I am looking for a console unit and will soon also add a bow unit. Both will be Helix 12. I want to install the console unit first. I can't figure out if these come with transducers but it seems like they do. I am looking for DI and DI and this looks like my first unit to buy at the console which will get me going?

http://www.cabelas.com/catalog/product.j...WTz_l%3DProduct http://www.cabelas.com/catalog/product.jsp?productId=2194220&categoryId=0&parentCategoryId=0&subCategoryId=0&indexId=0&productVariantId=4509169&quantity=1&itemGUID=fe19ada3ac108454347d32c3eced47f2&destination=%2Fcheckout%2Fitem_added_to_cart.jsp%3Fresult%3Dsuccess%26categoryIds%3D104793480%257C104707080%257C104588280%26productId%3D2194220%26backToPreviousUrl%3D%252Fcatalog%252Fproduct.jsp%253FproductId%253D2194220%26WTz_l%3DProduct

For the bow unit, do I order the same thing? Or do I get a cheaper version since they can both run off the same transducers?

If you want dedicated Down Imaging, at least one unit has to be a Helix 12 CHRIP DI GPS.
If you want Side Imaging, at least one unit has to be a Helix 12 CHIRP SI GPS.

Any version will display any sonar technology from another unit, just need a source for the processed data.
The Helix 12 CHRIP Sonar GPS is just 2D sonar.

One thing to consider is if you share sonar, the unit that is getting data from another unit will display that data from the transducer location so what you see will not be where you are.
If you use vertical presentations at the bow, you won't see your presentation if the transducer is on the transom.

If you will be considering the 360, any of the three versions are compatible and can get SI and blended DI from the 360.

You can do better on price than Cabela's and certainly BPS. The big box stores are full retail. Do some searching on line at the out of state vendors. I've bought stuff from Hodges Marine and also Star Marine, just off the top of my head. Much cheaper than retail, no sales tax, and usually free shipping saves you a bunch of money. Between two Hummibirds, networking components for them, and a Minn Kota Riptide I-Pilot TM, I saved hundreds. Customer service is good and if you think about it, if you have an equipment problem, you are going to be dealing with the factory or a service center anyway.

Thanks for the input guys. I am trying to learn more about sonar and the options. It looks like the transducers have to be bought separately. I'm trying to figure out how to know which transducers are compatible and which to get. I assume it has to be a Humminbird transducer?

Any suggestions on the best place (bow/transom) to install a DI or SI transducer? It seems like SI on the bow would change every time I turned the trolling motor.

The more I read about sonar the more I realize I how complex it is. If I have both DI and SI, when would I use DI? I never cast under my boat.

transducers come with the helix units. A helix 12 DI will come with a DI tducer that's gives 2d temp and dedicated down image. Helix 12 si comes with a transducer that will give si/di/2d and temp, only the di will be blended from the si . The basic helix 12 comes with just 2d temp transducer. Only a trolling motor transducer would be the only transducer that does not come with the Helix, but they can be obtained with the trade in program if you desire.

DI is like a new version of the 2D sonar. It will give you a better picture of what really is below you. It will do a better job of scanning directly below the boat for structure than SI. Before you go buy anything, you should start watching some videos on youtube. They will explain most everything and show how it works and go to a store and play with the display models. Just remember, the clerks don't always give correct advise.

You can have multiple screens showing at the same time. For instance, on my 899m, I can run SI on one side of the screen and something else on the other or I can run SI,DI and 2D all on the screen at the same time.

The Humminbird website says that SI models will do DI. I hope I am understanding all this.

This is the one I am looking at:

Humminbird Factory Outlet http://fishfinders.factoryoutletstore.com/details/186150/humminbird-helix-12-chirp-si-gps.html

Yes, the Helix 12 si will do all three 2d/si/di

The Down Imaging will be a blend of the two Side Imaging pulses, not dedicated DI from a DI sonar crystal.

Only a ONIX/ION Side Imaging transducer has a dedicated DI crystal.

Not sure which trolling motor you have and in the above reading I may have overlooked it, but for reference, if you have an electric steer, you cannot put an external transducer on the motor without using some sort of "external rigging" to handle the transducer cable. In that instance, all you would be able to see would be sonar through a built in transducer. This means a sonar only unit would be fine for the front if connected to a SI/DI type unit at the console, in which case you would read the DI/SI from the transducer on the back and sonar from the front.
John

With a Minnkota Terrova, there is a groove in the shaft that the Humminbird transducer cable can fit in to avoid the cable management "external rigging" issues associated with that motor type.