(CNN) -- BP has abandoned use of the diamond wire saw that jammed, thwarting the company's latest attempt to slow the Gulf oil spill, and will instead use the giant robotic-arm cutting device that made Tuesday's successful first cut on the leaking well's riser, Coast Guard Adm. Thad Allen told CNN Wednesday.
The diamond wire saw was supposed to provide a clean cut on the pipe -- or riser -- that is designed to bring oil up to the surface, to fit a cap over what's called the low marine riser package.
Because the larger, less precise cutter won't leave a clean cut, Allen said, BP will have to use the "top hat" -- a larger cap the company abandoned last month to try an insertion pipe that ultimately syphoned off about 20 percent of the oil gushing from the broken well.
The top hat is a 5-foot-tall, 4-foot-diameter structure that weighs less than two tons. It has been on the ocean floor since May 12 when BP was considering its use.