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]

[QUOTE=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" :).

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]

[QUOTE=ShoalDiverSA]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.

[mddolson]

Sorry about the link.
TAM Dive Peterborough closed last December

I'll dig up some pics of my scooter for you.

Mike D

[mddolson]

Sorry about the link.
TAM Dive Peterborough closed last December

I'll dig up some pics of my scooter for you.

Mike D


As promissed here's my scooter.
The cover (not shown) is just a piece of the pipe wall straightened slightly to fit evenly on the outside of the body. The gasket is cut from a sheet of 1/4 inch silicone foam rubber. The cover is secured by two large hose clamps. Not rocket science but it works.

My switch is a DC rated angle grinder trigger switch actuated by an Ikelite camera control lever.

The inside frame work is 1/2" thick plywood , unfortunately it has to be dis-assembled to be removed. Hind sight being 20-20 an end opening like Willy's would have made this easier.

[mddolson]

As promissed here's my scooter.
The cover (not shown) is just a piece of the pipe wall straightened slightly to fit evenly on the outside of the body. The gasket is cut from a sheet of 1/4 inch silicone foam rubber. The cover is secured by two large hose clamps. Not rocket science but it works.

My switch is a DC rated angle grinder trigger switch actuated by an Ikelite camera control lever.

The trolling motors were prewired for two speeds.
I used two Ikelite switch boots on toggle switches to turn main power on/off and to set speed for hi or lo.

[mddolson]

The lever mechanism was too stiff for the Trigger switch to shut off automatically.
So I rigged a simple return spring to ensure the unit shuts off when the switch lever is released. KISS approach worked for me.

Mike D

[mddolson]

My power source is two 12 Volt sealed lead acid Gates (now Hawker Energy) 25 Ahr batteries.

Mike D

[ShoalDiverSA]

Mike,

That is a seriously intimidating DPV! Others divers must flee when you come along "flying" that machine. I am really impressed by what other divers are building in the DPV department. It gives me a lot of inspiration to be creative rather than build another Gavin clone. Leave that to the professionals... (and those that can actually get hold of Mako parts!).

What depth have you taken your DPV to? Again, I am wondering about the prop seals on the trolling motors.

Thanks for the pics.

Cheers,

Andrew

[willydiver]

Watch out for the Silver Bullet! Mike, that DPV is sweet. Great welding on the Al, by the way. With two of these 54# motors, you could run with the tuna. I like the handle setup, too. Nice work!

WD

[mddolson]

Mike,

What depth have you taken your DPV to? Again, I am wondering about the prop seals on the trolling motors.

Thanks for the pics.

Cheers,

Andrew

The seals of all trolling motors (mine were no exception) have to be reworked. Trolling motors are only intended withsatnd about 3-5 ft of water pressure. I had to disassemble the motors, remachine the bearing seats to accept a new bearing and urethane shaft seals.
I've taken my "Silver bullet" to 100 ft.

I need new motors. My little thrusters are only 12 lbs each.
Now a couple of 25 or 50's and we'd be jammin. LOL

Mike D

[willydiver]

Mike, do you have a source for the urethane seals? I had a rough time just finding the original equipment replacements for this motor.

Thanks,
Will

[mddolson]

Urethane shaft seals.
MMmmm... long time, short memory,
I'll have to look around, check my notes
I haven't worked on the scooter in 8 or 10 years.
I'm in Ontario Canada so I don't know if I can help.

Mike

[mddolson]

Here's a couple of sources.
http://www.msseal.com/
and
http://www.epm.com/epmlinks.html



Mike D

[willydiver]

Walked up on a suitable shroud for the scooter's prop at the local Home Depot. Found a 10" irrigation box that had a nice taper to it that resembles a kort nozzle. With a little trimming, it worked suprisingly well. Still have to fasten it with aluminum braces. It's coming together.

WD

[ShoalDiverSA]

Looks great!

