Deadweight Survey

A view of the ship from the water, can see a drydock behind the vessel.

On June 10th, I was taken along with Jeff Reifsnyder, a stability specialist, to the Southwest Shipyard which is about 20 miles east of downtown Houston. We were sent to perform a deadweight survey on a vehicle transport ferry, the Michael W. Behrens. This ferry is used to allow travelers along the 361 highway to Port Aransas, a small island near Corpus Christi. Vehicles simply drive onto the ferry and make the short journey across the bay to the island. 

Measuring the freeboard, under observation of the Coast Guard.

Some locations where more difficult to measure than others.

I was brought along to help Jeff with taking the measurements. We needed to measure the freeboard (the distance between the water and the deck) at 12 different locations. My job was mainly to hold the level while Jeff dropped a weighted tape measure off the side of the boat. I also helped located objects that needed to be accounted for and weigh them and find their centers of gravity. This involved a lot of climbing into tight areas below deck.

The Coast Guard had to observe our measurements to ensure they were done properly.

The deadweight survey is done in order to find how deep the vessel sits in the water, as well as how it is trimmed. Trim measures how level the vessel is, for example whether the front of the ship is lower than the back due to the weights placed on the vesssel. Jeff and I had to find temporary objects onboard (things such as tools, a lift, a trash bin, and other objects that are not permanent fixtures) and weigh them and record their locations. This information was used in calculations of the trim and draft (the draft is how far under water the bottom of the boat reaches). 

We needed a weight for this trash bin and the workers (who spoke little English) were not a huge help.

I was very happy to help out with the survey, as it was the first time I felt I truly applied my education to the job. It also was a nice change from sitting in an office all day. Hopefully I will get taken along to a few more surveys in my time down here.

The vehicles simply drive on deck and the ferry takes them across the bay.