GPS recommendations and advice please...

[Donzen]

Would like to hear all interested voice their opinions of their GPS units.  I have been a window shopper for a long time  - and am now about to take the plunge and purchase a Garmin 478 GPS Plotter.  Can anyone advise their experience with this unit.  Pros and Cons.  Maybe there is something better on the market.  My idea is that it be portable to switch between my CPac-23 and my power boat.  I'm not especially interested in a unit that needs an external antenna.  I would like for the unit to have charts for Chesapeake Bay, and ICW South to FL and over to the Bahamas.  And, is there a way to get software for a portable PC that would have identical charts ??  I would also like to purchase a unit that could be powered by AA type batteries and 12volt as well.  Any recommendations will be greatly appreciated

I'm really looking for all your input as to your experience. Also, where you have installed your unit on your boat.  Thank you,......Donzena

[Craig Weis]

Raymarine 435i chartplotter unit.  i = internal antenna. Why run another wire and something else to be sticking up in the way? I mounted mine permanently in a hole in my cockpit bulkhead.

The 435i has no battery in it. to answer that above question. Yes speed as it takes it's speed very x seconds. The x varies as per the speed input. Like a sail boat with a 'pings' every, I don't know, every 10 seconds. A power boat say twice a second. Just an example.

I have 1000 cold cranking amps topped off when I leave the dock on Friday. Running the St-40 and chartplotter and the VHF scanning and the Davis Anchor light at night and the navigation LEDs  [I love to sail at night] a few cabin lamps, plus my oil lamp with my solar cell adding a few electrons into the battery [I have measured 18 volts at 300 ma on a sunny day. It's like peeing in the sea to make it overflow. I can run out of juice Sunday heading home. I know when I do because the ST-40 starts giving funny readings from the speed paddle. If I don't run the chart plotter and turn off the VHF radio and use the oil lamp I'm fine.


Switching from power boat to sailboat will require a recalibration for each switch.

Use any a chartplotter GPS sparingly as no solar cell will keep up with any chartplotter GPS power consumption.
skip

[Donzen]

Skip,

Does this R-435i have aux battery back up?  I'm thinking...because I do not have an Out board engine to charge my battery I want a unit that will accept disposable batteries as a back up.  Also, do you happen to know what the drain would be (approx) on a 12V battery if one used it intermittently?

Why would you need to recalibrate it?  Wouldn't it just be a speed thing?  And the unit should calculate that speed anyway -- right? -- or am I wrong?

Appreciate your input.........Donzen

[Shawn]

The Garmin 478 is a nice unit, I have one on my boat. Comes with Coastal maps and full detailed street maps for the entire US built in. It can be linked to a depth sounder if desired and I have it networked with a Raymarine autopilot. I run it off the boats battery and have an alarm set in the garmin if the external voltage drops below a preset level. That is a good warning if the boats battery is getting low. If that happens you can always pull the plug and run on the internal lithium battery too.

Shawn

[Shawn]

"Use any a chartplotter GPS sparingly as no solar cell will keep up with any chartplotter GPS power consumption."

I have 2.5 amps of solar, the 478 has a 1.5amp fuse in it so its actual consumption is going to be quite a bit lower then that but I haven't measured what it is drawing yet.

Shawn

[Donzen]

shawn,

Can it be linked to the ST2000 tiller pilot?

[Shawn]

I use it with the ST2000+. Just finished the install last week but looks to be working fine. The ST2000+ sees the NMEA data from the 478 no problem.

IF you were looking at using the depth sounder attachment with the 478 just be aware you can't use the sounder and feed the autopilot GPS data at the same time. Only one at a time can be used with the 478.

Shawn

[Craig Weis]

"I have 2.5 amps of solar, the 478 has a 1.5amp fuse in it so its actual consumption is going to be quite a bit lower then that but I haven't measured what it is drawing yet."

How can you say actual consumption is going to be quit a bit lower because it has a 1-1/2 amp fuse?
Ummmm so what does that mean. 2-1/2 amps? So with a 1000 cca battery it would need 400 hours or 16 days to charge if it was dead flat, which it won't be.  I really don't understand this but here goes...

Not counting about battery 40% efficient and not counting that your using juice faster then your putting it in.
What is Ohm's Law? It's down in 'Off Topic', Lets see.
Here is one. Not much help:

So why does the electric wire have many more 'conductors' for electric wire that carries a high number of amps and less 'conductors' if the electrical wire carries less amps?

The electrons that make up electricity want to follow the path of least resistance. So that means that the electrons do not want to flow through a wire [conductor] but would rather travel on top or on the surface of a wire.

Why use energy to push into a wire, heating up the wire, when electrons can skate over the top surface and keep the wire cool.