Cheers,

Andrew

[mddolson]

Outstanding. Kinda looks like a flower pot with the bottom cut out LOL.
Don't know if you've ever heard of Red Green. (Canadian comedy ) He's kind of a back woods handy-man, DIYer. His common saying is "The only two places you need to shop are Canadian Tire (combination auto parts/sporting goods/harware store) and Home Depot. If They don't have it , You Don't Need it!" LOL

Seriously it looks great.

Mike


Walked up on a suitable shroud for the scooter's prop at the local Home Depot. Found a 10" irrigation box that had a nice taper to it that resembles a kort nozzle. With a little trimming, it worked suprisingly well. Still have to fasten it with aluminum braces. It's coming together.

WD

[willydiver]

MD, that's a great compliment! Thanks. The use of "off-the-shelf" components was kind of a goal for this project. Sounds like Red Green has a great philosophy. I spend so much time in Home Depot, I kick myself for not buying stock when they opened their first store.

I actually had been hunting for the "perfect" flower pot or bucket for this purpose for a while and just happened to look in the right direction and found the meter box solution. This thing is 3/16" thick ABS so it's pretty rigid and tough. Luckily it fits the motor prop just right.

I've just got to bracket the shroud and wire the batteries for a maiden voyage. Only thing is, it's heavy on land at 45#. I was hoping to come in lighter than the standard scooter models. Due to the stock motor seals, I probably won't be able to push the depth too hard. Mark II will have to have improved seals.

WD

[mddolson]

I've just got to bracket the shroud and wire the batteries for a maiden voyage. Only thing is, it's heavy on land at 45#.
WD

Don't feel bad the silver bullet with two batteries is 75 lbs.
But a 2lb weight makes it neutral.

Quotes from Red Green : "If the gilrs don't find you handsome, then at least they should find you handy", "Keep your stick on the ice, we're all in this together", "Don't forget the handyman's secret weapon, Duct Tape, and never leave home without it"!

Mike D

[O2BBubbleFree]

Quotes from Red Green : "If the gilrs don't find you handsome, then at least they should find you handy", "Keep your stick on the ice, we're all in this together", "Don't forget the handyman's secret weapon, Duct Tape, and never leave home without it"!

Mike D

Don't forget the Possum Lodge motto:

"Quando omni flunkus moritati."

When all else fails, play dead.

http://www.redgreen.com/

[mddolson]

Spoken like a True DIYer.
The Mark I isn't even wet yet and you've got improvements planned for the Mark II.

Ah, I can see it now, you'll be 85 years old, in a wheel chairs but still diving, cause you've just finished the latest improvements on the Mk MCXXIV. Ah yes, this ones got lithium regenerative batteries, that are water cooled so they recharge continuously, and the hull's been refinished with boundry layer grooves so she slipps through the water like a dolphin.

Power is up 75%, efficency has improved 87%, speed is millitary classified just like the XRS-71 black bird.

Yep this baby should rip the tanks right off your back.

LOL

Hope the maiden voyage is some what better than the"Bullet's was.
Freakin thing leaked like sieve.

regards

MIke D




I've just got to bracket the shroud and wire the batteries for a maiden voyage. Only thing is, it's heavy on land at 45#. I was hoping to come in lighter than the standard scooter models. Due to the stock motor seals, I probably won't be able to push the depth too hard. Mark II will have to have improved seals.

WD

[willydiver]

Man that's great. Hmmmmmm... just look at all the possibilities. Boundary layer grooves to decrease the cohesive forces. I could knurl the cannister in the lathe to simulate shark skin.......
Yep, I'll be the crotchity old guy in the wetsuit with the Depends undergarment adapter, zipping by all the young bucks taking notes on how to make it "better". My fiance is going to put me on project restriction one of these days!

This is great! LOL!
WD


This is too much fun. LOL!

