Surveying with the Fairweather

This past week I have continued working with our sister ship, The Fairweather. The following pictures are from surveying Elliot Bay in Seattle. This data acquisition process is the same as described before...casting the CTD to measure and calculate the sound velocity and logging data from the multi beams (which is done by running lines, usually going no faster than 7 knots, over our planned survey areas).

The greater the depth, the slower you should go. This is due to the swath width. If the pings from the multi beam have to travel further, the data tends to be a bit choppy. As an example, we surveyed over an area with a depth of about 120 meter. At this depth we drove lines at about 4.5 knots to ensure higher quality data.

It was interesting to survey Elliot Bay because of all the traffic. We often had to stop logging and get out of the way of various other vessels (ferries, water taxis, tugboats, etc.). Additionally, we would often have to get very close to other anchored vessels in order to gather as much data as possible.

Logging and monitoring the multi beam data

Areas surveyed

Launch surveying next to a cargo ship...you can see how close we can get with the launch

Another project we worked on this past week was measuring the antennas on the (Rainier) launches. This is vital information that we input to make sure our calculations are matching up with the systems calculations. The purpose of this is to understand where the antennas are in realtion to the IMU (Inertial Motion Unit) which gives information as to where the sonar is in relation to the IMU which gives us the goal of knowing exactly where we are in relation to the seafloor.

Tools on top of the launch used for measuring the antennas

Since we have been in Seattle the past couple of weeks, I have been taking advantage of exploring the city after work on the ship. Here are a pictures/views from the Space Needle.

View from the Space Needle

Finally, on Friday (6/1/2012) the Rainier ran safety drills. This included learning how to use the emergency pumps, information on fire suppression, how to load and unload the launches from the Davits, etc. It was a very active day and a lot of information to learn. The following picture is of me hooking up the launch on the bow.

Laoding the launch into the Davit

QUESTIONS:
A great question was posed on my blog last week: "Is the seafloor the top of the muddy surface or is it the firm ground underneath?" A simple answer would be, yes, or both. This can be a very subjective question and depends on who is surveying and where. As far as what we are doing, our sonars have set algorhythms entered that will tell us where the seafloor is. It is hard to tell sometimes.

And just for fun, here is a bald eagle. I see them almost everyday here.