Dear Sirs;
First, let me say hello and thank you in advance for your time.
I’m considering building a submersible with the following characteristics.
L: 25’
B: 6.5’
D: 2.5 - 4’
Operational depth 30’ – 50’
Brief dives to 60’
The vessel will conduct itself primarily in semi-submerged/ low-profile condition (aside from the conning tower stacks etc.), showing full freeboard only in harbor, or as dictated by necessity. At the desire of the operator, the vessel can make brief, excursion dives up to the aforementioned depths.
The exact depths are yet undecided.
In other words, I’m looking to build a David-boat/Monitor type vessel capable of excursions to a designed depth, mostly 1.5 to 3 atmospheres with extended submerged endurance. Early-early WWI submersibles were treated (and designed) as surface-craft with limited submersible capability. I would like to mimic this design concept.
The nature of these requirements clearly points to a dry-ambient submersible but I wish avoid the dry-ambient for the reasons of decompression. Even at thirty feet, there are no-decomp limits, and I would like to avoid these issues if possible. Although I’ve considered limiting dive depths to 20’, in which case ambient would make sense.
Materials:
Some pre/post-Victorian vessels were made of thick wooden planks, metal sheathing, riveted construction, and included deadlights and scuttle-glass portholes. Many of these vessels were capable of greater depths than I am now proposing. What are some today’s hull materials that could give me the same performance more cheaply?
Why not consider steel/fiber/carbon/etc. reinforced plastics, or wood, given the limited design parameters. Indeed 60 psig is large, but it seems a trifle to many of today’s resources. Far older and more poorly designed submersibles dropped past 70’ with materials of lesser quality – and lived to tell the tale.
Would it be folly to sink 5’ in a hull made of 3” wood? What about10 feet? or 25? At what depth does wood betray you to the abyss?
What about 5/16” steel? Would I be called an engineering marvel for using 5/16” in a vessel designed to dive 5’ feet?
Personally, I suspect that most industrial strength materials will bring you safely back from a depth of <33’ – even those of mediocre design. Informally, it appears that most shallow water (1.5 – 2 atm) accidents related to through-hull/porthole failure, as well as entanglement and swamped with decks awash. Hull failure due to pressure buckling appears to be a rare event in shallow waters. I could be wrong, of course.
Ultimately, I suppose I’m looking for design/hull-materials advice given the operational characteristics I’ve already mentioned.
Thank you all for you time and I look forward to a response.
TC