Hi Steve d.
I like your logic in making the decision.
Insignificant cost, they do no harm and have no contraindications, why not buy them? At most they will be useless, patience.
Having said that, since this is a forum and, in addition to planning, drawing and building, we also like to talk about these topics, I make some considerations.
Meanwhile, congratulations to GregHiltz who not only gave you his opinion, but also indicated the type and capacity in microFarads to choose the capacitor to buy. I like helpful and pragmatic comments.
He rightly pointed out to get a ceramic capacitor.
Without knowing it, a person could have chosen the electrolytic ones which are not good because they are polarized and therefore the polarity must be respected.
I would have needed to do some calculations to establish the capacity of the capacitor to use, so I greatly admire those who (perhaps also based on their own experience) immediately give an answer.
Experience and practicality are very important; I have always held these two aspects in the utmost consideration.
Colin confirmed the possibility of using capacitors in parallel and/or inductors in series in another topic and this reassures me a lot.
The capacitors on the motor will filter out interference caused by the motor.
Disturbances on the radio link between transmitter and receiver can be caused by other sources.
From direct experience I can tell you that some interference could be caused by the external environment, coming from sources that are not always identifiable. In that case there isn't much you can do except change seats.
From indirect experience I'll tell you some causes could also be switching power supplies, such as non-linear but switching BECs (Not appropriately shielded).
Doing (serious) tests is not so simple and not decisive.
If I remember correctly, in another post (which I have not yet been able to dig up) Doug (RNinMunich) showed the screen of an oscilloscope, writing a very interesting post.
Again if I remember correctly, but I wouldn't swear by it, the display showed the classic duty cycle of a PWM controlled power output. However, the variable rectangular wave of the duty cycle was contaminated by some clearly visible disturbances.
However, I have to look it up better and reread it. I could probably understand it better today.
On purpose! If Doug intervened on this topic he could certainly give us a lot of useful information and advice.
However, the oscilloscope can detect what passes in the circuits, and therefore in the wiring. To observe whether the disturbances actually propagate in electromagnetic waves (more precisely in radio frequencies) a spectrum analyzer would be needed.
Some time ago I observed fixed radio frequencies caused by PC power supplies (which we certainly do not consider RF transmitters) on a Rohde & Swartz FSH8.
Both the oscilloscope and the spectrum analyzer are very expensive but in these areas, in my opinion, superfluous.
Furthermore, I also want to make another consideration, the loss of the signal for a very few fractions of a second can be harmful for the RC model of a car or an airplane but is much more unlikely to cause serious problems for naval RC models, unless it is of a very significant and persistent disorder.
RC ship modelers most likely do not even notice temporary signal losses possibly caused by noise.
It is no coincidence that disturbances introduced by equipment placed close to the receiver are a widely discussed topic among dynamic modelers of racing cars and airplanes, but much less discussed among RC naval modelers.
If you are very unlucky it could happen, at least in theory, that one of the cables is tuned (of the length corresponding to the wavelength or fractions of it) for an external disturbing frequency and acts as an antenna.
Finally there would be another cause of disturbance caused by the arrangement of the wiring which however I want to leave out because it is very difficult for me to explain in English.
I confirm (as I have already written in another post) that with transmissions on the 2.4 Ghz band you hear much less talk and discussion about disturbances and interference unlike transmissions on the 27 and 40 MHz.