I think I have a video clip from my new i-Pilot Link series that shows the configuration I run at the bow. I have an 1158-DI unit up there, with its own GPS receiver, in close proximity to the Terrova/i-Pilot Link combo. This little snippet will show you how I have things arranged. There's no editing or context here.....just take a look and see how my arrangement compares to yours.
Everyone should remember what Spot Lock's job is....its job is to return you to your locked location if you drift more than 5 feet away from it. Does that mean you zip right back once you break the 5-foot circle? No. It means that once you break the circle, Spot Lock goes through its standard procedure of setting a heading and dialing up the prop speed to get you back there. It starts at prop speed of 0.5, check for progress towards the location, and then dials up the speed as necessary. Sometimes that means that the boat will move beyond 5 feet....sometimes 10...sometimes 15....before i-Pilot adjusts the prop speed/heading enough to get you back to your locked location. It has to adjust the speed slowly to avoid tossing people out of the boat. Imagine how many people would get dumped in the drink if their trolling motor turned hard left or right and their prop speed went from 0 to 10 without warning. So, let me make this point again: Spot Lock is not designed to keep you in a 5-foot circle. It is designed to return you to a locked location if/when you drift more than 5 feet away from it, and to return you there in a safe, steady fashion.
With i-Pilot Link, new information has been added to the remote's display to show the user distance and heading fro the current location to the locked location. Yesterday evening, I fished some main channel wingdams on Pool 4/Mississippi River with i-Pilot Link's Spot Lock feature. We had some pretty gusty winds from the south and a fair amount of current (I was working the 1st and 2nd dams in a sequence). I watched my i-Pilot Link remote display to see the maximum distance I ever moved away before I started making progress back to the locked location. I never saw that distance go beyond around 20 ft.....just about a boat length.....pretty darn good for the tuna boat wakes, current and cross wind conditions I was asking i-Pilot Link to handle, and plenty good enough for me to avoid having to use a traditional anchor to hold me in place. I'll see if I have a screen capture of my tracks while I was locked on one of my Spot Lock locations from last night for us all to see; will post if I do.
(Side note: with gusty cross winds and tuna boat wakes, I'm willing to bet that an anchored boat would be moving around just about the same amount as a Spot Locked boat!)