You're providing information about a sensor depth and a tape measure reading, but you haven't given any context about velocity. To calculate velocity, we need more information.

Here's why:

* Velocity is a measure of how fast something is moving and in what direction. It needs both speed (magnitude) and direction.

* Sensor depth and tape measure reading are measurements of distance or position. They don't inherently tell us about movement.

To determine the velocity, you need to know:

1. What is moving? Is it a sensor, an object being measured, or something else?

2. How is the object moving? Is it moving in a straight line, a curve, or oscillating?

3. Is there a time component? Velocity requires knowing the distance traveled over a specific time period.

For example:

* If the sensor is moving at a constant speed of 1 meter per second and the tape measure reading of 6.2 meters is the distance traveled, then the velocity at a depth of 0.30m is 1 meter per second in the direction of the tape measure.

* However, if the object is moving in a more complex way, the velocity will be different.

Please provide more information about the scenario, and I can help you calculate the velocity.