A 230lbs person will NEVER be competitive in a class that has NO minimum crew weight rule. (F16)
Ask the F16 2007 global champion about this !
He is about the same length and weight as "Brokenships"; he did use a mainsail that was optimized for his weight and sailing style by Landenberger as the F16 class rules allow; a great equalizing ability of the F16 class rules.
And yes it was a big wind regatta that year (>20 knots winds) with short steep waves and the F16 fleet was combined doublehanded and singlehanded sailing. Against all predictions (by not F16 sailing people) ; a singlehanded F16 skipper won this event. He came close to repeating this feature in 2008.
Just to be clear about this aspect. Reality has shown different results than what some (entrenched) believes dictate.
Additionally, a singlehanded sailor will indeed NEVER be competitive in a doublehanded class that doesn't allow singlehanded use of the boat (I-20, F18). He will simply get protested out in any serious event. Same for a 1-up boat used in a 2-up manner (F17, A-cat). With respect to not having minimum weights I think the F17, A's and F16 are practically the same. The latter two not having any minimum crew weight regulations and the first only having a switch over weight from where onward you may use a larger spinnaker. Having a minimum weight on a modern singelhander like the F17, A's and F16's is pretty silly really; there is simply not that much performance difference between different skipper weights and the dependency over the range of weights is like a flat dome. The latter meaning that being to0 light is the same as being too heavy, you'll loose some performance to the mid range guys. Therefor the concept is fully selfregulating and no need for a minimum weight rule is encountered. Due to the ability to have you own optimized sails this range appears to be very wide in both the A-class and F16 class; think roughtly 60 to 100 kg (130-220 lbs). The spinnaker adding additional performance equalizing by shifting the downwind legs performance more to skills then ideal specs.
I think the other suggestions are all good (I-20, F18, F17, F16, A's) and brokenships will have an excellent boat in all of them. The right choice however being dictated by his expected use, local conditions and local fleets. Where the F16's main argument is the versatility (both 1-up and 2-up sailing are officially regulated and sanctioned) and ease of use and handling without sacrifizing any performance compared to the F18, F17 and A's. F17's having bigger and better fleets up north and the F18 being the best choice for 2-up racing, A's being the preferred choice for very competive 1-up fleets in USA and the I-20 being the preferred 2-up boat for his weight and for real distance racing.
A challenging choice when looking to find all desires met in one single boat !
Wouter