2008 MCYRA Yearbook
Electronic Edition

MEASURMENT

ARTICLE I. OBJECTIVES

Section 1. To maintain the legality of any boat built prior to the adoption or changes of this specification, provided that it conforms to the specifications in effect at the time of its measurements being accepted, or unless the change expressly states it is to apply to such boats. *(25 July 1959)

Section 2. To maintain the one-design characteristics of the Mercury Class Yacht

Section 3. To permit construction of the yacht by professional or amateur builders.

Section 4. To provide for the adoption of new construction practices and materials.

ARTICLE II. CERTIFICATION

Section 1. The drawings listed below are hereby adopted as the official design and by this reference are made a part of this specification .
(a) Drawing # 1 Profile, Mercury Class Yacht
Drawing # 2 Offsets, Mercury Class Yacht
Drawing # 3 Stem and frames 1 through 5
Drawing # 4 Frames 6 through 9 and transom
Drawing # 5 Rudder
Drawing # 6 Mast and mast hardware
Drawing # 7 Rigging Plan
Drawing # 8 Not Used
Drawing # 9 Arrangement
Drawing #10 Sail Plan
Drawing #11 Boom and boom hardware
Drawing #12 Optional booms
Drawing #13 Keel Profile
Drawing #14 Trailer
Drawing #15 Not Used
Drawing #16 Not Used
Drawing #17 Not Used
Drawing #18 Assembly details
(b) The official drawings will carry the approval date. (c) Drawings are available from the Mercury Class Secretary only.

Section 2. The Association’s measurement certificate is the only recognized proof of eligibility to the Mercury Class. Infringement of the following specifications subjects a yacht built or modified after adoption of this specification to remeasurement and voiding of the original certificate.

Section 3. In the case of any variance between these specifications and the design plans of the Mercury Class, these specifications shall be supreme.

Section 4. The Mercury Class Yacht shall hereafter be built as stated in these specifications and the Mercury Class Yacht official design plans. There are tolerances but they are known to the MCYRA Measurer only. Build as close to the specifications and plans as possible.

ARTICLE III. HULL

Section 1. dimensions
(a) Length overall 18 feet
(b) Beam 5 feet 4 inches
(c) Water Line 13 feet (approximately )
(d) Draft 3 feet 1 inch (approximately )
(e) Weight (less spars & loose gear) 1100 lbs min. *(1 July 1964)
(i) An under weight yacht may be brought up to weight by adding weight above a plane parallel to the waterline and intersecting a point 4-1/4 inches above the top of keelson at station 5. *(1 July 1964)

Section 2. Construction - Hulls must be constructed of wood or fiberglass. The material used in constructing fiberglass hulls must conform to the specifications established by the Technical Committee and the molds used must be certified by the Measurement Committee. Franchises to build fiberglass Mercury Yachts will be issued by the Executive Committee. (a) Keelson - Hardwood, 1-1/4" thick one piece or laminated.
(b) Deadwood - Douglas fir, mahogany, port orford cedar or plywood, providing that all internal space is filled with wood. *(17 Nov. 1962)
(c) Planking - 3/8" douglas fir, mahogany or fiberglass.
(d) Transom - 3/4" plywood, solid hardwood or fiberglass.
(e) Stem - 2" hardwood, one piece or laminated.
(f) Frames - 3/4" plywood as per plan or 3/4" x 3" hardwood with suitable joiners at keelson and chine.

Section 3. Wood decks must adhere to the following:
(a) Deck must be planked with douglas fir plywood or hardwood not less than 3/8" thick. (b) Beams must be wood and not less than 3/4 x 1-3/4 inch throughout.
(c) King Plank, covering board, and deck covering - optional.
(d) The deck at it’s narrowest point opposite the cockpit, shall not be less than 12 inches or more than 15 inches.
(e) The crown of the deck at the mast partner shall be per plan.
(f) Beams may not be altered to lighten boat.

Section 4. Deck arrangement
(a) Open cockpit per plan.
(b) Cuddy optional as per plan.
(c) Dimensions and shape of cockpit are controlled as follows; the aftermost extremity of the opening must be not less than 5-1/2 inches forward of station 8. The forward most extremity of the opening must not be less than 8 inches aft of station 3.
(d) The maximum overhang of deck or splash board at sheer shall not exceed the Schock overhang at any comparable location. *(28 Jan. 1978)

Section 5. Hull and deck fastenings - The use of aluminum and magnesium is prohibited.

