned regattas.
      • 5.1.2 The mainsail shall be constructed of woven polyester. The jib shall be constructed of a woven polyester or polyester substrate/polyester film laminate. The asymmetrical spinnaker shall be constructed of nylon; polyester is prohibited.
      • 5.1.3 Each mainsail, jib and spinnaker, shall carry a Johnson 18 royalty sticker. The sticker shall be firmly fixed near the tack of each sail on the starboard side. Stickers shall not be transferred from one sail to the other. Stickers were available from Johnson Boat Works, 4495 Lake Avenue South, White Bear Lake, MN 55110.
      • 5.1.4 Sail reinforcement shall be in accordance with current IYRU Sail Measurement Instructions.
      • 5.1.5 The Johnson "18" insignia (Diagram 1.0) shall be black in color and fall between the top two battens midway between the luff and leech and shall closely fill up a rectangle that is 610 mm long and 457 mm high. The upper insignia shall be on the starboard side. The word "JOHNSON" shall be placed on the starboard side of the sail, be black in color, parallel to the leech, and halfway between the lowest batten and the clew. These decals are available from the Johnson 18 Class Association, 4495 Lake Avenue South, White Bear Lake, MN 55110.
      • 5.1.6 The sail number of the yacht shall correspond to the hull number and shall be placed on the mainsail and on the asymmetrical spinnaker. The sail number shall not be less than 305 mm in height and have a space of at least 60 mm between them. The upper number shall be on the starboard side.
      • 5.1.7 The minimum cloth weight for the mainsail shall be 160 grams per square meter. The jib shall be 160 grams per square meter for woven material and 150 grams per square meter of substrate/film laminate. The asymmetric spinnaker shall be a minimum cloth weight of 40 grams per square meter.
      • 5.1.8 Unwoven transparent material for windows is permitted below the half height of the main, jib, and asymmetrical spinnaker. No window dimension shall exceed 1400 square mm. Ant edge of the any window shall not be less than 80 mm from the nearest edge of the sail.
  • 5.3 Jib The jib shall be fitted with a 1X19 luff wire of not less than 3 mm. The bearing surface to bearing surface length shall be 5305 -0 +13 mm.
    • 5.3.1 The leech length shall not exceed 4752 mm nor be less than 4676 mm.
    • 5.3.2 The foot length shall not exceed 2207 mm nor be less than 2131 mm.
    • 5.3.3 The luff length shall not exceed 5240 mm nor be less than 5164 mm.
    • 5.3.4 The weight of the head of the jib shall not exceed 38 mm.
    • 5.3.5 The leech shall not be convex.
    • 5.3.6 Clew boards and battens are prohibited.
    • 5.3.7 The midpoint of the foot is determined by folding the jib vertically and superimposing the tack and clew matching the edges of the sailcloth. The head of the jib is held firmly and a measurement taken from the "measurement point" of the head to the lowermost edge of the roach at the midpoint with two pounds tension. This dimension shall not exceed 4984 mm. This specification is to take precedence over any other specifications insofar as any conflict is concerned.
    • 5.3.8 Leech and foot lines are permitted.
    • 5.3.9 Jib cunningham shall not lead to the deck.
  • 5.2 Mainsail The headboard may be of any material not exceeding 153 mm in weight and length. Including the luff rope, the total weight of the head shall not exceed 191 mm.
    • 5.2.1 The length of the leech shall not exceed 6629 mm. All mainsails built prior to November 1, 1993 shall be grandfathered in regards to leech measurement.
    • 5.2.2 Total weight measurements for the mainsail shall be taken at 3/4 height, 1/2 height. 1/4 height measuring points on the leech to the nearest points on the luff. The total weight measurements, include the luff rope, shall not exceed: 3/4 height = 1219 mm; 1/2 height = 1994 mm; 1/4 = 2438 mm. The leech shall not be hollowed to evade weight measurements.
    • 5.2.3 The mainsail shall not exceed rule 4.0.4 and rule 4.2.1 (E = 2591 mm and p = 6248 mm).
    • 5.2.4 The mainsail shall have four battens that divide the leech into five equal parts. The top two batten shall be full length. The bottom two battens shall not exceed 991 mm. The maximum weight for the battens shall be 50 mm.
    • 5.2.5 The mainsail shall be loose footed. There shall be a non-adjustable slug attached at the tack and at the clew. The foot round shall not exceed 102 mm. A cunningham cringle within 254 mm of the clew is permitted. A leech line is permitted.
  • 5.4 Asymmetrical Spinnaker Leech length shall not exceed 5370 nor be less than 5218 mm.
    • 5.4.1 The luff length shall not exceed 6883 nor be less than 6655 mm.
    • 5.4.2 The foot length shall not exceed 4674 nor be less than 4445 mm.
    • 5.4.3 The midpoint of the foot is determined by folding the spinnaker vertically and superimposing the tack and clew matching the edges of the sailcloth. The distance from the midpoint of the foot to the head shall not exceed 6426 mm nor be less than 6325 mm
    • 5.4.4 Total weight measurements for the asymmetrical spinnaker shall be taken at 3/4 height, 1/2 height. 1/4 height measuring points on the leech and the luff. The total weight measurements shall not exceed: 3/4 height = 3823 mm maximum, 2070 mm minimum; 1/2 height = 3823 mm maximum, 3696 mm minimum; 1/4 = 4585 mm maximum, 4253 mm minimum.

Learn from our mistakes experience!

Also available here is our Repairs and Maintenance page, which details some common or no-so-common work that owners have encountered over the years.