a block designed to take the thrust of the propeller
                                                            
                                                     
                        
                                                
                        
                        
                            A massive block of concrete built to withstand a thrust or pull.
                                                            
                                                     
                        
                                                
                        
                        
                            A mass of concrete of similar material appropriately placed around a pipe to prevent movement when the pipe is carrying water. Usually placed at bends and valve structures.