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  Reducing Spray From HUMMINBIRD Transducers

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Author Topic:   Reducing Spray From HUMMINBIRD Transducers
gabollini posted 05-22-2008 11:04 AM ET (US)   Profile for gabollini   Send Email to gabollini  
Just recently picked up my boat from dealer who installed a HUMMINBIRD fish finder and a HUMMINBIRD digital depth guage. So, I've got two [transducers] hanging on my transom. Both pick up [SONAR echoes] just fine. My problem is that there is a very healthy stream of water that comes up vertically from the transom to the point that it is pouring water onto the cowling of my new Evinrude E-TEC on my initial water test. Pointed this out to the dealer (who installed and charged me to do so). Dealer moved up both [transducers] and told me this would solve the problem. Took boat out again on water yesterday, still have the same problem, but less so. As I look forward, both [transducers] are on the right side of the transom, about even with the plane of the bottom of the boat. I don't want to drill too many more holes in the transom for mounting. Is there any sure fire way to get this problem taken care of aside from drilling and testing? The water stream about the size of a stream of water coming out of a garden hose. It's not just a small little stream. Any input would be appreciated.

thanks gabe

dbrown posted 05-22-2008 02:28 PM ET (US)     Profile for dbrown    
Gabe, the "rooster tail" problem with the Humminbird transducers is somewhat common. The cause of this "vertical spray" is due to the rectangular gap between the transducer and the transducer mounting bracket. Water forced through this gap is directed upward and creates the spray. The solution is to block this opening and it will eliminate the problem. Below is one fix that works. You may be able to come up with another.

http://i48.photobucket.com/albums/f250/rickdb1/fall07027.jpg


jimh posted 05-25-2008 10:51 AM ET (US)     Profile for jimh  Send Email to jimh     
Most SONAR transducers intended for transom mounting have a mounting bracket which will permit some adjustment of the mounting position so that the immersion of the transducer can be optimized without having to drill additional holes in the transom.

Many installers have used an intermediate plate of material fastened to the transom and of 0.5-inch thickness or greater, often using KING StarBoard or similar ultra-high molecular weight plastic, or any material which is suitable for holding screw fasteners, even perhaps wood which has been well sealed with epoxy. Such a plate is installed on the boat transom in the general area where the SONAR transducer is to be installed, using the usual screws and sealant to make a strong and water-tight attachment of the plate to the transom. The mounting bracket of the transducer is then fastened to the intermediate plate using fasteners which do not penetrate into the boat transom but are just long enough to find purchase only in the intermediate plate. In this way you can avoid having to drill multiple holes in the transom during the process of fine tuning the mounting position of the SONAR transducer. The technique of using an intermediate plate is also employed when a new transducer of different design or brand is installed on a transom with existing holes. The intermediate plate is drilled so that the existing holes in the transom are used to receive the fasteners for the plate. The new transducer is mounted only to the plate instead of to the transom itself.

In the case of the Humminbird transducer, it sounds as though the technique of using an intermediate plate could be expanded somewhat. The plate could be fashioned to extend the plane of the hull bottom outward and aft to meet the leading edge of the transducer. In so doing this might reduce the spray that results from the gap between the transom and the transducer.

jimh posted 05-25-2008 10:52 AM ET (US)     Profile for jimh  Send Email to jimh     
By the way, as an aside, why do you have both a depth sounder and a fish finder installed? I suspect that the two SONAR beams might cause interference with each other.
boatsalltheway posted 05-25-2008 11:32 PM ET (US)     Profile for boatsalltheway  Send Email to boatsalltheway     
I just got a Humminbird sideimaging unit installed and I have the same probblem. It is mounted so the transducer goes down below the hull, but the mechanic told me this was so it would still have a good reading on a plane. When I had a 5' rooster tail, I was going to tell him to try moving it up, but I did research first and found that this is a common problem with Humminbird and I didnt want to drill more holes if it may not make a difference. However, I also didnt want to drill holes for a spray guard. I found that the spray was coming up through the little gap. Below is a website with a picture of where im talking about.
http://forums.iboats.com/attachment.php?attachmentid=9928&d=1205158128

That is not my same transducer, but it shows the gap. My gap is actually bigger. I took some clay and jammed it down in that gap really tightly. Now I have no rooster tail. It does not seem to affect its performance at all either. The clay stayed in there about 1 month with the boat being moored in the water that whole time and with the boat being used alot. One day it finally blew out when I was running at about 30 mph, but thats after surviving many previous high speed runs. I think I have it packed in even better this time, so maybe it will last longer. It only takes about 1 minute to put the clay in with the boat being in the water, so I would just keep a small bag of clay in the boat with you so you can repack it when it eventually blows out if you decide to go this route. Let me know what you decide. What model did you get? I have been really happy with my 797c2 so far other than the spray.

highanddry posted 05-29-2008 09:58 AM ET (US)     Profile for highanddry  Send Email to highanddry     
I took a tiny piece of .016 6061 aluminum and made a small clip that slides up behind the side scan Xducer. I over bent it so that it pinches down and holds itself in place. I added two small pieces of 3M tape to finsih securing it. The large side scanning Xducer is known to kick up spray, this helps a lot.

I wonder if just filling the void with clear or black GEII pure silicone sealant adhesive or the white 5200 would seal that gap without having to fabricate shields?

jimh posted 05-30-2008 09:15 PM ET (US)     Profile for jimh  Send Email to jimh     
Boaters who have a HUMMINBIRD transducer and are having problems mounting it so that it does not produce spray should contact HUMMINBIRD and let them know about this problem. From what I have seen of HUMMINBIRD they appear to be a modern company that is keen to get feedback from users. Some engineers of HUMMINBIRD participate in a few on-line discussion web forums about their products, and they seem to be genuinely interested in improving them.
mikejoyce77 posted 06-02-2008 10:57 PM ET (US)     Profile for mikejoyce77  Send Email to mikejoyce77     
I also have a [HUMMINBIRD] fishfinder and been having a rooster tail from the tranducer. It is causing the engine cowling to get wet and also the back corner of the boat. I'm going to try adjusting the transducer, but I'll think I'll make a LEXAN® shield.

I also sent an e-mail to [HUMMINBIRD] about this topic.

Feejer posted 06-06-2008 08:18 PM ET (US)     Profile for Feejer  Send Email to Feejer     
PROBLEM SOLVED: See my thread

http://continuouswave.com/ubb/Forum3/HTML/014981.html

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