Motion Sensor Performance

Direct Comparison Using 2005 Common Dataset
Integral components of a swathe bathymetry system are the motion and heading sensors. The current trend is to offer a system that combines both components in one package, either as an aided inertial sensor or as two sensors linked by component software. The quality of these inertial sensors has a direct effect on the quality of the final survey. This paper compares five leading available sensors, concluding that they produce markedly differing results. Most surveyors when purchasing or specifying a particular inertial system for a project will base their decision on information generated by the manu-facturers, which often shows all... (read more)
2008-01-01 01:00:00

Businesswoman in the Middle East

Interview with Susan Murray, General Manager of the Seatronics’ Middle East office
Ms Murray joined Oceonics (the forerunner of Seatronics) in 1981. It was here that she got her first taste of business in the hydrographic Industry, specifically in the sales environment. After spending a couple of years gaining valuable experience with another equipment rental company in Aberdeen, she returned to Oceonics as Sales Manager. Between 1987 and 1996 she was the General Manager of her own equipment rental company in Aberdeen, selling this in 1996. In 2000 she decided it was time to move on and, believing herself too young to retire, agreed to take on the role of Middle East... (read more)
2008-01-01 01:00:00

The ROV in Nearshore Site Investigation

Nearshore engineering surveys are undertaken for the purpose of gathering information pertaining to the bathymetry and morphology of the seabed, along with the geotechnical characteristics and geophysical profiles of the sub-stratum. Standard practice tends to involve a low-resolution bathymetric and sub-bottom survey of the approximate area of interest, followed by a higher-resolution, site-specific investigation entailing detailed analysis of the location and form of the materials present. The traditional survey technique in the nearshore region is to use surface towed equipment and jack-up rigs, with diving teams and ROVs (Remotely Operated Vehicles) acting as support systems, performing very basic investigation tasks.... (read more)
2008-01-01 01:00:00

Surveying in the Ross Sea

The deepwater research vessel Tangaroa of the National Institute of Water & Atmospheric Research (NIWA) of New Zealand undertakes regular research expeditions to the Antarctic waters. In the last eight years, this 70m ice-strengthened vessel has successfully completed seven voyages to Antarctica: three of which were to the Ross Sea. This article describes her 48-day voyage in 2006. During this latest voyage, she once again collected data to extend our knowledge of the geophysical and biological make-up of the Ross Sea region Looking Back Tangaroa ’s first voyage to the Ross Sea was in February–March 2001, when it undertook a... (read more)
2007-05-09 12:00:00

Altitude and Dynamic Error in TPE and CUBE

Total Propagated Error (TPE) and Combined Uncertainty Bathymetric Estimator (CUBE) help automate data cleaning and filtering. This paper discusses the effect of using altitude in place of heave for survey data processing and that of using error estimates in TPE and CUBE for both variables. Final hydrographic data quality is examined. Total Propagated Error (TPE) and Combined Uncertainty Bathymetric Estimator (CUBE) are designed for use with hydrographic survey data to minimise subjective user intervention and help automate data cleaning and filtering. With the trend in hydrographic surveying towards objective estimation of data quality, these methods rely heavily on error estimates... (read more)
2007-09-04 12:00:00

A Farewell to Times Past

HI Interviews Admiral Steve Ritchie, Columnist ‘As it Was’
We have all enjoyed the column entitled ‘As it Was’, contributed since the very first issue of Hydro international by Admiral Steve Ritchie. The piece has always been very much appreciated and we have received many positive reactions to it. Steve’s lifetime has encompassed the technical revolution in hydrography; it is seventy years since he entered the surveying service and forty since he became UK Hydrographer. So that in terms of memory alone he was the perfect man to carry the ‘As it Was’ column. But he also had a reputation as author of some interesting publications, including his books... (read more)
2007-03-02 12:00:00

OpenSeaMap – the Free Nautical Chart

The biggest worldwide geodatabase, made by the crowd
Nautical charts are expensive, and in many countries data are not always up to date. OpenSeaMap is an alternative solution which is free for anybody to use worldwide. Following the example of Wikipedia, the data are collected by volunteers and are visible on the chart within just a few minutes. OpenSeaMap involves experienced mariners, programmers and thousands of data collectors, all of whom are working to produce a nautical chart with comprehensive, relevant and up-to-date data for water sports which is open to everyone and free of charge. OpenSeaMap – the free nautical chart – covers oceans and inland waterways... (read more)
2013-03-26 01:57:05

Communications to the Deepest Point on Earth

Underwater Communication Solution for James Cameron’s Deepsea Challenge
In March 2012, filmmaker and explorer James Cameron successfully completed his one-man dive to the bottom of the Mariana Trench. The dive was the centrepiece of the Deepsea Challenge expedition, a joint scientific project by Cameron, the National Geographic Society and Rolex to conduct deep ocean research and exploration. A range of technological innovations were required for the venture, one of which was a reliable method for sending voice and data between the 'Deepsea Challenger' submarine and its support vessels on the surface. At a depth of almost 11km, the Mariana Trench is the most remote and isolated place on... (read more)
2013-03-26 01:37:16

Shallow Survey 2005 Common Dataset Comparisons

Shallow Survey 2005 Common Dataset Comparisons As part of the Shallow Survey Conference 2005 held in Plymouth, swath sonar manufacturers were invited to survey a common dataset. Two regions were chosen: an offshore area south of Plymouth breakwater suited to larger vessels and Lidar operations, and an inshore area around Plymouth Hoe. The data collected for the inshore area serves as the basis for this study. The manufacturers and systems that provided data for the inshore area are listed in Table 1. Each of the surveys was undertaken with the same supporting equipment, and mostly using the same vessel. RTK... (read more)
2008-01-01 01:00:00

F I S : Re-survey Decision System

Using Fuzzy Inference Systems for Area Selection
Navigational safety and political-economic considerations make it essential for port administrations and hydrographic services to have a prioritised survey programme. Finding criteria that reflect the importance of re-survey over a given area is fundamental here. A better way must be found than traditional thematic classification. Fuzzy Inference Systems (FIS) have been used successfully to deal with such problems. This article presents its use for hydrographic re-survey selection. Establishing a re-survey priority programme is no ordinary task. Specialists must analyse many kinds of information that, due to their complexity, must be combined in criteria: first to find where re-survey is necessary... (read more)
2007-03-02 12:00:00
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