Finally, DIY DPV sneak peak...

[willydiver]

Finally getting close to completion on my DPV. It's not the prettiest beast by any means, but it's a first shot at a prototype. I've still got to roll a piece of aluminum sheet for a prop shroud. The hose clamp that secures the motor in place and the toggle switch aren't shown. Toggle operates a relay that closes the circuit on two 12V12ampHour SLA batteries. I rebuilt the seals on the trolling motor. It's a 52# thrust. Used acrylic for the lid so I could detect any leaks. Body is made of 6" Scd.40 PVC. The handle was shaped out of 1" thick PVC sheet. There are definitely some weak points on this design, but this is a first iteration.

WD

 

[ShoalDiverSA]

Willydiver,

That looks great - good job!. With the handles so far forward, you better have a good prop shroud, otherwise you might change your name to just "diver" .

I think you have taken the best route for getting a DPV made easily. A modified trolling rig seems to be the way to go. I have tried to get parts for a more conventional scooter a-la Gavin, with no success thus far...

Having said that, I have also tried to get trolling motor parts here, but you either buy the whole thing or nothing. Gotta love it.

Have you done anything to improve the propeller shaft seal? I would think that the dynamic seal on the shaft of a trolling motor will not be rated for SCUBA depths. I recall reading that some of them use a grease packing instead of a dynamic seal - which I guess would really not work for SCUBA.

You have really done a neat job. Given the simplicity, maybe a low-cost production model might be in order...

I suggest that you get rid of the toggle switch in your next iteration. A reed relay switch would be much better (from the perspective of reducing hull penetrations and therefore (hopefully) failure points). You could use a reed relay from a home alarm system (typically used on door and window sensors) to switch a high-current relay (automotive headlight relays are cheap and easy to source). The mounting of the magnet externally will probably be the biggest challenge, but judging from your work, you should not have a problem getting around that.

Cheers,

Andrew

 

[Tom Winters]

After you get that baby working, you're going to have to change your name to "Willypedo".

 

[willydiver]

Willydiver,

That looks great - good job!. With the handles so far forward, you better have a good prop shroud, otherwise you might change your name to just "diver" .

Andrew, thanks for the nice words and suggestions. This project definitely was a challenge! The toughest part is utilizing (making them work) the components that I was able to obtain. As you mentioned, finding a suitable motor was the most difficult part.

I settled on the trolling motor because it is already designed for marine use and was cheap ($20, used at a local boat shop). There are some disadvantages to it, though. I don't particularly like the power cord having to be exposed like that. I couldn't get around this because there is no way to run it through the interior of the motor casing. There is a rotating rotor in there. It's ugly, I know. The cable glands in the motor mast and the battery cannister are potential leak points.

The original shaft seal is composed of two rotating shaft oil seals stacked together. No doubt, with some machining, a shaft seal that utilizes a compression spring would be more secure, but I opted to try the stock set up. I did replace the seals, as well as the main body orings to help out. I have heard a range of statements on the depth ratings of "off the shelf" trolling motors. Some people say they've had them down to 100' with no problems. The manufacturers will only commit to 10'. I'll have to gradually test it to see. I'm fairly confident in the water tightness of the battery cannister.

Suprisingly, I wasn't able to find a small, inexpensive DC motor to use from the interior of the battery casing. It would be fairly easy to machine a bulkhead utilizing compression shaft seals. If I could ever find a source for a cheap motor with a stainless steel shaft. Of course, heat dissapation comes into play with interior motors. The overall looks would be alot cleaner versus an exterior trolling motor.

I'm impressed by the Gavins, Farallons, Dive Rites, etc. but they all have one "non-DIY" characteristic in common. They all seem to use the same manufactered motor/handle/prop component (I think from Oceanic?). The sleek looking cannisters look great all the way to the business end, and then you see the same old motor system. I know, this system is "tried and true", but I'm not into just buying the main part of the project and bolting it onto a battery cannister. Got to be a way to build these from scratch.

The toggle switch mechanism is probably the highest potential fail point in the whole project. On the next go-around I'll probably utilize a magnetic reed switch or a camera housing control like Ikelite produces (suggested by mddolson). I'll give this design a try and am sure I'll be back at the work bench trying new ideas.

This project is definitely a first shot at a DIY DPV. I know there is alot of interest in them from this group, so any and all suggestions are great. This one is not really meant to be used for deep cave penetrations or deep technical diving, just to play around with in relatively shallow water. More of a concept trial than anything.

Definitely would save money on haircuts if used without a shroud! I'll continue to post pics as I get the shroud on and other finishing touches.

Thanks again for the input!
WD

 

[willydiver]

After you get that baby working, you're going to have to change your name to "Willypedo".

24 empty tubes and a mushroom cloud. Now it's MILLER TIME!

WillyPEDO

 

[mddolson]

Used acrylic for the lid so I could detect any leaks.

WD

This will also allow you to add a head light in the future (assuming you have room for it).

Mike D

 

[mddolson]

Willydiver,

I settled on the trolling motor because it is already designed for marine use and was cheap ($20, used at a local boat shop). There are some disadvantages to it, though. I don't particularly like the power cord having to be exposed like that. I couldn't get around this because there is no way to run it through the interior of the motor casing.
\
WD

Here's a suggestion to solve the problem for the MkII
I made my cannister from a 10" aluminum pipe, 1/4" wall.
I uses two trolling motors, like out-riggers. One on either side.
I used pipe nipples to thread the trolling motors to the cannister sides. No exposed cable.

It does cost more (two motors and two prop shrouds).

Mike D

 

[willydiver]

Ahhhhh, a headlight! Now there's a cool idea...... Thanks MD! Another feature for the WillyPEDO MKII.


WD

 

[ShoalDiverSA]

Here's a suggestion to solve the problem for the MkII
I made my cannister from a 10" aluminum pipe, 1/4" wall.
I uses two trolling motors, like out-riggers. One on either side.
I used pipe nipples to thread the trolling motors to the cannister sides. No exposed cable.

It does cost more (two motors and two prop shrouds).

Mike D

Mike,

Please post some pics - you have piqued my curiousity! Sounds impressive.

{PS: Your website link doesn't seem to be working - maybe it's me. It is a different URL (http://www.tamdivepeterborough.com/) to the Yahoo group site you had for the dive light.}

Cheers,

Andrew

 

[derwoodwithasherwood]

.

The original shaft seal is composed of two rotating shaft oil seals stacked together. No doubt, with some machining, a shaft seal that utilizes a compression spring would be more secure, but I opted to try the stock set up. I did replace the seals, as well as the main body orings to help out. I have heard a range of statements on the depth ratings of "off the shelf" trolling motors. Some people say they've had them down to 100' with no problems. The manufacturers will only commit to 10'. I'll have to gradually test it to see. WD

What about filling the motor with glycol, like a submersible pump? Instead of keeping water out of a compressible air space, the seals only have to keep to incompressible liquids separated.

Of course, it would affect the weight on land and the bouyancy in water.