I use 2 Component Acrylate Glue (UHU Plus Acrylit / Stabilit Express) and sometimes slow setting Epoxy (UHU Plus Endfest 300) for most cases in my subs especially when different materials need to be bonded.
Check these out : - I didn't know how to edit my video so I explain here what is about it . That method used on video was applied to make the holes for flooding the hull . As I sad before , these type of material (fiber glass resin ) is great .
I never understood so many flood holes when the vent holes are only so big. Only so much air can escape not matter how many flood holes.
Besides USA boats are not fast at diving anyway. The ballast tanks are under pressure due to bottom of boat being open to sea. Unlike Russian boats which use Kingston valves and the pressure in the tanks on the surface is equal to open air.
The models with their very small vent valve openings can dive only so fast. I think most of the flood holes could be deep scribed and everything would work just fine.
Can you tell. I don't like all the drilling and filing of flood holes. Number one reason I haven't built old boats with all there deck openings.
I remember years ago when we here in the USA would talk about the European boats that are dry hulls and their weighing so much more than our wet hulls.
Actually the only real difference in weight is after our boats are out of the water and drained of water. Much easier to move around and work on than the fixed ballast weigh. But I must say some of those European boats are design marvels.
I have long wondered about building a early US boat that has a fixed external keel and actually building in a slot almost the full length of the boat down the center line hidden in the bottom of that keel with bridges every so often to keep it's strength. This is because the boat in mind does not have ballast tanks open to sea but internal tanks that where pumped in and out through only two 3" pipe openings.
The ballast tanks are under pressure. The tanks have pressure in them to hold the water out and keep it out. So the pressure in the ballast tanks on the surface is equal to the pressure cause by the water at 43'+-. Sort of.
The Russian boats have Kingston valve on the bottom that close once all the water is blown out. Then the top vents are opened and the pressure is released. The pressure in the tanks is now equal to outside pressure. The Russian subs are basically floating as a surface ship would.
Russian sub can dive faster due to not having to release the extra pressure in the ballast tanks. US subs have to dump the pressurized air from the tanks which take a little longer.
Then again this all depends on boats of the same volume.
I don't think we do emergency crash diving any more. We go down and stay down until patrol is over.
Experiment. Take a clear water glass and turn it upside down. Put it in a bowl of water. As you do, the water level will rise in the glass compressing the air until the pressure builds up enough to counter act the water pressure pushing up in to the glass. The water level will then be stable. A submarine uses pressured air to counter act this and blow the water out.