Author Topic: Sonar Fuse Question  (Read 242 times)

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Offline Mooch

Sonar Fuse Question
« on: January 09, 2019, 11:17:05 PM »
So I'm finally getting around to swapping out my boat's Garmin black box sonar unit.  Both the new (GSD 24) and old (GSD 22) power cords have inline fuses on their positive wires.  Of course, I'll be replacing the old 3A fuse with a 7.5A  required at the fuse box for the new unit.  But my question is: why is the inline fuse on the cable necessary if it's fused at the fuse box too?  Guess I'm not getting why I have so many inline fuses connected to my fuse box.  Any thoughts?

The new GSD 24 sounder also has a boat water ground terminal on it's chassis.  I'm kinda confused where this ground wire attaches, if not to the same negative buss  on the fuse box as the negative power cable wire.

Another unexpected difference between the two units is the doubled minimum recommended compass distance.  My compass happens to be just opposite of my helm bulkhead.  Never experienced issues with the compass previously, but wondering how effective King Starboard is with isolating magnetic interference. 

At times it seems like simple upgrades and boats are mutually exclusive.   :facepalm:

thanks

2006 Sea Ranger Skip 21, Honda 150, Honda 9.9

Currently accepting hot waypoints from WA MA 2-10

Offline First Cabin

Re: Sonar Fuse Question
« Reply #1 on: January 09, 2019, 11:44:08 PM »
The electronics companies have learned not to trust the electrical abilities of Joe Numbskul.  If you asked customers to install fuses, how many would?  What would they install?   “Hey, if a 3A fuse is good, wouldn’t a 10A be even better?”.

I cut out the factory inline fuses on my Garmins.  But should I have a problem and have to send one back to the factory, I’m sure they would try and say it was due to me removing the factory fuse....
First:  1982 15' SeaHunter, Yamaha 70 2-stroke, Yamaha F6
Second:  1987 17' SeaRanger, Merc 90 2-stroke, Yamaha F8
Current:  2002 17' SeaChaser, Yamaha F100, Yamaha T8

Online Croaker Stroker

Re: Sonar Fuse Question
« Reply #2 on: January 09, 2019, 11:46:08 PM »
I removed my inline fuse and used a dedicated (no other accessory connected) fuse panel fuse of the correct value.

The Starboard is a poor magnetic shield. You could screw a piece of sheet metal (ferrous) on it to block the magnetic field.

Have you tried your compass yet ? Maybe it will be OK ?.
« Last Edit: January 09, 2019, 11:50:37 PM by Croaker Stroker »
1987 - 17' Sea Pacer - 2004 Evinrude 90 E-tec
15' Sea Sprinter - **SOLD**

"Ex Tridente Pax”. 🇺🇸

Offline davidsea

Re: Sonar Fuse Question
« Reply #3 on: January 10, 2019, 01:14:53 AM »
 :yeahthat:

  I took out all my inline fuseholders  (plotter, sounder, flowscan, VHF, etc.) and used the same size ATC fuses for each at the fuseblock. I really hate cheap white plastic fuseholders and glass fuses.   To check for compass issues, fire up your electricals, mark the compass rose position with tape, power down, install the new gear, power up, and see if the compass has moved - if not, you're good.   If you need shielding, try mu-metal - a soft metal sheet made specifically for shielding.  It's available from electronics supply houses, marine or aircraft electronics shops, and compass adjusters.  It usually works best when grounded to the electrical system ground.
1996 SR19 Hdtp. - 2018 Honda 115
2009 Duroboat 16 CC, Honda 50  -  SOLD
and 19 other boats (I think, lost count)

Online DevMah

Re: Sonar Fuse Question
« Reply #4 on: January 10, 2019, 06:11:25 AM »
Simply that protection is provided as per the manufacture recommendation and that if the unit is hooked up improperly it would be protected.

You should always use the same size supplied fuse as supplied or what the manual specified if removing the inline to a branch application.

Why are you doubling the fuse size.

Dev
2015 21' Sea Ranger  (Tight lines)
2015 Yamaha F150
2013 Mercury 9.9 Bigfoot 4 blade
2012 Lund 1650SS  w 2012 60HP Mercury-Sold

Offline Mooch

Re: Sonar Fuse Question
« Reply #5 on: January 10, 2019, 07:14:09 AM »
Thanks gents.  Very helpful, as always.

Dev, Garmin calls for a 7.5A with the GSD 24, which is a significantly beefier unit than the GSD 22.

From the look of it, I may have purchased this used unit from Mr. Joe Numbskul himself.  Look what I found in the fuse holder.  Hope it isn't fried.   :hoboy:

2006 Sea Ranger Skip 21, Honda 150, Honda 9.9

Currently accepting hot waypoints from WA MA 2-10

Online Fisherdv

Re: Sonar Fuse Question
« Reply #6 on: January 10, 2019, 07:20:53 AM »
Looks like at some point the original fuse must have blew, and it was replaced with whatever was available.
2018 Sea Chaser 16, Honda 60HP