Section 6. Hardware - deleted. *(31 Jan. 1970)

Section 7. Mast Step, Mast Placement and Mast Movement - (There are three elements that control the aforementioned items; mast step height, foward most position of the mast step,and from which point the mast is allowed to pivot. Each element has an absolute value and the procedure for obtaining each is described further below.For this section, all measurements are from the stem, excluding the stem fitting. The mast must be stepped on the keelson or on a base, no part of which may be more than 7-1/2 inches above the upper face of the keelson or, in a boat without a keelson, the equivalent of the keelson location. The mast at the deck may not be foward of 63 inches from the stem. Refer to Subsection 7 (b). (28 Jan 1995)(22 Jan 2005) (a)Mast Base Location- The mast at all times be stepped aft of the vertical perpendicular from a point measured 65-3/4 inches from the stem. Refer to subsection 7(c). *(28 Jan 1995)*(24 Jan 1998)*(22 Jan 2005) (b) Mast Movement- The mast base may be allowed to move fore and aft, but not more than 2-3/4 inches.However, if the measurement of the mast, at the deck, is less than 65 inches, the mast base may not be moved at all. *(30 Jan 1993)*(22 Jan 2005) (c) Mast Base Location Measurement Procedure- The vertical perpendicular described in subsection 7(a) is measured perpendicular to the deck, along the centerline. Thus, extending a carpenter's square laid along the centerline of the bridgedeck downward to the mast step from a point 65-3/4 inches aft of the bow defines the foward most position of the mast at its base. However this procedure assumes the deck is unaltered from its original shape, which must be either consistent with plan or from an approved mold. To the degree this procedure conflicts with Subsection 7(a), Subsection 7(a) shall be controlling.*(22 Jan 2005) (d) Mast Step Measurement Procedure - For a Boat without a keelson, the equivalent location is determined by laying a 3/4 inch high by 4 inches wide board in the athwartship center of the boat as closeto the mast step as possible and measuring vertically from its upper face to the upper most portion of the mast step. If in so doing the board is high centered, the amount of the high center shall be deducted from the measurement. To the degree this procedure conflicts with Section 7, the intent of ,Section 7 shall be controlling. *( 22 Jan 2005)

Section 8. Lead keel:
(a) Must be a lead casting. *(2 Aug. 1967)
(b) The weight of the keel together with the bolts, washers and nuts shall not exceed 635 pounds.
(c) Keels cast in any mold owned by the Association or certified builder, need not be certified as to weight or measurement.*( 25 Jan. 1969)
(d) The MCYRA drawing #13 is the official plan for keels and any keel which measures to this plan and is within the weight restriction, shall be acceptable.
(e) Keels on Mercury Yachts which otherwise measure, may at the discretion of the Chief Measurer and three officers of the MCYRA, be exempt from weight measurement if previously installed and the owner had no knowledge of the MCYRA rules or has no proof of purchase. *(15 April 1967)
(f) The keel may be physically measured by the method established, and approved by the Chief Measurer and any three MCYRA officers. *(15 April 1967)

Section 9. The tiller is to have a metal jaw, to be fitted and fastened securely to the rudder post, diameter as per plan.

Section 10. Rudder and rudder post shall be as per plan.

Section 11. Fiberglass covering - Boats made of wood may be covered with fiberglass except that its use must not interfere with the official plans and specifications.

Section 12. Fillets between hull and deadwood shall not exceed 1/4 inch radius.

ARTICLE IV. SPARS

Section 1. Mast
(a) Mast and rigging as per plan.
(b) The height from the deck to the top of the mast shall not exceed 24 feet 6 inches.(21 Jan 06)
(c) The mast must be of solid wood or aluminum. *(31 Jan. 1970 )
(d) There shall be no revolving mast.
(e) The mast must be slotted to take a sail bolt rope, and the diameter of the slot shall not exceed 5/8 inch when wood is the material.
(f) Deleted. *(27 Jan. 1979)
(g) The mast shall have from one to three pair of painted horizontal bands not less than 1/2 inch wide. In each set of bands, the distance between the top edge of the lower band and the bottom edge of the upper band, shall not exceed 21 feet 11 inches. When multiple bands are used, different colors shall be used for each pair of bands, contrasting from the color of other bands in the set and and in all cases from the color of the mast. The same sequence of colors used in the lower set will be repeated in the upper set.The measurement from the deck to the bottom of the top band shall not exceed 24'1"(21 Jan 06)
(h) The entire mainsail at all times must be between the lower edge of one of the upper mast bands and the upper edge of the corresponding lower mast band.
(i ) The minimum spacing in the sets shall be 5 inches between individual bands.
(i) The masthead board must not extend more than 6-1/2 inches aft of the after face of the mast measurer perpendicular to the mast. *(1 Jan. 1963) Retroactive, applies to all boats.

