Ok ,
Its really not to bad, You want to measure about 15" to one side or the other "your choice" and make a mark , look under the boat and make sure you are not lining up with one of the runners, try to center the transducer between the runners, You want it to be in a area that has the least amount of turbulance when you are moveing, also make sure it will not interfere with the bunks on the trailer when you take the boat on and of the trailer, mark this spot this is where the transducer will mount,
There is a seam on the transducer " in the middle" you want it to be even with the bottom of the boat, keep this though in mind you want the transducer to be level front to back and side to side when the boat is floating so the trasducer shoots "or sends out a signal" straight down. The mount should have two slotted holes in it, when you get the transducer where you want it mark the holes in the middle so you can move it up or down if you need to adjuast later.. drill the holes with the apropiet drill bit , then "and dont go cheep with this one" get some GOOD silicone RTV Marien 5200 you can get at boaters world is the best that ive used, use plenty to pad the mount and seal the holes, Bolt or screw it to the back of the boat, check to make sure "best you can" its level with how the boat sits in the water, run the cable up the back of the transome I fasten mine in two places one in the middle one on the top and seal those holes as well, then rought the cable to the FF where it will be out of the way and you pritty much done, go try it out and see how it reads, and if you have to move it up or down re-seal it..
A word of info, some guys say there FF work good when they are moving fast, mine has never been real good beyond a fast idle so dont exspect to much when you are running to a spot, if you not SURE about the water your in, slow down so it has time to read.. When you are on the water always be on the caution side of things, be safe..
Puddle emoThumbsup