[PSUBS-MAILIST] Conning tower hatch O-Ring

Mon Oct 20 03:41:20 EDT 2014

On the R300, I use a standard sized O-ring with specified dash number with o-ring grove designed based on PArker free software to match the o-ring.  I  installed this on the lower hatch face. While this o-ring has provided a watertight seal, I find that sometimes the o-ring can become dislodged.    Based on lessons learned,  going forward, my new boat is designed with a 1/2 dove tail grove on the upper hatch exactly as Alan has described, i.e., external pressure force ring into flat side.   Going to the 1/2 dove tail grove should keep the o-ring from popping out of the grove while not impacting its ability to seal . Putting in the o-ring in the upper hatch face will keep garbage out of the grove.

While you can make up o-ring to any size by cutting and gluing, I know of one case in another boat in which this caused a small leak because they got the length wrong and were not precise enough on aligning the ends when adhesive.  To me it is better to use the Parker  software which is on online, and pick a standard dash number and design the grove to match this o-ring.  O-rings are cheap and this tends to remove the two issues that caused this leak,

Cliff

________________________________
 From: Alan James via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Sunday, October 19, 2014 10:38 PM
Subject: Re: [PSUBS-MAILIST] Conning tower hatch O-Ring

Hi Mark,
I have heard of people with the square grove having trouble with the O-ring falling out, & having
to stick them in with copious amounts of grease. That could be a sizing issue though.
I think it's a 1/2 dove tail grove they have on the K boats with the angled edge to the outside so that
the O-ring is squashed by external pressure against the flat side of the grove.
(someone correct me if I'm wrong)
I vaguely remember Phil saying the Deep Workers have the 1/2 dove tail grove.
Alan

________________________________
 From: via Personal_Submersibles <personal_submersibles at psubs.org>
To: personal_submersibles at psubs.org 
Sent: Monday, October 20, 2014 1:03 PM
Subject: [PSUBS-MAILIST] Conning tower hatch O-Ring

Hello Psubs group,

I would like to ask the group where I can purchase an O-Ring for a 24" conning tower hatch ring.  I also need to mill the slot in the hatch ring and would like to know the width and depth of the slot.  I've heard some folks recommend a dove tail slot for the O-ring. 

Many thanks for your advise.

Mark...
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