--We have a general concensis to revise existing i F 20 rules to meet conditions in N A .
<br>
<br>-specific discussion of min weight rules -
<br>
<br> overview -
<br> -Existing slightly modified iF 20 Euro rules are listed below as revised by Barry for rules discussion reference.
<br>
<br>-Existing rules use a graduated jib and spin sail area with increased crew weight ,-{see table at bottom } ----Basically the heavier the crew the more jib and spin sail area are compensated to them . -They begin at under 300 LB and provide weight catagories and compensations then allow corrector weights to be added for teams close to a higher weight catagory wishing the increase of spin and jib area .
<br>
<br>-Another simple solution proposed is to set a higher min weight {350LB is suggested }-and elininate all the variation and long list of jib and spin sizes and corrector weights , {much easier for measurers } -allowing standard sail areas in main jib and spin for all .-
<br> The problem may be setting too high a min. weight discouraging a large segment from competing , the F-18 s will attract many husband wife type teams of lighter weight ,but this cannot be the determining factor .
<br>--One added solution along with a higher min weight is to allow teams below min.crew weight to carry water weight as part of their corrector to min. consistant with safety and life jacket flotation requirements . One gal. of water weighs 8 LB s.. --
<br>
<br>-Please comment on this min weight concept proposal --
<br>
<br> Existing modified iF rules per Barry listed below only for reference purposes.
<br>
<br>-North American F20 Class Association
<br>Proposed -NA-F20 Class Rules 2002
<br>
<br>NORTH AMERICAN FORMULA 20 CLASS RULES 2002
<br>
<br>
<br>The North American Formula 20 is a restricted class, reserved for sport catamarans, with two crew and of amateur or professional construction and destined for racing on elapsed time.
<br>
<br>A. ADMINISTRATION OF THE RULE
<br>
<br>A.1 AUTHORITY
<br>
<br>The rules of The North American Formula 20 are established under behalf of The North American Formula 20 class association, which publishes the interpretations of The North American Formula 20 and recognizes them as the authorized interpretations and explanations of the rules. The North American Formula 20 class will here on will be referred to as NA-F20
<br>
<br>
<br>A.2. ADMINISTRATION
<br>
<br>The NA-F20 Class Association measurement committee nominates the measurers
<br>
<br>A.3. INTERPRETATION
<br>
<br>After having eventually consulted NA-F20 Measurement Committee, the chief measure shall give an interpretation on all points of the NA-F20. In general, what is not expressly permitted is prohibited.
<br>
<br>A.4. REFERENCE TEXT
<br>
<br>For the interpretation of the rules, the original text in English shall prevail over all translations.
<br>
<br>A.5. SPIRIT OF THE RULE
<br>
<br>In case of doubt, the intention of the rule makers, which is the spirit, shall take precedence over the letter of the rule.
<br>
<br>A.6. DISPENSATION
<br>
<br>For the boats constructed before 1st January 1998 dispensations, limited in duration, may be given by the Formula 20 Measurement Committee after examining the owner’s request.
<br>
<br>
<br>A.7. AMENDMENTS
<br>
<br>The NA-F20 Measurement Committee will propose amendments to the rule if necessary. Amendments shall be placed on one year’s notice unless it is considered essential to act immediately to prohibit or penalize an undesirable feature.
<br>
<br>B. MEASUREMENT RULES GENERAL
<br>
<br>For the construction, only the following materials are authorized: polyester or vinylester resin, glass fibers, sandwich of PVC or balsa or felt, the combination of wood-epoxy, injected plastic, steel, extruded aluminum profiles of constant section, which shall be not altered, other than locally for the fixings and passage of equipment and normal reinforcement.
<br>
<br>Every material that is not expressly permitted is prohibited. Epoxy glue is permitted for joining components. For the trampoline: all types (except netting).
<br>
<br>B.1. PLATFORM
<br>
<br>B.1.1. DIMENSIONS
<br>
<br>The maximum overall length measured on the hulls is 20.08 ft. excluding rudder assembly.
<br>
<br>1.2.1. The maximum overall beam is 8.5 ft.
<br>
<br>B.1.2. MINIMUM WEIGHT
<br>
<br>1.2.1. The minimum weight of the platform is fixed at 308.5 lbs.
<br>
<br>1.2.2. The minimum weight of the boat ready to sail is fixed at 4198. Lbs.
<br>
<br>1.2.3. A corrector weight of maximum 15.5 lbs. may be used to satisfy these two conditions. This corrector weight shall be fixed to the outside of the forward beam on the starboard side and shall be removable for checking.
