1. Hawsehole 



2. Mooring line 



3. Power cable 



A four-point moor would be provided for the surface plant hull. The 

 four wire rope moorings enter the bottom of the hull close enough to the 

 center to retain the desirable characteristics of a single-point moor but far 

 enough outboard to prevent rotation and the consequent twisting of the power 

 cable. A four-point moor reduces the excursion limits of the surface hull and 

 therefore reduces the length of power cable required. The moors entering the 

 bottom of the hull would prevent the hull from towing under in high sea states. 

 Figure A-13 illustrates a four-point mooring attachment to the surface hull. 



Three ships would be 

 required to set the four-point 

 mooring system: a heavy lift 

 ship (HLS), a supply ship (SS), 

 and a station-keeping ship 

 (SKS). The HLS or the SS 

 could be used to tow the sur- 

 face plant hull to the site. On 

 arrival at the site, the SKS 

 would establish and record 

 the site geography for compar- 

 ison to a prior site survey and 

 would position itself at the 

 center of the moor. The SS 

 would take a position at 90 

 degrees to the SKS while the 

 HLS would position itself 

 over the first leg. The HLS 

 would first lower the anchor 

 slowly. When the anchor has 

 bottomed, the HLS would 

 then proceed slowly toward 

 the SKS to bottom the anchor 

 clump. When the clump bot- 

 toms, the HLS proceeds to 

 the location of the catenary 

 support buoy, paying out the 

 remaining mooring leg. The 

 anchor would then be set and 



the support buoy emplaced. The HLS then continues toward the SKS to lay 

 the synthetic mooring line for the first leg. This procedure would be repeated 

 for the other three mooring legs. On completion of the mooring system 

 emplacement, the mooring lines would be transferred from the SKS to the 



Figure A-13. Four-point moor accommodations 

 on surface buoy. 



110 



