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T100/T200, push or pull?


(Stefano Cavalli) #1

Hi everyone, first of all i want to congratulate with you for all the job you’ve done with all of these stuffs! When i saw “kickstarter” i thought: “ok, who are them?”, most of your youtube’s videos and articles all around your website were my entertainment tonight (i’m in Italy, it’s 2 a.m. lol)
By the way, i was wondering…
I’m studying computer engineering in Italy, and i would probably need the T100, or T200 as well (and i’ve got a lots of questions xD), for my degree’s thesis, but what’s best?

Push a boat or pull it?

I think that may depends on what kind of project is, but if we think about a mini-boat floating in the water, so NOT UNDERWATER, what should be probably better, put it on the front(for pull) or on the back(for push)? Have you made some experiment, or kind of testing efficiency?
Thanks everyone!!


(Rusty) #2

Hi Stefano,

Most boats have the propellers mounted at the rear. I don’t know enough about boats to say why or whether that’s best, but it is definitely the standard way to do it.

-Rusty


(Kevin) #3

Hi @stecava92,

Have a look at the T100/T200 thruster comparison chart:
http://docs.bluerobotics.com/thrusters/t200/#comparison-to-t100


As you can see, the T200 is a bit more efficient at 12V DC

Regarding the push/pull line of thinking, if you were going in a straight line and only in a straight line, it wouldn’t matter if your propeller was on the front or rear. However, ships and boats need to have steering control. This can be done in a few ways: differential propulsion (2 propellers), a propeller and a rudder, steerable nozzles, etc. For this reason, propellers are almost always at the stern. Here’s a decent overview of how rudders are used to turn ships and boats and the forces that are acting on everything.: http://www.marineinsight.com/naval-architecture/rudder-ship-turning/

With that being said, I have seen propellers on the front end of ships, but these are highly specialized. I’ve seen them on ferries (with both a propeller and rudder on both ends) and on the bow of icebreakers to break up ice.


#4

Probably much of it depends on your design and intended use, but generally speaking most boats that operate at any appreciable speed are designed/balanced so that the bow hydroplanes to some degree while the stern stays firmly planted in the water. (Nose-diving a boat into the water at speed is bad). In such a case, it wouldn’t seem ideal to have the props in the front where they could potentially be out of the water at random points of time or create an undesirable forward weight bias (which is why you don’t generally see them located there.) Of course there are situations where additional bow-thrusters are positioned to aid in the manoeuvrability of vessels like ferries (as Stefano mentioned above.)