Powering Small Boat with T200s

I have a friend who is making me a boat which I plan to use for remote missions near the coast line.
The boat is the following one: boat (1) — Postimages
I wonder if it is enough to use a T200 Thruster to power the boat along with a rudder to have steering control of the boat.
My plan is to use 6s LiPo but I can go to 5s or 4s if necessary. I do not intend to have a speedy boat, just cruising around at let’s say 10mph max.

Thank you and best regards,

João Fonseca

Hi @JF2021, welcome to the forum :slight_smile:

Max speed depends a lot on the mass being accelerated, and the surface and drag area of the boat. As a very rough reference, this post discusses using two T200 thrusters to propel a human diver underwater (using our 4S6P battery), and ends up with an estimated max speed of about 43m/min, which is ~1.6mph.

Presumably your boat will have a decent amount less drag than a human diver, since it’s smoother, partially out of the water, smaller, and doesn’t need oxygen tubes and the like. I would also guess a remote control boat of this size would be lighter than a human (and perhaps quite significantly so), but that depends what you put in it and make it out of.

Without knowing more about the boat properties it’s difficult to give a meaningful max speed estimate. My intuition tells me you’re unlikely to get 10mph with a single T200, but may do with two or three. Then again, I don’t have much experience with boats so I have very little trust in my intuition here, particularly given the lack of important parameter details :slight_smile:

As per the T200 Product Page they’re rated to use 7-20V, and we don’t recommend going above that without power limiting, so if you want to use 6S you’ll need to be quite careful with how you set up your throttle control.

Hello all,

I’m looking for a power system to a 1.2m boat similar of what is shown on the picture below.
Currently looking for the T200 but wonder if it’s a good match for it or better to use a brushless outrunner. Also don’t know if I need one or two T200 thruster if I go to that route.
The boat is still being fabricated so I don’t know the weight, I can only estimate the weight of the parts I’ll be putting into it. Thinking in getting 4s Lipo batteries as the T200 max 20v is limitating going to 5s or 6s.
Any help will be much appreciated.

Sem Título

Hi @JF2021, I’ve merged this with your previous post, since it seems to be on the same topic.

Given there isn’t any additional information provided here beyond the example photo, I don’t have anything to add to my previous response :slight_smile:

Many thanks for your reply Mr. Eliot.
For some reason I missed your reply.
I guess It will be better to get two T200 to have some headroom if I go with a 4s Lipo heavy battery pack to have better efficiency with the T200 vs 6s setup.
Do you think that using a brushless outrunner will be somehow more suited for my application?

Thanks again

I don’t have experience with powering boats, or with brushless outrunners, so am ill-suited to answering this question meaningfully. I’ve asked about it internally in case someone else on our team has a better idea, and will get back to you if there’s a response :slight_smile:

Much appreciated!

So basically, our thrusters already are brushless outrunners (which I suspected but wasn’t able to easily confirm when I was originally responding). Rusty said

In my original searching I found that outrunners don’t require a shaft, which is part of why I wasn’t certain if that’s what our T200s were, but

So I guess I’ll use two T200 thrusters.
I plan to use differential thrust steering. Any advice on placing them in this boat?
Thinking about the lateral distance… too small in a boat like this? Maybe using some lateral mounting option?
Also… best to be placed on the stern?

Thanks again

Something like this?

Lateral distance affects how well you can turn (wider spacing → stronger turning moment), but if you go beyond the width of the boat then it increases the risk of something getting caught on/in the thrusters. You would also need to make sure they’re kept low enough

For the location from bow to stern, my intuition is that having the thrusters roughly midway along would provide the best flow characteristics (because the smooth straight part in front and behind would help keep the force in the forwards direction), but as mentioned I don’t have much experience with boats, so I’m unsure whether there would be other favourable characteristics from disrupting the wake with thrusters at the stern. I expect turning will be most effective with thrusters roughly aligned with the centre of mass, which I assume would be a decent amount closer to the stern than the bow.

Thank you very much for your input.
I have taken some measurements to get an idea of at what distance the T200 thrustline will be one from another. In this picture I have set the centre of mass in ~30% of hull’s length (yellow line). Distance shown is measured at this location. Seems reasonable to use 2x T200 with the shown distance between them?!

That doesn’t seem immediately unreasonable, but I also know very little about the system or requirements so it’s hard to say what you would consider to be reasonable results. If you don’t have particular specs in mind then likely the best recommendation I can give you is to try it out and see if the result runs the way you want it to (movement and turning speed, runtime, etc).

If the results aren’t as hoped, you’ll at least have some idea of what’s missing (e.g. “it’s too slow”, or “it doesn’t run for long enough”). That can then help you determine what to change/add, or if you’re lost on how to achieve the performance improvements you want you can discuss them here with a better idea of what you actually want to achieve :slight_smile:

Many thanks for your detailed reply!
In terms of stabilization, seems that is preferable to have a fin installed on the hull at the bottom. Do you advise to get a fin installed in front of the thruster? Something like this:


As in the description for the file you posted, a fin would likely be helpful for deflecting debris. Fins help streamline water flow, which means they’re good for helping an object travel straight through the water (which is likely beneficial), but may make it harder/slower to turn (which may or may not be acceptable - depends on how you plan to use the boat).

Many thanks for the explanation, make sense!

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