LBV150BE2 - Umbilical

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One of the many unique and industry leading aspects of the SeaBotix line of systems is the umbilical. What makes it so unique is the revolutionary small diameter at just 8 mm (0.3 in). No longer does a small ROV have to be controlled by its umbilical.

The LBV150BE² system is supplied with 100 meters - 328 ft of umbilical. Internally the umbilical is very simple with only a single twisted pair, shield, Kevlar strength member, flotation and outer jacket. This unique design reduces drag on the LBV150BE² system, yet is incredibly strong with a 45 kgf - 100 ft/lb working load and 318 kgf - 700 ft/lb breaking strain. The umbilical is supplied with connectors, strain relief and a shackle for secure attachment to the LBV150BE². Also, the umbilical is neutrally buoyant in fresh water and slightly positive in sea water.

To many the understanding of how important the umbilical characteristics are to the capability of the ROV is unknown. Drag from umbilical is the largest of any part of the ROV. Consider that the drag is the square of it's diameter. To compensate for larger diameter umbilicals the ROV typically gets larger. Small ROVs with larger diameter umbilical are difficult to operate in conditions where there is current or longer lengths of umbilical in the water. The often used term "Tail Wagging the Dog" is an example of a larger diameter umbilical used on a small ROV where there is not sufficient power or mass to overcome the influences made by the umbilical.

From the conception of LBV there were three (3) very important factors:

1. Small diameter umbilical
2. Bollard thrust
3. Power to weight ratio

LBV benefits from one of the smallest diameter umbilicals of any ROV. When demonstrating a ROV be sure to operate with longer lengths of umbilical and in a current to see how they perform. At depth the power of the thrusters should be such that it can maintain position without the umbilical greatly affecting the operation.

An example of umbilical diameter drag comparison (using 0.6cd):

• 8mm umbilical at 2 knots creates a drag of 16.75lbs
• 10mm umbilical at 2 knots creates a drag of 21.99lbs
• 10mm umbilical creates 24% more drag thus the ROV must have 24% more power to overcome the additional drag.