The stand out choice was to reduce bulb weight.
Calculations on stability indicated a required bulb weight of 1.3kg. This weight is impractical; it would make the boat prone to stalling when tacking in waves. Guessing at 2.1 kg, an IOM class bulb was adapted for the purpose. The test hull, though based on the Nexus lines, was scaled to take into account the decreased displacement.

To approach the problem laterally, we break it down to its natural components. The sail force is applied above the water and it forms a couple with its underwater opposite. Sailing craft performance is directly related to the ability to provide an opposing couple with minimum penalty (energy redirection).
Multihulls use the leverage afforded by massive beam. Skiffs use crew weight on trapeze. Windsurfers use body and rig weight. Open 60's use some combination of the above in addition to water ballast or a canting keel (some have experimented with canting rigs albeit using cantilever of the heel. The class promptly banned canting rigs). Conventional yachts must use heel.
M class r-c yachts are symmetrical and hence restricted to form and mass stability derived through heel.

To form a couple some distance must displace the forces of gravity (at CG) and buoyancy (at CB). Heel reduces the efficiency of keel and sails.
Within this restriction boats have been refined to exquisite levels, but they must face the above limitations. Trading displacement for beam does not result in a net gain due to the scale. Furthermore, since the class rules restrict sail area, the ratio of wetted area to sail area would increase prohibitively.

Varying geometry means the necessary moment can exist before heel. It also means that the boats equilibrium will not be the upright position. Stability will increase in a different manner with applied heeling moment.
Canting keels have been proven in open60 and 50 class yachts. They offer a marginal advantage in some conditions to those classes albeit with some drawbacks. Canting keels are prohibited in the M class rules but could be included once their merits are proven. Providing lateral resistance would require an additional appendage.

The chosen mechanical solution was to pivot the rig at the hull, sweeping it bodily to windward within a watertight 'well'. This maximizes the stability effect desired. It also presents the sails to undisturbed wind. Options considered for mast control included rack and pinion type mechanical arrangements, cogs, miniature hydraulics and chain-drives. All the above options were discarded on account of parasitic weight. A 3:1 purchase with a standard winch drum and continuos loop was selected. This purchase system also moved the sheet lead ring with cant."

Looking back now, it is clear that the concept had merit but the practical issues to resolve are significant. The principal technical requirement is finding a solution to address the change in helm balance with mast cant. This was anticipated on the experimental boats and addressed by positioning the mast further aft than would otherwise have been called for. A more comprehensive solution was found to be required since the reduced 'lead' made tacking difficult. Perhaps varying rake with cant or shifting the CLR with adjustable foils would address the problem. From the point of view of the skipper, managing mast cant is an additional challenge but the performance gains may justify the effort. It remains to be seen whether the new class rules, with their modified wording specifically addressing the trail blazed by Pi, would still sanction such a configuration. This is a path that demands a renewed foray when the opportunity arises.

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Ajax 1, Design MDV08

Ajax Mk1 incorporated the lessons from Nexus etc. The general look of the boat was more angular, with sharp gunwales and a different deck patch geometry. Cerberus (Design MDV06-05) marked the culmination of the Nexus family of hull shapes. It is worth noting that with Cerberus we reached a turning point as it marked the beginning of the move toward fuller forebodies. This trend was followed by boats such as the 2006 Waliki Skalpel and the V5 IACC fleet. Our move was rooted in a better understanding of wave interference in displacement hulls. The effects of the study on 'blunt' bows were interesting and surprisingly far-reaching.

Cheron (Design MDV06-11) drew from these lessons, attempting to tie in the positive dynamic effects with a longer wavetrain. Comparison with internationally proven boats went something like this: whilst beam was still on the narrow side (15mm wider than Cerberus on deck, BMAX at about 60% LOA), hull proportions were more conservative than Bantock's Rock. His wide stern, heavy displacement and powerful hull point to a boat where the compromise is shifted more toward blasting out of the tacks, powering through in waves and being able to foot well. The Berlioz, with a dished hull and large section rigs, shows impressive top speeds on the reaches but seems to struggle upwind when pressed and on all points of sail in light airs.

