I noticed last night that I am getting a lot of half arcs (tailing to the left) on my Eagle 480. I looked at the transducer (a skimmer mounted on back) but it looks level.

Are these fish that are just on the edge of the cone or is there a problem?

I never see very many full arcs.

This is a very bad drawing of what I am seeing.

I have a Lowrance and mine does the same thing. It looks like my transducer is level as well. I've just learned how to read it like it is. I may try and tilt a little more one way or another and see how it reads because what looks level to me may not be level once it is in the water.


John

Guys,

Jed as you mentioned your unit as level....and that you might tilt it....

I believe that maybe the key to correcting the problem at least by the owners manual. Try tilting the tranducer until you get a solid arch.

Good luck

These guys are correct. You need to raise the rear end of your transducer 1, maybe 2 clicks. It's shooting forward which is why you only get the first half of the arch.

Thanks for the info guys.

MrG, that is exactly what I was wondering about.

I am getting the same thing on my Lowrance LMS480. Thanks for the info! regards, Bart

I got the same thing today with my new Eagle fishmark 480. I figured it was the transducer angle so I tilted the rear downward as it was already one click up from level. Tilting the rear of the transducer downward as I did made the arcs still appear as only half arcs but to the right instead of to the left. Back to the original position which was already one click up from dead level. I left it there figuring one more click up would make it worse. Now I figure I shoulda tried it. Figured they must be turtles or fish doing sychronized swimmin' or somethin' as I was getting full arcs at other times.
So I guess in the morning I'll be tilting it up one more click. Thanks for info, good timing!

Just my $.02
Look at the way your hull rests in the water in relation to the angle of your transducer. If you set the transducer level or on plane with your hull; sitting on the water the bow will be higher than the stern. (Engine,Fuel cell, Batteries, bilge water ect.) The greater weight is most times towards the stern resulting in an angle on the transducer if it is set level with the hull. I set mine level with the scumm line left on the hull after an outing. A good template.

I'm still getting used to my electronics and had the same question. I found a great deal of good info. Some of the graphs look like yours. http//heartlandtackleservice.com/spooning.stm

Just think about the cone (field of view) coming down from the transducer. The fishfinder "arch" is a plot of the distance of the fish from the transducer, as the fish passes through the cone. If you have a 20 degree cone (which most of them are), a 10 degree tilt will chop off one side of the arch on your display. Back end down too much will chop off the right side. Back end too high will chop off the left side. Anything less than perfect will have a little lopsidedness to the arch, which is no big deal. If it is really tilted, you will also be chopping off the true center of the arch, and the top of your "partial arch" won't show the right fish depth.

If your like me, it means I have to make the guy in the back move to the front. Since he's not a "little" guy the angle changes drastically!

Jus' right. Out this mornin' an tilted the rear of the tranducer up one more click an' I got nice arcs. Maybe just a hair off but pretty good and a dang sight better'n it was. Again thanks for info.

Tried to adjust my transducer last night and snapped the dang thing off! I hate when that happens...

So it was off to Gander Mtn and decided to upgrade my finder. Went with a Lowrance LMS-334C. Spent tonight installing the new transducer and finder. I think the addition of a gps and color will be a big help.

Old finder and new transducer will be going on my father's boat.