Vessels We Supply

Fishing vessels are the hardest duty we routinely supply. The main engine runs at high sustained load for days, the deck hydraulics work continuously through a haul, the refrigeration plant runs from the moment there is fish in the hold, and all of it draws seawater from inshore ground that is warm, silty and full of things that block a strainer. On top of that the boat earns its money in a window, so a cooler failure in the middle of the season is not a maintenance issue, it is a lost trip.

A tug at full bollard pull is an engine at rated load with a hull that is not going anywhere. Every other vessel type gets some help from water moving past the hull and air moving through the engine room; a tug on a hawser or pushing on a barge gets neither. If the cooling depends in any part on forward speed, this is the duty that finds out. It is also why keel-cooled boats in this trade are sized carefully and why exchanger-cooled boats need a raw water pump that genuinely delivers at working RPM.

A passenger vessel on a schedule has a duty cycle nothing else quite matches. Twenty to forty berthings a day, each one with ahead and astern engagements, ramp work and a hold on the fenders, then a night alongside and the same again tomorrow. Engine hours accumulate at moderate load while the reduction gear takes a beating that no rating table describes. On a double-ended ferry with two gears and two shafts, that clutch duty doubles.

The thermal duty on most yachts is undemanding and the failures are still frequent. A sportfisher might run three hundred hours a year, hard for six of them and idle for the rest, and a motor yacht may do less. Yet the coolers on those boats fail regularly, because the enemy is not heat load. It is a marina berth with shore power connected, stagnant seawater sitting in tubes for weeks, stray current from a dock with a marginal ground, and a set of zinc anodes that has been quietly gone for two seasons.

Offshore support, patrol, fire and rescue vessels are bought and judged on availability. A charter day lost, a station left uncovered or a callout missed carries a cost nothing about the equipment can offset, and that changes how cooling is specified. Margin is bought deliberately, spares are held on board rather than ordered on failure, and the construction and material records are expected to be in the file before anyone asks for them.

An engine at 85 percent load for two hundred hours a trip rejects heat continuously, fouls its tube side steadily, and leaves no window for cleaning. That argues for extra surface at selection, generous margin on seawater temperature, and a spare bundle in the ship's stores. It also argues for two-pass arrangements that are easy to rod out at sea.

Warm harbour water carrying silt and sulphides is harder on a cooler than cold clean offshore water at the same temperature. Chlorinated water, whether from a treatment system or a nearby discharge, is harder still on copper alloys, and that is the condition where titanium starts to justify its cost.

A ferry with a fixed timetable and a fishing boat mid-season have the same problem for different reasons: a cooler failure costs revenue immediately. For those operators a spare tube bundle, a full gasket set and two sets of anodes in the stores are cheap insurance, and we stock accordingly.