<br>
<br>B.1.3. DAGGERBOARDS AND RUDDERS
<br>
<br>
<br>The platform shall be equipped with a pair of rudders and, if fitted, a pair of daggerboards or centerboards. The daggerboards or centerboards and rudders may be using epoxy resin. Carbon may be used for the construction of daggerboards, centerboards or rudder blades.
<br>
<br>1.3.1 Minimum weight of rudders:
<br>
<br>The minimum weight of each complete rudder assembly comprising blade, stock and tiller is fixed at 6.6 lbs.
<br>
<br>1.3.2. Maximum weight of daggerboards or centerboards:
<br>
<br>The maximum weight of daggerboards or centerboards is fixed at 15.43 lbs.
<br>
<br>Distribution of the material of daggerboard or centerboard shall be homogeneous. Ballast or mass use of whatever nature is prohibited.
<br>
<br>B.2. RIGGING
<br>
<br>B.2.1.THE MAST
<br>
<br>Carbon may be used for the construction of the mast.
<br>
<br>The perimeter of the mast shall be a maximum of 15.16 in.
<br>
<br>2.1.3. The maximum distance between the top of the forward crossbeam and the bottom of the
<br>upper measurement band of the mainsail shall be 32 ft.
<br>
<br>2.1.4. The maximum distance between the bottom of the mast section and the axis of the point of attachment of the highest standing rigging shall be 20.05 ft.
<br>
<br>2.1.5. The maximum distance between the bottom of the mast section and the point over which the spinnaker can not be hoisted shall be 28.81 ft.
<br>
<br>2.1.6. The mast shall be watertight.
<br>
<br>2.1.7. The mast shall have a profile of constant section
<br>
<br>The Minimum weight of the mast is fixed at 39.68 lbs.
<br>
<br>2.1.9. A corrector weight of maximum 2.2 lbs. may be used to satisfy these conditions. This corrector
<br>weight shall be fixed at the top of the mast and shall be removable for checking.
<br>
<br>B.2.2.THE BOOM
<br>
<br>A loose-footed mainsail is permitted. If used, the boom shall be made of extruded aluminum profile of constant section.
<br>
<br>B.2.3.THE BOWSPRIT
<br>
<br>3.2.1. The bowsprit shall be made of any material. A headsail retrieval system may be used.
<br>
<br>2.3.2. The length shall not be greater than distance, measured in total from its attachment point (on the mast or on the cross beam) to the forward upper theoretical point of the deck, more an additional 31.5 in..
<br>
<br>2.3.3 The bowsprit shall be fixed and approximately on the longitudinal centerline of the boat.
<br>
<br>B.2.4.RIGGING AND EQUIPMENT
<br>
<br>2.4.1.The standing rigging shall be constituted at most with: 2 shrouds, 1 forestay, 1 bridle stay, 1 pair of
<br>diamond with a pair of spreaders, 2 pairs of trapeze wires.
<br>
<br>2.4.2. The standing rigging shall be of conventional stranded steel wire (1x19). Dyform® or similar materials are prohibited.
<br>
<br>2.4.3. It is not permitted to adjust while racing: the rake of the mast, the tension of the standing rigging, the angle or length of the spreaders, the tension of the diamonds other than by one or two turn block’s appropriately blocklable.
<br>
<br>B.3.WEIGHT OF CREW
<br>
<br>B.3.1.MINIMUM WEIGHT OF CREW
<br>
<br>The combined weight of the two crew shall be a minimum of 298 lbs.
<br>
<br>3.2.1.There are three categories of crew weight:
<br>
<br>(i) of 298 lbs. to less than 331lbs.
<br>
<br>(ii) 331 to 364 lbs.
<br>
<br>(iii) above 364 lbs.
<br>
<br>
<br>3.2.2. The crew in the category 298 lbs. to less than 331 lbs. shall carry a weight equal to half of the difference between 331 lbs. and the actual weight of the crew. The weight shall be fixed to the outside of the forward crossbeam on the port side and shall be removable for control.
<br>
<br>B.3.3. CHANGE OF CATEGORY
<br>
<br>The crew in the category of 342 lbs. to less than 364 lbs. may use a corrector weight to compete in the upper category. The weight, equal to half of the difference between 364 and the actual weight of the crew shall be fixed to the outside of the forward crossbeam on the port side and shall be removable for control.
<br>
<br>B.3.4. RESPOSIBILITY OF THE CREW
<br>
<br>The respect of the weight declared is the sole responsibility of the crew, which may be controlled and
<br>protested at any time during the race.
<br>
<br>B.4. THE SAILS
<br>
<br>THE SAIL PLAN
<br>
<br>The sail plan comprises a mainsail, a jib and a spinnaker. The sails shall be made of a material of dacron type, or mylar® or similar and shall fit in a bag of normal dimensions. The ISAF Measurement and Calculation of Sail areas Rules shall apply.
