Skippers' Checklist: Propulsion

Practical: Skippers' Checklist

Before starting the engine, check oil, water and battery levels, advises Alan Lucas.

Never press the button until these essentials have passed muster, then, immediately after starting, confirm that all instruments are monitoring correctly and that cooling water is expelling normally. If there is the least doubt shut down immediately.

Belt tensions also need checking. Belt-dust in their vicinity indicates slippage and the cause may be a transverse crack that is ready to snap. Belts need to be fully inspected by removing them or turning the engine over slowly (if it has decompression levers and hand-start). When replacing belts, always seek the highest quality.

Engine controls

Wrong moment
Unchecked engine controls have a bad habit of failing at the wrong moment. If you are unable to select a gear during a critical manoeuvre, stop the engine immediately and prepare to fend off, but it is easier to check linkages before casting off. And because they can loosen and disconnect under way, it pays to check them again before manoeuvring.

In the next checklist, we will return to the engine and see how small malfunctions might be diagnosed and fixed more or less immediately, but for now we will presume all is mechanically healthy and look at propulsion.

Hard astern
A useful preliminary check for gearbox and prop-function is to go hard astern then full ahead in very short bursts at the berth or mooring. This tests three things: gearbox and linkage function and whether the prop is clean enough to propel the vessel. If you cast off and find yourself unable to make way despite the engine running flat out, you won't be the first. I have even done it in a fresh-water river where alien straw-like weed had fouled my propeller so profusely and quickly that I couldn't even steam against a one-knot current.

However, barnacles remain the more common problem after the prop has lost most of its antifouling (usually around three months after application). In some areas during summer, barnacles can accumulate and grow to adolescence in one month, covering the entire propeller enough to reduce its efficiency by at least half. If this proves to be the case, don't cast off until the prop is cleaned because you may become a plaything of wind and tide.

Colliding with the law
This is where checklists and environmental laws collide head-on. Someone in authority, who has obviously never been under a boat surrounded by dozens of hungry fish snapping at freshly scraped barnacles, believes that the practice of prop-cleaning is bad for the environment. Fish, apparently, are unaware of this, but we, the boating public, need to be cognisant if heavy fines are to be avoided. None of us can afford to slip a boat every time barnacles encrust our propeller, so when you scrape it clean in the water, take a large kitchen sieve with you and collect the debris. Fish think you're mean, but it's the law.

Engine and gearbox control cables and terminals are notorious for divorcing each other at critical moments. Check that they are not rattling loose before casting off and again prior to critical manoeuvres.

A well-used propeller loses its paint around three months after application, thereafter depending on in-water barnacle removal. To avoid breaking the law, collect the debris in a large sieve.

DIAGRAM
V-belt failure can cook the engine in minutes. Check tensions regularly and watch for belt-dust and transverse splits like this. The alternator setting (or an idler pulley) adjusts the tension.

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