Unmanned Submarine

Not sure how well the GPS will work underwater. H2O is a great attenuator, that's why subs have to send things up to the surface to establish communications etc.

There was a documentary I watched a couple of years ago where a group created an autonomous sub and sent it across the Atlantic on its own none stop. Cant remember the name of it but Im sure a Google search would soon find it for you

I looked at their project and yes the gps signal would have to be transmitted once it surfaces.  Probably have to program some dead reckoning type logic for the subsurface course.  So I guess it would also require a compass and a way to measure drift/current/speed.

Quad Copters have all the sensors you may need

Accelerometers to detect drift and turns to help with direction and inclination, barometer for depth sensing or other model pressure transducer

GPS for when surfaced to re-set the dead reconing system

How deep are you planning on going with this

Yes I also found a trial test of the glide type AUV's (like the one Rutgers launched) which listed the manufacturer of the electronics they used.  Checked their website and waiting on some pricing.  Only plan on going as deep as needed to avoid boats and shipping, so prob 50'.

Hi Tom, It might make sense to plan for surface travel except when it gets to areas of interest. On the surface you could use GPS for navigation and a satellite phone for communications as well as solar for energy. Under the water you would have difficulty even detecting if you were in a current or not. I am sure that there is mapping of major ocean currents that could be used for estimating drift. How big are you planning on making this submarine? Size is a consideration as scaling smaller reduces volume needed for battery capacity and infrastructure. This is illustrated by the reduction in range of small drones as compared to the large ones.

Good luck, ideas like this are fun to think about.

John

Actually depth will have to be variable due to reefs and shallows here in South Florida until out in open water.

Wanted to stay sub surface as much as possible only surfacing for solar recharging and position checks.  Wanted to keep it small as possible. No more than 1 meter in length hopefully.

50' is a lot of pressure, meaning thick walls and less room for kit

Waterproofing will be a big challenge as many parts will require external mounting with holes for wiring to get through to main part of sub

Made a propulsion type system once for diving using PVC and lexan.  It was able to stand more pressure then I will need at 50' little less than 44 psi.  Yes it will be challenging to maintain water tight integrity with any penetrations so the fewer the better.

Here is a link to a book about the technology on AUVs that might be of interest.  http://www.amazon.com/dp/0415301548/ref=asc_df_04153015483180506?smid=ATVPDKIKX0DER&tag=pg-1583-86-20&linkCode=df0&creative=395097&creativeASIN=0415301548    . The specification of 1 meter in length coupled with the need to keep the shape hydrodynamic will limit your space for batteries. You might get an hour between needing charges. You will also have to have a high pressure air supply on board to control depth with ballast. This will be a consumable resource and will limit the number of times you can go up and down unless you have room for a high pressure compressor and related support mechanisms. Your other option is to have the sub slightly positively buoyant so that it will naturally float to the surface. The disadvantage to this is that it will have to use its planes to pull itself underwater and this will increase the resistance in the water and shorten the distance between recharges. When one starts to think about all the complications it makes you really appreciate the advantage of a biological organism like a fish that can swim and dive for years, pull its fuel from the environment, and probably know exactly where it is all the while.

John