Help Required On Home Project
08-21-2009, 08:20 PM,
Help Required On Home Project
Hi Everyone,

Im new to the forum, not an engineer & I am hoping you maybe be able to help/guide me on a home project but firstly,

...Im 22, irish, currently studying Pharmaceutical Chemistry & an avid rec & tech diver. project is simply (or maybe not) to build a "scooter" or for its technical term, DPV, Diver Propulsion Vehicle which is a underwater propulsion system.
[link dead]
examples attached above.

My plan thus far is to use mains gas pipe with is plastic, approx 25mm (1inch) thick, which is rated to 10bar (147psi). I would rebate this like a tongue & groove setup so three o-rings can sit there, use loop latches to seal the two body pieces together. To achieve this I have located a large lathe. The o-rings will be x-ring which will trap air & thus seal better.

I have big 12v batteries for the power side of things that I can rig up to 24v etc

For the electrical set-up I will run a wire through the housing into a handle which will be for holding onto while using the DPV, fill this handle with electrical potting compound to waterproof is with a magnetic reed switch for stop/start with the magnet stitched into a diving glove on my hand. So basically when I grab the handle, the magnet will cause the reed switch to closes & off the DPV will go.

Now is where Im confused, motors! Ive been advised to use a DC brushless motor but alot of models use sealed trolling motors but Im lost as of which one's because of the sheer choice of motors.any help would be great.

Next is the shaft & how to seal it for the water. Its be suggested to use a rifled shaft so that when the DPV is running the water will be pushed out constantly but what about when the DPV is not running.any help here would also be great.

The propeller will be plastic, some commerically available units have metal blades but I think plastic would be better for safety in case someone got a limb into the prop then the blades would break as appose to chop limb off.

So any help will be greatly appericated on the issues I outlined above & if you have another ideas to improve please say so.

08-22-2009, 08:43 AM,
RE: Help Required On Home Project
Dear Ian,

welcome to surface engineering Forum,

we are a dedicated forum to discuss and solve surface related issues like corrosion and wear and temperture resistivity of surfaces. I hope you may found sollution at any of the mechanical engineering forums.

I wish you all the best for ur project

09-07-2009, 04:31 PM,
RE: Help Required On Home Project
Hi Ian

Sign0016 to the Surface Engineering Forum.

Interesting project. Not sure I can help, but may be someone else can. I will move this thread as it is not strictly surface engineering.
09-07-2009, 04:40 PM,
RE: Help Required On Home Project
Hi SeyCren and ShockWave17

Seems like Sign0014 - Please prove me wrong, otherwise your posts will be deleted and you will be banned from SEF.

(09-02-2009, 06:03 AM)ShockWave17 Wrote: Unity can lead you to succcess. So, you better help each other towards the attainment of a certain goal.

Sample storage

(09-03-2009, 03:13 AM)SeyCren Wrote: I achievement you may begin band-aid at any of the automated engineering forums.

Furnace filter
09-08-2009, 07:07 PM,
RE: Help Required On Home Project
A simple lip seal or even a packing gland can be spec'ed for your propeller shaft to keep water out of the DPV. Choose a propeller shaft material which will not corrode under water. It does not need to be real hard. A low grade stainless steel would be sufficient. The sealing surface should be very smooth to avoid chewing up the seal.

If you wanted to completely avoid the lip seal arrangement, you can also buy magnetic couplings. The cost would be significantly higher, but they would allow you completely seal your motor inside the DPV, completely eliminating your problem. Then your problem becomes how to support your propeller shaft.
12-14-2010, 07:48 AM,
RE: Help Required On Home Project
Hi !
I've just visited this forum. Happy to get acquainted with you. Thanks.


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