[PSUBS-MAILIST] vertical thruster orientation

[Alec Smyth via Personal_Submersibles]

Another thing to consider is that the thrust developed by the vertical thrusters, regardless of direction, is rather small compared to the lift provided by an emergency blow of MBTs. At least for a conventional Kittredge-type sub. Shackleton has two 100lb Minnesota’s for vertical thrust. That’s nominal and I recall actual thrust being a considerably less. They’re angled to enable crabbing, which takes away some from vertical efficiency. Their prop wash goes through a grated deck, losing some more. The net vertical force is probably well under 100 pounds between them - compared to 900 lbs from the MBTs and close to 200 from the drop weight. I’ve come to think of thrusters as tools for maneuvering, but not really for solving an emergency with brute force.

Thanks,
Alec



> On Aug 10, 2018, at 4:27 PM, Jon Wallace via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Thanks for the feedback folks.  The issues of bearing wear and running in reverse mode to control a positively buoyant sub is well taken.  I was thinking more about potential entanglement and having maximum forward thrust available to help push to the surface if necessary.  I will have to think about this some more.  
> 
> Although I was intent on fixing the thrusters permanently for simplicity it looks like I do have the option to retain the original rotating configuration and maybe that would give me the option to position them for multipurpose use.  If I take this route I plan on utilizing the SNOOPY approach of locking them down rather than having to hold onto them.  
> 
> Jon
> 
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