Section 2. Boom
(a)Boom as per plan - must be made of wood or aluminum and shall not extend more than 9 feet 5 inches from the after face of the mast at the bolt rope slot. *(31 Jan 1970)
(b) & (c) Deleted. *(Jan. 1969)
(d) The boom must be slotted to take a bolt rope and the slot is not to exceed 5/8 inch.
(e) The boom shall have a 1/2 inch band painted on both sides, the forward face of which shall not be more than 9 foot 1 inch from the after face of the mast at the bolt rope slot. *(3 Aug. 1966) Retroactive, applies to all boats.

Section 3. Wisker pole
(a) No restriction on length.
(b) When in use it must be held to the mast. (inboard end)

ARTICLE V. RIGGING

Section 1. The rigging shall be as depicted on Rigging Plan, Mercury Class Yacht, drawn by W. L. MacDonald, 4 Nov. 1957 and numbered drawing number 7, as revised 7 Aug. 1963. *(15 April 1964) Retroactive, applies to all boats.

Section 2. Jib stay
(a) The projected intersection of the jib stay with the forward side of the mast at a point not more than 17 feet 5 inches (+ or - 4 inches) above the deck.
(b) The projected intersection of the jib stay with the deck shall be at a point no more than 8 inches aft of the forward most part of the stem and on the centerline.
(c) The minimum size of the jib stay is 3/32 inch diameter.

Section 3. Upper shroud
(a) Installed as per plan.
(b) Adjustable tension device (other than a turnbuckle or other tension device not readily adjustable under way) and/or quick release device is not a permissible installation *(4 December 1988) Retroactive. Applies to all boats.
(c) Minimum size 3/32 inch diameter.

Section 4. Lower shroud
(a) Installed as per plan. Projection of intersection point with mast, shall not be more than 5 inches below centerline of spreader. *(15 April 1964)
(b) Adjustable tensions device and/or quick release device is a permissible installation. The intersection point of the shroud with deck, projected or actual, must be fixed. *(4 December 1988) Retroactive. Applies to all boats.
(c) Minimum size, 3/32 inch diameter.

Section 5. Lower shroud (optional) (forward )
(a) An auxiliary lower shroud may be added which attaches to a chain plate located forward of the mast. It shall be fastened to the mast at the same point as the regular shroud . (Not shown on drawing No. 7, not recommended )
(b) Minimum size, 3/32 inch diameter.

Section 6. Backstay
(a) The permanent backstay shall attach to the mast head and the after face of backstay shall not be more than 1 inch aft of intersection of deck and transom. *(15 July 1964)
(b) Adjustable tension devices and/or quick release device is a permissible installation.
(c) Minimum size, 1/16 inch diameter.

Section 7. Chainplates - The shrouds shall attach to fixed chainplates either above or below the deck and the method of fastening to the hull is optional within the limits of Article III, and Drawing No. 7 . *(Jan. 1979)

Section 8. Jumpers
(a) Installed as per plan. Projected intersection point with mast shall not be more than 16 inches above centerline of spreaders. *(4 December 1988)
(b) Minimum size, 1/16 inch diameter.
(c) Jumpers are optional. *(September 1986)
(d) Maximum separation 90 degrees. Masts prior to 1-25-97 allows an addition 20 degrees.* ( Jan 1997)

ARTICLE VI. SAILS

Section 1. Only mainsail and jib allowed - General requirements. *(May 1972)
(a) Material: Sails shall be of woven material. Stiffening material if used in the head, tack and clew corner must be of the same kind and weight as that used in the body of the sail. (Mainsail headboard, Section 2 (f) is excepted.)
(b) Sails must be dry at the time of measurement.
(c) Transparent window(s) of nonwoven material may be used in the jib and/or mainsail. The max. area of the window(s) must be less than 10 square feet in the jib and 15 square feet in the mainsail.*(Jan 1979)*(24 Jan 1998)
(d) Sail control - all approved sails shall have a serial number inscribed in the box of an emblem stamped on the port clew of each sail. The first two digits of the serial number will be the last two digits of the year in which the sail was built, followed by a dash, then the boat sail number.