In a nut shell that's it. Use 'big' wire for big amps. Just for s--t's and grins I used two 14 ga wire conductors to carry juice to and from my added electric automatic/push to test bilge pump. I just put the two wires into each positive and negative lug and taped each of the two wires together. How neat is that? More conductor surface than is needed but without a large, less flexible wire [conductor] to deal with. skip.

Maybe this?


Ohm's Law
 
Virgins Are Rare
for: volts = amps x resistance

E = Volts
I = Current (Amperes)
R = Resistance

I = E/R or Current = Voltage / Resistance
E = I*R or Voltage = Current * Resistance
R = V/E or Resistance = Voltage / Current

So what do you have? [My 435i chartplotter draws 300 milliamps at 12 volts]...
skip.

[Shawn]

"How can you say actual consumption is going to be quit a bit lower because it has a 1-1/2 amp fuse?"

Because nothing is fused at exactly what the current draw is. Fuses are over rated by some factor. For example the autopilot has 2.5 amps of draw when it is actively moving the tiller, it has a 15 amp fuse on it.

The GPS with its 1.5amp fuse will draw less current then that. Probably somewhere around 1/2 to 1/3 of the fuse rating.

" So with a 1000 cca battery it would need 400 hours or 16 days to charge if it was dead flat"

Not even remotely. A CCA amp is rated to put out that current for a very short amount of time, 30 seconds as I recall.

What you should be talking about is the amp hour capacity of the battery. That is not the same thing as the CCA rating. Real deep cycle batteries aren't even rated in CCA at all, that is a starting battery rating. FWIW my group 27 deep cycle is rated for 90 amp hours. That means it can put out 90 amps for 1 hour or 1 amp for 90 hours. But of course you don't want to run a battery flat, 40-50% discharge is a good limit on a true deep cycle. That means I have about 40-45 amp hours of straight battery power. So if I used 40 amps hours from the battery I'd need about 16 hours of full charging from the solar to recover that.

But of course if the battery is charged and it is a sunny day the panel could put out more power then the GPS uses so I won't even be draining the battery at all while the sun is out. If your 300ma draw of your GPS is accurate it means you could run it for 133 hours on my battery (no solar) before hitting the recharge point. Even if you ran it 24 hours a day (7.2s amp hours per day) with my solar setup you would need sun for roughly 3 hours of full solar charging to get the battery back to 100% charged. And that is with the GPS still running during the charging.

Shawn

[Donzen]

C'mon Guys....

Let's try to get back on topic here.  I wasn't asking about intricate wiring, power and electricity demands, I was asking about some recommendations re the use of GPS and what you're using and why you like what you've got.  I did mention that I wanted a unit that could take disposable batteries though.

Can we get back on topic please................? Donzen

[Craig Weis]

This is interesting and I didn't know this. Thanks for the heads up. It's so very complicated. One day at the factory we were standing outside and the guy next to me says, "See those three wires coming into the building?" Yes. "Those three wires no bigger then your thumb in diameter run everything electric in this plant."

Wow. I started thinking about the hundreds of fractional and greater sized electrics used on the conveyor, light, fans, laser cutter, punch press, turret press, electric fork lift chargers, computers, welders, lift tables, shears, light curtains, motor starting cabinets, and about a 'bizzion' other electric things. Electrics are just amazing. And it's simply electrons running up and down on the outside of coper wires at 60 hertz a second.

OK if I have 1000 cca for 30 seconds, how do you 'size' the battery for a 'draw' over a day on the water? Still baffled.
It's a chemical reaction that occurs in the battery and when this or that are fagged out, that's the end of the chemical reaction and the flow of electrons. And requires far more electrons to flow back into the battery to bring the battery back up to the start point when the chemical reaction was 'young'. That's the solar cells job I guess. And this chemical reaction slows down of course and is cut in half at a temperature at or below freezing. It's all mind bogging.
skip.


"What you should be talking about is the amp hour capacity of the battery. That is not the same thing as the CCA rating. Real deep cycle batteries aren't even rated in CCA at all, that is a starting battery rating. FWIW my group 27 deep cycle is rated for 90 amp hours. That means it can put out 90 amps for 1 hour or 1 amp for 90 hours. But of course you don't want to run a battery flat, 40-50% discharge is a good limit on a true deep cycle. That means I have about 40-45 amp hours of straight battery power. So if I used 40 amps hours from the battery I'd need about 16 hours of full charging from the solar to recover that.

But of course if the battery is charged and it is a sunny day the panel could put out more power then the GPS uses so I won't even be draining the battery at all while the sun is out. If your 300ma draw of your GPS is accurate it means you could run it for 133 hours on my battery (no solar) before hitting the recharge point. Even if you ran it 24 hours a day (7.2s amp hours per day) with my solar setup you would need sun for roughly 3 hours of full solar charging to get the battery back to 100% charged. And that is with the GPS still running during the charging."

