It is reccommended that you use only Navman transducers with Navman equipment. Because of the wide range of transducer frequencies, pinout configurations and output power; use of any other Transducer could potentially damage your Navman unit.
Yes, When upgrading to a current model Navman unit from an old model Navman unit it is possible to still use your existing Navman transducers. Adapters will be required to change from the older style Fuji connectors (chrome locking collar) to the newer style Liangtei connectors (plastic locking collar) Contact your local Navman dealer for mote info.
The most important thing to understand is the use of the gain controls. These settings have a significant affect on the performance of the fishfinder. The manual gain setting is very much as it appears. The gain of the receiver circuit can be set to a fixed value and remains fixed at that value until the user changes it.
The Auto Gain setting is very different. In Auto Gain the software continually varies the gain of the receiver section to match the environment and the level of the return signal. In other words the software continues to alter the receiver gain to obtain the best possible return signal. The purpose of the Auto gain setting is to control the displayed width of the bottom. A low Auto gain setting results in the bottom contour appearing narrow or thin. A high Auto gain setting causes the bottom to appear wide or thick on the display.
It is worthwhile to experiment with different Manual gain settings. This single setting has the largest effect on the performance of the Fishfinder.
There is always a conflict between low and high manual gain settings. Lower Manual gain settings usually produce a better "fish" image. With the higher Manual gain settings the fish images may appear corrupted and look more like a 'blob' on the screen rather that the usual arches. This is particularly important when looking for fish near the bottom. With a higher Manual gain setting fish near the bottom will start to blend in with the bottom making them hard to recognise.
In softwareversions 1.09 and earlier the fuel calibration may produce incorrect fuel flow readings. See your nearest Navman dealer for a free software upgrade.
All Navman fishfinders will power up in simulate mode if there is no transducer connected to the unit when powered on. If there is a transducer connected to your unit and it is still powering up in simulate mode, try manual taking the unit out of simulate mode and seeing if it still finds the bottom. Also check that the battery voltage on the boat is good while the unit is running.