Furuno LS4100 setup trouble

[brischutz]

Hi all, Have fitted this LS4100 to my 4.2tinny.
It is not reading the bottom depth correctly, is out by about 1.5mtrs. The transducer is mounted level and true to the specifications supplied.
I am wondering if there is a systems adjustment or some sort of tuning I have to do to to calibrate the true distance from transducer to ground?

Any help would be great fully received, Thank you all.

[Snapp]

Hi mate,
I have a LS-6100.
Look in manual, it may have to do with "setting the draft"
ie; where you want your transducer to read from.
I can go from -15 to 50 feet. so you could make adjustment there.

[brischutz]

Thanks Snapp, will give it ago.
Nice boat in your pic...