I would recommend you call the Raymarine tech staff at (603)324-7900. I've called them numerous times and had excellent results. Don't bother with the folks who answer the phone, they apparently don't have much training and have given me bogus information. Just ask immediately to be transferred to the tech staff. They are some of the best. Fully knowledgeable about their products, short succinct answers to my questions. Always helpful. Always encourage me to call back if I have more questions.