Fish Finder Questions: Garmin 551DV

Hi everyone--

I am fortunate enough that I may be getting a Garmin 551 dv fish finder for a price I shouldn't pass up as a return favor from a friend.  I googled it and it appears to be a really nice fishfinder, but is it too nice for a kayak? 

I am mainly worried about power consumption and whether or not I'll fry it should I ever decide to invert my kayak on accident 

Being that I know nothing about fish finders, amps, or anything really having to do with electronics or wiring, I had a few quick questions.

1.  I see fish finder kits selling with 8 AA battery holders vs. the small 12v batteries.  I would LIKE to go the AA battery route because weight is a major concern for me since I have to lug my kayak up 2 flights of stairs to get it back in my condo.  If I were to get this ff and use the AA batteries would it severely limit the length of time I'd get out of the FF?  I don't mind buying a few sets of rechargeables to keep with me.  I don't know what the power draw is but maybe someone with a similar fishfinder can help me out there.

2. I am not really comfortable installing the fish finder myself mostly due to the drilling part and the fact that I just don't have the tools up here to do a really crisp job.  Is there somewhere I can have it installed?

3. If I dump my kayak (which I almost did this weekend) will it fry the fish finder? I know some of them are water-ish proof but I can't figure out if this one is.  I'd probably pick up a ram mount for it and just plug it in after I launch, but I cant help but be a bit worried about that.

Again, my biggest concern is keeping the weight down on my whole rig.  I know 5-10 lbs isn't a lot, but when it comes to luggin the kayak up stairs after a full day of fishing, sometimes I can barely do it as it is lol.

Thanks for the help!

1. A: Most of use the 12v "Brick-style" batteries that you find in Emergency Exit Lights; and re-charge them with a 12v charger..

2.) Give Dan over at Headwaters, he does installations.

3.) Most units nowadays are IPX7 Water proof; I;ve rolled a few times in the surf with my Garmin, no problems except my pride...

I'm sure others will chime in but I'll throw a few things at ya in the meantime:

1)  Batteries:  Don't do AA batteries.  You won't get a long period of use & Garmin has a long history of very high power consumption.  They are getting far better than they once were, however.  In addition to either disposing of AA batteries or needing to buy rechargeable, it isn't the best solution considering you can get a good starter 12v brick battery for around the same cost; ~$25 for battery & then add a small charger.  Last thing you also want to be dealing with is changing batteries while on the water.  Also consider LiPo battery pack for weight savings & increased run time over a "brick" battery -- cost will be a bit more, though.

2)  Weight:  Go with a RAM mount & you can remove the head.  If you mount the battery in a small plano box or tray, you can also remove it for weight savings while carrying up the stairs.  You just use a 2-wire waterproof in-line plug to connect between the Garmin power cable & the battery box.

3)  Check with your local kayak shop to see what they would charge to install the FF unit.  Be sure to search the site as there are LOTS of pictures of various installation configurations to be found on here.

Thanks guys.  Your input is really helpful.  It's a bit challenging to find fish finder info online sometimes because they are in boats and not kayaks so they don't have to think about the things we do sometimes.  If all goes well I'll be set up in a few weeks.

True.  Most boats already have an on-board 12v system.  We do the same, just on a far smaller scale.  Look at some of the pre-made kits to get an idea of components.  Google 'Hobie Fishfinder Install Kit' for ideas.

Random side note or question...but I wonder if Garmin will continue servicing this FF? Because I think that's one of the models that infringed upon Lowrance/Navico patents. http://www.lowrance.com/en-US/News/Garmin-Violates-Navico-Patents/

What size AH battery should you be buying for running units like this?

That depends on how long you want to run it for between charges/while on the water.  Most go with 7-9 amp hour battery.

If you can spend a bit more, you might consider a lithium iron phosphate battery---very lightweight, durable and safe.

I have a Garmin ft and it's been beat up in the surf many times, so no worries there.

Thank you all for your help.  Nowhereman, I looked at the lithium iron phosphate battery and they are nothing short of awesome, but my wallet actually shriveled up a little bit when I saw them  .  With that said, I'm going to see what I can work up.  The power cable for the Garmin appears to have an inline fuse and there's a "spypoint" battery, box, charger on Amazon for $45.  Then I'm going to drill the ram 7' mount to the center mounting spot on my Tarpon and cover the wires with a wire cap from West Marine.  All in all the equipment should run about 100-110.  So total cost w/the fishfinder should be about $370.  I am also going to have a friend help me with some quick connector plugs so I can quickly plug in and unplug the battery.  If I have an epic collapse I may end up getting the hobie fishfinder installation kit 2.  That is more expensive but the parts are all there, the battery seems to be good quality, and its waterproof.  I'll post up some pictures when I get around to doing this.  Unfortunately, the kayak inside doesn't look so hot next to the xmas tree according to my significant other.