I am considering the HDS 7 with SS and lake insight. Have acouple of conserns first the water tightness of the unit. It seems there have been some folks that have there units stop working after fishing in the rain. Secondly I fish a lot of relatively shallow lakes ie. 8-10 FOW. is the side scan gona be very usefull in shalllow water? any thoughts or experinces would be apppreciated thanks