humminbird gps problem

I bought a 998 brand new a couple months ago. Before that I had a 997. And 957. Also a terrova with I pilot. My 997 957 and ipilot. All read the same speeds while I was trolling along. Within .1 or .2 mph. But now I got my 998 its off about .5 mph on the slow side. So when I'm trolling less than 1 mph according to my I pilot control. it says I'm doing .4 -.5 on my 998. Leaving me a big fat donut!!!! I am obviously moving 1mph. I troll often and can tell by line angle and bends in the rod approx how fast I am moving. And I asked hummingbird and they basically told me I was out of luck Cuz they only guarantee to be within .5 mph. Any of you guys have any ideas. Very frustrating!!!!!!!!

Get you a heading sensor gps puck (external) and you will be done with the donut!

I've been thinking about that. Where is the cheapest place to get it? Is there different models of them?

Universal Mania has the best price i have seen.

Get you a heading sensor gps puck (external) and you will be done with the donut!

The HB AS GPS HS antenna definitely removes the donut...

But it does nothing to fix the GPS slow speed reading problem...

"Heading" and "GPS Speed"...are 2 completely different functions...

Rickie

If it's the GPS antennae that came with the 998 that's bad and causing the speed problem, replacing it with the Heading Sensor antennae will fix that. The HS sensor will also cure the donut issue because it has a built-in compass.

I change to the Heading Sensor GPS (external) a couple months ago on my 998. The location is critical or you get error from TM or any metal. I wish I had changed when it first came out. If you slow troll below .6 mph it is wonderful (no donut). I'm not sure the new HS GPS will correct the speed issue, but you will be happy with the improved boat position and "no donut" rdjj

My boat is aluminum and I have no carpet anywhere. I will be mounting it to my console which is also aluminum. Trolling motor wires will be several feet away. Any way to avoid any of those problems?

Quote:

---

Originally Posted by jhill10

My boat is aluminum and I have no carpet anywhere. I will be mounting it to my console which is also aluminum. Trolling motor wires will be several feet away. Any way to avoid any of those problems?

---

You can test positions for the AS GPS HS antenna by using a small handheld magnetic compass...

If the hand deflects at all (in a certain spot on the boat)...there is magnetic interference in that spot...

Continue moving the handheld compass to different potential mounting spots on the boat until there is no movement of the compass hand...

Rickie

Aluminum is not normally magnetic so you should not have any problems but I would still check for any magnetic interference like Rickie stated to.

OK. Thanks

I've the 898 and it was during about the same thing. Was running the 6.49 updated to the 6.74 and it took care of the problem
LittleJohn

I'm late getting into the last part (magnetic interference) I have an aluminum boat also and when I first installed it I had problems when I had the trolling motor in the stored position. It was ok when it was down. I had to move it a couple feet from the TM.