1991 Ranger 690C walleye style boat. I put a "drill-thru-the-hull" transducer. It only works off plane, but it is protected and it won't get hit.
http://f9g.yahoofs.com/groups/g_1756...Y3ZFHBb9V7FABI
http://us.a2.yahoofs.com/groups/g_17...Y3ZFHB1BejOXjr