Tether Management

Tether management can have a significant affect on the ability to pilot the ROV and achieve the objectives of the mission.

Tether Management includes selecting the appropriate type of tether and managing the deployment and retrieval of it during operations.

Choosing the right tether and managing it can have a very significant impact on the outcome of an ROV dive.

Tether is available in neutral or negative buoyancy. Negative tether sinks but has larger conductors, which means longer lengths can be used without affecting the power available at the ROV. Neutral tether is neutral in fresh water (slightly buoyant in salt water), but has thinner conductors. Neutral tether is available in standard diameter and performance diameter (also called PPT), which is thinner. Thinner tether has less drag, but also has smaller conductors and less power transmission capacity. Selecting the right tether is a balancing act between performance and handling characteristics.

General Tether Use Recommendations

• Make sure tether connections are secure.

• Use the shortest amount of tether required to operate in the target area.

• Use Performance or Neutral tether at the ROV and if more tether is needed use Negative at the control panel.

• Do not use more than one section of Performance Tether.

• If possible, select a deployment site that aids in ROV piloting and tether management. Usually, this means up-current from the zone of operations and with a direct line of sight to avoid snags.

• Only deploy what is needed - too little will affect piloting - too much may result in snags, tangles or propeller cuts.

Typical Tether Configurations

Typical tether configurations are provided in the tables below. When using more than one tether type, tethers should be connected in the order shown from left to right from the control panel to the ROV. Maximum recommended length for a specific configuration is indicated in the "Maximum" column. It may be possible to use more tether under certain conditions, but these are general guidelines for optimal performance. In challenging conditions of swift current, minimal tether lengths are recommended, and using weights or other operating techniques may be required.

Meters

Control Panel	Negative	Neutral	PPT	ROV	-	Total Length	Maximum for this Configuration
Control Panel			40 m	ROV		40 m	Yes
Control Panel		76 m		ROV		76 m	No
Control Panel	76 m		40 m	ROV		116 m	No
Control Panel		76 m	40 m	ROV		116 m	No
Control Panel	76 m	76 m		ROV		152 m	No
Control Panel		152 m		ROV		152 m	No
Control Panel	152 m		40 m	ROV		192 m	No
Control Panel		152 m	40 m	ROV		192 m	Yes
Control Panel	152 m	76 m		ROV		229 m	No
Control Panel		229 m		ROV		229 m	Yes
Control Panel	229 m		40 m	ROV		269 m	No
Control Panel	229 m	76 m		ROV		305 m	No
Control Panel	229 m	76 m		ROV		305 m	Yes

Feet

Control Panel	Negative	Neutral	PPT	ROV	-	Total Length	Maximum for this Configuration
Control Panel			131 feet	ROV		131 feet	Yes
Control Panel		250 feet		ROV		250 feet	No
Control Panel	250 feet		131 feet	ROV		381 feet	No
Control Panel		250 feet	131 feet	ROV		381 feet	No
Control Panel	250 feet	250 feet		ROV		500 feet	No
Control Panel		500 feet		ROV		500 feet	No
Control Panel	500 feet		131 feet	ROV		631 feet	No
Control Panel		500 feet	131 feet	ROV		631 feet	Yes
Control Panel	500 feet	250 feet		ROV		750 feet	No
Control Panel		750 feet		ROV		750 feet	Yes
Control Panel	750 feet		131 feet	ROV		881 feet	No
Control Panel	750 feet	250 feet		ROV		1,000 feet	No
Control Panel	750 feet	250 feet		ROV		1,000 feet	Yes

Tether Storage

Make sure the connectors are clean before mating, and clean the connectors after each use by soaking in fresh water. Do not let the tether connectors drag on the ground.

Tether should be stored on a TDS or coiled using an over/under or figure eight technique. Coiling the tether in one direction will result in twists that are hard to remove.