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Joe & Frank, One of the 3 recommended
design books (Chapelle, Hamlin, & Brewer are the three authors) for the
naval architecture course goes into to this issue to some extent. The
frontal area and skin area are the two major factors in determining resistance
at speed skin area dominates at low speed and frontal area dominates at higher
speeds (i.e. if I remember correctly, the transition occurs somewhere at or
just above 3 kts. for a submerged body). Six knots will take 8
times the power that 3 knots will; 4 tons will take a bit to accelerate but God
forbid if you have to stop quickly! I have seen pictures and talked with
crewmembers after the USS Ray ran
into a seamount (now named after her) at slow speed. What purpose do you
have to run at 6 kts? If it is to make headway against a swift current,
there are places a PSUB shouldn’t operate safely. R/J2 Respectfully, Jay K. Jeffries Andros Is., It is the mark of an educated mind to be able to
entertain a thought without accepting it. From: Hi Frank "I
hope to be able to get 6 knots submerged speed out of her." As I understand it, your typical fast attack submarine is faster
submerged then when surfaced. This because on the surface, a displacement hull
speed is calculated at 1.3 x the sq rt of the waterline length. So submerged,
the surface wave no longer factors. So my question then...is there a rule of thumb formula that can be
applied to a submerged body? Or does one have to calculate total plate area
-vs- resistance of seawater and then account for thrust? Joe |