TM 5-5420-209-12 Table 2-13. Bridge  Assembly  Requirements. Bays Boats Bridge Length (Feet/Meters) Ramp Interior Launch  Sites  Desired Need Desired 80  (24.38) 2 2 2 3 4 102 (31 .1) 2 3 2 4 4 124 (37.8) 2 4 2 4 5 146 (44.5) 2 5 2 5 5 168 (51 .20) 2 6 3 5 6 190 (57.9) 2 7 3 6 6 212  (64.6) 2 8 3 6 7 234 (71 .3) 2 9 3 6 7 256 (78) 2 10 3 7 7 additional  (Note  1) 0-66 (20) . 1-3 . 1 1 additional  (Note  2) 0-88  (26.8) 1-3 . 1 1 additional  (Note  3) 0-132  (40) . 1-6 . 1 1 Notes: 1. In currents of 6 to 8 feet per second for each additional bridge length increase of 0 to 66 feet add the indicated number of boats. 2. In currents of 3 to 6 feet per second for each additional bridge length increase of 0 to 88 feet add the indicated number of boats. 3. In currents up to 3 feet per second for each additional bridge length increase of 0 to 132 feet add the indicated number of boats. (Includes the safety boat but not the backup boats.) 2–14. Bay Free Launch.  (figure 2-14) Where conditions permit, a bay maybe free launched. This method allows the  bay  to  roll  off  the  transporter  and  unfold  in  the  water.  The  water  depth  required  varies  with  slope  and  position  of  trans- porter in water. A maximum slope of 30 percent with a minimum water depth of 36 inches (44 inches for ramp bay) is allowed for safe free launch (transporter on a 10 percent slope and backed into the water until the rear wheels are hub deep  in  the  water).  When  free  launching  on  a  5-10  degree  sideslope,  in  heavy  winds  and/or  fast  water,  adjust  boom  and winch cable hook to maximum height before paying out. This is to permit maximum range of motion for the tiedown hook mechanism. The crew required for a free launch consists of an operator and an assistant. When an assistant is not as- signed  to  stay  with  the  transporter,  a  temporary  assistant  maybe  designated  from  the  staging  area  crew  or  shuttle  crew for duties to be performed in the staging area, or the launch site guide for duties to be performed at the launch site. This will generally be the case in rapid bridge construction. The operator will drive and be responsible for the safe launching of the bay. The assistant will help prepare bay and transport for launch. The free launch procedures are the same for either a ramp bay or interior bay. 2-48