Selden Hydraulic Boom Outhaul — Owner's Manual

How the System Works

The outhaul line is gathered inside the boom on a four-part tackle moved by a double-acting hydraulic cylinder, driven by its own below-deck hydraulic unit and two cockpit buttons. One person can furl, unfurl, reef and trim the mainsail from the cockpit. If power or the control system fails, the main can be furled by hand; unfurling then needs an optional emergency outhaul.

Battery, cabling, below-deck hoses and other standard materials are not normally included. Professional installation is required. Selden recommends a 24 volt DC system on boats with hydraulic rig systems.

Installation

• Boom: supplied with cylinder and outhaul line / block fitted; connect its two hoses to the mast or deck gland with the quick couplings. It is significantly heavier than a standard boom of the same size.
• Buttons: the outhaul and in-mast furling are separate systems run together, so mount the two OUT buttons side by side and the two IN buttons side by side (e.g. on the pedestal, OUT to starboard, IN to port). Buttons are watertight and lit.
• Control box: fed from the boat's panel via switch and fuse; mount it near the valve unit with cables entering from underneath. Pre-set the changeover switch to separated.
• Pump unit: near the mast = short hoses, near the batteries = short cables (safer). Tank longitudinal; mount on rubber feet to cut noise. Never run the pump with the reservoir empty.
• Valve unit: leave access for adjustment, especially the red emergency valve; mount close to the control box for functional checks.
• Filter: on the return line from the valve units to the pump, with access for element changes.
• Hoses (not supplied): SAE 100R7 – ISO 3949, min 3/8", min bend radius 125 mm (175mm for ½'' hose). Secure them, keep them off sharp edges, allow for movement under pressure, keep all ends plugged during fitting. Cylinder hoses are marked A and B (A on the port side of the boom) and must match A and B on the valve unit – crossed hoses mean the sail won't stay unfurled under load.
• Batteries: 300 Ah for a 24 volt system (typical for a 50' - 70' yacht). Have the battery-to-pump cable installed professionally – a short circuit can cause a fire.

Deck gland (deck-stepped masts)

• Two sizes: the smaller for ¼" quick couplings, the larger for 3/8". Hoses are tailor-made to the gland position and your choice of exit-hole side; boats with Selden hydraulic in-mast furling have a separate deck gland for those hoses.
• Keel-stepped masts: two pairs of tailor-made hoses, emerging from the same exit hole as the in-mast furling hoses where fitted.
• Quick couplings (acid-resistant steel, self-sealing male and female halves): disconnect by pushing the knurled sleeve away; after connecting, push the locking ring towards the sleeve and turn it about half a turn. Always check they are locked, and fit the protective plugs and sleeves whenever hoses are disconnected.

Cylinder, Venting & Outhaul Line

The outhaul line runs from its shackle on the outhaul traveller, through a block in the sail, back to a block on the traveller and via the boom-end sheave to the four-part tackle; the free end carries a stopper knot. Cylinder pull (N) = oil pressure (bar, valve-unit manometer) × 28.2 cm2 piston area × 10 – e.g. 100 bar = 100 x 28,2 x 10 = 28200N. The cylinder is delivered full of oil but air can get in at connection, through a leak or a low reservoir, making the outhaul elastic: vent it once installed.

Pump Unit, Filter, Oil & Valves

• Pump unit, valve unit and filter are separate; the assembly drives one function at a time. Pump unit weight 12 kg excl. oil.
• Electric motor: compound-wound 12/24V DC, rated for intermittent use (1,5 kW 12V / 1,8 kW 24V nominal). Continuous running trips the built-in temperature sensor, which resets automatically once cool. The pump sits inside the reservoir; pressure line P=1 and return T=2 connect to the adapter, which carries the manometer and the pressure relief valve.
• Oil change: every four years with a filter change. Tank: 8.8 litre horizontal, 7.4 litre vertical. Mineral hydraulic oil (Norsk Hydro Hyndla Hydraulic Oil 46 in outhauls from May 2005); don't mix hydraulic oils of different origin.
• Filter: intermediate-pressure, max 110 bar and 25 l/min, 10 microns, bypass opens at 6 bar. Replace the element every four years.
• Cleanliness is critical: never use Teflon tape, flax or similar sealants; use the protective plugs and sleeves whenever couplings are open.

All adjustable valves are set for your boat at delivery and normally need no adjustment. If in any doubt, call in an expert.

Valve Settings & Clew Force

F_Pump is the clew force the outhaul can apply (set by the pump relief valve, read on the pump-unit manometer). F_wind is the clew force from wind and mainsheet that the overcentre valve will hold (read on the valve-unit manometer). Factory settings:

• F_Pump = P x 28.2 x 0.5 x 0.8 x 10 N = P x112 Newton.
• F_wind = P x 28.2 x 0.5 x 1.25 x 10 N = P x176 Newton.
• Force in the outhaul line f = 0.5 x F (two parts to the sail). 1 bar = 14.50 psi; 1 N = 0.225 lbf.
• Consult your sailmaker for the right max clew force. Keep the relief pressure as low as possible: less risk of overstretching the sail and lower peak current. At 30° heel under main alone, F_wind is close to the maximum that should be allowed.

Operation

• A furling main is more prone than a genoa to hang and crease (its extrusion is near vertical vs approx. 17° for a genoa): keep light outhaul tension and use any side wind.
• When unfurling, the extrusion must turn and the outhaul must pull the cloth out at the same time, or the sail unrolls loosely inside the mast and can jam.
• Leech and foot tension should be equal; the clew should ride freely above the traveller. Max tack angle 86° recommended (E = 6 m and 86° puts the clew 0.4 m above the boom when furled).
• Changeover switch: separated = MAIN OUT/IN and BOOM OUT/IN pressed together; integrated = MAIN OUT also runs BOOM OUT, MAIN IN also runs BOOM IN. Learn on separated first. Releasing the buttons stops any manoeuvre.
• Fitting the main: separated; fit as per the in-mast furling manual; tension the clew block and furl with MAIN IN until only the clew shows; reeve the outhaul line; set the traveller stop approx. 1 m behind the clew, then fine-tune.
• Unfurl (separated): BOOM OUT to tension the line, then MAIN OUT + BOOM OUT together, letting the lagging function catch up if not speed-matched. Mark the luff where the sail is fully out.
• Unfurl (integrated): BOOM OUT to tension, release, then MAIN OUT only.
• Trim: BOOM OUT tensions, BOOM IN eases. In heavy weather ease the mainsheet a little to tension further.
• Furl (separated): BOOM IN to ease, then MAIN IN + BOOM IN together; stop in time so the clew isn't furled into the mast. Integrated: BOOM IN, release, then MAIN IN only.
• Manual operation: set the in-mast furling deck-gland safety valve to "winch handle", insert the handle in the furling drive, open the red locking nut and knob of the emergency valve (anti-clockwise). Furl with the handle; to unfurl, pull in the outhaul at the stopper knot at the same time. Never leave the winch handle in the drive – it spins very fast if the motor starts.

Checks & Safety

Switch off the pump-unit main switch before working on the system, and confirm both manometers read 0 bar before disconnecting anything. Disconnecting the boom quick couplings keeps the oil in the cylinder.