HB 898 issues/questions

I was on a lake yesterday trying to find structure with my HB 898. I was watching the map while I went under a bridge at about 4 mph. When I was about 20 feet on the other side of the bridge, the boat image on the screen was just getting to the bridge. Doesn't seem right to have that kind of lag. Another issue I seem to have is after I mark a brushpile with side imaging, when I go back over it with the down imaging or sonar, it isn't where the waypoint is. Sometimes 10 - 15 feet away. Do I have some settings that are off? One more question - Once I have marked a waypoint, when I use the map to go back over it, if I drop a bouy, should I drop at the console where the GPS antenna is or in the back of the boat? Hopefully one or more of you can help me figure this out. Thanks in advance!

Being under the bridge.probably blocked sat. signals. When the brush is in the middle of the screen it is right under the TD. I would think depending on water depth that when it first starts to show on the screen it should be close to the console if your TD is in the back.

Or the location of the bridge/road could just be off that much on the map. I've had that happen with my handheld gps while driving. If I look at my track later it sometimes shows I was 20 feet into a field on the map. That's why they always post the discalimer that these are not to be used as a sole means of navigation, such as using at night. They are not down to a gnats ass accurate.

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Originally Posted by JTMavs

I was on a lake yesterday trying to find structure with my HB 898. I was watching the map while I went under a bridge at about 4 mph. When I was about 20 feet on the other side of the bridge, the boat image on the screen was just getting to the bridge. Doesn't seem right to have that kind of lag. Another issue I seem to have is after I mark a brushpile with side imaging, when I go back over it with the down imaging or sonar, it isn't where the waypoint is. Sometimes 10 - 15 feet away. Do I have some settings that are off? One more question - Once I have marked a waypoint, when I use the map to go back over it, if I drop a bouy, should I drop at the console where the GPS antenna is or in the back of the boat? Hopefully one or more of you can help me figure this out. Thanks in advance!

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If your transduce is on the back of your boat and your GPS is in the middle of the boat you are already 8 to 10 feet off you need to have your GPS as close to your transducer a possible.

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Originally Posted by Grizzly2k1

If your transduce is on the back of your boat and your GPS is in the middle of the boat you are already 8 to 10 feet off you need to have your GPS as close to your transducer a possible.

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Grizzly - Where would I drop a bouy when I am crossing the waypoint? At the antenna or the transducer since there is about an 8' difference?

Got to remember that we are on guest satelites. We don't always get the most up to date info. That thing about sun spots and sun flairs also can change things alot. We are a few years from having true satellite info and this whole 9/11 thing and wanting to protect government installations keeps us from getting true locks on our waypoints.

Found this in your 898 manual....
Attachment 57412

I think you can adjust your map to read your correct actual position this way...

Rickie

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Originally Posted by JTMavs

Grizzly - Where would I drop a bouy when I am crossing the waypoint? At the antenna or the transducer since there is about an 8' difference?

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Not an easy question to answer. If the antenna was 8 feet ahead of a brushpile you marked heading south, it's going to be 8 feet behind you when when heading south again. If heading north, it would be 8 feet ahead of you. East or west it could be 8 feet right or left. Then throw in how you marked the brushpile. If you were watching your sonar, by the time the brushpile shows completely on the screen, you are already past it. So it's not necessarily just 8 feet behind the antenna when you marked it. I'd follow your GPS direction arrow towards the waypoint while watching your sonar. Once you see the brushpile show up, pitch the marker buoy behind you. Make a pass from the other direction and do the same thing. The brushpile should be between them or if you are good, the marker buoys will be together.

Rnvinc, I don't have a 898 yet but am trying to learn. How would you know how off to adjust the map offset?

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Originally Posted by JTMavs

Grizzly - Where would I drop a bouy when I am crossing the waypoint? At the antenna or the transducer since there is about an 8' difference?

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Transducer!

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Originally Posted by tommyboyrn

Rnvinc, I don't have a 898 yet but am trying to learn. How would you know how off to adjust the map offset?

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Not really sure on this tommy as I 've never actually used it....

I'm gonna start a new thread talking about this and maybe we can all learn something....

Rickie

Thanks, good idea

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Originally Posted by JTMavs

Grizzly - Where would I drop a bouy when I am crossing the waypoint? At the antenna or the transducer since there is about an 8' difference?

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JT Part or your problem lies with the installation. That antenna needs to be as close to your transducer as practically possible. When dealing with GPS you already have and error factor of +/- a couple of yards at best. If you have a 20' boat and the transducer is on the stern & the antenna is at the console, you have increased that error by maybe 2X's. That translates to 12' to 15'.

When I first installed my 997 I had the same problem with my marks being way off. I did some study'n & moved the antenna to the stern right over the transducer. I immediately noticed a big difference in accuracy.

I also try to come at my target from the direction that it was scaned from. In other words if I'm traveling east I will circle around & come back at it from the same direction. I don't know if it makes a difference but it works for me.

Thanks Wiskers!

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Originally Posted by JTMavs

I was on a lake yesterday trying to find structure with my HB 898. I was watching the map while I went under a bridge at about 4 mph. When I was about 20 feet on the other side of the bridge, the boat image on the screen was just getting to the bridge. Doesn't seem right to have that kind of lag. Another issue I seem to have is after I mark a brushpile with side imaging, when I go back over it with the down imaging or sonar, it isn't where the waypoint is. Sometimes 10 - 15 feet away. Do I have some settings that are off? One more question - Once I have marked a waypoint, when I use the map to go back over it, if I drop a bouy, should I drop at the console where the GPS antenna is or in the back of the boat? Hopefully one or more of you can help me figure this out. Thanks in advance!

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I don't believe the problem is your GPS at all.. The problem is your screen scroll speed. Set your scroll speed to your MPH you are traveling. If your scroll speed was on... Lets say... 2 and your boat was traveling 4 mph.. Then YES.. there will be a lag. If your scroll speed is on 4 and your MPH is 4 then you should see the bridge soon as your tranducer gets there.. This will also give you the best image quality.

If dropping a bouy, drop it as close to the GPS pluck as possible.

DoubleG

I think that Shellback and Wiskers stated the best fix for what you are seeing. The sepration of the transducer and GPS Receiver can introduce an inaccuracy of up to two times the linear distance between them. That is in addition to the inaccuracy of your GPS Receiver at the time you marked the waypoint as well. Move the GPS Receiver as close to your transducer as you can get it and be sure that it is not mounted where some GPS satellites will be blocked (this may mean mounting it on a stem or VHF antennae mast) for the best possible accuracy.