DIY DPV Motors

[merseydiver]

Hi All.

Apart from canabilising an electric outboard motor (eg. a Yamaha M20) does anyone know what types of 12 Volt electric motor are suitable for building DPVs.

Thanks in advance

Steve

[scubatech]

I recomend trying to find a battery powered industrial floor cleaning (buffing machine)
reason:
run on dc
are usually well constructed of corosion resistant materials.

or possibly some other form of simmilar machine.
:doctor:

[mmakay]

merseydiver once bubbled...
Apart from canabilising an electric outboard motor.........
[/B]

If you're looking for a reasonably simple project, that's by far your best bet. Nearly all electric motors use a mild steal for construction which would need to be perfectly sealed to last more than one dive. Given the physics of sealing a spinning shaft under pressure, that's no small bit of engineering. Add that they (electric outboards) come supplied with an appropriate prop, and you just can't loose. Trial and error finding the right prop for some mystery motor is going to set you back any money you saved in the first place.

[jamescaswell]

Bosch Gpa(?) 24 v 750 watt is an suitable motor for a dpv.(used in aquazepp,s).
Needs a step down gear and you neeed to source a prop for your dpv.Low rpm,s,,,3-500 revs,big prop for max thrust.
good luck
james

[DennisS]

If your thinking of building a DPV there are some parts over on E bay,

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1300&item=3690701619&rd=1

[Shaka Doug]

I would consider using a motor from an electric boat trolling motor. They are already waterproof and wired up. You could modify it quite easily. They come in various power ranges too. Do you plan on running in salt water? I am also interested in building a DPV. Do you have plans on how to do it or are you figuring it out as you go?

Aloha,

Shaka Doug

[PRL]

Dont have ANY experience in that field but I'm pretty sure that trolling motors are water tight only at the surface and the pressure at the expected performance depth would blow the seals in. I dont like the idea of equlizing the pressure with air and a regulator. electric motor brushes produce spark, motor is lubed with petrolium based grease, and the partial pressure of O2 at deapth could cause an explosion. I've heard of filling the motor with transmission fluid to seal it off, but I,m not sure if the temperature drop wont condense the fluid to let water in or even worse if the temperature rises it might bleed fluid into our already polluted waters

I would consider using a motor from an electric boat trolling motor. They are already waterproof and wired up. You could modify it quite easily. They come in various power ranges too. Do you plan on running in salt water? I am also interested in building a DPV. Do you have plans on how to do it or are you figuring it out as you go?

Aloha,

Shaka Doug

[PRL]

I dont know the specs and dont know if these sources will help you, like I said, no experience in this field. You might consider an automobile starting motor for your motor. For the seals you might be able to use hydraulic pump seals, or automobile power steering pump seals. For the output shaft cone you might use an old scuba tank neck. I wouldnt use a scuba tank for the entire case because it will probably be to heavy, but for the ends it might be worth considering.
Just thinking out loud.

[Buccaneer]

If you search the net you can find many plans, often for free on building dpv and open water 1 and 2 man subs. All the plans I have seen incorporate trolling motors, and all claim thier dpv's can be operated at any recreational scuba depth

for a starting point search under homebuilt submersible

[Gary D.]

Take a close look at some of the DPV's. They have trolling motors on them. Even some of the ROV's arer trolling motors.

Motor Guide has a smoother shaft so it is easier on O-rings than Minn Kota and a metal shaft which is easier to work with than the composite shafts.

The companies will say they are good for 1atm when diving but I have had them over 200' without problems.

A 32# thrust motor will run 1 hour on a Sears Gel Wheelchair battery.

Gary D.

[O2BBubbleFree]

If you search the net you can find many plans, often for free on building dpv and open water 1 and 2 man subs. All the plans I have seen incorporate trolling motors, and all claim thier dpv's can be operated at any recreational scuba depth

for a starting point search under homebuilt submersible

Back in the late '70s my dad's Popular Mechanix magazine had plans for one built from PVC pipe, with a trolling motor in the back and an auto headlight in the front. Several times over the years I have run across reprints of the plans available on different web sites. You should be able to find them for free.

[Gary D.]

Here are just a couple.

http://www.atlantisdivers.com.au/rec_courses/dpv.html

http://www.deep-six.com/page98.htm

Gary D.

[O2BBubbleFree]

I guess it's Mechanics, not Mechanix...

Here's a site selling the plans. The single motor model is the one I remember seeing:

http://www.scubatow.com/scuba.html

[Gary D.]

I guess it's Mechanics, not Mechanix...

Here's a site selling the plans. The single motor model is the one I remember seeing:

http://www.scubatow.com/scuba.html
The delta twin is a good little unit that is easy to modify for twin batteries or anything else.

The only major change is make the battery compartment and the nosecone seperate. If you don't water will wick in and flood it at deeper depth.

I have made lots of changes to it and it is a pulling sob.

Gary D.

[RichLockyer]

electric motor brushes produce spark, motor is lubed with petrolium based grease, and the partial pressure of O2 at deapth could cause an explosion.
Not an issue. It's FO2, not PPO2, that increases the combustion potential.

