The Coast Guard says a C-130 aircraft searched overnight for Kirschbaum, and at daybreak a helicopter joined in the search, which also included a Coast Guard cutter.
"The county lifeguards up in Venice saw his boat tracking into Venice Beach. When it came ashore they put somebody on board and realized there was nobody onboard the vessel and at that point our search efforts, our coordinated interagency search efforts really ramped up quickly," said U.S. Coast Guard Lt. Jim Hiltz.
"We've covered over 2,000 square miles of ocean with over 20 sorties searching for him. We just haven't located him yet," said Hiltz.
Kirschbaum is an accomplished sailor, having sailed across the Pacific to Hawaii.
"All the people that I have spoken to that have sailed with him in the past have said that he is known to be very well prepared, always has the proper safety equipment, always is rigged properly wearing his life jacket. So we're not dealing with a novice sailor here. We're dealing with a very experienced mariner," said Hiltz.
Searchers say a GPS was found on Kirschbaum's boat and that they're using it to help them track the boater's course from Catalina Island.
Kirschbaum's wife reportedly says she received an e-mail from him Sunday morning before he left Catalina.
The GPS equipment shows he sailed a mostly straight course from Emerald Bay near Two Harbors toward the Palos Verdes peninsula. He then sailed north.
Even though the Coast Guard has suspended its search, the Marina Division of the L.A. County Sheriff's Department continued to have a boat out in the water until around 10 p.m. Monday but were not able to find Kirschbaum.