Carsten is absolutely correct here. You can't calculate failure depth from operational depth. If you plug the K-350 design data into the PSUBS hull calculator (thank you Cliff) you'll find that it's predicted failure by calculation is somewhere around 875 feet. George applied a 2.5x safety margin to limit max operating depth to 350 feet.
If you know the max operating depth and the safety margin you can calculate the failure depth, however you cannot assume either one of those data points. The failure depth must be calculated either by formula or FEA. Even then, it is a prediction not an absolute number.
Jon On 12/11/2010 4:47 AM, MerlinSub@t-online.de wrote:
Hi Guys wrong way thinking! You have to know the failture depth and than reverse from that the maximum opertional and test depth. Without to know the failture depth you know nothing.. The calculation goes that way: 01) calculate failture deep 02) divided by minimum saftey factor (2,0) is operatioanl depth 03) mutiple by safty factor (1,25) is test depth Note that some sub designers use higher saftey factors because there 60-70ies calculations are only rough. Recalculation of this subs iwith modern analysis method may result in higher dive depths (or found conctruction mistakes). vbr carsten "Alan James"<alanjames@xtra.co.nz> schrieb:Hi Scott, I've heard that George Kitrige advised that his boats be tested to twice their operational depth unmanned for an hour. So this would mean that there failure depth would be more than 700ft. I'm not sure what their failure depth is; someone else may be able to help with this. Regards Alan ----- Original Message ----- From: Scott Waters To: psubs Sent: Saturday, December 11, 2010 3:12 PM Subject: RE: [PSUBS-MAILIST] Design depth I'm confused, haha. So on a K-350, the operating depth is 350 feet and the test depth would be 437.5 feet (multiplied by 1.25) and the failure depth would be 600 feet? I'm just trying to understand the thread of posts. -Scott Waters
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