4-1 



MATERIALS AND MOLDING METHODS 



Unidirectional Construction: Consists of a relatively large number of uncrimped and 

 closely aligned heavy yarns in the warp, and a smaller number of light yarns in the fill, 

 Fig. 4-10. This construction can be made in any style of weaves. 



Fig. 4-10. Unidirectional Cloth 



Cloth is presently one of the more expensive types of reinforcement but where con- 

 sistency of high performance and structural efficiency in terms of strength to weight is 

 required the cost can be justified. 



The advantages of cloth reinforcements are: 



Cloth provides an effective surfacing material to cover woven roving and 

 mat laminates to provide a better appearance and strength. One or several 

 layers of cloth laid up over a rough surface laminate can improve the appear- 

 ance of the finished hull. 



Cloth covered mat laminates can be fabricated by hand lay up, to work out 

 excess resin and to obtain higher glass loadings. 



Cloth laminates and sections have the most consistent glass content, and 

 have less deviation in physical properties and laminate thickness than any 

 of the other types of fiberglass laminates. 



Cloth may also be used at high stress areas. 



