Design 

These trawls are primarely designed and  optimized for my trawlers "PRINCESSE"
and "SAGAR" which power and speed had  been carefully calibrated.
Naturally they can be used with other fishing boat models, after all, it's all about the tow.

The difference may be in how you'll feel the drag of the trawl
depending on the size and power of the boat you are using.

4 trawls are available. They are submerged vehicles [however boats not
submarines] without propulsion and which can be towed.

They are geometrically identical but "float" at different depths -20m, -50m, -100m and -200m, with a setting margin provided by the loading slider [in %] in the vehicle menu.

Note: by adjusting the depth of the net below its nominal value, the trawl will take on a certain horizontal speed that will eventually dissipate, but oddly there will be always less drag.

Designed and optimized for VSF 2.7.6 only. Cannot properly work in VS NG, it needs specific design.

Once you're on your chosen heading, reduce speed to 3-4 kts.
From the pilot's view, preferably in the center position, switch to the chase view [F2] and then to the remote view [F2 again].

Increase the simulator's rate at will [press F4 as long as needed] to
move away quickly from the trawler (about 400-500m).

Then press F3 continuously to get the sim rate back to 1.

Go to  vehicle menu [V] and add the trawl of your choice.

Let the trawler tow the trawl.

When you return to the trawler, you will notice a significant decrease in speed
(except perhaps in the case of a tailwind), 
so adjust your engine RPM to maintain a speed of 3-3.5 kts.

That's it!

You can check out this related video: https://youtu.be/OszE87YVXeU