[Fishlips_1]

Right on,
Looks great! Who suggested two motors? That sounds like a much better idea.
That way you wouldn't be in the prop wash. Not to sound like I'm cutting on your project, it looks awesome!! Let know how it works.
Good Luck,
Lips

[mddolson]

I did.

Mike D


Right on,
Looks great! Who suggested two motors? That sounds like a much better idea.
That way you wouldn't be in the prop wash. Not to sound like I'm cutting on your project, it looks awesome!! Let know how it works.
Good Luck,
Lips

[Brewone0to]

I once looked into this and found costruction cost to exceed purchase (for my purpose) I don't expect to go deeper than 90-100 ft nor do i intend to use it as a life support item(just transpertation out to and back on beach dives)NO CAVING OR WRECKS on cheaper dpv's or experimentals .
But your homebuilt looks good(My purchased dpv is a converted trolling motor as well,not sure about seals but they claimed it to be good for 125'deep)So your definitly working in the right direction

[Fishlips_1]

What is the make/model of your dpv? How much did it cost?

Lips

[radarguy]

Have you considered Automotive DC motors? I am thinking about a small 4 cylinder starter motor. I know they have a lot of torque but they are not meant for continuous use either. But they should be cheap enough to experiment with. another option is a geared down electric fan motor. Another option is to use an AC motor with a DC-to-AC inverter. Easy to vary the speed with this setup. I would lov eto experiment to just have to put it in the Queue.
Russ

[Brewone0to]

What is the make/model of your dpv? How much did it cost?

Lips
The Brand is "Cayman" Model Is "Tyger ray"I bought it on E-Bay online.Was brand new in factory sealed box(West Marine store Overstock) 48#thrust 60 min. run time
All that is needed to do to this DPV is to seal area insde where wire to magnetic swich goes through ,tighten and seal where wiring goes to motor (All above sealed with silicone caulking),grease O-Ring on access panel with silicone gel,and replace Washer/nut on prop shaft with good quality stainless steel hardware.(Ive been told these model scooters can be used at depths 175'+ with these mods)but I only bought mine as transportation at beach dives (out & back)
Hope this helps Brian
ps: also advisable to put 2# or so weight inside to keep neutral
It was an auction item that ended to be 220-230 USD+35 S&H (I know that may seem like a good bit but consider this "In one day it's ready to go"

[fishb0y]

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
What did you do to re-build the seals on the trolling motor? My buddy and I have decided to take on the project.

[hilk]

The seals of all trolling motors (mine were no exception) have to be reworked. Trolling motors are only intended withsatnd about 3-5 ft of water pressure. I had to disassemble the motors, remachine the bearing seats to accept a new bearing and urethane shaft seals.
I've taken my "Silver bullet" to 100 ft.



hi mike... just wondering how you seal ur trolling motor to take depth until 100ft.can you descripe step by step... i plan to DIY one unit.but stuck at how to proper seal the trolling motor. or do you have any other idea to replace with trollling motor???

thanks

[hilk]

to seal DIY thruster for DPV : this article i get it from homebuilt ROV pages.


http://aquaticus.info/research.html#thrusters

Thrusters
The main problem in thruster design is how to isolate engine from water. There are two popular solutions:
simple, using o-rings. Additionally you must fill the engine housing with oil to compensate pressure. This is good solution for low pressure (and depth).
magnetic coupling, the best and more complicated. The engine is perfectly isolated from water because it is connected to the propeller using magnetic coupler.
Below you have schematic view how it works

http://img374.imageshack.us/img374/5692/magcoupling3d3kh.jpg (http://imageshack.us)

http://img374.imageshack.us/img374/6782/thrusterscheme3d7pb.jpg (http://imageshack.us)


do you think it will work for DPV.????????? .. isolate the motor from water and reduce the % of leaking/flood...;) ;)

[hilk]

here: how about this motor for DIY DPV ???

