Dredges

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SEASAM builds and maintains Scripps style rock dredges. These are rectangular dredge buckets (36″ x 13.25″) with 4″ teeth. We also have a few circular dredges that some PIs prefer for sampling pillow basalts. SEASAM has multiple pingers and a ultra-short baseline (USBL) beacon that can be used for more precise tracking of the dredge location.

SEASAM generates shear pins to be used with weak links on the dredge-wire interface. We employ a variety of bolts but based on our laboratory break testing experiments, brass appears to be the most reliable in breaking at the desired tension limits. Therefore, we have transitioned to fabricating and using brass pins.

On a dredging focused expedition we will send the SEASAM dredge van. This is a 20′ van that contains tools, supplies and spares needed to quickly diagnose and fix most issues that may arise during operations.

SEASAM has improved upon the old fashioned double shear weak links and has standardized with a single 3/4″ hole size accommodating 3/4′ brass pin stock. Brass pins were common in early UNOLS designs and SEASAM is returning to this material choice for it’s easy machinability and low variation of break values per given diameter. A single stock diameter is thus inventoried and alleviates preparation rush before a cruise. Stock is then turned on a lathe with material removed in line with each shear plane of the weak link to the diameter needed for the working depth.  Identification of break strength can always and easily be determined with calipers if the pins become mixed up on deck or labeling information is lost. When new targets are found a pin with any new value needed can easily be created at sea which is helpful if new targets need to be identified at depths not previously accounted for before sailing.  Please see our dredging video tutorials for more information.

In addition to shear pin improvement and standardization, SEASAM has also championed dredging with USBL navigation, 12khz pingers and other dredge and wire mounted sensors.  You can still collect rocks without electronics; however the improved location accuracy for sample collection is scientifically desirable and when the dredge is hung, the situational awareness on the bridge is vastly improved with known dredge location and redundant depth information.

We have an archive of past dredge designs and/or we can also build something for you in house. However, the SIO-designed dredges are preferable. Contact us to discuss.