If it were PPO2, then you would need to have an O2-clean reg set to take AIR to 130ft.

The problems with equalizing with air are that of maintaining ambient pressure. A regulator system with automatic dump would be quite complex... you'd be looking at a gas addition/dump system not unlike that found on a rebreather.

Another method that does not require a change in pressure would be to fill the housing with mineral oil or some other kind of nonconductive fluid. The benefit of this would be that it would keep the motor very cool by acting as a heat sink to the outside world.
One problem....
The thing would weigh a TON on the surface, and you'd need some kind of added buoyancy to make it neutral in the water. A BC jacket would work, but now you have to mess with the buoyancy of not only yourself and perhaps your drysuit, but also your scooter. I don't know if you could find a foam that would be resistant enough to compression to work.

[Gary D.]

I dont know the specs and dont know if these sources will help you, like I said, no experience in this field. You might consider an automobile starting motor for your motor. For the seals you might be able to use hydraulic pump seals, or automobile power steering pump seals. For the output shaft cone you might use an old scuba tank neck. I wouldnt use a scuba tank for the entire case because it will probably be to heavy, but for the ends it might be worth considering.
Just thinking out loud.
That is old tech. we used in the 60's. Starter motors take way to much power and are a lot of work to set up. There are a lot of better options out there right off the shelf.

I built a wet sub that took 4 auto batteries to get an hour run time out of it. Not worth the effort.

Gary D.

[PRL]

Yeah, I kind of figured. Never built one my self and don't really know what I'm talking about in this field. Just was thinking out loud as to what options the author might have besides a trolling motor.
In any case, for the authors expectations of the performance, it probably would be a good idea to get plans of DIY DPV that has been succesful at 300ft. Trial & error can cost more $$ than the bribes the author was talking about.


If it were PPO2, then you would need to have an O2-clean reg set to take AIR to 130ft. DOHH, I know that, Why would I get a brain fart like that. :)

[ShoalDiverSA]

I am busy resurrecting my DPV project, because my brain is starting to rot from too much work.

I am investigating the electric golf cart/wheelchair motor route at the moment. I have looked into trolling motors, but getting parts down here has been challenging.

I was wondering if anyone knew of a source for Oceanic Mako parts. They seem to be widely used by the makers of DPVs, yet they do not seem to be freely available. The variable pitch prop assembly, prop guard/nozzle and motor would be obvious contenders for the basis of a DIY design.

Cheers,

Andrew

[ba_hiker]

I dont know the specs and dont know if these sources will help you, like I said, no experience in this field. You might consider an automobile starting motor for your motor. .

Auto starter moters are not a good choice. They draw a LOT of current and heat up fast. The evelope a lot of power too probably too much. I tried one long ago in a kids electric car project it was realy quick for about 7 min, at which time the battery went dead. The motor was way to hot to touch and seized up.

Instead find an old VW generator and take it to an electric motor shop and have it rewired as a motor. Also remember that the motor/battery/and prop are a set, for a given motor you need a given size/weight battery (for a give length of run time) and a prop that will transfer the power to the water.

Also you may need a reduction gear, as spinning the prop too fast causes cavitation and a loss of thrust.

[ShoalDiverSA]

...
I was wondering if anyone knew of a source for Oceanic Mako parts. They seem to be widely used by the makers of DPVs, yet they do not seem to be freely available. The variable pitch prop assembly, prop guard/nozzle and motor would be obvious contenders for the basis of a DIY design.
...

Any takers?

Cheers,

Andrew

[oxyhacker]

Any Oceanic dealer can help you. The markup on parts is 100% so they have a lot of room to to discount; and if you are buying the full kit your would be crazy to pay list price - your best bet is to check around local Oceanic dealers and see if you can find one who is amused enough by the project to give you a good deal. Expect to pay about $700 for the motor, shroud and prop parts.

We have a sheet listing all the necessary Mako parts numbers and approx. prices, PM me with your email if you want a copy.

If you are building a fun scooter it makes sense to look into cheaper alternatives, but if you are trying to build a serious, expedition-class scooter along the lines of a Gavin or Submerge the savings by skimping on the motor are small enough that it probably is worth going with the Mako.

Trolling motors are not as well suited for running a DPV being lower torque/higher speed motors - the Mako motor is specially designed for the purpose, for high torque and lower speed. There have been a few trolling motors with internal reduction gearing that are more suitable but they are hard to find.

Oil filling is often used with trolling motors on DIY subs and ROVs, the secret is to fill just the motor housing not the whole unit :-)


I was wondering if anyone knew of a source for Oceanic Mako parts. They seem to be widely used by the makers of DPVs, yet they do not seem to be freely available. The variable pitch prop assembly, prop guard/nozzle and motor would be obvious contenders for the basis of a DIY design.

Cheers,

Andrew

[critterc]

Anyone looked at these 12v. scooter motors the kids are ridding up and down the road on. I have seen replacement motors for them on ebay real cheap ????