[PSUBS-MAILIST] G.L. summary Design Loads

[Alan]

Hi Jim,
Yes you are right.
I used feet as an illustration, where they use metric pressure
in their table. 
I like their scale system, because if you are building for a
shallow depth, with a thin sectioned hull, then any small margin of
error will have a bigger impact than on a thicker hull.
As a simple illustration, if you were building 3mm thick & ended up
2 mm that's a 33% error, whereas if you built 10mm thick & were out
by the same 1mm, that's only a 10% error.
Alan
Sent from my iPad

On 7/12/2013, at 5:11 AM, Jon Wallace <jonw at psubs.org> wrote:

> 
> Jim,
> 
> Yes, there's certainly a point in all brackets where it would behoove the owner to bump up the nominal dive depth (operating depth) to take advantage of lower ratios.  I believe ABS uses a static 1.25 ratio for all vessels regardless of operating depth.  GL would appear to be more conservative than ABS in this category.
> 
> Jon
> 
> 
> On 12/6/2013 6:03 AM, jimtoddpsub at aol.com wrote:
>> Hi Alan,
>>  
>> If I understand the requirements correctly, then for designed maximum operating depths of 320 feet and the 340 feet respectively the test depths would be as follows:
>> 320' x 1.4 = 448' test depth
>> 340' x 1.25 = 425' test depth
>>  
>> And the designed collapse depths would be:
>> 320' x 2.4 = 768' collapse
>> 340' x 2.0 = 680' collapse
>>  
>> Therefore if my designed operating depth is near the lower limit of a bracket, increasing the stated operating depth enough to push it into a deeper bracket would actually lessen the requirements for test depth and collapse.  Do I understand correctly?
>>  
>> Thanks,
>> Jim
> 
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