Section 2. Mainsail Maximum dimensions. *(17 May 1972)
(a) The mainsail luff and foot shall not be extended beyond the bands on the mast and boom defined in Article IV, Section 1, (g) and Section 2, (e).
(b) The length of the leech shall not be more than 22 feet 8 inches from the topmost forward corner of the headboard to the extreme left corner of the clew excluding the bolt rope. The leech shall be a fair curve over its entire length.
(c)Roach-luff to leech maximum measurements.
(i) Deleted (Nov 04)
(ii) The half sail point 5 feet 10 inches
(iii) The three quarter point 3 feet 5 inches
(d) Battens - The centers of the batten pockets must be located within 3 inches of the corresponding three girth measurement points. Maximum lengths of the batten pockets measured from the leach to the forward edge of the pocket material a re :
(i) Top pocket 25.5 inches
(ii) Center pocket 37.5 inches
(iii) Lower pocket 37.5 inches
Battens shall have a minimum width of 1/2 inch and a maximum width of 2 inches.
(e) The mainsail may have a headboard made of any material. The maximum headboard width when measured perpendicular to bolt rope and immediately aft of it to the intersection point of the headboard and material of the sail shall not exceed 6-3/4 inches. (See drawing.)
(f) The mainsail may have an extra luff and foot grommet for tension adjustment.
(g) A loose footed mainsail is permitted with foot roach not to exceed seven inches. The clew shall be attached to the boom independent of the outhaul *.(30 Jan 93)

Section 3. Jib -maximum dimensions. *(Jan. 1979)
(a) The jib measurement profile shall have sides measuring 188", 92" & 177" (see drawing). The jib and all parts there of (except the foot roach) shall, when laid flat and with sufficient tension applied simultaneously to the three sides to just remove all wrinkles along the edges, fall entirely within the profile. The foot roach shall be measured with the cloth below the lowest horizontal seam laying as flat as possible. It shall not exceed 5 inches. "All Parts thereof" -includes grommets, cringles and leather work edging the corners of the sail. It does not include jib sheets, jib luff wire or thimble at the head of the sail. "The foot roach" is defined as cloth that extends below a straight line between the lower outside edges of the tack and clew grommets. The tack of the jib shall at all times be fastened aft of the forestay and on the center line of the boat. A forestay is obligatory.(Nov 2004).
(b) An adjustable luff is acceptable. *(28 Jan. 1978)
(c) A headboard is not permitted, likewise battens are not permitted .
(d) All jibs built after Aug. 24, 1978 shall be able to be hoisted and lowered without disconnecting forestay .

Section 4. Spinnaker - (optional at fleet level) *(2 Aug. 1967)
(a) Luff 17 feet 6 inches
(b) Foot11 feet (c) Girth . . . . . . . . . . . 12 feet (d) All dimensions are maximum out to out on sail plan. Girth to be measured at a point 8 feet below hoist. (e) Tension during measurement shall be just enough to remove wrinkles. (f) Spinnaker pole to be a maximum of 7 feet. (g) Spinnaker may be hoisted from any point between jib block and jumper, however, it is recommended that the spinnaker block be located at the intersection of the jumpers and mast.
ARTICLE VII. OPTIONALS

Section 1. Rudder post may be such that the tiller is above or below the deck. Section 2. Flotation devices are optional.

ARTICLE VIII. REQUIREMENTS

Section 1. Ballast - no inside or shifting ballast shall be allowed *(24 Jan 1998))
Section 2. An anchor with a minimum of 100 feet of 1/4 inch diameter nylon or dacron line attached, shall be carried. The anchor may not weigh less than 4 pounds not more than 30 pounds *.( 30 Jan. 1993)
Section 3. Each boat shall have a personal floatation device for each person aboard and one USCG throwable buoyant cushion or life ring *.( 25 Jan 1997)
Section 4. One oar or paddle shall be carried.
Section 5. A signal horn or whistle shall be carried by each boat.
Section 6. Each boat shall carry a workable bilge pump or bailing can.
Section 7. No mechanical hiking device, outside of the cockpit will be permitted. Existing stays and spars may be used for hiking but may not be modified in any way for this purpose. *(25 July 1962) * Effective date