Re: [PSUBS-MAILIST] hydraulic drive idea

thank you again. seems to me that hydraulic sys are not to be used at all. I guess I should have told you that it will be built for fresh water use so I really won't be going that far. I seem to have a hard time finding these seals on line would you happen to know where I can go to find them. I am guessing that I will need to have shafts and all other hardware machined. would you know where I can look to show a good example of this motor and housing being constructed and assembled and maybe crude drawings? I have looked for photos in the archives to get an idea of how things are constructed but not on these thruster pods I guess I can call them. I take it you have a p-sub of your own. I think it would be most helpful if someone took the time to take more photos and draw more diagrams for the archives while building in the future. I guess I just recruited myself once I get started eh. you may also be able to help me with some buoyancy issues so I can get an idea of how large or small I can make this sub in comparison to the weight I am looking on carrying. do you know if there is any way to figure this out as a rough figure. no big deal just wondering. I did find the calculator for the sheet steal weight so I can calculat my hull and tanks. as for the batteries I was thinking of around six plus. since I will need the weight I might as well use it for the hull or for power. since I won't be going that deep I think power would be good for me. keeping my drop weight in mind of coarse. someone did run some numbers by me on water displacement and lift for cubic ft of air but I seemed to misplaced it. it also seems that the added factor that steel and other materials weigh less in water also complicates the ! figures. any help in this will help me continue my design plans.

Chad,

I had to wear earplugs daily for years around the hydraulic systems on a submarine. If I had pursued a graduate degree in acoustics, my focus would have been on reducing this noise for the Navy for our nuke submarines. Instead I elected to go out and make some money. The hydraulic noise in a small submersible quickly gets unbearable.

Place regular off-the-shelf motors in a metal housing with mechanical or flexible seals. Later K-subs went to this method and moved away from trolling motors. For the size of your submersible, you are going to need big motors and lots of batteries for any duration. There is a method to calculate cross-sectional area and skin area to calculate the necessary HP for a given speed. Shaft, flex-joint, seal, and prop losses also have to be added to this along with an additional HP% for safety. Pick up some naval architecture books and they will assist you with this. You will find that you will have to tow or carry your submersible out to most dive sites as the batteries have limited range.

R/J²

Respectfully,

Jay K. Jeffries

Andros Is., Bahamas

It is the mark of an educated mind to be able to entertain a thought without accepting it.
- Aristotle

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of skrewgun007@aim.com
Sent: Sunday, September 17, 2006 7:27 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] hydraulic drive idea

Thank you Jay for fixing the misspelled word in my subject. I realized it was misspelled as I sent it. so as it is a solution to rotating shaft seals hydraulic pump sys it is not efficient. I was also wondering about the flow noise. have you witnessed this noise? What kind of bat life can be expected out of that sys. In theiry I would be loosing 60-70% of my possible range. What would be, in your opinion, the best way to drive a sub. and I am sure you are going to say trolling motors, but what are other over the counter options? If there are any. I would like to avoid towing for most of the time. I know I keep asking ques that you have heard before. maybe one day I can do this for others.
Thanks again,

Chad Beller

-----Original Message-----
From: bottomgun@mindspring.com
To: personal_submersibles@psubs.org
Sent: Sun, 17 Sep 2006 5:55 PM
Subject: RE: [PSUBS-MAILIST] hydraulic drive idea

From recent reading for my Naval Architecture program, hydraulic powered propulsion system are one of the most inefficient ~30% of pump drive shaft HP makes it to the propeller. As to noise, you can go through all the problems of sound isolation but there is still excessive flow noise.

R/Jay

Respectfully,

Jay K. Jeffries

Andros Is., Bahamas

It is the mark of an educated mind to be able to entertain a thought without accepting it.
- Aristotle

From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of skrewgun007@aim.com
Sent: Sunday, September 17, 2006 6:24 PM
To: personal_submersibles@psubs.org
Subject: [PSUBS-MAILIST] hydrolic drive idea

someone mentioned that hydraulic drive sys being loud inside the sub. is this true? and if this is true could the noise be reduced by mounting the motor and pump on rubber mounts and insulating? still considering hydraulic instead of sealed assembly "I have found a bolt up solution in granger catalog". many have said that they get plenty of power from the hydraulic system. efficientcy for extended use is more my concern.

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