Well now remember you asked for it. : )' Here is a hatch 3D CAD model I was working on for use on allot of different PSUB's. I was thinking it would be a workable basic design for a hatch on the K-350 and K-250 model submersibles. I was always a little worried about the unprotected half sphere acrylic domes on the K-250. Part of it is based on the hatches used on the U Boat Worx submersibles http://www.uboatworx.com/flash/index.html and the DeepWorker subs http://www.nuytco.com/products/subs.shtml.
Now keep in mind this is a unfinished basic concept design so there will likely be some resizing of things for various reasons. It could be made out of stainless steel, carbon steel, or aluminum. I don't have the hinge and spring models done just yet but there is plenty to see here. I will also be adding the hex bolt and washer fastener's to hold the protective bars to the top seal plate. Also there will need to be a rubber contact on top of the dome attached to the protective bars to hold the dome tight against the two bottom O-rings while on the surface. I may also need to add more space between the protective bars and the dome.
With regards to O-rings for hatch sealing, most the O-rings I've seen on subs are of a small diameter. For what reason I'm not sure but I would guess it has to do with not wanting to have a lot of rubber to keep compressing at greater depths. So for the moment I have four larger O-rings in this model. I'm using a double O-ring set up for the dome, as well as the hatch seals for back up protection. This may not be the best way to go about it, but it looks good to me so far. I've seen and installed allot of plumbing products that have back up O-rings, so it must work, right. Any way the O-rings in this model are in a compressed state.
You'll also notice I got a little groovy putting a small trough groove in the lower hatch sealing plate, on the inside of the two O-rings. This is for dealing with a slow leak in the O-rings, and/or for draining the small amount of water that gets on the lower seal plate. When I was on the Atlantis tourist sub in Kona, Hawaii a while back they had water dripping in when they opened the hatch at the surface and had to have towels to clean it up before we could exit in dry comfort. I don't want to get wet ya know or I'll melt. I'm melting, I'm melting. Any who, I'll need to drill and tap a hole on the underside or the bottom seal plate and then attach and run a stainless steel tube down to a high pressure sump pump.
That's all folks
Regards,
Brent
"The reasonable man adapts himself to the world: the unreasonable man persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man." - George Bernard Shaw