Single Screw Vessels

Boats with one engine need special attention. Here is a list of desirable features, in approximate order of priority.

Separate battery for engine starting. with jumper system or cable.
3 gals clean diesel in jug for priming.
Fuel tanks known to be clean, by visual inspection. If not lots of fuel filters.
Inline visible inspection section in fuel line.  See sample units at: Sight Flow Indicators
Onboard engine manuals: owners, service/shop and parts.
Engine identification plate located and readable.
Engine model and serial numbers enterered in each engine manual, with notes locating engine id plate. 

One line stout enough for use as towline or anchoring, at least 100, better 300 feet long.

Transmission capable of locking down clutch.
Dual fuel filters, with valving to allow changing filters while engine running.
Tested method for priming fuel system.
Bleed screws marked with red paint.
2 Micron Primary Fuel filters, also in secondaries.
Engine hour meter.
Dry exhaust.
Extra belts tied into position, ready to install by cutting the old one out.
Keel cooling, not raw water cooled.
If raw water cooled, alarm sensor in inlet to warn of no flow. Dual water strainers.  (see sight flow indicators and FW Murphy, above and below).
No flex fuel hose unless rated for suction use.
Engine alarms tested and working. Temperature alarm for transmission.

Murphy guages for coolant level, water flow. See FW Murphy
Exhaust gas temperature gauge.
Tools: metric and SAE, open end and box, socket wrenches.
Tubing wrenches for injector nuts(similar to box end with slit).

Spare parts.
Belts, hoses, pump impellers, injector lines, spare injector.
Water pump, alternator, starter, lift pump(fuel).
Crankcase and transmission oil. One piece of hose long enough to replace longest end to oil cooler.
Identify specialty molded hoses that are hard to get, most likely expensive, stock them aboard.
Carry aboard any engine component likely to be needed(see maintenance manual) as long as you intend to keep the boat.
Spare propeller, shaft, keys, nut, cotter pins, spare coupling if needed to match.
Emergency tiller and way to disable hydraulic steering.

Practice routine maintenance.
Replace, pump impellers and belts at regular intervals. Impellers: 200 hours, belts: one year or 500 hours.
All other recommended practices, per engine manual. Including add-on hydraulic systems.

If internal circulating water pump weep hole shows any signs of leakage, replace pump.

First rate anchoring system. Tested to determine that chain in anchor locker can't fall over on top of itself and jam up. Use beach balls to keep chain from falling over.

I had an experience with a Cat D-334, where someone had installed a 1/4" pipe fitting to support a gauge. Someone had added enough stuff to this lashup to create a Christmas Tree. The 1/4" pipe having threads cut almost all the way through, this being schedule 40 pipe, the pipe broke. This resulted in a fuel leak, way far from home.

Anyone with a single screw boat should inspect all such installations to be sure that thin wall pipe is not used in any similar fittings such that a failure could bring the engine to a halt or cause serious damage.

Suggested replacements include pipe of schedule 80 or 120. Or the use of 1/4" HEX pipe nipples. Or similar thick wall fittings from a hydraulic fittings supplier. In some cases a hydraulic flex hose with fittings might be the best solution.

This suggestion is not limited to single engine boats, but at least on a twin screw the loss of one engine won't bring you to an absolute halt. Although twin screw boats aren't much to shout about on one engine.

I had a similar problem on a twin screw boat where thin wall galvanized pipe was used in the salt water side of a heat exchanger and broke off. Get wary of using thin wall (40) pipe aboard the boat.

If you choose not to replace these problem spots, at the very least you should make a list of them and keep the list around just as a reminder of the risks you are taking.

I don't have any special problem with playing with a deck short of cards. Just so long as you know explicitly which cards you are missing.

If you don't want to buy, install or maintain all of this, them put in a second engine.
If you think that commercial fishing boats run with one engine, then note that they carry this stuff and since they often go together, someone will have any missing component.

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