Oyashio II.

This is coolbert:  

From a submarine forum a discussion of what is called the "leaf coil hull".

Question: " Leaf coil hull: I've seen pictures of this submarine hull form and cursory mentions in books but I have found absolutely no info on it whatsoever."

"Does anyone have anything on this? Why it was used over a teardrop hull, advantages and disadvantages thereof?"

Question: "I was under the impression a true cigar shaped sub was very hydro-dynamically efficient and more quiet than a tear shape hull.

Answer: "Leaf coil is a . . . mistranslation of cigar."

Answer: " The advantages of a cigar over a pure teardrop are internal volume and simplicity of construction. It's not quite as hydro-dynamically efficient, but the teardrop has been ditched pretty much everywhere."

Answer:" It's also probably easier to fit a conformal array like the Oyashio class has on a cigar."

Answer: "Teardrop is more efficient, with smoother flow, and therefore also quieter. However building teardrop hulls is a pain, fitting equipment inside is a pain, and the whole thing is a waste of money. Performance difference is too small."

The teardrop shaped hull as was used in the design of the American Skipjack class of submarine no longer in fashion. Advantages [and undeniably there are advantages to the teardrop shape] are offset by disadvantages. There it is in the nutshell. Or rather the "cigar" should I say?

coolbert.