Richard Edlin, boat builder and designerMatakohe, North Auckland, New Zealand
Overdrive

Overdrive Continued - pg4

The engine is a two-litre Toyota 2C diesel, shaft driving a two-bladed MaxProp through a Volvo marine gearbox. A qualified diesel mechanic, King chose the Toyota on the basis of its reputation for reliability and life expectancy and marinised it himself. Although not the lightest auxiliary - around 200kg all up - a dyno-proven 63hp provides ample grunt for head winds or big seas.

The sailing:
We planned to test Overdrive in a decent breeze, but the forecasted NE 25 knot breeze didn't eventuate and we spent the scheduled test day sliding over flat waters in variable four to eight knot breezes. Even so, Overdrive regularly matched wind speed and, with masthead gennaker and a hot angle, just cracked nine knots. Given the lack of overlapping headsails, light weather performance is perfectly adequate and should save considerable motoring.

Three days later, we tried again. An 18 to 25 knot northerly left flat water inside the harbour, but generated a 0.5m chop over a one-metre ground swell out in the main channel. In those conditions, Overdrive felt and sounded solid underway. No creaking, no groaning, no loading up noises - just the sound of the wake boiling off the transoms. Overdrive's floats are deliberately set low to dampen rocking at anchor.

Underway, the angle of heel, for a trimaran, is modest, yet the windward float is high enough to clear waves upwind. However, the junction of the curved rear beam and the leeward float is perfectly angled to occasionally clip the top off a wave and toss it at the leeward trimmer. Nice in the tropics, less so mid-winter in Auckland - I'd be adding a fabric deflector.

Overdrive certainly felt comfortable in rough water. We sailed through the Motuihe Channel at an easy eight to 10 knots against closely spaced 1.5m pressure waves from an outgoing tide opposing a 20-knot breeze. Sure, the trimaran hurdled each wave like a champion steeplechaser, but the landings were soft, and there was no trace of hobby horsing.

The highlight of the day for me was at the helm broad reaching back through the same channel homeward bound. Under main and jib, Overdrive sat easily on 12 knots, with regular surfs to 15-18, and once to 20. There was no sign of the lee float bow digging in going down backless waves - it felt safe. Edlin credits this to the shape of his float shapes - they are full forward with generous rocker aft.
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