Most references give US fleet boat endurance in terms of nm at 10 knots. At 10 kts, I've found that SH4 fleet boats will exceed their historical range by about 20%. A good compromise would be to run at 12 kts, which gives close to the documented range and cuts transit times by 17%. Whenever you have the time, using the knotmeter to set speed gives you better control than the telegraph.
It's not hard to refine the estimate of when to turn for home. On the nav map, use the compass to draw a circle from the nearest friendly case to your boat. The radius of the circle is your crow-flies distance from base. Based on what lies between you and home, you will want to add to that distance - sometimes a little, sometimes a lot. Then use the "Range at current speed" function to see how much range you have remaining. Like the RT guys, you should always add a "Bingo" (10% of your rated cruising range). After that, it's just a matter of how tight you want to pucker.
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