<br>
<br>B.4.1. MAINSAIL
<br>
<br>The mainsail shall have a surface area of maximum 208ft² including the mast. No parts of the sail shall be above a perpendicular passing through the highest point of the halyard.
<br>
<br>B.4.2. JIB
<br>
<br>It shall be possible to roll the jib around the stay. The leech shall not be convex. The head shall be not more than 2 inches wide. There shall not be battens on the foot. Two sail areas of jib are available as a function of the crew weight:
<br>
<br>4.2.1.The crew category of less than 352lbs:
<br>
<br>Maximum jib sail area: 44.82ft²
<br>
<br>4.2.2.Crew categories of more than 364lbs.and crews over 342lbs.changing of category (see B.3.3.):
<br>
<br>Maximum Jib sail Area: 52.27ft²
<br>
<br>
<br>B.4.3. SPINNAKER
<br>
<br>Two sails areas of spinnakers are permitted as a function of crew weight.
<br>
<br>4.3.1. Crew less than 342lbs:
<br>
<br>Maximum surface area for the spinnaker: 249²ft.
<br>
<br>4.3.2. Crews of more than 364lbs.and crews over 342lbs.changing of category (see B.3.3.):
<br>
<br>Maximum surface area for the spinnaker: 270m².
<br>
<br>Battens and stiffening devices, except textile leech lines, are not permitted.
<br>
<br>B.4.4. SUIT OF SAIL AUTHORISED FOR AN EVENT.
<br>
<br>A single suit of sails is authorized for the duration of an event.
<br>
<br>B.5. MARKING
<br>
<br>B.5.1. MARKING OF SAILS.
<br>
<br>All the sails measured shall be marked wit a colored sticker affixed near the clew on the starboard side. The sails corresponding to different weight categories of crew weight shall be identified by following color code:
<br>
<br>Jib Mainsail Spinnaker
<br>
<br>44.82ft² red 208ft² blue 249ft² red
<br>
<br>52.27ft² blue 208ft² blue 270ft² blue
<br>
<br>5.1.2. The maximum permitted area shall be on the colored stickers.
<br>
<br>5.1.3 The actual measured area shall be on the measurement certificate.
<br>
<br>5.1.4.The area and the dimensions of the spinnaker (SL1, SL2, SMG, SF) shall be written in an indelible manner near the starboard tack.
<br>
<br>B.5.2. MARKING OF CORRECTOR WEIGHTS
<br>
<br>The weight defined in B.1.2.1. and B.1.2.2. shall be noted on the measurement certificate. Mention shall be carried near the stern of each hull, on the inward facing sides, under a transparent NA-F20 sticker.
<br>
<br>B.5.3. IDENTIFICATION
<br>
<br>The number of the measurement certificate corresponding with the boat shall be written by the measurer:
<br>
<br>-at the stern of the hull, on the inward facing sides:
<br>
<br>-at the bottom of the mast, starboard side:
<br>
<br>-at the starboard tack of each sail.
<br>
<br>B.5.4. CLASS EMBLEM
<br>
<br>The mainsail shall carry the NA-F20 logo supplied with the measurement certificate. The NA-F 20 logo will be put starboard side within 1m from the clew point.
<br>
<br>C. DEFINITIONS AND MEASUREMENT PROCEDURE
<br>
<br>The method employed for the measurement and calculation of sail area shall be that defined in the Measurement and Calculation of Sail Area of the ISAF.
<br>
<br>The measurements shall be taken and expressed in feet and inches, pounds and ounces.
<br>
<br>c.1. WEIGHT OF THE CREW.
<br>
<br>The controlled crew weight is based on the weight on the weight of the crew in swimming costume.
<br>
<br>c.2. CONTROL OF MINIMUM WEIGHT OF THE BOAT.
<br>
<br>c.2.1. THE PLATFORM:
<br>
<br>2.1.1. This shall be weighed assembled, dry and clean.
<br>
<br>2.1.2. It comprises: the hulls, the crossbeams, the trampoline, the daggerboards or centerboards, the steering system, the mainsheet and jib traveler cars, steering compass, all the equipment normally bolted, screwed or fixed in a permanent manner on the boat and used during racing, the righting system when existing, and eventually the corrector weights specified in (B1.2.3.)
<br>
<br>c.2.2. THE MAST:
<br>
<br>This shall be weighed assembled, dry and clean.
<br>
<br>2.2.2. It comprises: All the equipment normally bolted, screwed or fixed in a permanent manner on
<br>the mast and used during racing, and the diamonds with a pair of spreaders.
