True Max Depth For La688(i)

[Kazuaki Shimazaki II]

Originally Posted by whiskey111

I'm reading the book "Submarine-a guided tour inside a nuclear warship" of Tom Clancy. There are many interesting informations of US subs. One of the most important thing which I have read is that LA688(I) max depth is not more than 950ft (300m). This happened after reduce thickness of hull for obtainment of easiest weight of about 600-800t. This was necessary for mount new propulsion wchich was very big and heavy.
My question is: why in patches or LWAMI mods the true depth for LA is still more than 1500ft (460m) ?

I don't trust TC all that much, but seeing he's supported by Polmar and that author of Running Critical, this point is probably as credible as non-classified sources will get on the subject. Besides, Tom Clancy is not one to err on understating the performance of American weapons.

It is very doubtful for the 688 to be able to dive deeper than Thresher. They use the same grade of steel (HY-80). Barring a weak link in Thresher, the only way the sub could possibly gain any depth resistance is to have much lighter onboard equipment, thus allowing the hull to be thickened while maintaining buoyancy. Another alternative is for Thresher to have a much higher reserve buoyancy, and by cutting into that the 688 managed to thicken her hull, but there seems little evidence of this.

Since it is very doubtful this happened, the 688 would be lucky to tie. Rickover wasn't even too desirous of depth - a nice thing to have, but really there are more important things according to him.

IIRC, TC (and definitely Polmar) is referring to test depth, which in the US leaves a 1.5 safety factor before crush depth. So crush depth would be about 1350. If the test depth is 1000 feet, then crush can be 1500, so 460m is on the strong side of crush depth.

It is actually a little optimistic to enter the crush depth as the max depth in the DW database, because above that depth you are simulated to be absolutely safe. But within bounds of plausibility. A better move would have been to use Never Exceed Depth. But, customs choice...

For the Akula, according to Polmar you might push the depths a bit further yet and still be within the valid zone. The AK-32 steel they use is supposed to have a resistance of 100kg/mm^2, which makes it HY-140 equivalent (do the conversion from kg/mm^2 to PSI...). All that titanium cutting was worth it...

If true you can have Akulas with a crush depth of 960m and a test depth comfortably over 600m - you will almost be able to dodge Mk48s simply by outdiving them, and they would be so much slower at Max Depth with LW's new Torpedo doctrines meant to simulate the slowdown of torps with depth...