The Skalpels are the most similar to Ajax Mk1 in concept (with a notable difference being the extra forward beam at deck level, necessary to provide an adequate shroud base) but are more critical on the run. Ajax Mk1 likes to sail with a bit more heel, winding up tight and high. Sydney offers a wide cross-section of weather conditions, so a bias toward stronger breezes (e.g. Nordic boats) or toward the light stuff (e.g. US and Italy) really shows over a season.

Results of experiments with sharp gunwale profiles led to the abandonment of the radical moulding technique perfected for Nexus.
The trade-off here is between windage to windward and separation of the water flow to leeward. Once again we are reminded that wetted area is everything on these little boats. Short of a peaked foredeck, sharp gunwales are the most effective compromise solution.

As far as hull geometry is concerned, centres gradually moved forward, prismatic moved toward the higher range and draft was reduced slightly from the rule maximum. The whole package was parred down, eliminating fittings and reducing the total number of parts in the perennial battle with weight. The emphasis on simplicity lowered costs as a side benefit.

There were also simpler and lighter swing rigs. They used Walicki spars spliced into cantilevered 12 and 14 mm tube just above the boom/yard junction. Each spar was 'tied' together at four points using carbon tow to give the largely unidirectional tubes better 'hoop' strength.

With new carbon booms, the rigs were incredibly light and mainsail leech control had improved. Nexus had successfully married a stayed rotating wing with a swing-rig. Compression adjustment had allowed the rigs to 'fall off' in light air and ‘fall forward’ on the run.

The new masts were not over-rotating, but the aerodynamics were still acceptable and still superior to a round tube. Beyond the weight saving and simplicity, the main improvement was in gust response. Instead of having a tendency to invert (as they did with the pivot point on the leading edge), now the spars bent athwartships, spilling the leech of the main and flattening the sails when necessary.

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Ajax 2, Design MDV09

Ajax 2 was an all new production standard design that aimed to be competitive across all conditions. This meant a careful compromise between wetted area and wave drag with painstaking treatment of the transition from entry, through midsection, to stern. The fin and LCB were placed fairly centrally though slightly further forward than most contemporary designs. Foil sections were highly optimised and foil areas were based on the results of a long evolution.

Crosspollination with the IOM class had taught us precision. This was reflected in the deck layout and adjustment modes. ‘Bowsies’ were completely eliminated in favour of 'hooks and holes' adjustors and turnbuckles.

The winch could be ordered through-deck or below deck according to owner preference. The deck detailing included the option of sophisticated soft ‘padeyes’ for standing rigging and an elegant moulded solution for the sheet lead to the winch when this was mounted below deck.

Since the deck was flat and sat within the sheerline, it made sense to use foam-sandwich in its construction. The top skin was carbon. We used Corecell in the middle because it has the right compromise of density, rigidity and resilience. Nomex was considered but with so little deck area (large lightning and access holes were standard) the advantages would have been utterly marginal compared to the cost. The lower deck skin was of very thin S-glass scrim.

With the deck assuring rigidity, the hull consisted of a layer of 120g/m^2 carbon cloth and an internal glass scrim for resilience/watertightness. Paul Armstrong invested heavily in the plug and female mould. The time and effort he poured into fairing are immediately visible in every Ajax 2 hull. The centreboard lived in a carbon case glued through the hull and through the lower deck skin.

The rudder tube was supported in the hull and deck with an intermediate section cut out of it so the tiller could capture the shaft. The fin had a foam-core that tapered to almost nothing toward the thin tip. The rudder used a lower density core and a carbon shaft.

Perhaps the single most distinctive feature of this design was the use of conventional shroudless rigs for all suits with the exception of A-rig.

Overall Ajax 2 has proven fast, reliable and rugged. The design represents the culmination of a long evolution that is now taking another new turn with Octave.

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