<br>
<br>c.2.3. BOAT REDY TO SAIL:
<br>
<br>The minimum weight of the boat ready to sail shall be the assembled platform conforming to rule 2.1. above and carrying the dry and clean equipment normally used for navigation: mast, boom (when exist), bowsprit, mast rigging, halyards, sheets, sails, blocks, except the safety equipment defined by Chapter E rule 2.
<br>
<br>c.3. OVERALL LENGTH OF THE HULLS:
<br>
<br>The overall length of the hulls, outside rudder pintles, corresponds with horizontal distance between the vertical passing through the extremity of the hulls, the boat being leveled on its waterline.
<br>
<br>c.4. SAILS.
<br>
<br>c.4.1. GENERAL
<br>
<br>The intention is to establish a reliable and simple method of measuring the active surface of the entire sail plan, including the mast. In the measurement of sail area, the term sail shall be considered as defining the part of the sail outside the mast and including headboard. Crinkles that are totally outside the edge of the sail or the boltrope that is inside the mast shall not be included.
<br>
<br>c.4.2 MAINSAIL AND JIB:
<br>
<br>The battens shall be without tension in their pockets, the sail shall be pinned on a flat surface with the tension just sufficient to eliminate creases, then smoothed flat to give the longest dimensions.
<br>Whilst the sail remains pinned, all the measurement necessary shall be taken, the tension should not be
<br>adjusted.
<br>
<br>c.4.3. MAST MEASUREMENT.
<br>
<br>The measurement of the perimeter of the mast shall be considered as the distance, at right angles to the mast axis, measured around and back to the same point. The dimension shall be divided by two to give the value for the half-circumference.
<br>
<br>c.4..4. SPINNAKER
<br>
<br>4.4.1. Definition of a spinnaker
<br>
<br>All triangular sails not complying with definition of a mainsail or a jib are spinnakers, on condition that the girth at mid-height is equal or greater than 75% or that of the foot
<br>
<br>4.4.2. Calculation of the spinnaker CSPI:
<br>
<br>CSPI=SF x SL1 +SL2 + (SMG- SF) x2 (SL1 + SL2)
<br>
<br>4 2 3 2 Where SMG > 75 % of SF.
<br>
<br>Where SF is the length of the foot measured around the edge of the sail between the lowest point of
<br>the luff and the leech:
<br>
<br>Where SL1 is the length of the luff of the sail, from the highest point of the sail, to the lowest point of
<br>the sail on the luff:
<br>
<br>Where SL2 is the length of the leech of the sail measured along the edge of the sail, from the highest
<br>point of the sail, to the lowest point of the sail on the leech.
<br>
<br>Where SMG is the width at mid-height, which shall be taken between the mid point of the luff and
<br>the mid point of the leech.
<br>
<br>CONTROLS.
<br>
<br>d.1. MEASUREMENT FORM AND MEASUREMENT CERTIFICATE
<br>
<br>d.1.1. COMPETENCE
<br>
<br>Only the controls, measurements and calculations by a measurer recognized by the NA-F20 Catamaran Association, a National authority or the ISAF ( Multihull Committee) are considered valid.
<br>
<br>d.1.2. MEASUREMENT FORM AND MEASUREMENT CERTIFICATE
<br>
<br>The measurement form competed (measurement sheet and calculation) and signed by a measurer is not a
<br>measurement certificate.
<br>
<br>1.2.2. The measurer shall record on the measurement form anything he considers as departing from the
<br>concept of the NA-F20 rule, he shall send it with detailed explanations on the contentious points to the NA-F20 Catamaran Association for a ruling.
<br>
<br>1.2.3. The measurement certificate is issued by the NA-F20 class association responsible for the administration of the rule in the country of the owner. When after examining the completed measurement form signed by the measurer, it considers that the boat conforms to the Rules off the NA-F20.
<br>
<br>1.2.4. A competitor has an obligation to present with his entry the measurement certificate and measurement form of his boat.
<br>
<br>d.1.3. REGISTRATION
<br>
<br>The measurement form (measurement sheets and calculations) and the measurement certificate are
<br>established and registered by the NA-F20 Catamaran Association or a National Authority.
<br>
<br>d.1.4. VALIDITY
<br>
<br>A change of ownership shall be invalidate a measurement certificate, a re-registration shall be made by
<br>returning to the national authority the initial measurement certificate accompanied by the details if the new owner. The valid certificate and registration will be returned to the new owner, it is not necessary to re-measure the boat.
<br>
<br>All modifications or replacements of parts of a significant change shall be re measured and notification made on the measurement certificate by a measure recognized by the NA-F20 Catamaran Association.
