Chapter 5 — CLOUDS AND VISIBILITY 



it should be oriented in the following manner: 

 Loosen the knurled hand knob, raise the cli- 

 nometer to eye level, aim the sighting tube at 

 the center of the light beam, and tighten the 

 hand knob (fig. 5-6). Loosen the pendant lock 

 stud assembly and the pendant clutch assembly. 

 Adjust the pendant index to zero while the line 

 of sight is parallel with the deck. 



This may be accomplished by placing a 

 spirit level at a level point on the deck and a 

 spirit level on the top of the sighting tube 

 and adjusting the index to zero when the bubbles 

 of both levels read the same inclination. 



An alternate procedure is to adjust the index 

 to zero while sighting at a spot on the ship which 

 is the same height above the deck plane as 

 the center of the sighting tube. 



When the clinometer has been accurately 

 leveled, establish a permanent orientation check 

 mark on the ship. Read and record the angle 

 with respect to the orientation check mark 

 and the height of the mounting bracket above 

 the knurled hand knob. 



For subsequent orientation checks, sight 

 on the orientation check mark and adjust the 

 pendant index to the recorded angle when the 

 mounting bracket is the correct height above 

 the knurled hand knob. 



Operation 



Operation of Clinometer ML-591/U is per- 

 formed as follows: 



1. Remove coated nylon cover from cli- 

 nometer. 



2. Perform the orientation check as de- 

 scribed above. 



3. Loosen the knurled hand knob, and raise 

 the clinometer to eye level. 



4. Adjust the sighting tube so that the 

 cross wires are centered on the beam of 

 light (fig. 5-7) and tighten the knurled hand knob. 



5. Release tension on pendant lock stud 

 assembly. 



6. Sight clinometer on center of the illumi- 

 nated spot on the cloud base. 



7. Secure pendant lock stud assembly. 



8. Record elevation angle reading to closest 

 l/2 degree. 



9. Repeat steps 5 through 8 three times. 



10. Compute average of three readings. 



11. Use tables to obtain measured cloud base 

 height. (See fig. 5-7.) The actual cloud base 

 height will be the measured height plus the 

 height of the clinometer above sea level. 



12. When the clinometer is not in use, re- 

 place the coated nylon cover and secure the 

 drawstring. 



13. If the clinometer will not be required for 

 an extended period of time, remove it from 

 the pipe support and store inside. 



Maintenance 



Check the accuracy and performance of the 

 clinometer periodically on a 30-day cycle. 

 Accomplish the clinometer performance test 

 as follows: 



1. Remove coated nylon cover. 



2. Loosen knurled hand knob on mounting 

 bracket base. Mounting bracket should slide 

 freely within mounting bracket base. 



3. With mounting bracket in extended po- 

 sition, secure knurled hand knob handtight. 

 Clinometer must be capable of supporting at 

 least 25 pounds. 



4. Loosen pendant lock stud assembly. No 

 more than one-quarter turn of stud must be 

 required to free or secure sighting tube and 

 quadrant plate assembly. Quadrant plate must 

 swivel easily without binding or scraping. 

 Swiveling quadrant plate must not cause lock 

 stud assembly to turn. 



5. Secure pendant lock stud assembly hand- 

 tight. Sighting tube and quadrant plate assembly 

 must be immobile. 



6. Loosen pendant clutch assembly. Pendant 

 must swivel freely. 



7. Secure pendant clutch assembly finger- 

 tight. Pendant must be held immobile. 



8. Return clinometer to correct height and 

 heading and replace cover. 



9. Check cross wires to determine if they 

 have been damaged or bent out of alignment. 

 Check alignment with a straightedge. 



85 