24 volt, 600 watt, 3300 RPM Permanent Magnet Ventilated Motor, OEM for E-10 Diamond Back & Tiger Shark Rad2GO Scooters, ideal for bicycle and robotic projects, includes 12 tooth sprocket for 1/4" pitch #25 chain

Dimensions: 5-1/2" long by 4-3/8" diameter with 12 mm (.472)diameter shaft, 1.050" long

Weight: 10 pounds

Price: $ 89.95
Weight: lb. 10.00
Items in the cart: 0

http://img374.imageshack.us/img374/415/34845ki.jpg (http://imageshack.us)


web page : http://www.evparts.com/shopping/product_details.php?id=519&product_id=3484

what do u all think??? suitable for DIY DPV project.. other option from trolling motor!!

:05: :05:

[Daylonious]

You know, I've never even THOUGHT of doing something like this but the little DIY boy inside me really wants to try.

Hilk - that motor looks like it should do the trick, but i'm no expert.

D.

[V. G. McGillicuddy]

Hi Guys!
I am almost finished building my first DPV. So far I have only tested it on the surface, but it seems to work well.
I don't have much experience, but I did discover that attaching a common tire valve to the main body enables me to pressurize the DPV, which makes finding leaks easy.
On a website called psubs.org, they say that Minn Kota rates their motors to a depth of 33 feet, and people have taken them to 100 feet with a failure rate of about 4 to 5 percent.
Also, on the Psubs website, they say that filling the motor housing with transformer oil is an effective way to waterproof it. I believe someone mentioned something along those lines earlier in this thread. Does anyone know the best way to do this? If so, where can I get transformer oil?

Just my 2 cents' worth.

Regards,
V. G. McG.

[mddolson]

Just a quick note: some transformer oils are commonly PCB's poly-chloro-biphenols. They are nasty carsinogenics. (Cancer causing agents) I would avoid them at all costs.

Mike D

[Cold_Under_Here]

Ohh wicked!!!

[Jorbar1551]

Can someone give me instructions on how to build a dpv? Also, how much did building your own dpv cost?

Jordan

[Jorbar1551]

Willy, im looking to make my own dpv, could you give me some advice so i can maybe not make some stupid mistakes?

Jordan

[DiverBuoy]

Now here, we are talking:

[Larry Horne]

All,

25657

25658

25659

I am starting a PDV project this weekend. I plan on using a Minn Kota 55lb thrust trolling unit lower unit for the motor with a 3 blade prop (new $125 motor, $35 prop). I am going to hand form a composite body. I have a few questions to throw out to you all. If the motor gets wet, its $15 in parts to overhaul.........easy. I'm going new verses used because of contacts in the business and new will provide performace IAW specs.

1) Over all design. I have two options. Linear body like a Apollo or Torpedo. Or something like that shown in the images attached. This is basically a trolling motor lower unit shoved up into a battery compartment. I perfer the torpedo design. Has anyone any info on the Shakespeare Submobile? What is its depth rating? The Tiger Ray uses a trolling motor configuration and rates it to 125 ft. Any thoughts as to what depth a stock Minn Kota will test to? I read one thread here where one of you re machined the seal locations for additional seals? Since I plan composite material either design is doable. Thoughts?

2) What is the pressure in pounds per square inch to be expected at 150ft? Can anyone help me with the formula to calculate?

3) Can Minn Kota motors run dry or does the lower unit transfer heat via the housing for general cooling? My tech personl locally indicated they can run dry but wet is the preferable obviously. Thoughts here is that I can add a second degree of water sealing by extending the output shaft and running it through a water tight seal outboard of the trolling unit lower unit. Basically placing the motor inside a water tight compartment on the stern of the unit.

4) Batteries. I can locate a 12V 55Ah sealed lead battery. The trolling unit pulls 45A on high speed. Battery weight is 39#. Is there another option? This may provide 30 - 45 minutes of good run time before the voltage drops too much where repeated cycles will damage the battery. Are there better options such as runnig smalleer twin batteries? Thoughts?

