I have a Lowrance Elite 5 which sits on a Ram mount and have found it to be very secure. I do recall reading some where about Ram mounts loosening when securing "rocket launcher" style rod mounts while trolling. (Please correct me if I'm wrong, but I believe this was related to a Ram ball fastened to a track and, when a snag or fish strike occurred, the threaded Ram bolt in the track would loosen with the lateral torque applied by the fish or snag.) Without any significant lateral torque placed on the Ram mount, it has proved to be quite secure.
On a somewhat different tangent:
I ordered and received the Hobie battery holder and installed it on the sail post inside the forward hatch only to learn that my Hobie Outback hatch liner would not fit in the hatch with the battery installed on the sail post. Next I thought to install the battery in a modified Hobie hatch container much like the ingenious method described by Captain Yak Catcher. Alas, my Hobie Safety Kit is installed there and since the twist 'n seal directly in front of my seat was desired to be kept open, the safety kit was destined to stay in the rear hatch. (Someone will eventually come up with a modified deep hatch container which will carry a battery and the safety kit?) My third and final choice for battery placement took me back to the forward hatch while still desirous to use the Hobie Outback hatch liner. My solution was to mount the battery just aft of the sail post on the port side (same side as the sonar/GPS mount). The battery I've used was purchased complete with a waterproof Pelican box and plug-in outlet installed on the side of the Pelican box. (http://www.kayakfishingsupplies.com/ser ... wer/Detail
) I did add a fuse to the inside of the box but that was the only modification made to the unit. How to secure it to the hull became a larger concern. I had another kayak in which the battery box was secured with 4" wide velcro to the hull. That worked very well and proved to be surprisingly quite durable. I purchased a foot-long strip of 4" wide velcro with adhesive backing on both male and female pieces. One piece was adhered to the desired battery location (flat on the hull bottom) and the other to the back side of the battery box. The battery stays in place with the hull inverted; don't believe it would hold if hull was inverted and dropped (much like a surf launch gone bad?). I used some leftover velcro to secure the transducer cable to the hull along its entire length. Not sure if the velcro solution will work for all but it has worked well for me for a couple years now.
Just my $0.02.