One was built for the RNLI by the USCG in Curtis Bay Coast Guard Yard , Maryland .
This was put through extensive trials and proved capable of operating in restricted spaces , even though the propellers lacked the usual protection afforded to lifeboats .
One was built for the RNLI by the USCG in Curtis Bay Coast Guard Yard , Maryland , and this was put through extensive trials and proved capable of operating in restricted spaces , even though the propellers lacked the usual protection afforded to lifeboats .