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= < oeid - 28 Recommended Maximum Price TWO SHILLINGS AND SIXPENCE S.A. & CANADA SIXTY CENTS HOBBY MAGAZINE MODEL BOATS HARE : F @ = 8 -— | { —S has a 10 inch beam and 20 pound displacement, but q YD ry has been well tried and does not appear to have any disadvantages in any conditions. Its exceptional abilities are that it points high on the wind, planes — both early and fast downwind, and planes on the reach even when it is quite close. Although its poten- / tial is good enough for competition, there are a few | 5 | : \ ratio which results from the construction. Daredevil ; { ) slightly better stability owing to the improved ballast ; : Fa from Daredevil, on which this is based. March Hare : eae = than that of White Rabbit in redetailing an existing boat for glassfibre construction. No experimental ideas were involved in the design of the latter, but in this design there are features which differ basically Ux dL \ THE design of March Hare goes a little bit further Le —— The second of Roger Stollery’s trio of top-class Marbleheads = a mance vate ; : points on which it could be improved. Planing on the reach adds a new dimension to this eg course of sailing and changes the whole concept of — | eee ; Marblehead design. When Daredevil was designed, this was thought of only as a side advantage of features that were primarily intended to improve performance in the other wind conditions, However that boat showed that on this point of a sailing, planing is such a regular occurrence that one can no longer think of the Marblehead as a displacement concept, but more as a planing machine. The stern of Daredevil is not as good as it could be, as part of a planing shape, because the transom is not powerful enough to flatten the stern wave and make it form further aft. Therefore on March Hare the transom is more powerful and the hull is shallower, producing a shape at the stern that is flatter and more suitable for planing. It also has the advantage that it helps to damp pitching in rough water by increasing the difference between the ends. Although Daredevil is able to get through a chop reasonably well because of its fine waterlines, the flare forward does not help the boat’s action, particularly when heeled. This is also a problem downwind, when it can be just as important to drive through the waves as when going to weather. This is noticeable on lakes such as Hove Lagoon, which suffers more than other concrete lakes from a very confused wave pattern, set up by the edges and the shallow bottom. The flare on March Hare is reduced as much as possible so that the bow is fine both at the waterline and above it. By sharpening up the bow and enlarging the stern one is creating the same balance situation that was explained in the White Rabbit article. This reference to balance should really be qualified as hull balance because it is only a very small factor in the overall balance of the boat. The designer only helps to make the boat easy to balance, by ensuring that, when the boat is heeled, any tendency to wander off course is 110 _ OM BF NG S' MARCH + line of maurum —s Ln — ze OALBEAM 12" DSPLACEMENT 2018 BUTTOCK & WATERLINE SPACINGT iia ied a i i rae ee en 35 : +s Arg ip VD Ad oe | : ! s 3rd suit ee | yee | —_ | 736 e a =S S — 1968 reduced as much as possible. Whether a boat is balanced at any time depends on how the skipper arranges all the forces acting on the boat. The hull balance of March Hare is achieved, exactly in the same way as for White Rabbit, by reducing the immersed volume at the stern by the use of heavy tumblehome. This has the effect of helping the boat to sit well down in the water when it heels; this appears to be important because it maintains the length of the boat in the water and prevents it being lifted out and tossed around by the waves. The rigs shown are similar to those used on the original March Hare last season with the exception of the gaff rig, which was added after that particular rig had proved useful on Mad Hatter. This type of rig will be discussed in the article on that boat, but basically this rig provides better planing potential in reaching conditions. Reaching is a course of sailing that is neglected, but it is surprising how many races are sailed in these conditions. One puts up a special sail for going downwind, so why not use a special rig for reaching? Actually the reach is a good test of the character of a boat; it is the only real com- parison of resistance to drive ratios at high speeds, since downwind things are confused by the addition of the spinnaker. In analysing ideal rigs in different wind conditions there seemed to be an advantage in using just a mainsail in very light airs. The “una” rig has the rae eas a advantage that it is capable of working efficiently at closer angle to the wind than the two-sail combination, which makes it useful in light weather when this ability is most important. A more obvious (Continued on page 113) ape Fes xy* MARCH