[PSUBS-MAILIST] Thruster Reliability

Wed Jul 26 04:35:50 EDT 2023

 Cliff,That really sucks you had this happen.  I always drain my motors at years end because I dont want them weeping in my shop.  I always have black oil come out and a wee bit of water.  The only difference I can see is, I use 55 lb and 30 lb motors.  I had my 55 lb motors on Gamma at one point and have travelled 1.6 km each way to a dive spot.  The motors worked fine and still do, but were under powered, so I went a different rout.  I used 30 lb motors for vertical thrust on Gamma with no issues, in fact, if I recall, with no provision for expansion..  The motors were positioned vertically with a fill plug under the propeller.  I used those vertical thrusters at Lake Tahoe and in Montana.  
I am diving tomorrow in my DDW with two systems.  For me oil is reliable, but I don't like the mess.  I have two motors with oil (30lb). and two with air compensation.  I have a good feeling about the air system.  I am using a first stage regulator with the spring removed, giving me a 2 pound over pressure. The regulator gets  psi from the first stage regulator on the supply tank.   The 2 pounds is a guess.  To relieve the pressure, I have added an adjustable relief valve that will vent both motors.  I think the problem with air compensation has been the regulator choice.  I had no luck with the Parker valve or the second stage scuba.  My theory on the scuba regulator failure is the lack of over pressure and the length of lines going to the motors.  The scuba second stage does work well on my arm, but it is mounted to the arm with a large junction box.
If the new air compensation system works, I will convert the aft motors as well and continue testing over the summer.  I do however plan to make magnetic coupled ends for the motors over the winter, regardless. Hank
    On Tuesday, July 25, 2023, 07:41:09 PM MDT, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Oh my, hope that misses you! Please keep us in the loop.
Alec

On Jul 25, 2023, at 9:33 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Sean, We have the trucks full of fuel and submarine hooked up in case of lightning strike.  There are 4 fires burning from lightning around us.I dont think the fires are too bad though.  We also have some big rain clouds hanging around that might help.Hank
    On Tuesday, July 25, 2023, 07:11:03 PM MDT, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hank - I just heard on The National that a wildfire is currently threatening Invermere. Not sure exactly where you are, but wondering if you're affected?

Sean

-------- Original Message --------
On Jul. 25, 2023, 18:54, hank pronk via Personal_Submersibles < personal_submersibles at psubs.org> wrote:

 Alec, I am working on a magnetic coupler end cap this winter.  I have had very good luck with WD-40 and have two 55 lb motors still running after more than 20 years.  The only difference is, I use much smaller motors.  My oil goes black right away and I do get a very small amount of water by season end.  I drain the dirty oil and replace.  
The first thing to do is to strip down a motor and plug the shaft hole and do a pressure test on the housing.  No point in working on a seal or magnetic coupler if the housing fails early.Hank
    On Tuesday, July 25, 2023, 06:19:24 PM MDT, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Here's my inspiration. I've seen several original Kittredge subs still kicking with their original 1-atm, ceramic seal thrusters that are probably 40 years old. Their use is occasional, for sure, but they're maintenance has probably been zero. What I'd like to explore is doing what the Captain did, except with a Minnkota. If the bushings and brushes are dry and in 1 atmosphere, with the normal lubrication (a little grease on the bushings,) then I don't see why they can't have the same life as when they go fishing. 

On Tue, Jul 25, 2023 at 7:53 PM Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Thanks for the credit Alec, I think it was Brian Hughes ideafrom a previous discussion. Glad we are making some progress.As far as the oil / air debate is concerned, I believe Carsten said that you only need a few drops of sea water into an air compensated thruster to wreck it, whereas if there is oil in there the water doesn't do the same damage.Your compensator can be used as an air over oil system.You could even run 2 thrusters off the same compensator as a test. One with oil, one just air.Alan
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  On Wed, 26 Jul 2023 at 11:19 am, Alec Smyth via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   _______________________________________________
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