Ok guys,
I've been in IT for 20 years and fishing for double that and I recently acquired a boat ....man can these things be a money pit... especially when you like technology.
Since an HDS 12 is out of my price range....I found a cost effective way to upgrade your navigation on your boat without spending $3000+
First I have been using my trusty Hummingbird monochrome 170 that came with the boat...

surprisingly this has been a fantastic unit and I believe it picked up fish better than my recent upgrade to my $89 Lowrance Hook 3...Was so excited to finally see fish in color ahh but I digress...

Up until recently I haven't had navigation so I have been using Navionics on my iPhone and a boat mount like this: Ball Mount System

(I also use a case with a wrist strap, that I tie around something that is bolted to the boat in case that magnet doesn't hold.)
It has worked reasonably well so far but I wanted something bigger...this is Texas so go big or go home.

So I recently purchased a Humminbird 689CI - it has Side and Down imaging and navigation....

I thought all my problems have been solved....well after using it on the water a few times I realized that I mainly use the Side imaging and Down Imaging and the native mapping system is not very user friendly at all. Also you are using a lot of real estate on the screen to see everything you want. Well a Navionics chip is $199...so I thought maybe I can do something better....

So I did some research and I realize that most Android devices come with native GPS built in....this means you DO NOT NEED 3G or WIFI service in order to use the GPS out on the water...

So here is what I did:

1. Obtain a Galaxy Tab (I already had one) but there are a few different flavors: a 6inch or an 8inch model all about $50-$150 on ebay

2. Purchased Ram Mount Ram Mount - $79 for 8 inch or for a smaller unit like a tab 4 I used Small Mount $14

3. Purchase Navionics App $9.99 (There is also a free version of Navionics with less feature if you like but I prefer the paid version)
4. Next step is to connect your tab to a wifi and download Navionics, then use Navionics offline feature to download a portion of an area locally to your tablet....
- Pick the area that you plan to fish the most and download those maps onto your tablet.
4a. If you like you can get some SD cards to increase the storage space and allow you a lot more routes on the water
5. Install your mounts with screws into your boat. (One of the mounts I posted has a suction cup mount, I drilled through it and placed screws to hold in it place, I don't know if a suction cup would work but I don't think I would chance it on the water).

A few other things:
Ram Mount - The Ram mount has a really cool feature - it has a button that releases the Tablet with a twist and there is a lock on it, so it's really easy to put in and take out the tablet and/or lock it up . It comes with a lock and key set. It has held up in 2 foot waves and the unit did not bounce around at all. It fits snug

Battery Life: I get about 5-7 hours of battery life from the Galaxy Tab, I leave it on all day and turn up the brightness and with the GPS activated it does eat a lot of battery, I would suggest having it plugged into a dedicated power port if you plan to do this full time.

**Let me just say this: The Galaxy tabs are not waterproof but I used them the whole day on the boat and they barely got wet, I'm trying to find some waterproof covers that will fit in the mounts. I'm still looking and will update you when I find one. For now I cover them when I am driving with a plastic cover.

Here is the final results on my brand new 85 Stratos...

Navigation works great on the water and no wifi or 3g needed. Also these have great cameras on them as well for recording fishing.

WAY KOOL Cruzfishin!! Neccessity is the mother of invention

nice work

Check out these: https://www.lifeproof.com/en-us/ipad-air-cases

I've been using my older iPad on the boat with this case for years and it works great. It's even been underwater. I don't however suggest their phone cases. I tried two and they both had problems.

Awesome thanks for the cool write up OP!

Think this will be the future of fishing electronics. Imagine one screen that u could move front or back.

Let me fist say, love the idea and your execution.

How accurate is it compared to other units? I find my andriod GPS sometimes isn't showing exactly where I am when in my car....

Great thinking

Awesome job!!

If you get a Lowrance HDS3, you can connect your tablet using the gofree app and then use the tablet just like the hds unit.

How sunlight readable is it? I would guess that it isn't very good, but still on the cheap.

Nicely done sir!

You should definitely do your research on tablet screen brighness if you are going to use it during the daytime. I bought a nice tablet (forgot what brand) for running Navionics and it was not useful in daylight. I ended up buying a Nexus 7, which has a very bright 7" screen, and is usable during the day.

*This post is not directed at the OP. Just wanted to mention it because screen brightness varies a lot among tablets.

We link the iPad via Bluetooth for a mirror image and can even change settings and mark waypoints with the Garmin or Lowrance unit. Even have a ram mout for the iPad with a life proof case and ran a power wire to the front of the boat for a permanent charger. Not sure what price point the units start at with Bluetooth capabilities.

I can buy a 60" LED TV with WIFI, Bluetooth, and basically a computer in it for under 1000 bucks. However, it cost 3k for a 12" fish finder? I've never understood that math. I can't wait for fish finders to go to the way of most other electronics and finally start to drop in price. It's gotten absurd.