II. TEST PROCEDURE AND RESULTS 
1. Equipment. 
The equipment tested during development of the lightweight pneumatic 
corer consisted of two support frames, 2.4 and 4.3 meters long, and five 
industrial vibrators. The frames were designed and constructed at CERC. 
Both were of the same basic design, which closely approximated the final frame 
design shown in Figures 2, 3, and 4. The criterion for design and materials 
was to keep the frame as compact and as light as possible commensurate with 
the intended use. Also, the frame assembly was constructed in sections for 
easily disassembling and packing for transport in a panel van or pickup truck. 
During the early phases of testing it was determined that the small frame, 
which could be readily extended to any desired length by lengthening the 
guide pipes, was capable of supporting the largest vibrator to be tested. 
All field tests were made with this frame after modification to an overall 
length of 3.0 meters. 
The vibrators tested consisted of a 2-inch and a 3-inch long-stroke, 
flange-mounted piston vibrators and three paired ball-type vibrators with ball 
sizes of 25, 38, and 64 millimeters. All vibrators were commercial off-the- 
shelf items. During testing, the piston vibrators were mounted on a shelf 
section bolted to a slide plate. The paired ball vibrators were mounted 
directly to the slide plate with the bases opposed and the long axis of the 
flanges in a vertical position with the inlet ports up. In this configuration 
the forces generated by the two vibrators become linear in the vertical plane 
and cancel each other in the horizontal plane. In the final design the slide 
plate was modified to more effectively support the piston vibrator. 
2. Testing. 
Preliminary tests of the vibrators in a sandfilled barrel, 2.4 meters deep, 
were conducted at CERC during the winter of 1979-80. From these tests it was 
concluded that the 2-inch piston vibrator and the 25-millimeter ball vibrators 
were not large enough for their intended purpose. Only the three larger 
vibrators were tested in the field. 
Field tests were conducted in Lake Erie from the DGS research vessel GS-1 
(Fig. 5), a steel hull vessel 14.5 meters long and a 4.3-meter beam with a 
normally loaded draft of 1.4 meters. The GS-1 was moored over the coring 
site by two 12H Danforth anchors emplaced fore and aft. The corer was deployed 
over the stern (Fig. 6) by a 3.3-meter derrick crane with an electric winch 
which has a lifting capacity of about 454 kilograms. The system was strong 
enough to extract the core tube from the sediment. No significant problems 
were encountered in holding the vessel within tolerable excursion distances 
with the two point mooring in seas 0.6 to 1 meter high. Deploying and 
recovering the corer with the help of the derrick crane and two persons were 
carried out without difficulty. 
Field tests were conducted throughout the summer months of 1980 by DGS; 
a total of 181 coring sites were occupied. The results of the tests are 
