By Ed Ostermeyer (Master Engineer – Grade 2)

Young Inventor! It is good to see you once again.

Have you been applying what the two of us discussed in our last conversation?

Well done. I am pleased with your diligence, both in study and application of what you are learning.

Today, our topic involves one of the forces of nature: water’s current. Though direct control of it is beyond the scope of your, umm, project, you can learn to anticipate, prepare for and deal with its effects upon said project.

Known as “current,” the flow of water is judged by direction and by speed of outside forces upon the water. A transition from a height to a depth can cause water to increase its rate of flow. Therefore, with a steeper slope to the current, the greater the current’s rate of speed.

Wind can also have an effect upon current, though this is usually in the form of a gust of wind that occurs at the water’s surface. You may have experienced this when either docking or departing from your craft’s wharf. A strong gust of wind striking your fishboat beam-on can cause it to unintentionally move laterally sideways; in some cases striking the wharf or other craft moored nearby.

The theaters where your fishboat will ply its trade are of two types: coastal and riverine.

River currents are controlled by quantity and gravity: the quantity is augmented by rainfall, both local and upstream. The increase in quantity can turn a river with as little as a 2% grade into an unnavigable torrent. 

Coastal currents themselves are also influenced in estuaries by river current outflows, as well as the tides and weather. Their main power comes from off-shore global ocean currents that in some cases span the globe in their extent. One ocean current in particular is created by the rising temperature of the seawater itself (averaging 80 degrees F.) as it courses northeastward from the sub-equatorial Caribbean Sea. It travels at a distance of seventy five miles along the east coast of North America, gathering to itself speed (from ten to as high as fifteen knots at some points) and a breadth of sixty miles in width, becoming the mighty Gulf Stream.

 In its wake spin a number of in-shore eddies that occur off the Carolina coasts and Chesapeake Bay. The sizable eddy off Charleston, South Carolina rotates counter to the Gulf Stream’s southwest to northeast direction of travel, its flow nearest the coast traveling northeast to southwest.

Its drift is of sufficient strength that small craft such as your fishboat, leaving a port on the South Carolina coast can find themselves caught up in the eddy’s current, ending up several miles or more down the coast than where their crews had expecting to be.

Here we return to the concept of Crank Intensity on the part of your fishboat’s crew. It is axiomatic that, to counter the effects of a water current upon your fishboat’s forward motion, its power source, whether steam, electricity or muscle, will not only need to equal the current’s opposing strength, but surpass it. Thus a competent fishboat captain will avail his crew of the rest periods offered by sailing his fishboat with the current, so as to leave their muscles rested and spirits calmed for the moments when the current’s flow opposes their progress.  

This reduction of Crank Intensity can also apply to the steam (boiler) engine and the magnetic (electrical) engine. In either situation, limiting power usage to that needed to maintain headway lessens strain on the mechanism, and also lowers the chance of the mechanical version of Fatigue.

Conducting operations in a coastal theater allows the fishboat captain and crew the opportunity to use the tide shift period known as Slack Water to gain a favorable current both toward and then away from the target. The occurrence of Slack Water itself can be governed by the time of year and as the result of the tidal influence caused by the Moon.

This condition is not available in riverine operations. Here, the current flows in one direction (downstream) which, depending upon your fishboat’s starting Launch location, can mean an easy coast with the current down river, followed by a hard slog against the current on the return trip, (a condition familiar to the Confederates) or a trip upstream that finds your crew (or engine) arriving at the Target in a state of Fatigue that could affect the outcome of the fishboat’s Attack Run (as the Union Navy would experience).

The power of a current’s Drift cannot just be equaled; it must be exceeded by the Power Grade of your fishboat in order for your mission to proceed. This requires coaxing that extra effort out of your crew or your engine, boosting its power rating at least one and possibly two Power Grades.

If this is not possible, then the current will cause your boat to Drift in its direction.

(Addendum to the Fifteenth Edition of the Inventor’s Vade-Mecum (Nautica edition.)

So now, my mechanically-minded young friend, you understand how the forces of Nature can conspire against you, your fishboat and her stalwart crew if you are not careful in your mission planning, your fishboat’s construction, and your crew’s training.

And always remember:

No matter what the outcome of a mission you undertake, it is always best to return home.

Nail the enemy?

Yes.

Give as good as you take?

Yes.

But always, always come home, alive and afloat.

That is enough for now, young Inventor.  

Now go and apply what you have learned.

(Note: All graphic images of Infernal Machine game materials used in The Inventor’s Vade Mecum are subjective and may change and appear different in their final form.  All images show sourcing unless otherwise noted.)

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