I am thinking about upgrading to the new Minnkota Ultrex trolling motor. When looking at choices, which shaft length would you suggest for a 21' bass boat...the 45, 52 or 60"? Also, what is the difference in the option of i-Pilot and i-Pilot Link? Thanks.

The shaft length you need is determined by the height of your bow above the water. MinnKota has a chart on their site for figuring that, Also account for if you will be fishing in rough water or you may have a lot of time with the prop out of the water.
The I-pilot link provides some features if you are using a Lakemaster chip. Personally, I think it's a good upgrade for the money and expensive if you do it later.

52"

IPilot Link is an Ethernet connection to an Ethernet capable Humminbird unit.

The link does everything the pilot does plus allows you to follow a contour line, use the hummingbird to control the tm, go to feature (tell it a waypoint to go and unit will drive there) and a few other things

Let us know if we can assist you with a quote once you determine which motor you go with.

Ultrex has shaft like the Terrova so according to Minn Kota Support, you can have the shaft cut & shortened to any length you want by Authorized Minn Kota Service location.

This is Minn Kota's current policy, but call Minn Kota Support 800-227-6433 to verify no policy change.

Actual shaft length needed depends on how you fish and the waters. Just because someone has a 52" on a 20' boat, doesn't mean you need it, unless it is one of the boats that sits "bow high" such as a Champion or Skeeter. On most bassboats, 45" is fine, but if you find yourself fishing in the wind or heavy wave action you will want to go with the 52". The Ultrex will literately raise all the way to the top of the water, but it is not recommended. It has a depth collar on top like the Terrova to manage the depth, however the newer ones also have a depth collar under the bowguard/transmission to keep it from being raised too high. This is usefull if you should decide on the Humminbird 360 at a later date. The Ipilot version is shipping now and the "link" version will not ship til late December/January. The Link will connect to an eithernet compatable Humminbird unit and allows some options that are not available on the IPilot. The standard IPilot does allow for spotlock and heading. If you have any questions, or if I can help with your order, give me a call.
John

I have a Ranger Z521. A couple of the Elite guys with similar Rangers suggest that I go with the 45". That said, I do have a bow mount 360 if that makes a difference with the choice.

The 360 will not make a difference, it will limit how high you can raise the motor for shallow water fishing. As it is now, the 360 is attached to the trolling motor shaft so it moves up and down with the trollingmotor. On the Ultrex, the 360 will mount to the bowguard so it will stay stationary when the motor is raised or lowered. You will not want to raise the lower unit into the 360, so on the newer ones a collar is placed below the bowguard that limits the height and keeps this from happening. You will probably have to get a different bracket (if an adapter is made) to connect the 360 to the Ultrex.
Back to the shaft size, on most Rangers, a 45 is OK, again, unless you fish water with substantial wave action.
John

Your 360 will not work with the Ultrex. The 360 shaft is too short and the clamp won't work with the Ultrex mount.

There will be a Ultrex version of the bow 360 that has the Ultrex mount and longer shaft 360 pole.

Your choice would be the new one, invent your own rigging system, or wait for someone to do it for you.

There may be enough demand for a production adapter. Sort of like Transducer Shield and Saver did for metal shaft Motor Guide motors.

Check with Cumberland Crappie. They may be working on a mount for the Ultrex.