Noting its strong capitalization and financial support from parent company Berkshire Hathaway, A. M. Best has reaffirmed a pair of ratings for its Seaworthy Insurance Co. of Annapolis, Md.

The ratings service affirmed a financial strength rating of A+ (Superior) and issuer credit rating of “aa” for the marine insurer, indicating the outlook for both ratings is stable. The company provides coverage for yachts, sailboats and charter vessels.

Other factors in A. M. Best’s assessment were sustained operating profitability indicative of management’s niche ocean marine expert and support from a Berkshire Hathaway reinsurance subsidiary, National Indemnity Co. of Omaha, Neb., in the form of two significant transactions.

They include a loss portfolio transfer and quota share agreement between Seaworthy and National Indemnity, which acquired Seaworthy’s immediate parent, Boat America Corp., in August 2007.

“In addition to Berkshire Hathaway’s track record of supporting its member companies, these transactions demonstrate in effect the explicit commitment provided by Berkshire Hathaway, for which Seaworthy receives rating enhancement,” A. M. Best noted.

The positive rating factors are partially offset by Seaworthy’s product and revenue concentration, but despite these factors, the insurer’s outlook is based upon its enhanced financial flexibility, strong balance sheet and historic underwriting profitability, according to the ratings service.