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.
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<br>I ran the weight to sail area figures that you propose through the ISAF spreadsheet and here are the results
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<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
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<br>as you can see if you implement this rule the heavier the boat the faster it will go.
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<br>You say you want faster boats with bigger sails, but increasing sail area without increasing righting moment will slow the boat down.
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<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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