Blocker Drilling and Marine Co., a subsidiary of Blocker Energy Corp., Houston, Texas, has applied for a Title XI guarantee to aid in financing the construction of two semisubmersible drilling vessels.

Each of the 85-foot vessels are to operate in the Gulf of Mexico. Chicago Bridge & Iron Co., Pascagoula, Miss., is the proposed builder. Deliveries are set for October 1982 and February 1983.

If approved, the Title XI guarantee would cover $47,460,000 or about 75 percent of the estimated actual cost of $67,150,000.