<br>
<br>d.1.5. COST OF THE MEASUREMENT
<br>
<br>1.5.1.INITIAL MEASUREMENT:
<br>
<br>The cost of measurement is at the discretion of the relevant National Authority corresponding with the provision of the class emblem, the marking stickers for the sail, the hulls, the mast and the establishment and registration of the measurement certificate.
<br>
<br>1.5.2. The cost of additional measurement, marking and registration is fixed at the discretion of the National Authority.
<br>
<br>1.5.3. The other (travel and accommodation of the measurer) are at the owner’s expense.
<br>
<br>D.2. EVENT MEASUREMENT.
<br>
<br>The travelling and accommodation expense of the measurer are the responsibility of the event organizer.
<br>
<br>It is sole responsibility of the competitor in a race to maintain his boat in accordance with its certificate.
<br>
<br>SAFETY
<br>
<br>E.1.RIGHTING
<br>
<br>The crew shall be able to demonstrate their capability to re-right the boat.
<br>
<br>E.2. SAFETY EQUIPMENT
<br>
<br>Minimum mandatory equipment to be on board;
<br>
<br>1 re-righting line 13 feet long an 10mm of diameter minimum, 2 lifejackets (conforming to the rules in force.)
<br>
<br>E.3. BALLAST AND WEIGHT JACKETS
<br>
<br>Ballast on the boat or worn by crew is prohibited.
<br>
<br>E.4. STEERING COMPASS
<br>
<br>A fixed steering compass may be used
<br>
<br>E.5. COMPLIMENTARY ARRANGEMENTS
<br>
<br>REDUCTION OF SAIL AREA
<br>
<br>If specified in the Notice of Race, the organizers may require the following complementary equipment:
<br>Jib mounted on a roller. Mainsail equipped with reefing points not less than 39.4 in from the foot.
<br>
<br>WEIGHT CHART NORTH AMERICAN FORMULA 20 CLASS
<br>
<br>NOTE: CREW WEIGHT IS THE COMBINED WEIGHT OF BOTH PERSONS SAILING THE NAF-20 AT ANY GIVEN EVENT.
<br>
<br>CREW WEIGHT IN LBS JIB SQFT SPINNAKER SQFT ADDED WEIGHT
<br>
<br>297lbs. 44.82ft² 254ft² 16lbs
<br>
<br>300lbs. 44.82ft² 254ft² 15lbs
<br>
<br>301lbs 44.82ft² 254ft² 14lbs
<br>
<br>304lbs 44.82ft² 254ft² 13lbs
<br>
<br>306lbs 44.82ft² 254ft² 12lbs
<br>
<br>308lbs 44.82ft² 254ft² 11lbs
<br>
<br>310lbs 44.82ft² 254ft² 10lbs
<br>
<br>312lbs 44.82ft² 254ft² 9lbs
<br>
<br>314lbs 44.82ft² 254ft² 8lbs
<br>
<br>316lbs 44.82ft² 254ft² 7lbs
<br>
<br>319lbs 44.82ft² 254ft² 6lbs
<br>
<br>321lbs 44.82ft² 254ft² 4lbs
<br>
<br>323lbs 44.82ft² 254ft² 3lbs
<br>
<br>325lbs 44.82ft² 1254ft² 2lbs
<br>
<br>328lbs 44.82ft² 254ft² 1lbs
<br>
<br>330lbs 44.82ft² 254ft² 0.0lbs
<br>
<br>332lbs 44.82ft² 254ft² 0.0lbs
<br>
<br>334lbs 44.82ft² 254ft² 0.0lbs
<br>
<br>336lbs 44.82ft² 254ft² 0.0lbs
<br>
<br>339lbs 44.82ft² 254ft² 0.0lbs
<br>
<br>
<br>341lbs 52.27ft² 270ft² 11lbs
<br>
<br>343lbs 52.27ft² 270ft² 10lbs
<br>
<br>345lbs 52.27ft² 270ft² 9lbs
<br>
<br>347lbs 52.27ft² 270ft² 8lbs
<br>
<br>350lbs 52.27ft² 270ft² 7lbs
<br>
<br>352lbs 52.27ft² 270ft² 6lbs
<br>
<br>354lbs 52.27ft² 270ft² 4lbs
<br>
<br>356lbs 52.27ft² 270ft² 3lbs
<br>
<br>358lbs 52.27ft² 270ft² 2lbs
<br>
<br>360lbs 52.27ft² 270ft² 1lbs
<br>
<br>363lbs 52.27ft² 270ft² 0lbs
<br>
<br>SAILORS ARE RESPONSABLE FOR TAKING THEIR OWN ADDED WEIGHT, WHICH MAY BE CONTROLLED AND PROTESTED AT ANY TIME DURING A RACE.
