Human powered submarine

Hi folks, my son is building a human powered submarine (wet sub) to enter the international submarine races. I thought folks might be interested to see how it’s going. We are about half to 2/3 done with the hull structure. Check it out on YouTube. We are making it all up as we go so advice and recommendations are welcome. Powertrain is getting worked on now. It’s been a blast!

 

I'm guessing Naptown USA? AKA Indianapolis.

Great project, great video, great way to die, so please do be very mindful.

Just because I know it's going to come up eventually, you're going to get ~100 watts of power at the prop , sustained.
And 200 - 250 watt bursts of 1 - 5 minutes depending on the individual's level of fitness.

Pedal drive?

 

Yes pedal drive. See the latest video where we chop up a bike. Looking to run the chain to a shaft across the boat to two different props connected with a bevel gear. Currently looking at angle grinder bevel gears as a cheap and easy way to shift the drive 90 degrees. Some said they are too weak here. Wondering if We split the power between two props if these can handle the power? Any thoughts on that? The drives folks recommend are pretty spendy.

 

Oh I forgot to answer your question. We are in Annapolis Md

 

Thank you.
That was actually what I meant.
(More to follow...)

 

The drive gears are the pricey part I'm afraid.
Torque is the issue, they can't handle the big push that occurs just past top dead centre in the pedal rotation.
Twinning your props won't help at all, it may make it worse.
Spend the money on the Matrix 1:1 or build your own using swivel drives from the socket wrench world.
A guy named Jeremy somethingorother posted on here years ago built a really cool 90 degree drive.

 

Ok, where to start.
If you are doing this for the International Submarine Races (ISR), please read the safety requirements well and make sure you meet them all. It would not help to get there then have to spend your time modifying your boat like I have seen many teams have to do. Make sure all the "i"s are dotted and 't's crossed. BlueBell is correct here, there are many ways to get hyperbaric trauma doing this; in the case of a casualty, speed and your own air are your enemies. You need to make sure you have a way of getting all the trapped exhaust air out of the boat as fast as a scared person can breathe. This is a major failure of first-time teams.
Next, try to get your hands on all the ISR publications, especially the ones that include team research papers. I don't know if there have been any from the recent races, but I know the 1991 and 1993 races were documented by IEEE.
BlueBell is also correct here that ~100 watts is all you will get sustained, but because the race is no longer an open water race but a speed trap in a tank, you should expect ~200 watts for the 2-3 minutes. As for the gears, a well trained bicyclist will put out ~450 ft-lbs of torque on the cranks.
Finally, I have to ask if this is an "experience" project or a "win" project. Very different how you go about each.

 

Great video.
You can mount the crank arms right onto the Matrix 1:1 box and run a curved 3/8" spring steel drive shaft straight out the back to a 18" x 0-18" variable pitch prop.

EDIT: That is incorrect, I forgot the 6:1 up gearing... How about a bigger prop? 24" x 0-24" VPP.

 

Wow thanks so much for the replies folks. We are considering a win to be a successful run down the course and maybe meeting some folks from good engineering schools. Hell it’s already a win, we are having a blast with this thing. Once the race is over he plans to convert to electric trolling motor propulsion. Good tip on the socket swivel drives. I was really hoping for that grinder gear because they are cheap but you guys probably know best. Is there a lot of friction loss with the socket swivel? The sub design pretty much calls for twin props because of its shape plus we can have better maneuvering with two trolling motors later on. I don’t think two flexible shafts would work with the configuration? The hull design is high drag compared to the typical torpedo shape but we can live with that for the cool factor. Not going to beat a university team anyway so may as well make it fun looking. I will post some of the latest pics so you can see what I mean about the hull shape.

 

Build pics from last week (upside down) and one of the mock-up to show what it looks like from the top.

 

Re the getting the exhaust air out of the boat, do you mean the air in the cockpit? Do most teams just have a hole above the drivers head to release the exhaled air? We have read the competitions guidance manual and know about the float, dead man switch, strobe light and orange colors for emergency releases and such. I don't think I saw anything else that was more specific, though I will have another look.

 

Sorry I keep replying so much but you guys have so much knowledge here. My assumption is that the shape of the boat precludes a singe prop because the *** on this thing is so wide and we won’t have clean water flow if we mount it in the back. Is my assumption incorrect? I imagined two props sticking out the sides would work better. Plus that’s what the kid wants and it’s his project. One thing I’m not doing is overriding his design unless it’s safety related. I don’t want this to be his thing that’s really my thing, if you know what I mean.

 

It blocked out *** so let’s just say transom lol

 

Pic of stern for reference

 

I found Jeremy's post #1549 in:
Pedal Powered Boats https://www.boatdesign.net/threads/pedal-powered-boats.23345/page-104#post-552378
Seems to me he went into it in much more detail, perhaps somewhere else.
You can search for more now that you have his full name.

Also, I got the name of the 1:1 box wrong!
US$300 each, and your going to need two for twin screw.
You could easily sell them for what you paid for them when you're done.

EDIT: I found this while trying to find the name of the 1:1 box.

Post #9
Homemade stern tube https://www.boatdesign.net/threads/homemade-stern-tube.44918/#post-585212