The first indication that current measurements are a challenge to obtain is the fact that to deploy and maintain a current meter is anywhere from four to ten times as expensive to do as similar activities to measure water levels. This has important implications for the quality and breadth of current observations and tidal current predictions available today to the Nation's mariners. Back This increased expense can be readily appreciated by noting a few sharp contrasts between the behavior of water levels and currents. By contrast, current speed and direction can be very localized, varying greatly over short distances as bottom contours and shoreline configuration alter both the current's speed and direction of flow as well as spinning off eddies.
Installation is done mostly from the safety and working convenience of dry land.
By contrast, the equipment and deployment of current measuring devices is more expensive and involved. Next, your truck will only get you to the ship's dock. You and yourequipment need to be out on and in the water and the boat to do that willtypically cost several thousand dollars per day. Routine maintenance on such an installation typically occurs once each year. By contrast, all of a current measuring system is typically in salt water and thus subject to both rapid corrosion and fouling by marine growth.