A Husband and Wife Build a 19th-Century Wooden Submarine

A nice craft and family project. From what I can tell from the photos, nice workmanship. I only have one suggestion, on the hand crank you need a few pieces of larger diameter pipe over the the crank rods to hold onto while you crank so you don't blister your hands as much.

As for exploding when the weights are dropped, I kind of have my doubts about that. You left the surface sealed with about 15-PSI and took it to the bottom. If you came up fast, you are still at 15-PSI, the only pressure difference is on the outside of the hull. If it were on the inside, you and the sub would be crushed.

Actually Phil the fear of the submarine exploding is well founded, since the pressure inside the hull is the same outside the hull at depth. Due to Boyle's law as the pressure increases, volume decreases; the ratio is about one Atm (15 psi ish) for every 33ft of depth at 1/Atm volume. So if the sub at 1 atm (surface) dove 99ft (3 Atm)the air in the sub would take up 1/3 the space at depth. however this sub matches the pressure outside so it won't crush so it has 3 Atm pressure at the full volume. If there is a rapid acsent to the surface the air in the submarine will expand to match the surrounding pressure and blow the submarine apart at depth. It's the same reason scuba divers have to exhale as they surface. Their lungs could overexpand causing serious injury or death.

DanMechEng, very nice description, but I believe the pressure at 30 meters is 4 Atm. Surfacing from this depth, air should expand 4 times it's original volume (as opposed to 3). This is only a minor detail.

wjrussell, Dan and you are both right, just different points of reference. Dan is referencing gauge pressure, you are right with respect to absolute pressure. Dan's is more correct for this instance, as the craft is not starting with a perfect vacuum inside on the surface, so a gauge reference (1 atm.=0 gauge)is more appropriate.

And to the Jackson's my congratulation, you are every bit of whom T.R. was talking about:
It is not the critic who counts, not the man who points out how the
strong man stumbled, or where the doer of deeds could have done them
better. The credit belongs to the man who is actually in the arena;
whose face is marred by dust and sweat and blood; who strives
valiantly, who errs and comes up short again and again; who knows the
great enthusiasms, the great devotions, and spends himself in a worthy
cause; who, at the best, knows in the end the triumph of high
achievement; and who at the worst, at least fails while daring
greatly, so that his place shall never be with those cold and timid
souls who know neither victory nor defeat. - Teddy Roosevelt

"It's a trap! Are ye blind?" Yep, it's a deathtrap, certifiable. The history of home built submarines is not pretty. Salute then scuttle.

Dang OldCarGuy, that's a nice compliment. Makes me feel a lot better about all the stuff I do that does not work. :) Thanks. And it's really heart warming to see people discussing Boyle's law. Best of luck to each of you and your projects.

Hey Nicholson, didn't you read the disclaimer? Keep your bike helmet on and don't make any left hand turns. :)

Doug "Death Trap" Jackson
Skipper, Argonaut Jr.