Re: [PSUBS-MAILIST] No Machining Hatch Sealing Concept

[Jon Wallace <jonw@psubs.org>]

Hi Brent,

You have presented an idea that so far has garnered no support based 
upon reasonable countering arguments against the design.  No matter how 
many rings you add to the configuration to change the design, the 
functional issues remain the same.  The fact that Peter used this design 
on his sub and submerged with it could be fortuitous, since there is too 
much information missing such as depth, duration, and long term effects 
on the material that could weaken it.  A perfect example of not 
depending upon the fact that you did something, to continue doing 
something, is the Seaker100 accident.  They dove their sub successfully 
in the same configuration numerous times which led them to believe 
continuing to do so within the same parameters was safe.  It wasn't.

Since the idea has essentially been rejected, it would seem the next 
step if you truly believe the design is worthy of continued discussion, 
would be for you to prove the design by installing it and testing it on 
your own sub, and performing many dives to various depths including the 
rated depth of your sub over an extended period of time.  Then you would 
have much more data to bring back to the group such as the difficulty 
level of fabrication and even photos of how the materials are 
interacting with each other over time.  Since you are now rebuilding a 
K-250, this would seem like a perfect opportunity for you to install and 
test Peter's design if you believe it has merit and is something that 
others should consider.  That sort of hard data would be much more 
interesting and carry more weight than theoretical discussions.

The discussion has led me to wonder however, if a similar arrangement, 
but using o-rings in the resulting groove (or grooves) provide the same 
level of safety as an o-ring within a machined groove?  For the welders 
out there, how difficult would fabrication be, and how much time will be 
required, to weld on the bar stock?  It seems like more than $300 worth 
of work involved (in other words, might as well spend the money and have 
the groove machined) but I don't have enough welding experience to 
determine that absolutely.

Jon



Brent Hartwig wrote:
> *Hi Jon,  The square stock would give you a thicker base right off the 
> bat.  It might be that my Sekaflex sealing means is best suited for 
> subs that have a general operating depth of 300 fsw or less. But even 
> if that's the case, it could work for a good number of subs. Peter 
> isn't going that deep as you say. But I suspect the weak point on his 
> subs, are not the hatch sealing means. His hatch sealing arrangement 
> might be able to take a lot more then 100 fsw. You could add another 
> square ring to create another gland, and install a second thick O-ring 
> to more or less split up the load on the O-rings, until/or unless the 
> pressure becomes enough to make the hatch and hatch land go metal to 
> metal. You could make the interior O-ring a harder durameter hardness, 
> and make the exterior one a little larger cross section size and 
> softer for sealing more easily at the surface, as is done on the 
> SEAmagines.  One example of a primary and secondary seal on a hatch 
> using thick O-rings is this one.*




************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
	removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************