Won't work over certain speeds

Question edited for a lot more clarity and correct spelling of the maker.

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Question edited for clarity.
Question moved from Eagle Televisions.

Phone and ask them if you can send it in. Very often your local marine electronics shop will have a preferred technician.

https://www.manualslib.com/manual/41681/Eagle-Fishmark-320.html?page=90

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it is possible that the length of the leg is insufficient and the pump pick up holes are in the clean area behind the keel of the boat when at speed and on the plane
if it is a deep V boat and you have a standard length leg for the outboard , that would be worth checking

try hitting the on and off button it should fix it that is your lite skle and britness

Connect the trasnducer on a SS plate bracket behind the transon of the boat.

It seems most likely that your manual range has accidentally been set for 50' or less. Go into the menu and set to auto range. Here are the exact keystrokes as shown on PAGE 51 of your manual:
MENU> scroll down to DEPTH RANGE> ENTER> Exit

If this doesn't work, try doing a ful reset, as shown on PAGE 64 of your manual:
MANU> MENU> scroll down to RESET OPTIONS> <- to YES> ENTER

The Fishmark 320 is an excellent unit, and it works great in full-auto mode if you have the transducer mounted properly. Let us know if this doesn't fix your problem.

go to www.youtube.com and search for fiberglass repair

Cut the battery wires where they hook up to the machine. When cut they might need some more wire spliced to them. Get some alligator clips to put on your red and black wires to hook right to your boat battery. When not in use on the boat get a small 12 volt battery, cheaper then two 6 volt disposables.

There are three styles of regular fishing boats; deep v, regular v or modified v. The v determines how well the boat cuts through the depth of the water. The deep v is better suited for large lakes because they can handle heavy waves better. Regular "v" is more appropriate for smaller lakes and a man made body of water. As the water is not as deep and the waves are not as heavy, this type of boat is able to handle the situation. The modified v is the most popular version. It is capable of handling speed best. Most fishing boats on the market today are made of fiberglass or aluminum. What is best for your fishing situation? Do you want to fish in large lakes or small lakes? The options are endless. There are several classes of fishing boats for different situations. All purpose fishing boats are great for your basic fishing needs. This type of boat has space for some bench seats, fishing gear and a simple steering station. They are made of either fiberglass or aluminum and are between 15 and 20 feet long. Another type of fishing boat is a bass boat, which comes fully equipped with space for rods and fishing gear. The boat is fully built with electronics and livewells. This boat also is made out of fiberglass and aluminum. The advantage to this type of boat is it is made especially to catch bass, fast. The third type of fishing boat is the center-console. It allows a fisherman to angle from any place on the deck. The control center is located in the center. Depending on the size of the boat they can be used offshore as well as near. Flats boats are mostly made up of fiberglass. The advantage of these boats is they allow easier angling access to saltwater flat fish. Another advantage it has is a poling platform that allows for fish spotting. Finally, a casting deck allows the angler to keep control. This makes this ype of boat convenient for fishing. The final category of fishing boats is the fun boat because it combines the motor of a yacht and the functionality of large a cockpit to work trophy fish and bring them on board. If ou are a fishing fanatic then it is important to have all the things that you need to make your fishing trip a success. Fishing boats are definitely the finishing touch to a nice fishing trip.