Bertha Boatworks – On the Water the Way it Should be. We are a full service marina on Lake Bertha. We have a large selection of SouthBay pontoons ready to test drive as well as a variety of used boats – ask us about consignment boats. We are available to service your new and current boat. We also rent Four Winns boats and SouthBay pontoons as well as wake boards, skis, tubes & paddle boards.