Tritone, two channels only being used for steering. A Mighty Midget drives, through a worm fitted to its countershaft, an old clock wheel spring-held on the rudder stock. The spring allows the motor to drive past the normal limit stops, the rudder being physically checked at 45 deg. each way. Thus the steering motor cannot be stalled, but starts to move the rudder back as soon as the appropriate key is pressed, Overall gearing is such that full left to full right takes about 3 seconds, which is a reasonable cycle enabling all the intermediate positions to be easily found. According to the prototype the deck should be canvas covered, but I preferred the idea of planking and used } in. wide spruce for the actual planks. All other woodwork on deck is mahogany, both woods left natural colour and polished, to give a nice 1968 the photos; I like the inside to be easily reached but I don’t like the boat looking naked when being serviced, so detachable parts are kept as small as is practical. Double glazing is used, by the way, to protect the curtains—however carefully an exhaust is fitted, some oil is usually thrown off the flywheel and can soon make small fittings look tatty. contrast. Most of the deck fittings are from odd pieces of brass; windows are framed with spruce inside and + X gy in. brass outside, ordinary pins being recessed into countersinks to represent screws. To reduce the size of the carrying case, the mast is made to fold back in its tabernacle. Those parts which detach for access are clear from (Continued from page 111) not only in light conditions, but in higher wind strengths. Experiments in these conditions using the mainsail of a smaller suit in the forward mast position were most interesting; there was a marked improvement in pointing and speed to weather, even ward, not only in a chop but in flat water too. At first it was not certain what the effect of the broad transom and the coarse waterlines would be on the light weather performance, but in practice it has shown in no way detrimental in these conditions. Downwind the marginal planing properties are an improvement on those of Daredevil and the reduction of flare, which is really about the acceptable minimum, improves high speed travel in rough water. On the reach it demonstrates a great ability to plane even in the most moderate conditions, and the planing speed is considerably faster than possible with Daredevil. To give some idea of its performance on this point of sailing, March Hare has consistently been able to plane through 10 raters and finish a though the trim and tune were not perfected, but unfortunately it was uncontrollable downwind because of the excess area in the mainsail. More experiment with these rigs is certainly worthwhile, since the initial impression has been far from discouraging. Both the original March Hare and Mad Hatter were fitted with a trim tab on the after edge of the fin. This was an experiment to find out more about this item of equipment and after some experience of using it we found that it was not as useful as one two hundred yard course with a ten yard lead. The analysis of the potential of this design has been made easy by the keen sailing of Fred Shepherd, for whom this boat was designed. As a result of this consistent exposition of skill, March Hare’s success in competition is distorted somewhat in favour of the boat; however the design has played some part in achieving fifteen firsts last season, including a win in the district championship without the concession of a single point. leeward might have thought. The diagram shows how the section of the keel is altered by the tab to give more lift than when it is a symmetrical section, in the same way in which the skeg and rudder gives lift to turn the boat. It was found that the angle at which the tab operated efficiently could not be increased beyond 3 or 4 degrees before the flow over the keel broke down and the boat started to fall off. The effect of up to 3 degrees of helm was a reduction in the leeway made by the boat, but also a slight reduction in speed, so the advantage gained was, in fact, dubious. There are so many more important variables in sailing that it is not really worth fitting an item that has such a minute effect on performance. The original March Hare was very well sailed last season and its performance showed to be most encouraging. It has shown special ability to wind113 side windward side trim tab fin ~— MARCH HARE advantage is the extra area downwind gained by the whole of the measured area being in the mainsail. The original March Hare was fitted with such a rig in a forward mast position. Downwind it was about 2 to 5 per cent faster than with the conventional 80 in. rig shown, but to weather there seemed to be no advantage, although it was able to point higher. Although this particular rig was discarded because its use was limited to very low wind speeds, there is a great deal to be learnt about this type of rig, ARRANGEMENT OF A TRIM TAB FOR A WINDWARD COURSE
