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 That is a deep-vee'd hull, and from that pic  it looks like the transducer is being blocked by the hull when you get on the plane. As for any 83/200 xducer from Lowrance, they all seem weak, and the worst part of the deal if you get beyond 20 m of water. I had one of the 83/200 455/800 CHIRPS come with my Elite-7, and was not happy, just weak in 30m. So I plugged in the old 50/200 transducer from the LC-15 that came with the boat.  A heavenly chorus descended, angels singing, celestial trumpets--I COULD SEE !!  Unfortunately it had an analog temp signal, so no temp. I chased down the digital equivilant, one of which was a HST-DFSBL, 50/200. You'll pick these up for $100 s/hand or new/unused, i've gotten two off this forum for this price, one for me, one for a mate.  I've been very happy with it, look back through the posts in this sub-forum for fishwrecked.com/forum/hdi-7-elite-pics   . There are some screen shots and info there, works for me.

Transducer looks very high...

Agree with Ranmar. I was running a 83/200/455/800 and struggled at anything over 6-7knots regardless of transducer location. Switched to a 50/200 and is like chalk and cheese. I now get good readings at 20+ knots.

The problem is clear as day! "Lowrance"

 Wrong transducer. !  Horses for courses, we're not all deep droppers, and looking at the pix posted of shallow water stuff on the Furuno's, they really don't impress as being noticeably superior in that useage. That said, I am currently looking at four options for another sounder, as I want one with bottom lock, the one big omission from the Elite range, IMHO. All these options are available for no more than $1500, and the Elite-7 will remain as a good plotter.

1) Elite-9 Ti---has the touch interface, Track back, a lot of the HDS advantages, and I can run my current transducer. 

2) Furuno 628--They apparently are far better than the older small furunos with regards to that blocky, pixellated picture which was the worst thing about them..I had an FCV 600L previously. They have the interface which I am most familiar with, I was a big Shift user,  and bottom lock. No track back to place a mark on something you have already gone over, which is a great Lowrance feature. would need to buy a tx, P66 transom mount will come in on budget.

3) Simrad S2009  A brilliant 9" portrait screen, and all the features I want. I can run this with my existing transducer. And it can be fully expanded to go 3d if required later.

4) HDS-7 Gen 3. 

if you put a straight edge from under the hull of your boat out the back, is it straight? from this angle there looks to be like a reverse fin? IMO that could cause turbulent water to pass under your transducer while travelling, (causing bad readings) if this is the case i would look at putting it deeper in the water to get past the turbulent water. with the rear of the transducer slightly leaning towards the front of your boat.

 Also, looking closer at the pic, there appears to be a rough area under the hull directly in front of the xducer. It appears you have added a block to the transom to mount the xducer on, and faired it to the bottom of the hull, but it looks like the filler used  is cracking off leaving prominent edges to face the water flow? If so, this wouldn't help at speed either. 

 Thanks for the comments and suggestions. I have lowered another 10mm and smoothed off the filler in front of the mounting block. I have also turned off the surface clarity and interference and will play with the frequency this weekend. Will see how we go.

cheers 

Rob

Interested to hear how it performs now Knots, as I've just installed the hook 9 on my Reef Runner too. Only tested it once quickly in the river, but sounder was only any good to about 15 or so knots as well. I have adjusted mine a bit lower also and will see how it goes this weekend.

I have a HDS 7 GEN 3 and have had the gen 2 until I dropped it and cracked the screen .
Running a P66 and structurescan on a Trailcraft profish and get good readings up to 20 knots ,bit of fiddling but works a treat when adjusted correctly .

Cheers Andy

Will get a picture for comparison

 Well turning off the surface clarity and interference,  adjusted frequency to both 83/200, reduced sensitivity -12% and colour line to 76% and the modifications above resulted in an improved image it still drops out pretty quick.  I'll try the transducer a little lower again and see how that goes, though it did not see to make much difference turning left or right. 

Failing that, it looks like I will be in the market for a new transducer as suggested above. Thanks 

Rob