Upgrading to a Chartplotter (Location, wiring, batteries)?

[sanmi]

I'm thinking about upgrading to a 6" chartplotter with fish finder (something like a Garmin Echomap 64cv). I currently use a portable Garmin GPSMAP 78sc and a portable Hummingbird fish finder for depth. Everything works fine in good weather, but the GPS screen is hard to read when it is windy and wet and the fish finder doesn't register if the boat is going faster than 3 or 4 mph.  For most of my life, I've used the centerboard as a depth finder, but my current sailing grounds on the pacific coast have tides of 6' - 9' and the addition of a depth finder has been transformational. I already carry about 15 Amp-hours of little lithium power bricks for charging phones and tablets while cruising, so I'm not opposed to powered devices.

 

I'm comfortable with making the box and control panel (switches, fuses, breakers, etc) but I'm struggling with how to route the wires in the cockpit. I hate putting holes in the boat! I'm thinking about having an integrated battery box / control panel in the cabin (doubling as a companionway step) and putting the fish finder under the mizzen mast partner.

 

My current setup: the GPS is velcro'ed to the mast partner and the fish finder is velcro'ed to the transom with the transducer wires fastened using command outoor lighting clips (see photos below).

 

I'm soliciting opinions and suggestions about:

* Location of a chartplotter on a core sound 20 mk2 (I think Graham had his in the companionway at one point)

* How to route a power cable from the cabin to a plotter at the the mast partner. 

* How to route the transducer cable from the transom to the chartplotter

* How to get a waterproof seal when passing through bulkheads, cockpit or transom. For example, should I use waterproof connectors when passing through plywood panels, or just epoxy, putty, etc.

* Lithium-ion vs lead-acid batteries. 

 

Thanks!

 

 

 

 

[Steve W]

I'm not sure about a fish finder, but I put my transducer inside the boat. Here's how I did it:

https://messing-about.com/forums/topic/9419-core-sound-20-mark-iii-3-skeena/?do=findComment&comment=106509

[sanmi]

@Steve W I love what you did with the transducer. Have you tested it on the water? Is it working the way you had hoped?

[Randy Jones]

I wouldn't use a traditional lead acid battery again.  I'm happy with a pair of smaller Optima AGM batteries with an A/B battery switch,  portable charger, and 5 amp alternator connection on the outboard.  They are sealed so they won't leak juice and don't vent gas unless mistreated.  When you need to move them they are much easier to manage then a single big old group 24.

I suspect checking prices on lithium-ion batteries will probably end any consideration of their use.

 

[sanmi]

Thanks. I agree that AGM is better than old style. I won't be starting any outboards or powering any trolling motors - just charging phones and powering a chartplotter. I'm thinking 20Ah to 30Ah.

Google and youtube tells me that a Garmin Echomap 64cv with a regular CHIRP sensor will draw somewhat less than 1 amp, so a 20 Ah battery will theoretically last ~20 hours. If I get a smaller Echomap 44cv, it will be ~40 hours.

[Steve W]

The transducer works perfectly!

[Don Silsbe]

I used a 3s LiPo battery from my model airplane stuff.  It worked great, with one huge problem.  LiPo’s don’t like to dip below 3.0v per cell.  Once that happens, the chargers won’t even charge them anymore.  Worse than that, if they discharge too far, they can catch fire.  Mine didn’t go that low, but it would not recharge.  I trashed one of my larger 3s LiPo’s to learn that lesson.  If I do it again, I’ll install a low battery alarm.

 

I’ve been running with a blue Optima.  But that’s like squirrel hunting with a 12 ga shotgun.  It’s too heavy, at least for daysailing.  I want to try an AGM motorcycle battery.  Too bad they’re not deep cycle.

[sanmi]

Thanks @Steve W I think I will try your router trick! Do you have a photo of the finished product?

 

@Thrillsbe Thanks for the story about your LiPo batteries. I was leaning towards the LiPo for the weight savings and more charge cycles, but your story makes me doubt that I have the discipline to use it properly. Regarding motorcycle batteries, there are 30ah deep cycle batteries (like this one from amazon) which weigh a little more than 20 lbs. I would probably set it up with a guest charge pro 6 amp charger that I have from a previous boat (a bit overkill).

 

 

I'm also considering getting a solar panel and am open to suggestions about that.