Bow (and stern) thrusters - pros & cons

[Timothy L]

At Subex25 I heard about bow thrusters bring used in longer subs to reduce turning radius. My exposure to bow thrusters is in surface tugs using Raboesch. They don’t really impresse me that much because they are not very effective unless you’re using them when the tug is at a standstill and the instructions advised that they not be run for more than 30 seconds at a shot. At least with tugs it seems to me that the KISS Principal reigns and a well set up single Kort Is extremely hard to beat.
But long subs seem like they might be a good candidates. In my case it would be on a Virginia class about 5 feet long. I will have an extended ruddder cap which may be completely sufficient. However, I would like to know anybody’s thoughts on using bow and or stern thrusters. If you’ve used them and like them, what brands did you use or did you scratch build? Did you find them practical to operate or generally overkill? Thank you in advance.
Tim

[Albacore 569]

I thought about Bow thrusters but seemed a complicated mess, more controls and not scale with these big holes blowing water athwartships. Bow thrusters are fine n tugs and cruise ships but are very inefficient. They were in the way internally too.

My Suffern Model project developing building now in another thread here is using a swiveling pump jet I devised. The propulsor and shroud swivels like a rudder left right only. It will act like a rudder and thrust vectoring too. Posting here are early successful trial tests of my swiveling pump jet designed by me and Randy Sanders. I call it the Sanders swiveling PJ. Just a rudder servo turns everything, including the propulsor. The shaft for propulsor is connected via a telescoping drive shaft barrowed form RC car part. Bench tests while drive shaft turning very successful. Very smooth.

Placing the battery way forward and balancing the center of buoyancy the rudders on Virginia if small would have a long moment arm may work too. My D&E Skipjack had the battery in the dry compartment farthest forward and Merriman's arrangement made the boat incredibly maneuverable as the 1 to 1 scale boat must have been. the contribution of CG/CB and moment arms. For what it's worth.

[Timothy L]

Albacore 569 -
Thank you. That is a very interesting concept - which I suspect will be very successful. I will look at your other thread to explore more. . Again, thanks.
Regarding thrusters, one gentleman I talked to at Subex25 used “scale” gratings for the bow thruster ports and thus you don’t even notice them.
I still lean towards a KISS approach yet want the sub to be able to turn 180° in the space of (for example) of a public pool.
However I don’t want to blindly exclude thrusters as an option - weight distribution and smooth / simple operation are my questions.
After I made this post, I remembered that when the sub is Submerged the rudder area will be double and it should be much more maneuverable. Perhaps thrusters are over thinkkng (I threw that line in just incase David feels the need to turn the “dah light bulb” on in the newbie LOL). Thanks .
Tim

[He Who Shall Not Be Named]

Albacore 569 -
Thank you. That is a very interesting concept - which I suspect will be very successful. I will look at your other thread to explore more. . Again, thanks.
Regarding thrusters, one gentleman I talked to at Subex25 used “scale” gratings for the bow thruster ports and thus you don’t even notice them.
I still lean towards a KISS approach yet want the sub to be able to turn 180° in the space of (for example) of a public pool.
However I don’t want to blindly exclude thrusters as an option - weight distribution and smooth / simple operation are my questions.
After I made this post, I remembered that when the sub is Submerged the rudder area will be double and it should be much more maneuverable. Perhaps thrusters are over thinkkng (I threw that line in just incase David feels the need to turn the “dah light bulb” on in the newbie LOL). Thanks .
Tim

My Specter hovers over you like the Sword of Damocles'. Don't invoke my wrath!!!

[Albacore 569]

My Specter hovers over you like the Sword of Damocles'. Don't invoke my wrath!!!

Specter watches everyone Mr Speculate,,,lol/

You could use bow and stern thrusters on a 'special operations' sub. A Parche, or Halibut or a later Seawolf (the SSN 575) instead of your Virginia. just add a waterproof pump with rubber hose routed to to small brass tubes pointing out sideways flush to hull. To squirt water sideways. switch On squirts one way, reverse the pump motors polarity to squirt other way. David right, get back to your shop and build something. I am.