New combo unit

[Nabba1]

Sorry if this has been answered before, just point me to the tread if so please.

My trusty old JRC FF50 died recently and I am now looking for a replacement. I also have a HDS 5 combo gen 1 (50/200). My dilema is this.

My JRC transducer was mounted in the middle of the boat as a shoot through hull. Got great readings even at 30 knots but the transducer for the HDS 5 is transom mounted and never worked very well due to the interference from the JRC trans.

Ideally I would like to buy a new combo to have the option of either unit being GPS/sounder (convenience and backup) and preferably one with that down scan thingy. What I was hoping to be able to do is to use the HDS 5 as the shoot through hull to use when travelling and the new combo as a GPS and then switch to the new combo for the down scan when sounding around looking (transom mounted transducer) and the HDS 5 as a GPS.

Is there any easy way of being able to do this without having to unplug the transducer on the HDS 5 every time i want to use the new combo for sounding?

Hope that makes some sense...

BTW my budget is around the 800 mark preferably and generally fish 40 to 70m deep. Could spend more if necessary but prefer not to.

Cheers
Scott

[chocolatemoose]

so with your JRC retired. the through hull transducer is just ...ballast now. transom mount transducers are always going to be cheaper than in/thru hulls
for 800 your "well kinda only" choice if your interested in down scan tech. is lowrances HDI elite range.. or the Raymarine dragonfly range.
now the raymarine dragonfly also runs a chirp based transducer "so do the new elites...but...kinda..sorta...not" so for 800. a raymarine dragonfly is one of your better bets. being a modulated frequency it wont be as afected by the standard frequencies from the through hull.

if y our planning on using the shoot thru transducer with the hds5 "depending on transducer you will need a lowrance blue plug pigtail and splice the wires"

moose

[Nabba1]

Thanks Moose, a wealth of knowledge as usual.

So basically there is no easy way of just turning off the HDS transducer without unplugging it?

Also if you are up to it and have time could you give me a quick dumb down version of what is a "chirp" based transducer and why the elites is kinda sorta not? I have always had lowrance equipment and would prefer to get the elite as long as it is not too much inferior to the raymarine. Thanks again for your help

[Moonlighter]

Yeah, there is a very simple and easy way to turn the HDS transducer off but still leaving the screen on.

Go menu, sonar options, stop sonar, and check the stop sonar box. That stops the sonar screen and also turns the transducer off.

Takes 5 seconds, tops!

[Nabba1]

Awesome thanks Moonlighter!

[chocolatemoose]

so transducers are kinda like a very very powerful speaker and a very very sensitive microphone. tuned to pulse at a certain frquency. be it 200khz or 50 khz or 83 etc "times per second"

now.. the drawbacks to traditional sonars are
1. the "microphone" element can get confused with signals .unsure if its a signal it has JUST sent.. or one that has BOUNCE BACK off the bottom. this can cause noise and distortion
there is a rating attributed to how effected a transducer is with this noise. called a Q rating. most transducers sit between 25-30Q "higher = worse"...CHIRP transducers sit between 0 and 1.

2. efficiency. call it a 600w transducer. it will pulse out 600w of power. 1% of the time. the rest of the time its anywhere from nothing to 599.9w CHIRP transducers will pulse out 100% of power 99.9% of the time.

3. wave length. with "usually only 2" wave lengths... "200/83 or 200/50 etc" the distance between the waves is room for things to get lost. in other words. if objects are too close.. they get blured into ONE blob... with CHIRP pulsing HEAPPPS of wave lengths. the distance between waves is very very very very narrow. and therefor can separate objects that are within about 1cm. so often even things like banjos or eagle ways etc will be separated from the bottom.

ok so.. to recap
CHIRP is more efficient, sensitive and accurate

with the ELITE range.. what they found was they could CHIRP their existing transducer. so they have tricked the 2 elements inside to pulse at many frequencies... which is much better than before. but they don't have the raw out size of a chirp element. or efficiency of a chirp transducer ... however watch this space.
heres a photo i took this morning to demonstrate

the left transducer is a Lowrance HSTWSBL 300w 83/200 transducer. same power output as the right side transducer. a TM150 airmar transducer. also 300w. but the element "well you can see the element its that big" is easily 4 times bigger.

as for the raymarine. they have kept a bit tight lipped about specs.. we feel its at least 300w as well. but its true chirp.

moose

[scottar]

Just before you get too carried away with any particular unit in relation to "down Scan" find out what frequency they are using to generate the image. Not sure now but the earlier units were using very high frequencies and as such were limited in there depth capabilities - about 40 metres max. The other thing to take into account is that downscan/sidescan gives a great image at slow speed on flat water - no chop or swell. As soon as the boat starts to move around the images get distorted - typically not much use offshore. Chirp is a different animal as such and is essentially a different way of pulsing a transducer to allow a "traditional" sounder picture with a much higher definition possible and not as much noise. You could get an adapter cable fabricated for the JRC transducer to suit the HDS or have the plug changed if you wished if the transom mount is giving too much grief. The only issue will be whether or not the HDS has enough punch to go through the glass as effectivly.

[Nabba1]

Moose, thanks again a very good description in a language even I can understand, much appreciated. I think i will definately look at the raymarine a lot more closely...

Scottar, a very good point about the use offshore. So in your opinion would downscan be a waste of money given that its only dead flat occasionally offshore? Regarding the HDS punching through the glass, I think it should be ok as i'm not sure but I think its about the same output as the JRC and it worked fine up to about 60m (picking up fish etc) but that depth was at the limit.

Cheers

[scottar]

I certainly wouldn't be placing it at the top of my requirements list Nabba. Things have changed a bit since I got out of the marine elctronics game with the evolution of chirp and what have you but the requirements for offshore bottom fishing haven't. Too much emphasis is put on the ability to be able to detect tiny echoes and paint them into as lifelike a two dimensional image as possible. There are some incredible pictures available from such units nowadays but this ability doesn't mean a thing if the unit runs out of steam or you have to spend all day pushing buttons trying to tune your unit to get it to do what you want it to do.

Your old FF50 didn't have the highest pixel count or the most power output, but in their day I sold a bucket full of them to serious offshore fishos because they were super quick and easy to drive, zoom the image on and had a great bottom discrimination mode. Besides this you didn't need to spend all day pushing buttons. A lot of these guys were upgrading from sounders in combo units that were fitted by boat builders/suppliers as factory fits. My personal preference has always been for the sounders from the Japanese parent companies for this reason. They were the ones that just worked in deep water. If you were chasing fish in shallow or in amongst trees etc then it's a whole different matter.

My personal opinion in your case is that having had an FF50 you will probably be disappointed with most of the "Normal" sounders that are fitted in combos as they will simply not work as well or will be a pain to drive to work at their full extent. Chirp may well be a different kettle of fish in the performance stakes but do plenty of research and see if you can find "on water" shots of them showing images in the depths you are working in.