Humminbird Side Imaging Forums
Side Imaging Forums => 997c SI, 998c SI & 999ci HD SI => Topic started by: RV Sam on March 08, 2010, 08:16:41 PM
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I have this post on another forum but have not received an answer. I think it is straight forward, maybe no one knows :'(
Does anyone know at what angle the SI beam is coming from the transducer? I am about to mount the ducer for my 997 and I am trying to get the correct location the first time because once wet next month the boat will remain in the water until mid October. My plan is to hold the ducer on the transom with a 9 foot straight edge under it to check for side clearance. Just wondering if something 18” away straight across will be picked up or will I be seeing under it. I can mount it at the lowest point at the bottom of the vee down by the drain plug but if it ever kicks out of the bracket it’ll hit the outdrive and I will not be able to steer. Thanks.
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RV Sam,
The SI element inside the transducer is 30 down from Horizontal. But I don't think thats what you are looking for.
According to the specifications, the verticle angle is 87 degrees but with side lobes will cover more than 90 degrees. You have to understand that the sonar is not a razor straight definitive angle. Here is a great illustration by Rickard.
[attachment=1]
So will it see something 18" on the same level? Probably, but it should not really make a huge difference in your readings. The majority of the beam is for looking down at an angle. I would be concerned about objects projecting below the transducer.
Hope this helps!
Robert
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Thanks Robert. Looking down I'm ok. I just want to mount it as far away from the drive as possible without seeing other transducers and my trim tabs. As you know on a V bottom, "away" means sliding UP. That's when I start getting on the same plane as items mentioned above.
"Maybe should be a new post, move if you like."
Another question please. Not sure of the correct distance as my manual in out back in the boat, but. It says mount the bottom of the transducer 1/8" (?) below the bottom of the boat. Now remember V bottom. The transducer is about 3" wide, so 1/8 on one edge means the other edge is about 3/4" below the bottom. I have my other 2 bird transducers so this 1/8" is the down side on the V. Both of those units work great at all speeds. One is the quadrabeam on a matrix. I'm asking beause I read all sorts of issues with this 997 transducer. Thanks Again.
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RV Sam,
Its different for different boats but I would bet that you will have to have the HDSi transducer mounted like your other Humminbird transducers where one side of the transducer is 1/8” to 1/4“ below the bottom of the boat if you are wanting to use this for depth readings at higher boat speeds.