Adding an electric/hydraulic propulsion system to A169 (Kerry Piper) and thought it may be of some interest (attached plan). The mechanical installation is pending completion of structural work to the hull and bulkheads, but I aim to have it installed during the summer. Bernard Upton (Colchide) is a keen advocate of electric propulsion and my discussion with him during the 2012 AOA dinner got me thinking about this as a serious option. I had originally planned to add hydraulic drive to a 12hp 4 stroke petrol unit thus eliminating the need for a gearbox and the further elimination of fuel combustion was appealing. The Electric Seas forum group was a useful research resource, with many individual (and corporate) technical articles on battery type, amp hour consumption etc and worth a look for anyone considering electric propulsion. Benefits are: elimination of fuel (and tank space) – compact and versatile installation – smooth silent operation and potentially lower weight (I know – “what about the batteries!” – read on). Downsides for those who do a great deal of motoring are the higher AH battery installation required for extensive motoring, which offsets the potential weight benefit (until Lithium batteries are affordable). The combining of electric to hydraulic as distinct from purely electric drive was my preferred choice. Added attractions (over purely electric) for me are: – smoothness of hydraulic propulsion (minimal mechanics) – instant ahead astern (without overworking the electric motor) -efficient torque delivered from a hydraulic drive and possible use of hydraulics for lifting keels. NB: Vetus offer a ready made electro-hydraulic system for those with deeper pockets. Working out the correct system involves basic calculations like matching the correct electric motor to the hydraulics – my 7.5 kW motor was from a fork lift truck, so the correct pump was already there. Sourcing the correct hydraulic motor needs a calculation of the required rpm/torque etc. For those happy to keep a fixed prop there is the benefit of charging the batteries whilst under sail with reverse prop rotation – especially effective for direct electric drive systems. Cost wise – about the same as a standard diesel installation, although clever sourcing can substantially reduce outlay for principal components such as electric motor, tank etc.