<br>
<br><br><br>

Sorry Carl, I hadn't seen this post untill you mentionned it in a later post.
<br>
<br>To make things clear, crew weight is the weight of the participants in plain swimwear, and does not include any gear worn.
<br>
<br>I very much like the idea of a sail area to crew weight relation.
<br>Even better and fairer an overall weight to sail area relation.
<br>For this reason it is pointless to set a high minimum weight for either.
<br>We need to ask experienced designers/builders who have experimented with mathematical models giving us a realistic relation between power(sail area) and weight.
<br>
<br>Otherwise we could do it ourselves.
<br>
<br>The relation is probably not linear but will still produce a smooth curve on a graph. We know it must pass through (0,0) ;-) and any curve can be estimated accurately with some polynomial equation.
<br>Before everyone starts jumping at the complexity of this idea, this equation would be to set the sail area to weight scale in incriments of 30(?) pounds such that we could set up 3 or 4 weight:sail area groups. (I am better at doing this than writing about it ;-) )
<br>I'll have a closer look at the data on various boats already entered and maybe I can come up with something in a few days.
<br>
<br>For now my vote is for a crew weight minimum of 300 pounds and since I tend to favor an overall weight to sail area system, a boat weight minimun of 375 pounds for a total minimum of 675#s.
<br>
<br>I want this class to be as exciting to watch as the Aussi 18 foot skiff racing they used to show on Speed Vision .
<br>
<br>light & fast ... more power for the big guys.
<br>
<br>Marc<br><br>

Carl,
<br>
<br>We have talked about this before. You know my opinion and the direction that marketing would take.
<br>
<br>I can not endorse a graduated sailplan or a crew weight minimum below 350.
<br>
<br>If I present this scheme then kiss sponsor dollars good bye.
<br>
<br>It is too complex, concieved as unfair by the general public and trys to jam too many people into one niche market.
<br>
<br>Boat weight for the current should not go below 390 min.
<br>
<br>Steve<br><br>

There are two formalas that already exist that very accurately predict the relationship between total boat weight and sail area, they are the ISAF handicap formula and the Texel formula, they both come up with similar results although the actual numbers allocated are about 1% different. You can find links to them on the formula 16 hp website so you can download them, put in whatever figures you propose and they will predict performance very well.
<br>
<br>I ran the weight to sail area figures that you propose through the ISAF spreadsheet and here are the results
<br>
<br>your 420lb boat hcap figure .903
<br>your 390 lb boat hcap figure .908
<br>your 370 lb boat hcap figure .913
<br>your 320 lb boat hcap figure .925
<br>
<br>as you can see if you implement this rule the heavier the boat the faster it will go.
<br>
<br>You say you want faster boats with bigger sails, but increasing sail area without increasing righting moment will slow the boat down.
<br>
<br>In Europe the Inter 20 has smaller sails than in US, yet this boat is overpowered, above 9 knots of wind both crew are trapped out and the downhaul starts to be used (upwind),
<br> I sailed with my Tornado crew on one we weigh 350lbs and are 6 ft and 6ft 2.
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<br>In order to make the boat as fast as possible across the wind range the sailmaker had made a very flat mainsail. So the boat was compromised in light airs in order to help in strong winds, above about 12 knots of wind the boat would have been quicker with smaller sails since we were downhauling and trying to remove effective area from the top, and so the sail not being used is just drag.
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<br>Obviously downwind you can carry as much sail as you like, but the shape of the eu boats main is too flat and you could produce more power from a smaller, fuller sail.
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<br>Now you already have bigger sails than I am talking about and you want to go bigger still. I don't believe that you will make the boats faster this way.
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<br>Its simply this in any wind above about 9 knots the speed upwind of the boat is directly proportional to its righting moment, this is why in Eu the f18s quite happily sail to the same speed as the 20s, they are the same width have the same size crews, the boats weigh the same, ergo they have the same righting moment and can only hold up the same amount of power.
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<br>If you want these boats to be loads faster than the f18s, you must improve on the ratios of power to drag that they have, the drag factor is weght, the power factors are, length (you already have this one but its not that big), width and sail area, BUT YOU CAN'T increase sail area without increasing beam.
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<br>To summarise you will only get these boats faster if you either decrease weight and keep the sails the same, or if you increase sails and beam.
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<br>I am only talking about main and jib here becuse upwind accounts for about 2/3rds of a race and the all important first leg.
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<br>You could just increase spinnaker area but this will not make much difference to the speed round a race course.
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<br>Why not build your class around the inter 20 it appears to be the popular boat and it would be simple to produce a rule that will allow lighter boats and heavier boats to carry sails that will produce very equal performace to the inter.
