[Aktungbby]

extrapolation: "is the process of estimating, beyond the original observation range, the value of a variable on the basis of its relationship with another variable. It is similar to interpolation, which produces estimates between known observations, but extrapolation is subject to greater uncertainty and a higher risk of producing meaningless results. Extrapolation may also mean extension of a method, assuming similar methods will be applicable." If say, your '3' bubble is at 3000 meters on the the line you have drawn (always) on your TAC screen parallel for the course of your target's line,(2 lines) but the target is, say, 1000 meters away from that course line ie 1/4 more distance than the bubble method covers-envision a 'fourth bubble', mark with an 'X', and maneuver the eel fire line accordingly (extrapolate) a quarter or so past the third bubble and fire a salvo. I nailed a battle cruiser off Spain at over 6,000 meters with this-only two of the eels hit but enough to close and finish the cripple. Always bear in mind the speed of the target vs speed of the eels. In short -tiny bubbles meet mathematic extrapolative intuition- A little skeet shooting time with clay targets doesn't hurt either for practice and in a while your confidence in your own judgement will be solid...and your 'itchy neck' suitably adorned! Remember to have a a soft cloth to wipe the condensation moisture from your periscope lens.