Topic: GPS External 50 Channel Receiver For 898 Mounting Location

[calli1]

I have another question before my 898 arrives, which should ship on Thursday.

It will be coming with the 50 Channel GPS External Receiver. 

Should I mount the GPS Receiver close to the 898 unit or the transom SI transducer?

The 787c2i I have now has a internal GPS Receiver.

To me, it makes more sense to mount the GPS Receiver closest to the SI tranducer??

Then, do I need to mount the SI transducer on one side of the boat and the 2D exsisting ( from old 787c2i ) transom transducer on the other side.  In other word....It would also seem to me that it would be best for them to be on the same side of the boat about a foot apart?     

Thanks

[sonar2000]

Mount your gps near the transducer.  Unless you are not all that particular about exact GPS coordinates.  Some people are comfortable with a 10 foot margin.   Just depends on your requirements. 
Chuck

[Humminbird_Greg]

Chuck is right about the GPS Receiver: mount it as close to the Si transducer as you can.

Now about mounting the 787’s transducer:
How are you going to use this transducer; with the 787 only or with the 898 unit?

[calli1]

I am going to use the old 787c2i transducer in combination with the new SI.  Not using the old 787 transducer at all on the 787 anymore.

I already have the new trolling motor puck transducer on it.

So both of these transducers would be used only for the new 898 unit.

Ok....so does it matter if the transducers are on the same side of the boat and about a foot apart.  Also....I am planning on mounting the SI transducer about 2 inches above the bottom of the boat line.

Thanks everyone.

[Humminbird_Greg]

Calli1,
Yes it can make a difference.  The 2D sonar data will be offset to the side by XX feet if you mount the 787’s 2D transducer on the opposite side of the motor as the Si transducer – but, the closer you mount the 2D transducer to the Si transducer the more Si sonar to that side it will block.  So I think that your best option is to mount them on opposite sides of the motor.  If you have a fiberglass boat you could mount the 2D transducer inside-the-hull for better high-speed depth readings.

[calli1]

Greg....Thanks.

I have a Aluminum Boat.

How long is the External GPS Cable?  I thought I might leave the 2D where it is and mount the SI transducer on the opposite side like you said if the GPS cable is long enough.

If not, I will remount everything and have the new SI ducer behind the drivers side and the older 787 Ducer behind the rider side.  Either way...I need the 2D ducer just below the bottom of the boat and the new SI about 1 to 2 inches above the bottom line of the boat....correct?

Thanks for everyones help.

[Humminbird_Greg]

The transducer mounting you stated should work Calli.

The cable that comes on the GR50 GPS Receiver is 20 feet long.  The AS-EC10 extension cable is 10-feet long.

[fishinmusician]

I just received my 898 today and can't wait to start the installation process.

I want to mount the gps receiver in the corner of the stern of my boat a triangular flat metal plate.  (My boat is a 1675 Lund Explorer with a 60 Hp Merc tiller).  However, without some kind of stem/pole apparatus, it appears that the outboard motor will block the horizon on the opposite side of the ster, and I won't have a complete 360 degree view for the receiver.

Will this adversely affect my GPS reception?  If so, then perhaps a stem is the only way to go.  Thanks in advance for any replies.

[sonar2000]

With the number of available satelites in the sky and the fact that you wont be stationary for hours you should be fine.
When you get hooked and turned on,... look at the satelite screen and it will show the positions of the receiving birds in the air. You will see that the satelites are scattered over the top above you and that they are not fixed and will rotate across the sky giving you excellent coverage. 

Chuck

[fishinmusician]

Thanks, Chuck

[Humminbird_Greg]

You could try what Chuck suggested and see how many satellites are showing with it on the stern of your boat versus being held up in the air as if on a stem mount.  Look at the estimated position error number as well as this is a good indicator of how far off the GPS Receiver thinks it is and will give you a better means of comparison.  Which day and the time of day that you do this on will vary the results some but it’s a good way to gauge how much affect the motor will have on your position accuracy.  Than you can decide whether to install it flat on the stern or on top of a stem.

[Moose1am]

Well, I purchased an antenna base and 2 ft long extension to mount my gps antenna above the motor.   I did have it mounted on the flat panel on the back of my Aluminum boat.   

My gps accuracy was only about plus or minus 17 ft at best when it was mounted flat on the boat with the motor blocking the view of the sky.  The boat is parked in my driveway when I do this test. 

I have a hand held Garmin eTrex Vista GPS unit and with WAAS it get plus or minus 7 ft accuracy at times when I hold it up while standing in my driveway at home.   

I have not had the chance to get the boat out and do much testing of the new antenna mount as it's been too cold and raining all the time this past week or two. 

The way I figure it if the WAAS satellite gets blocked from the GPS antenna view by the motor I could lose a lot of accuracy.   That's the main reason I wanted to elevate the GPS antenna puck so that it had a complete unobstructed view of the sky.

[sonar2000]

Good tests.  We find that using the DD.DDDD format for display gets accuracy to about 3 feet.
Also remember that the WASS satelites (2) are stationary and do not rotate around the earth.   This means for now that not all are visible to all places.
It may be that of the two in space only one is turned on right now. 
Chuck