Meauring weight at sea

Place the material on the scale and you get a measurement. Right? Not when you are on a moving ship. The acceleration and deceleration on a moving ship means that it is not a simple procedure to weigh something for science. 
 
There is a bathroom scale in my office here, used for weighing boxes of samples to be shipped to scientists institutions. I placed my special gifts from the drilling crew on the scale. 10 lbs extra for my luggage. I don’t think I brought that much chocolate and dried fruits so I’m going back heavier than I expected. 10 lbs is a good enough measurement for me.
 
For the scientific measurements, good enough means something very different. Here is a short video on measuring weight at sea. Thanks to Mike Bertoli for agreeing to be video taped with his long hair (he’s growing it to donate for wigs).
 
 
The microbalance is on a gimbaled table. The microbalance measures the weight of the samples used to determine total carbon and total inorganic carbon.   The balances used in the video are used for the MAD measurements – MAD is moisture and density. Samples are pre-weighed, dried and weighed again. The moisture can be calculated from this.
 
 
 
Only a day left of drilling. Lots more igneous rock on board. First rock drilled from the Cocos Ridge.  This is  exciting because the ridge was created by the Galapagos hot spot.   The chemistry of the rocks will help scientists understand the history and chemistry of the hot spot over time.  Beautiful basalt rocks. 
 

 

Comments

Have you found any

Have you found any sedimentray or metamophic rocks? -GW

Measuring weight at sea using accelerometers?

Interesting...Gimbelling the scale would be OK for gradual roll & pitch, but not so well for vertical drops, so why not just measure the acceleration/deceleration in XYZ planes and subtract the effect in real time with the scale/balance? Many modern smartphones sport incredibly accurate built-in accelerometers (i.e. iPhones, Android phones, etc.) Even gaming Wii remotes (Wiimotes) that cost around $40 and are very sensitive with raw output sampled at something like 200 Hz. The new Wiimote Plus has gyroscopes and achieves 6 degrees of freedom (DOF). Maybe you could increase your accuracy this method than averaging over time as shown in the video? You can obtain this data with free software called g-force analyzer or GlovePie (for Windows), Darwiin remote (for Macs) and there is a version for Linux. The trick would be communicating the scale output with the acceleration output to achieve an "acceleration-free" balance output reading.