MC 31

2016 May 1

This one-design speedster is sporty and sleek, with lots of sail area for sizzle

The MC31 one-design, built by McConaghy Boats in Australia, looks to be a very fast boat. The design is most interesting but I really had to dig through the company’s material to find the designer’s name, Harry Dunning. 

The McConaghy team appears to have pulled out all the stops to endow this design with every possible speed-producing feature. The promotional material makes a point of stressing the efforts they went to so that they could reduce weight. They quote the famous race car engineer, Colin Chapman, saying “To increase performance, add lightness.” 

The first thing that grabs me when I look at this hull is that in plan view (looking down at the deck) there is absolutely no taper to the deck aft. The boat reaches max beam very far forward, just aft of the mast, then stays there to the transom with wide, flaring sections. My guess would be that the disposition of beam is for crew hiking effectiveness. I can’t find a DWL listed in the specs, so I’ll guess the DWL is 28 feet 6 inches for a D/L of 90.36. That’s light but not as light as the promo material suggests.


There is no chine but the bilge turn aft is quite hard. Amidships the bottom is very flat with zero deadrise and a moderate turn to the bilge. L/B is 3.00. DWL and LOA are close but there is a little bit of overhang aft, maybe 16 inches. 

Draft is 8 feet 6 inches with a long T-bulb on a very high-aspect-ratio, carbon fiber, retracting fin. I have searched the specs but I see no mention of a kelp cutter option. Having just had a kelp encounter in a race two weeks ago, I am suddenly very pro- kelp cutter. This style of T-bulb would be a problem in Puget Sound. The rudder is carbon fiber and very dagger-like in profile.

I get the feeling that a lot of refinement has gone into the deck layout. The deck gear specification is extensive with only two minor options. The material I have is a bit obscure on deck details but what I think I am seeing is an exit on centerline in the cockpit sole for control lines. The mainsheet traveler is aft of the tiller head. The deck forward is perfectly clean except for a very low, sliding hatch for chute work. Note the low drag, foil-shape stanchions. The bowsprit is removable for docking.

This is a very high-powered boat. With 690 square feet of upwind sail area, the SA/D is 39.42. That is a lot of horsepower per pound of boat. Downwind there is 1,710 square feet of sail area. That’s a bit hard to comprehend on a 31-footer. “Time to put your knitting away Mom and get that chute up. Don’t forget your helmet. ” The rig is all carbon fiber.

Construction of the MC31 is e-glass over a foam core and vinylester infused resin. There is a Yanmar 15-horse power diesel with saildrive to get you to the dock. There is kind of an interior. You get a gimbaled stove, some pipe berths, a portable toilet and a cooler that stows under the companionway steps.  As I mentioned, for close one-design racing the specifications are very extensive and there is not much you will need to add for some competitive racing.

I look forward to seeing an MC31 in Seattle.

LOA 30’; LWL 28’6”(est.); Beam 10’; Draft 8’6”; Displ. 4,696 lbs.; Sail area 690 sq. ft.; SA/D 39.42; D/L 90.36; L/B 3.0; Auxiliary 15-hp Yanmar; Fuel 11 gal. 

Our best estimate of the sailaway price: $185,000

McConaghy USA