522 ISAACS [chap. 24 



properly designed spar is the problem of handling it and coming alongside, 

 as its motion in a seaway is incompatible with that of any conventional 

 craft. 



The surface pennant to a responding float (skiff) must ordinarily lead almost 

 horizontally away from the float, or, if nearly vertical, it must be highly elastic. 

 This is because when the float is subject to white caps or combers its vertical 

 downward acceleration approaches that of gravity. Hence, any vertical string 

 depending only upon gravity forces for tension will slack and jerk in a way 

 that will greatly decrease its life, if, indeed, it survives at all. 



The pennant to a non-responding float (spar) must tend away almost verti- 

 cally because, if horizontal, it is subjected to severe flexing or abrasion at the 

 point of attachment from the vertical motion of water by the relatively non- 

 moving spar. 



Resonance of a spar to the waves is a condition to be avoided. 



Another requirement of the surface float is that it possess sufficient dis- 

 placement to support its instrument and power load. We have always used 

 floats that would also support the weight of the mooring wire and a swamped 

 submerged float to prevent the entire mooring being lost if the submerged 

 float were to leak. 



The characteristics for a responding float are best met by a skiff or boat 

 shape, and at the Scripps Institution we have used decked glass-reinforced 

 plastic skiffs about 16 ft long for the surface float. 



B. Pennants and Instrument Wires 



The pennant is the member of the mooring assembly that connects the surface 

 float to the submerged float or the main mooring component. 



The pennant to a non-responding spar necessarily tends almost vertically 

 and is difficult to relate to a submerged float because slack during calm weather 

 will foul the submerged float. 



The pennant to a responding-type float must either tend horizontally or, if 

 vertical, be highly elastic, as previously discussed. 



Both types of pennants are in use. A common pennant is a nylon float line 

 that tends upward in a floating catenary. In slack weather this floats forward 

 off the surface float and greatly increases the possibility of the mooring being- 

 run down by a passing vessel. This situation is intensified by the fact that in 

 slack weather the visual and radar detection range of vessels is increased and 

 the curious passing navigator is also more likely to investigate the con- 

 tact. 



The instrument line is then lowered independently over the stern of the float 

 using a harp of shock cord to provide elasticity. This system is limited to 

 instrument lines that are much shallower than the submerged float except in 

 weather situations that are constant, such as the trades, otherwise the pennant 

 and instrument line will foul. 



