Abstract: A decade old side scan sonars are now being modernised by way of dynamically controlling the width of the receiving beam in the horizontal cross-section. The result is a quasi-constant linear resolution of the sonar (replacing constant angular resolution), when it picks up echo signals as it moves further away from the targets. The advantage of the treatment is that the ship using the side scan sonar can increase its speed without risking the loss of near targets’ echo. The articles describes how the system of dynamic control was implemented. Special TVG systems were introduced to control dynamic signal gain from several separate sections of the sonar’s acoustic array, which was divided symmetrically into unequal sections. The location of these systems in the sonar’s receiver is presented. Examples are given of curves that control TVG and of the effects of dynamic horizontal stabilisation of the sonar’s linear resolution as it receives signals.