5) Motor modifications. If I take the motor unit direct from the factory what improvements can I do to increase the possibility of getting greater that 100' out of it. They are simple units, double sping shaft seals, casing o-ring, and o-rings on the two studs holding the assembly together. My thoughts are to cover the heads of the bolts with a polyurethane sealant and maybe try improving the body gasket. not certain much more is doable unless I take the approach like one of the posters here and replace the shaft seals with better units. Thoughts?

Well this is enough to chew on now.

Any and all technical advice is appreciated.

Larry
VA

[mddolson]

DPV (diver propulsion vehicle)
1) Normal trolling motors are not rated for pressure. (ie 3-5 ft) So they relyon simple sliding seals on the bearings and grease fille to prevent water ingress. I machined my bearing seats to take an add-on ureathane shaft seal. It worked for me.

2)Pressure at 150 ft (sea water) form basic scuba class there is 1 tm every 33 ft so P= 14.7/33 = 0.445 psi/ft x 150 = 67 psi.

3)Cann't comment on MinKota motors.

4) Thing to remember is that lead acid batteries drop in voltage as they are used. So you will not get full current/power at the end of a dive/charge. I considered using 3 x 6 volt batteries , but running from 2 at start and switching in the fresh battery as voltage dropped in the two prime batteris.

5) re Washer seals: ther are stainless steel washers with a moulded o-ring on the inner diameter . Check McMaster Carr.

regards

Mike D

[jgarysmith]

Just go out a buy a new Apollo.


Just kidding, I know Larry

Good luck on it so you can build me one when you are done with yours.

Why don't you start a new thread with your questions. You might get more responses with it.

[Larry Horne]

Mike D,

Thanks for the reply.

Here is one to ponder over (no laughing or assuming I'm too naive).

I have continued to do some off line investigation of submersibles used in various DoD research projects (my work affiliates) and found claims that a certain company well known in the States for design and test small remote submersibles has used the Minn Kota 40# thrust to depths of 300ft (134 psi effectively) with only minor modifications, none directly related to the sealing of the unit. I have this information from 2 sources including the vendor who sells the units to this company. Its the same vendor I am purchasing the 55# thrust lower unit from.

Their modifications include relocating the exit point for the electrical leads for the brushes/armature. They move them to the rear of the unit verses having them come out of the top. This allows them to place the unit in the stern of the vehicle with out the problems encountered by Williydiver with the power leads.

I have disassembled the Minn Kota and their design for shaft seals includes two (2) dynamic seals in line or in parallel. By this I mean a seal that has a small spring around the inner diameter opening which maintains a certain constant pressure on the shaft back to back with another identical seal.

Isn't this similar to the modification that you performed to your unit? Does it sound to you as though the manufacture may have improved the design?

I in no way assume depth containment to 300ft but may make a test rig for the shaft seals where by I pressure test them to 70 psi. I can do this with a hose clamp, rubber boot, and bicycle pump. Pressurize the boot and see if it holds constant pressure.

Thanks for the input on the other items.

Lar

[mddolson]

The seal sounds Ok, based on your description.
The tension spring adds drag but maintains a positive seal against the shaft. water preseeure will maintain lateral contact.
Add grease and you're away to the races.
I have no personal experience with MinKota though.
I used Shakespear thrusters in my project and that was 15 years ago.

I also heard (this is unconfirmed how ever) that Perry Submersibles in Florida also uses the Minkota thrusters.

Mike D

[Nemrod]

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
Hey, where did you get those spring clasps that hold the front plate on. They look similar to some I got long a go from AquaVideo but better. I could use some like those for modifications to my Tekna DPV. N

[Jorbar1551]

www.mcmaster.com

You can get anything there.

[RV]

I wish the attached images were still here

[Doc Ed]

Holy thread Resurrection, Batman! :D

But yeah, I wish the OP would re-link the original photos...