[PSUBS-MAILIST] Veiwport sealing

Mon Sep 16 09:53:43 EDT 2013

Hi Hugh,

No worries-you did it the right way. There are definately advantages to using a gasket, especially on smaller ports where you don't have to worry about overpressure causing a blow like you might have with a big dome. If you have a strong enough method of retaining the dome then that should not be a problem anyway. Obviously, we are talking about domes with a square edge ( not a conical seat).

Glueing it in is just a low tech method- but hey- back in the 80s there was no psubs website for all this great info- I was just "wingin it". I probably just asked George if he would glue it or use a gasket and he said "Glue it"! George never did like o-rings....

Greg

________________________________
From: Hugh Fulton <hc.fulton at gmail.com>
To: 'Personal Submersibles General Discussion' <personal_submersibles at psubs.org> 
Sent: Saturday, September 14, 2013 7:26 PM
Subject: Re: [PSUBS-MAILIST] Veiwport sealing

Greg,  I was under the impression that flat viewports are best to have the sealant between the gasket and the steel seat rather than on the acrylic.  Is this acceptable just on the one side.  Would this prevent having to demolish the viewport in your case.  
Or did you have just the UV sealant and no gasket?  I am concerned at what I have done which was on the gasket only.  Regards,  Hugh

From:Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of greg cottrell
Sent: Saturday, 14 September 2013 8:06 a.m.
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] Veiwport sealing

Just a short commercial about 295 UV-

The first forward dome in my sub was bedded in 5200 urethane by 3m (which is advertised as a marine sealant and used for acrylic ports on boats). About two years went by and I noticed that the seal looked different. So I removed the retainer and the dome literally fell out in my hands!  Wasn't expecting that! Luckily I caught it before it hit the ground. The surface of the 5200 was perfectly smooth but it had lost all adhesion to the acrylic. It looked like a rubber gasket.

I then removed all of the 5200 and re installed the dome with 295-UV (and the black primer that goes with it).
The dome spent the next ten years installed with lots of dives and no problems.
Eventually, because of its age, I decided to make a new one to replace it (although it still looked like new). I tried to push the old dome out with a 4 x 4 and a hydraulic jack from the inside. It wouldn't even budge. I pushed it so hard that the 4 x 4 was starting to split! The dome wasn't even phased! After a couple of hours I finally took out the recipro saw and cut the dome into radiating pieces to try to pry them out one at a time. Using a crowbar, the acrylic was breaking into pieces but broken shards were still stuck the sub! It took quite a few hours to remove the sikaflex- mostly with wood chisels (heated with a torch) and a wire wheel.

So, all I can say is that if you install your domes or ports with 295-UV those ports are NOT coming out without a lot of effort!

Greg

From:"MerlinSub at t-online.de" <MerlinSub at t-online.de>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
Sent: Friday, September 13, 2013 2:24 PM
Subject: Re: [PSUBS-MAILIST] Veiwport sealing

 http://www.svb24.com/en/sikaflex-295-uv-adhesive-for-plastic-window-panes.html

vbr carsten 

"swaters" <swaters at waters-ks.com> schrieb: 
Where do you buy the material you use to seal veiwports? I have heard everyone saying sikaflex but there are alot of different kinds of sikaflex and the one west marine sells says it is not compatible with plexiglass. Help?
Thanks,
Scott Waters

Sent from my U.S. Cellular© Smartphone

-- 

Carsten Standfuß
Dipl.Ing.Schiffbau @ Meerestechnik
Heinrich Reck Str.12A
18211 Admannshagen

0172 8464 420
http://www.euronaut.org/
Carsten at euronaut.org

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