Im still trying to figure out how this works...
Step 1. All tunnels are dry.
Step 2. The finger drains at Smith's Cove will let water in but since they are located close to sea level, there is not enough hydrostatic pressure to overcome the air lock at the bottom of the Money Pit. The mp remains one big airlock.
Step 3. If vertical shaft 2 or the mp are left open, the water coming in from Smith's Cove would flood to sea level and you would not be able to seal them and create the air lock shown in the OIS schematic. So they have to remain sealed.
Step 4. The four tunnels under South Shore would have to be blown in sequence. If blown at the same time, there would be a race condition where the first tunnel to get water down the tunnel creates an air-lock keeping water from the other three from filling.
Step 5. As already mentioned, the mp has to have enough empty shaft for the hydrostatic pressure (50ft at south shore) to compress the air and fillthe Money Pit. Quick estimate...the shaft needs to be 240ft.
Step 6. Once the sea water overcomes the MP air-lock, the hydrostatic pressure would push the water out through the finger drain.
My take away...
This will only work if the MP is 240ft deep.
Perhaps you are over thinking this, please look again at the CAD.
1/ I did try to explain to you that when the mine was being used to receive treasure it was completely
Dry. When flooding was eventually required it was achieved efficiently by not sealing the Cave In Pit shaft, this opening would simply allow any air in the tunnels to freely escape without disturbing the Smiths Cove Filter drains at all. Those filter drains were later connected to deal with with the powerful incoming waves on the exposed Smith Cove beach, it was done after the mine was already flooded. The drains were designed to filter sea water filled with sand when entering at high tide levels,
not to let air out.
2/
ALL the tunnels on Oak Island were descending either from Smith Cove or the outlets off the South Shore, this allowed sea water to enter and aided by
gravity the unwanted sand contained in it would (by design) slide down, it would eventually settle at the bottom of the Money Pit Sand Sump. No amount of air trapped in
any Shaft would effect this simple process.
3/ The only vitally important trapped (and very long) air bubble started at the (relatively clear of sand) stagnant water level marked 25/ It was a deadly booby trap rigged to drown unwanted intruders who were trying to enter the below sea level Repository 30/ filled with Treasure.
4/ Regarding the construction off the off shore outlets. The only real danger occurred when the miners were excavating up to a safe height at the end of each ascending tunnel, they had to be careful not to accidentally let in the sea too soon. To avoid that disaster they could only put a lot off explosives at the end of each dry tunnel. this was in readiness for the day when (in order to close down the mine quickly) the fuses had to be lit.
5/ The fuses could have been lit either simultaneously or independently because no air in the lower tunnels 3 & 9 will suffer any air lock action because the Cave in Pit 2/ was left open at that stage, it was sealed later like all the remaining shafts., the first to be sealed were the air locked 33,32,29, and 27.
Oak Island Sage