Anyone know of where I can get a dummy (blank) plug for my ST-30 Bi-Data speed transducer? I called Raymarine, who now owns and services the Autohelm-made units, and they didn't have it. They forwarded me to an aftermarket manufacturer (Jem Electronics), but they didn't have it either. I want to insert the blank plug when my boat ('97 Hunter 280) is not in use, as others on this board have suggested, instead of keeping the speed transducer in the water all season and it becoming inoperative with barnacles after a few months. Help! Any assistance in this matter is greatly appreciated.