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-Thanks again John , appreciate the racing experiences and rating info .
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<br> your correct on basing sail area to weight on the I-20 or even new Tornado w spin ,-
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<br> We need a simple proven relationship formula of sail area to weight , in the 20 ft L -8,5 BEAM CAT CATAGORY , -
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<br> What would be an accurate fair scale of sail area ,-main jib and spin progressively to boat weight , --
<br> All I have are older reference books like {Elements of Yacht Design } that may be dated and refer mainly to monos ,
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<br> -Can you propose one , or a basic sail area to boat weight formula we can apply based on current cat data.
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<br> Understand righting moment and other factors in the total , but we can address these with crew weight seperately .
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<br>-greatly appreciated -
<br> Carl
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Thanks Marc ,
<br> All catsailors appreciate the efforts and valuable information provided .
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<br> Reallize the scale may not equate evenly through a wide range of boat weights and sail areas , and will vary greatly in each wind strength , -we would have to establish a good average . ----weight to sail area formula , -or proposed scale ,but believe 10 lb increments from 420 existing cats down to potentially new 320 lb cats may cover completely the range into the future .
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<br>-Would also like to see an exciting fast class evolve , like the skiffs .
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<br> Carl<br><br>

Carl
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<br>You must also take into account luff length for mainsails and jibs, a 200 sq ft mainsail with a 30 ft luff will be lots quicker than a 200sq ft mainsail with 22ft luff
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<br>As I said before use the ISAF spreadsheet, give me your email address and I will send it to you<br><br>

Hi John,
<br>I guess I wasn't clear.
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<br>The 30 pound increment was meant for a crew + boat weight.
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<br>Although building for 320 pounds all up is very possible, it is not what I had in mind.
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<br>My minimum weight suggestions where 375 for the boat and 300 for crew for a total of 675 pounds. From there we can set a different sailarea for each additionnal 30 pounds.
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<br>group 1 - 675 pounds SA 240 (this would be similar to the old Tornado)
<br>group 2 - 705 pounds SA ???
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<br>group 3 - 735 pounds SA ???
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<br>group 4 - 765 pounds and over SA ???
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<br>Notice groupe 3 is pretty well what Steve is suggesting as his min weight suggestion (boat 390 + crew 350 = 740 ).
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<br>example: class 3 could define a 440 pound boat with a 310 pound crew(+/-15#) just as it would define a 400 pound boat with a 350 pound crew(+/-15#).
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<br>This type of system would make it very easy to amalgamate *most* existing ~20 foot cats in NA F20.
<br>*I say most because I am not sure what to do about the wide beam boats.
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<br>John, if you have time, can you run these numbers through the ISAF spreadsheet and see what it may suggest as a sail area for each group.
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<br>As in iF20 the sailarea difference would only be added to the jib and spi. This is fairly simple.
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<br>fair play all around
<br>Marc
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Marc
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<br>I guess I finally get what your saying here. I think we might be able to "group" like Formula GT does in motor racing where you race each other head to head but class out by group?
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<br>Steve<br><br>

First to finish wins !
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Marc
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<br>The only problemo there is that you place the additional sa in the jib and spin. Giving light teams a definite advantage up wind. If there was a way to adjust the total sa then MAYBE this might be fair. THe mainsail is the only sail that can really drive a boat on all points of sail. Additionally, I still feel that the bottom end is too low as our target market is not the H16 crowd. I feel that the class crew weight minimum should be no lower than 325 even applying this formula. The hobie 20' 295 minimum has always been a marketing issue and I feel it is grossly irresponsible of Hobie to allow it. Remember I sail a H20 and I'm saying this.
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<br>Steve<br><br>

Is the mast height carved in stone? If not there are several SC20s out there that could be easily modified without having to buy a new mast or cut off the original 33' mast by one foot. The beams could be drilled to 8.5' and still expand out to the original 12'. Just a thought...
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<br>thom
<br>ARC22 #2234
<br>FMS SC20 #57<br><br>

-new F-18 N A web site has been up a few days -- http://www.angelfire.com/mi4/naf_18/
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<br>The socialogical aspects as Mark S brought up , potential sponsors and racing as majsteve knows are there potentially for us , ALL THE ENTHUSIASTIC RACING SAILORS AND EXCELLENT BOAT BUILDERS , ---and THEN the opposition,--the terrible confused existing set of conditions we are attempting to address , combined with mfg. Class division that continues , along with the general decline of the sport , dead boat classes ,-open racing alternatives . –How do we revive the sport and encourage a new active racing 20 class to emerge in respect to existing cat designs and newly formed Formula 18 and 16 Classes in N A .
