rescue subs

[jehardiman]

Originally Posted by JLIMA

I spent about 11 years submerged (at about 3 month intervals) and I can tell you unless your real deep your going to at the very least have a hard time keeping depth when shallower that 200' down, on the surface even small waves give huge angles compared to a surface ship the same size. For example we were coming into Puget Sound in a sea state 2 and were taking 15-20 degree rolls much sea sickness all around, all that on a boat just short of 300'. The "life sub" might have some merit though imho.

No, a "life sub" would have worse motion because both initial and absolute stability would be lower. Ask anyone who has been in a DSV in chop or swell; you only see them being deployed in DFC for a reason.

Originally Posted by bntii

I have wondered about this.

My thinking was that challenges would include stability issues as the sub travels through laminar flows based on haloclines and thermolclines near any tidal body. I had not guessed that the surface turbulence would print so low.

No easy task to control these subs it looks like.

While halocline and thermocline fronts can be exciting for the control party, they are basicly a static balance problem and are easly overcome by planes and hull angle except at extreamly low speeds. Wave motion is a function of wave orbital decay and impossible to completely control out, much like roll stablization on surface ships reduces roll but does not remove it. Many people who are not seasick on the surface because they have a stable horizon, lose it submerged when the longest sight distance in the boat is all of 30-40 feet and you have no horizon.

FWIW, wave orbital effects are generally felt up to 1 wave length deep. This means that most local sea (5-7 sec period) motion is not appreciable to most people deeper than ~100 feet below the trough even at maximum wave heights (~1/7th the wave length). Swell (~11+ sec) on the other hand, especially in the Pacific, easily penetrates to operational depth.

Additionally, just as a discussion point that has already been brought up, a fair amount of submarine technology falls under the Wassenaar Arrangement (http://www.wassenaar.org). Now the enforcement and laws relating to the transfers of conventional arms and dual-use goods and technologies are country specific, but are enforced by the US, Canada, and most of the EU. A web forum is a fairly public place and one should always be aware of the trouble they could get into.

[Paul No Boat]

Damn, you guys know your stuff.

My question was somewhat juvenile but by the responces I guess you all like the concept. maybe in the future there will be boat designs that can maintain stability on the surface and still submerge to reletive safety under the storm. 50 years ago who would ever have thought there would be ships that could sink to get under their cargo and then lift it above the surface?

as far as seasickness goes, if that's the alternative to drowning, then bring on the nausia. LOL

[jehardiman]

Originally Posted by Paul No Boat

Damn, you guys know your stuff.

My question was somewhat juvenile but by the responces I guess you all like the concept. maybe in the future there will be boat designs that can maintain stability on the surface and still submerge to reletive safety under the storm. 50 years ago who would ever have thought there would be ships that could sink to get under their cargo and then lift it above the surface?

as far as seasickness goes, if that's the alternative to drowning, then bring on the nausia. LOL

Actually, you are far safer (by man-mile) on the surface in a storm than submerged just due to the inherent risk of being submerged. A submarine of the capability you imagine is more complicated and expensive than Space Ship 1 and a much more expensive to maintain (I have a note over my desk that says "NASA has it easy, because IT IS only rocket science and they throw it away after one use"). Submersibles or submarines are not consumer items like cars or even commerical aircraft. Even 100' max depth tourist subs, which is the closest thing to commerical mass produced submarines, number less than 100 wourldwide.

As for heavy lift ships....old concept dating from just before WWII, look up LASH ships, LSDs, or ARD's.

[Paul No Boat]

Holy Smoke, jihardiman I am learning a lot here. I admit I am a boating weinie. But I have fallen in love (again) with the water having spent 2 weeks last September in....are you ready for this? PORT ORCHARD, WASHINGTON where I toured the peninsula from and went out on a whale boat from Port Townsend. and I grew up in Chicago in sight of Lake Michigan which is no small pond either.

I think it runs in my family as my only maternal uncle was somewhat of a hero in 1942 when his merchant marine ship "John Carter Rose" was torpedoed off the coast of Venezuala and he (a leutenant) led a lifeboat and was rescued after five days by an Argentine tanker.

http://www.uboat.net/allies/merchants/ships/2248.html

The irony of the story is that after ww2 he returned home and while sailing on Lake Ponchartrain with his wife of 10 months and another couple, the sailboat capsized and he was never found. quite a family legend and I regret I never got to know him as this was before I was born, but family members who knew him say I am his reincarnation. Maybe that's why I am so drawn to the subject of rescue.

I love Port Orchard and the whole Seattle area and hope to spend many more visits there with my daughter and granddaughter. and my son in law who is a welder at Bremerton and I talk over the idea of partnering in a small boat to go salmon fishing. hence my interest in this design site but I am considering becoming a member of The Center for Wooden Boats in Seattle just to learn from the best and enjoy some of my visit time out on the sound. Can't wait till my granddaughter is old enough to take out on a boat. Had some Pike Place Market Jelly at my sister's on Thanksgiving. Awesome!!

Learning all I can here appearently from the right people too.
Thanks for your knowledge and willingness to share it.
Bless you and Merry Christmas to you.