[PSUBS-MAILIST] thruster sizing etc

Sun Sep 28 17:39:25 EDT 2014

Okay, I'm changing props. And I'm trying to figure an appropriate bribe for that nozzle design. My first born child is busy. What's your second choice?
Vance

Sent from my iPhone

> On Sep 28, 2014, at 1:03 PM, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan I will put my two cents in on thruster for psubs.
>  
>  
> I went down a similar path to yours in trying to sort out thrusters for the upgrade on the R300 and the new boat I am designing, the R500.  I looked at existing off the shelf thrusters for ROVs.  They are nice but expensive.  I got a quote about 6 months back from Robo Marine in Indonesia as well, the company you visited during your recent Indonesian trip.  My assessment was they were too costly for a home built for a 100 lbf thruster.  I also looked into designing a thruster with a kort nozzle.  It looked like it was going to take quite a bit of engineering to sort this out so I abandoned this approach.
>  
> I have settled on using four Minn Kota 101 lower units for each boat. I have them sitting in my shop. For the R300, I am using two fixed horizontals for propulsion /yaw control and two fixed vertical for pitch control /vertical station keeping.  You have to love the MK 101's.  They are super quite, powerful and the motor controllers work great with built in protection against slamming the units from full forward to full reversion. They are also potted.  On the motor controller, I did dome playing around with these with a MK-101 lower unit.  I removed the hardwired potentiometer that comes with the controller so that I could confirm that it was just a 0-5 analog VDC signal that was driving the controller and it was.  If you listen to the controller, there is a built in relay that electrically isolates the controller when you are in the deadband around 2.5 VDC.  This keeps the thruster from draining the batteries when the boat is parked.   About two weeks ago, I gave the machine shop I use the drawings for mounting the kort nozzles and for the nozzles themselves.  I am waiting on these parts.   I went with a Wageningen series 37. This is a good shape when both forward and reversing thrust are important.  I decided to go with Kipawa high performance three bladed props.  These are also in my shop ready to be installed in the kort nozzles.  I have decided to go with air pressure compensation on the MK's and am using the pressure reducing regulator that Hugh Fulton came up with mounting upside down for the reasons you mentioned.  I place an order using the Psubs discount through Subconn for MCBH3M bulkhead connectors and all the cables for the four thrusters for the R300.   I designed an adaptor to mate with MK 101 lower unit and the machine shop is currently fabriacating these.  I have one three axis joy stick Digikey (APEM) 679-2264-ND (HFX33S10) in my shop that I am going to use to control all four thrusters.  I am going to run these through the PLC in the R300 so that I can program different interaction between the thrusters but you could use the joy stick to directly to control the thrusters as each axis gives a 0-5 VDC analog output signal with a 2.5 VDC centralized position.
>  
> I am using he exact same set up on the R500 with the exception that I have tilted the vertical thrusters to get sidal movement of the boat.  
>  
> I agree with both Alec and Hank, yes, there are some nice features to being able to rotate the vertical thrusters but to me, the KISS aspect of fixed thrusters out ways these for psubs.   Hopeful I will have the workover done on the boat in time for Islamorada next summer if we hold the 2015 Psub convention in Florida again.
> 
> Cliff
> 
> From: Alan via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
> Sent: Sunday, September 28, 2014 4:40 AM
> Subject: Re: [PSUBS-MAILIST] thruster sizing etc
> 
> Thanks Alec that was helpful.
> Is that the normal mode of operation, having the side thrusters locked
> vertical? Were you putting them in reverse or just relying on positive buoyancy.
> I was planning on having side thrusters that are rotated by electric motors, so my 
> hands are just on a couple of joy sticks controlling all the motor functions.
> I liked the idea of using rotating side thrusters so that I could have double the power travelling
> horizontally if need be. Also there would be no need to ramp the motors down to change 
> from forward to reverse.
> Any thoughts on the pros or cons of this anyone?
> Alan
> 
> 
> 
> Sent from my iPad
> 
>> On 28/09/2014, at 4:55 pm, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Hi Alan,
>> 
>> On the stern, snoopy has a 55 lb Minnkota. The side thrusters are actually of unknown thrust, they came with Snoopy and are Motorguides but I'm not exactly sure which model. My estimate would be about 40 lbs (each). What you saw in Florida would have been forward motion based on the stern thruster alone, as I was using the side thrusters just for depth keeping, locked vertical. The K250 has very limited battery capacity, carrying three batteries in the standard design and four in Snoopy. I find the thrusters well proportioned to the limited battery capacity. The bottom line is that a K250 has perfectly adequate thrusters and batteries for diving, but not enough for surface runs. Something in the league of Minnkota 101s is great, but only on subs with battery pods.
>> 
>> Best,
>> 
>> Alec 
>> 
>> On Sat, Sep 27, 2014 at 8:17 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Alec,
>> what size motors do you have on Snoopy?
>> I remember watching you disappear into the blue surprisingly quickly in Florida.
>> Were you using the stern & side thrusters simultaneously?
>> Are you happy with the speed?
>> I have spent a LOT of time Googling brushless motors & haven't come up with
>> an easy solution.
>> I was looking particularly at inrunner motors, as they have a couple of advantages
>> over outrunners, however outrunners have lower revs. Whatever, they are both going
>> to need gearing down majorly & matching up with a planetary gear isn't looking easy.
>> Most of the motors that are available are found at Hobby King & are lightweight & made
>> mainly for model planes. So their strength & ability to sustain several hours of
>> continual operation are in question.
>> Must be a solution out there because 9 out of 10 thruster manufacturers are using brushless motors & I doubt they would be making there own.
>> Alan
>> 
>> 
>> 
>> Sent from my iPad
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