simrad nss7. they are sick units! bcf got them recently but i am sure u could probably find them cheaper somewere. very very detailed at all depths. and even has like a sonar type setting where you can actaully make out whats under you. if theres a dhuie in open space. you will be able to see that fish and be able to make out its a dhuie but that obvs works better the shallower or else the fish is just smaller. very very good little units. put a navionix card in it and your good to go.

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 It's a polycraft mate. I have the current transducer installed so that I get a fantastic picture, even at 25knots in slop, perhaps too deep it may be (Yoda is in the room).

In my investigations I see that it is possible to use a 1kw transducer with the 620, as long as the MB1100 is used inline.

Does the 585 give any better performance than the 620 in this situation?

Disjointed questioning but I'm sure you've heard it all before many times.

Thanks, Craig.

Can't comment on the furuno but tm260 is a good tranni have one on raymarine and happy and I fish out to 400 plus

 Thanks for that Tomcat.

What Raymarine unit do you run?

Going the tm260.

"Does the 585 give any better performance than the 620 in this situation?"

I went about researching a combo by getting info from tested systems with photos. Taylor marine were very helpful with various installation set ups with photos. With the polycraftt your probly after a transom mount set up. Check with poly craft if a thru hull set up is possible as with the right transducer best result are achieved IMO. 

Thanks for that, I'll shoot off a query to Polycraft.

Check pm's.

Cheers, Craig.

Not too sure where you’re at with your set up Craig but ill shed my thoughts on your question,

The FCV620 firing 600 watts with theTm260 will give a good account of itself.
Any 500 or 600 watt sonar will benefit from being used with a multi element 1kw transducer.
Keep in mind ..it is also about transducer sensitivity...and not all about output power.
Increasing the area and quality (Q) of a transducers piezoelectric element while keeping the sounders power level the same will increase depth of the signal and also increase the sonars ability to detect faint ,deep targets. At 1kw watts the FCV585 of course will do much better.

I think the 585 or 620 with the TM270W (wide 25 deg beam width) is the best for the depths you mentioned, At 40m the 200khz 25 deg beam will give you 18m circle on the sea floor vs the TM 260 which has a beam width of 6deg @ 200khz for a floor coverage of 4m hardly good ground coverage there, on the 50khz side of the TM260 you have a 19deg beam for a floor circle of 13m but understand the 50khz may not display faint echos aswell..
The FCV620 will work with both transducers, taking advantage of their sensitivity but since it is a 600W unit it will not take full advantage of their power (1KW).

The 585 and 620 have the same digital processor so it just screen size and pixels plus an extra 400watts that is the difference.

If you were going to upgrade to the 585 I would hang out for the new 587 that should be available around July the new units have increased screen resolution, bonded LCD screen, bottom discrimination software but most importantly post processing gain control. This means the gain of the whole screen will be updated immediately when adjusting gain. I like this function which I'm used to with Lowrance and Simrad.

Hope this is of some help

Quote "In my investigations I see that it is possible to use a 1kw transducer with the 620, as long as the MB1100 is used inline"

Craig im assuming you would have heard this from taylor marine the only time you would need the MB1100 is when using a Furuno 1KW transducer because they do not have an internal diplexer and are intended for the bigger brothers like the FCV295 and 1100 which have separate transmission lines for High and low frequency, where as the Airmar 1kws like the TM260 and TM270W are designed for Echo sounders that only have one transmission line for both high and low frequency.

Hope i haven't confused anyone

That's spot on simo have had to change my tm260 to a tm260rac because I fitted inline box in my raymarine And I needed a non diplexer tranni