In this paper, we show that it is possible to arrange for an 18-core photonic crystal fibre (PCF) laser to operate in the fundamental in-phase supermode. The mode divergence is as small as 12.5 mrad. The equivalent mode field diameter is about 52 μm. Mode filtering is provided by a pinhole in the far field. The laser is Q-switched using an Acousto-Optic Modulator (AOM). An output power up to 65 W at a repetition rate of 50 kHz (corresponding to 1.3 mJ per pulse), with 22 ns short pulses, has been obtained with a slope efficiency of 46%. Ongoing amplification experiments are briefly described. Limiting factors (end facet damage threshold and thermal dissipation) are discussed for further scaling of this laser concept.