It seems to me that if you’re going to have ballast, it may as well be in the right place, and the lifting keel of our aluminium forty footer, Kadash, certainly provides plenty of righting moment, with 3.5 tonnes of lead in a bulb 10’ below the waterline. In combination with good form stability, Kadash is “stiff as a church”. The short deep keel, upright sailing and multiple rudders seems to make the boat very steady on her course and so far, we’ve experienced no weather or lee helm, and no tendency to round up.
The boat’s draft with the keel up, 1.3 metres, is ideal for us, committed ditch crawlers as we are, and we frequently make use of the system. When entering a new port or anchorage, we generally lift the keel to the mid position, and occasionally fully retract it. Once we have arrived at a marina or anchorage, we often lower the keel as it dramatically reduces rolling and wind induced heeling. These are definitely upsides, but there is a downside - the keel has to be moved vertically about 1.8 metres. A hydraulic ram driven by an electric pump makes short work of this, a simple robust system identical to those used in millions of excavators, cherry pickers, cranes and similar machinery.
Inspection and overhaul of the hydraulics was a priority when we arrived at Almerimar in southern Spain, in June, our pickup fully loaded with tools and equipment. Kadash had been in the yard for nearly a year, and we could tell that the winter gales had been severe as the tarpaulins were in shreds, and any unanodised aluminium had a sand blasted appearance. Work during previous refits had been handicapped by the lack of a proper work surface, so this time I had made a bench at home which we set up next to the boat.
The keel slides up and down in a welded aluminium case at the forward end of the saloon. The top of the ram is attached to the case via a 38 mm diameter pin and a bearing system. At the bottom, the ram is connected to the keel by a pin which runs in bearings which fit into the casting. To minimise galvanic corrosion between the steel ram and the aluminium boat, the ram is electrically isolated from the hull with plastic bearings.
The bottom pin in the keel is not accessible with the keel up, so the first task was to lift the boat so that that we could move the keel to the intermediate position. In the lower and intermediate positions, the weight of the boat is taken by a pin through the keel case and keel itself. To avoid misunderstandings, I had prepared illustrated instructions for the yard personnel, and the lift and subsequent chocking went smoothly.
The lower pin in the keel came out easily, but the top pin was extremely stubborn, very tight in the plastic bearings. At home, I had made an aluminium drift so that I could drive the pin out with a hammer, but even with a sledgehammer the pin would not move. After several days of frustration, I made a “pusher” from 25 mm thick steel plate with an M20 tapped hole which I bolted to the keel casing. Eventually, millimetre by millimetre, the M20 bolt, torqued by a long lever on the spanner, pushed the pin through the bearings.
I disconnected the hoses, and attached a small chainblock, supported on the topping lift, to the top of the ram. It was a simple matter to lift the disconnected ram out of the boat and lay it in the V shaped recesses at the ends of the bench.
The lower joint of the ram, which has a spherical bearing, appeared to be quite corroded, but after a session with the wire brush it was clear that things were by no means as bad as they appeared, there was no significant corrosion, and the bearing moved freely.
Almerimar is surrounded on its landward side by the mar del plastico, a huge area of greenhouses which must supply a considerable portion of Europe’s vegetables. This specialised agriculture is big business, with the benefit to us that there is considerable infrastructure devoted to the repair and maintenance of hydraulic agricultural machinery. With appropriate hoses and adapters bought at distributors OLEO del Sur, I connected the ram on the bench to the boat’s hydraulic pump. The ram moved smoothly, there were no leaks, and there was no corrosion on the piston rod. Pleased with this, I went back to our apartment, intending next morning reinstall the ram after greasing and painting it. In the evening, I began to have doubts, and decided, having got this far, it would be a shame not to open the ram for inspection of the cylinder, and replace the seals.
I decided not to open the ram in the rather gritty and windswept boatyard, and entrusted the job to Hidráulico Emar, who specialise in the repair of agricultural machinery. When the ram was disassembled, we inspected it in the factory, finding that the cylinder bore was smooth and unmarked, and the piston rod was in perfect condition. The seals were replaced, the cylinder reassembled, and we put the ram back on the bench and carefully worked all the air out of the system. I fitted a hose burst valve to the inlet port of the control valve, so that the keel would descend slowly in the event of hose failure. I was concerned that the valve might have an effect on system stability, but bench testing showed that the system ran perfectly well with the valve installed.
With the plastic bearings carefully reamed out, refitting the freshly painted ram with new hoses and connectors was surprisingly simple, the only difficulty being alignment of the top bearing.
I now understand the keel lifting system very well, and the hydraulics worked perfectly during Kadash’s 2024 cruise, which took us out of the Mediterranean and across the Atlantic to the West Indies. I have great confidence that the system will give further years of trouble free service, and we will be able to take full advantage both of Kadash’s sailing qualities and her ability to access shallow anchorages.
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