Thread: SI question

The answer depends on whether or not the motor obstructs the SI beams when it is trimmed all the way down. On my system (Ranger 1860, Suzuki 175), I can trim all the way down and have absolutely no obstruction whatsoever.

In the worst case scenario, you may have to trim up just a bit....not all the way up, just a bit...in order to get clear SI data in the direction of the motor.

Tommyboyrn,
I just added an SI unit to my DH5 unit on a pontoon boat , I had to make modifications to the bracket so I could keep the reg transducer and si unit between 6-12 inches together but I called Lowrance and the SI unit is a 70 degree unit so that means that you need a 15 degree clear space on both sides of the unit but with my pontoons setting pretty low I had the 15 degree clearance and so far have not had a problem with blocking the signal.Also you only need the suggested 6-12" spacing for good overlay anything past that like tranducer one one side and SI on the othe side of transom will put the overlay off by that 4 or 5 foot..
Gary

Trim your motor down and measure the gap. You will need about 8 inches for the largest ducer. 6 inches min.

What gap are you talking about? The gap from motor to transducer?

Originally Posted by garyv

Tommyboyrn,
I just added an SI unit to my DH5 unit on a pontoon boat , I had to make modifications to the bracket so I could keep the reg transducer and si unit between 6-12 inches together but I called Lowrance and the SI unit is a 70 degree unit so that means that you need a 15 degree clear space on both sides of the unit but with my pontoons setting pretty low I had the 15 degree clearance and so far have not had a problem with blocking the signal.Also you only need the suggested 6-12" spacing for good overlayanything past that like tranducer one one side and SI on the othe side of transom will put the overlay off by that 4 or 5 foot..


Gary

I think tommy mention he will be getting HB SI....

HB units do not have the "overlay" feature that Lowrance units have...
Unless your referring to a different "overlay"...

tommy will be using only 1 xducer for his SI setup...

Rickie

Originally Posted by tommyboyrn

What gap are you talking about? The gap from motor to transducer?

Gap from transom to back of motor. The ducer is 6-8 inches long when mounted.

Originally Posted by tommyboyrn

What gap are you talking about? The gap from motor to transducer?

Tommy... The SI sonar beam is a "thin slice" that emanates out (both sides) 90 degrees perpendicular to the length of the xducer....

This "thin slice" sonar beam does not have "sharp" edges like a cardboard box would have...the sound waves kinda "feather" out past this "thin slice"....

Blockage from the motor can be picked up by the unit to some degree even if it looks like there is ample "clearance" of the physical size of the xducer...

I would think that the 6-8 inches lcookie mentioned should be fine...

Mount the xducer.... And test to see how far down you can trim your motor until you start seeing blockage on the SI screen....

Blockage will be noticed on the screen when the side of the image that is becoming blocked changes to look different from the other side....

Rickie

I wouldn't worry too much about the motor blocking the SI beam while you are in the slow search mode. As Jason said, all you have to do is trim out some. Frankly on a tiller steer motor, I think it reduces steering pull anyhow at slow speeds, at least it did with my G3. I have the 798 on a 16 foot Wheel steer boat now, and I might get some blockage trimmed all the way in, but I just trim out a little, and it's fine. Running at speed with normal trim, I've never experienced any problem.