Figure 4. The CRAB 



12. Total vehicle weight is about 8,200 kg; the distance between the 

 rear wheels is 8.2 m. Though it appears top heavy, the liquid-filled tires 

 and wide wheelbase make it very stable. It has passed a 20-deg tilt test and 

 is designed to withstand even steeper angles. 



13. Top speed of the CRAB is 3.2 km/hr on land and somewhat less in the 

 water. Since the maximum significant wave height for operation is 2 m, the 

 CRAB is capable of operating in all but the most severe east coast storms. 

 The large tires have a negligible effect on a hard rippled sand bottom; how- 

 ever, scour around the tires has been observed in areas of active wave break- 

 ing or strong currents if the CRAB remains motionless. The CRAB cannot be 

 used on soft silty or loose bottoms. 



14. All beach and dune surveying was accomplished with the standard 



10 