[Shawn]

Skip,

Forget about the CCA rating of your battery. It isn't relevant to your needs and doesn't tell you anything useful for battery power in a sailboat. In fact if one purchases a battery for a sailboat based on the highest CCA rating they can find they are most likely buying a less optimal battery for a sailboat. CCA is all about huge current for a brief period of time, not about long term battery power.

For high CCA the plates in a battery are built 'spongy' for lots of surface area for a high CCA rating.. to run a starter for a brief period on a big engine. However we don't care about lots of amps very quickly, we want a much smaller amount of amps for much longer. That is a deep cycle battery. A deep cycle battery is built with solid plates so it can be discharged much lower without damage then a starting battery can but because the plates have less surface area the batteries CCA would be lower.

The specification you want to look at in a battery for a sailboat is the amp hour rating. If the battery is rated for 90 amp hours that means it can put out 90 amps for 1 hour before it is flat. Or 1 amp for 90 hours before it is flat, or 45 amps for 2 hours...etc...etc.

But you don't want to run a battery down to flat as that is bad for them and reduces their service life.

On a starting battery you should only discharge them a small percentage... for example 10% discharge. That means if the starting battery even had an amp hour rating (and some don't) you could really only use 10% of its rating. So if the battery was rated for 90 amp hours you really only have 9 amp hours of useable capacity. 1 amp for 9 hours or 9 amps for 1 hour or some combination.

A deep cycle can be discharged much further. In my example earlier I said 50% discharge. So that 90 amp hour rating on a deep cycle battery would mean you have 45 amp hours of useable capacity. And some will run deep cycles down much further to even 80% discharge.

So even with identical amp hour ratings buying a deep cycle battery instead of a starting battery gives you 5x the actual useable battery capacity.

To determine your needs find out the current draw of each of your devices. Then figure out how many hours you want to be able to run each of those devices and multiply the hours times the draw for each device. Then add that all up and it tells you how many amp hours you need.

For example:

GPS at 300ma  (0.3 amp) * 6 hours = 1.8 amp hours
Navigation lights at 3amps * 6 hours = 18 amp hours
interior LED light at 500ma * 8 hours = 4 amp hours

Total reserve needed 23.8 amp hours.

The 90 amp hour deep cycle run to 50% discharged could handle this with over 20 amp hours to spare. The 90 amp hour starting battery run to 10% discharged can not.

If you have solar charging available take its output and multiply that by however many hours of that charge you get and subtract that from the number above. So in my example of 2.5 amps from solar if I get 6 hours of full charge that is 15 amp hours of charge.

23.8 amp hours needed - 15 amp hours from solar means overall the battery would end up down about 8.8 amp hours when you were finished. Just keep in mind the actual discharge of the battery could dip lower then this. For example if you started sailing at night with lights then the next day the solar was recharging for last nights usage.

Shawn

[Donzen]

OK Skip & Shawn..........Now that we are not talking about GPS anymore, pls tell me how I determine what size deep cycle to buy for my boat.

If for example there is a 90 and a 120 deep cycle creature out there somewhere for purchase, does a guy look for say 2 batteries, say 60 amp ("whatever") draw instead of 1 big beast?  Still assume that he's got no way to charge up until he gets back to dock.  What is the advantage / disadvantage in this scenario?

And then again, tell me please.....if I leave dockside with fully charged batteries, what is the drain on them if you don't use them AT ALL? 

Like say you leave your car for 6mos and come back to start it - it is dead.
How fast do these thing discharge when not used regularly?

Thanks,
Donzen      (PS.  All my electric buddies call me Don!)

[Donzen]

Shawn...

Does the Garmin 478 show navigational aid NUMBERS on the LED?

I read somewhere that the Garmin "Oregon", which is a hand held unit is a pretty good product.   Then this mariner fellow posted on another site -  he was quite peeved that he bought the unit and it doesn't supply nav aid numbers.  I can understand his disappointment and his consideration that it is "worthless" for marine use.

I gotta get a unit that works well with the ST-2000 Tiller Pilot and I'm still shopping.

As an aside, what have you found to be the best "papercharts" that correspond to the Garmin LED charts?
Donzen

[Shawn]

Don,

I don't know if it shows the numbers or not but will check that out next time I am at the boat.

The 478 works fine with the ST2000+. Was using it yesterday. No matter what GPS you get make sure it will output cross track error in any of the NMEA sentences that the ST2000 will understand. That way the ST2000 can correct for XTE. Not all chartplotters output XTE information.

Shawn