I highly doubt the software update will get a better picture above 10 knots.

I think i got a bit lucky with my HDS as when i fitted it i got a great picture right up to 25knots in good conditions while hearing many stories similar to yours. I have done the software updates also and its made no differece in readings.

When i first fitted my Furuno beside it i got horrible readings but after sticking the ducer as far down as possible I now get great readings right up to 30knots.

I'd suggest putting the ducer as far down as possible with a slight lean toward the boat. Thats how both mine a setup.

 throw up a couple of pics of the tranny so we have a better idea

P79-600W-Adjustable-In-Hull-Transducer.html
Allboats $200
Whitworths

A few photos up now guys. With it level it was very bad, so I angled it forward which improved bottom hold quite a bit. Still won't hold bottom on the plane though.

 I wonder if it is wash turbulence from the thing on the right of it

Hard to tell from the pics but if anything to low and to far angled forward (if its set up correctly in the first place), I'm guessing turbulence off the bottom of the hull - is it behind a strake on the bottom or anything else such as imperfections on the hull.

have a look over the back as your going along and see if its running in clear or turbulent water

Edit found a previous bit I posted on the subject

http://fishwrecked.com/forum/correct-sounder-settings-and-problems

 Too low and too much angle

 And i think its too close to the motor 

 way too much angle there mate, its only supposed to be slighty angled forward and just below the level of your hull about an 8th of an inch

 To low mate pm ur numba and ill send you a few piks of mine mate reads 25 knts plus. On the iPhone so can't post the piks

 Hi Veitchy.

Did you get it sorted?

I Have the same gen 1 unit same issues and for some reason can't get it to upgrade to 4.1 from my hds 5m gen 2 chartplotter.  Rang the lowrance help line 0299361000 and after giving them the serial number they issued me a return authorisation for a new gen 2 hds 5x (3.5 upgrade pre installed) for a change over price of $272.00.  Might be worth keeping in mind for when there's some spare coin available.

cheers 

Try increasing your chart speed!

 Hi guys,

Thanks for all of you info. 

I still haven't got it completely sorted but been making do. I'll have a bit more time to play with it over next few weeks so see what I can do.

When installing her I did follow instructions. Before positioning the trans I took the boat out, got her up on the plane and marked a spot with clean water. Trans was positioned more than the recommended distance from engine and at a height matching the diagram in instructions. Setup sounder with correct transducer settings (ie code off the little silver sticker) and setup based on setting I researched on FW. She worked well but would lose bottom above about 10knots. When on plane the trans looked to have plenty off water so I was a bit surprised she wasn't getting bottom at speed. That's when I tilted her forward which lowered her a bit and have a little forward angle. Have since tried a range of setting, hard resets etc etc but no luck. All that being said, she still works a treat when I'm not on the plane and has still accounted for a few good fish. One other possible issue could be that I've ran the trans cord along same side of boat as other wiring, however I'd think I'd be getting interference at slower speeds as well, which I'm not.

More research has made me question the software version as I was pretty comfortable with the trans positioning (at least before I angled her forwad too much - photos) and apparently the software upgrade improves bottom hold at speed. 

Thanks for for all of your suggestion. I'll keep plying a bit with positions and setting as most have suggested and see if I get a breakthrough. Otherwise I'll just make do and hopefully upgrade her to a Gen2 or Gen3 one day. 

Cheers,

Nick