Equipment: Photographic techniques were used extensively throughout the study. 

 This resulted from logistical difficulties encountered in attempting to deploy 

 the ducted impellor flowmeters originally proposed for use in this investigation. 

 Photographs of subsurface dye releases also provide details of the flow field 

 which are not obtainable from flowmeter measurements. 



One Nikonos II underwater camera equipped with a 35 mm lens and one equipped 

 with a 28 mm lens were used for most of the subsurface photography. Aerial 

 photographs were taken by NASA's NP3A aircraft. Dye releases were made using 

 both Rhodamine-B and red commercial food coloring. The later dye proved to be 

 superior for underwater photography because it provided a greater contrast 

 with the ambient water and did not have the persistent staining quality of the 

 Rhodamine-B dye. Subsurface dye releases were made with a one liter manually 

 operated piston type cylindrical injection gun with an orifice opening of 

 0.6 cm. The injection gun is 0.5 m long and has a slight negative buoyancy 

 when loaded. This makes the unit easy to handle underwater. Surface dye 

 releases were made from a 15 liter container, gravity fed through a 1.2 cm 

 hose. 



A Gurley current meter was used to make in situ profiles of the upper portion 

 of the water column, above the habitat. This meter was deployed from the 

 diving barge above the habitat and from small boats provided by the Cape Fear 

 Institute vessel S. S. Advance II. 



Procedure: The primary site for this investigation was the area immediately 

 adjacent to the TEKTITE II habitat. A secondary site was necessary because 

 of the large amount of dye which was released for the aerial photography. 

 Both of these sites are shown in Figure 1. 



The TEKTITE II habitat was located in fairly quiescent waters owing to both 

 its juxtaposition to the coastline and the nature of the prevailing wind 

 conditions during the investigation period (July 19-July 26) . Three current 

 profiles were made at the start of each current monitoring dive. These 

 profiles. Figure 2, showed that the mean current speed at the top of the 

 habitat was extremely low (0.09-0.19 m/sec) under these conditions. A series 

 of linear dye releases were made at positions around the habitat. Figure 3, 

 with the injection gun. Photographs of the dye releases were taken with high 

 speed ectachrome film and a Kodak SOB filter. 



On July 23 fifteen liters of Rhodamine - B dye were released at a rate of 1/2 

 liter per minute from the site shown in Figure 1. Aerial overflights of the 

 dye were made every ten minutes for one hour. During the overflights three 

 divers were deployed with underwater cameras and a calibrated grid to photograph 

 the vertical diffusion of the dye. High speed ectachrome film and an SOB filter 

 were used for these photographs also. 



VII-49 



