Looking for miniature underwater servos



Hi All,

I’m looking for miniature (very small) servo/motor to be used on an AUV/ROV





Try here
Be advised that these servos are only good for about 1 meter underwater.


If you want depth…

A few years ago I met someone named Emily McBrian while she was testing MSLED (section 6.1 of the paper below) for deployment at over 800m of depth.

This paper discusses the MSLED ROV and several details including its servos:

Recently, we had a chat about how it went. Of particular interest to me is how to run the push-rods out of a liquid-comp bottle. I am sure she wouldn’t mind me sharing some of her words here:

MSLED has 4 (33035S) HS-35HD Servos from servo city (link below). The entire tail section is full of Fluorinert to compensate the pressure and has a flexible silicon window to adjust for any left over bubbles.


She said they used compressed O-rings to to seal the servo push-rods leaving the bottle to connect to the steering fins in the water. She noted that particular aspect needed some work as the O-rings would wear and leak after a while.

On my some-day list of liquid-compensated things to test: fluted tubes like those shown at the bottom of this page (It is cool, but read nothing into the chosen link/site. This is simply the first page I found googling for pictures of fluted tubing.):


With liquid compensation, you’ll probably have to include some spare tubes that can let the liquid “breathe” fairly easily when the servos move.

If you try this, please let me know how it goes.

-John Winans


It can also be worthwhile having a look at @Arne_O has done as well