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<br>-Should we attempt to lobby Hobie Europe to meet Inter –20 specifications to equalize their actual speeds and set up a similar set of rules , basically a Formula Class for larger people , --what percentage of sailors are left for this class .
<br>-This would be simple to set up , if H were to agree , but is it needed or wanted , Total performance and ratings indicate that the 16 and 18 classes will actually be faster within a wind range and given set of conditions. I have already found this to be true on the race course.
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<br>-Should we attempt to address these problems as well and go the direction of a developemental class to solve these problems allowing a jump in total performance to the 20 class requireing more sail area , more beam , and less weight be allowed to develop within a class rules structure .
<br>-It may be one logical way to proceed
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<br> In attempting to establish a weight to sail area average performance scale we have several factors that are not calculated exactly in ISAF -TEXEL OR that need exact definition, -rating systems rate all boats to an av crew weight and av conditions through a much broader range ,--we only need to compare and attempt to rate 20 ft. class cats equally using the two other main variables of weight and sail area.
<br>--The ISAF uses a standard assumed crew weight, and believe Texel uses 75kg av. on all ratings. We of course actually have various crew weights, mostly larger on the 20s.
<br>-We have wind strength variables {beaufort scale} and the effects of righting moment which varies in each wind category, and crew weight, from it being a non factor in below 6 to 8 mph winds, except in relation to sail area to drag --{light air sailing}-
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<br> We have the various effects on total performance of the sail areas separately of main -jib -and spin through the ratio.
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<br>-We have L AND B as a set standard for the 20 class –should we reconsider total beam and allow wider cats like the Tornado in the class ,-or go beyond and allow racks to be added to increase total performance r
<br> How to formulate an accurate fair weight to sail area scale that factors or ideally requires larger crew weight, wind strength, righting moment, with defined sail areas and their effects individually in relation to weight and total performance factors through this range.
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<br>-There are performance ratings of ISAF and Texel, --there are more precised individual boat performance prediction programs used by designers, but none describe in exact terms an average number applied to relate sail area to weight as described above, such a number is at best an estimate or average, -inaccurate at the extremes of design or wind strength parameters.
<br> There are no existing classes or historically that have a rating based on sail area to weight only that can be applied to cats. -We have a Portsmouth system of rating providing average performance of existing cats that may give us insight, and the basic experiences of racing numerous similar cats in open competition.
<br>We have specifications of existing cats that we wish to include as a basic guideline.
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<br>-ISAF ratings indicate existing heavier cats with proportionately larger sail plans than newer lightweight cats with smaller sail plans currently as proposed rate faster indicating a bias towards the older heavier cats within the scale, and should be refined to some extent. --Again ISAF does not include heavier crew weight or it's added righting moment. -I believe individual boat performance predictions through the range of wind strengths would show a performance curve overlapping between light and heavy air sailing, favoring the lighter cat designs with smaller sail areas and equal crew righting moment as the wind increased, -contrary in this upper wind range to ratings.
<br> Additionally options of furling jibs are reefing mainsails are within existing rules instantly changing all rating equations and rating numbers .-Many other intangables also come into play when racing –actual conditions , waves current and effects, -and all the human elements of racing.
<br>--Should we attempt to propose a 20 ft –larger beam with added racks -weight to sail area racing class, when no one else has, what are the benefits.
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<br>-A large existing number of potential active racing 20s that according to ratings would be and remain very competitive for many years, unlike the new Formula classes that seem to be comprised of only new 418 LB iF boats. -
<br> All existing 8.5 B 20s can race as they are or modify as they choose.
<br> A younger sailor could refinish any existing 20 or 20 platform at reasonable cost and race this class. -
<br>-New development can occur within the class allowing new lightweight designs and innovation, geared towards less but more efficient sail areas in relation to existing but modified cats, and lighter safer faster sailing cat designs.
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<br>-Can existing iF CLASS racing fall within this weight to sail area formula as they are proposed, yes -
<br> Could this weight to sail area be applied to other length categories and keep existing if class racing within, -yes.
<br> Could this concept be applied to all spin length categories if found preferable by the majority of racing sailors ---yes -
<br> Could these 3 length spin classes 16 18 and 20 easily relate to each other and race together,-- yes. –
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<br>-We can formulate a sail area to weight ratio rule , we have a niche in the Formula classes for heavier crews , required for the added moment needed on these larger sail area more powerfull cats .
<br> Should larger beam cats be allowed , then coresponding racks be allowed ?
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<br> Currently this is as far as thinking takes me , certainly do not have all the answers ,-
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<br> Carl
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<br> Marc -your currently building 20s and have optional racks ,-
<br> can you provide costs , attachment , basic design , and performance increase est .
<br> THANKS <br><br>