I am refitting a 17' Siren sailboat that has a 5 HP outboard motor. I
plan to put a 12V deep cycle battery aboard for VHF, sounder, lights,
etc. Can anyone point me to any do it yourself websites that discuss
this issue in particular?

I am interested in findiing out more about:
1. Battery size (~120 Ah should be more than enough).
2. Charging concepts (solar, outboard). Willl probably be leaving the
boat in the marina, and might not have shore power.
3. Battery monitoring. Since power requirements are low, I do not
want to spend a lot on expensive monitoring devices.

Jim

Did you try what you suggested?
First check before you send this kind of info.
Any question here could be answer with Google for "..........."

Jim
I have copy of "The 12 Volt Handbook" - but it is 12Mb in total
Let me know here (rbe) if you need it and you can accept this size of
attachment
Adam

"Dennis Pogson" wrote in message
...
Jim Thompson wrote:
I am refitting a 17' Siren sailboat that has a 5 HP outboard motor. I
plan to put a 12V deep cycle battery aboard for VHF, sounder, lights,
etc. Can anyone point me to any do it yourself websites that discuss
this issue in particular?

I am interested in findiing out more about:
1. Battery size (~120 Ah should be more than enough).
2. Charging concepts (solar, outboard). Willl probably be leaving the
boat in the marina, and might not have shore power.
3. Battery monitoring. Since power requirements are low, I do not
want to spend a lot on expensive monitoring devices.



Google for "The 12 Volt Handbook", it will tell you all you need to know
about boat electrics.

Jim

--
Remove "nospam" from return address.

Jim Thompson wrote:
I am refitting a 17' Siren sailboat that has a 5 HP outboard motor. I
plan to put a 12V deep cycle battery aboard for VHF, sounder, lights,
etc. Can anyone point me to any do it yourself websites that discuss
this issue in particular?

I am interested in findiing out more about:
1. Battery size (~120 Ah should be more than enough).
2. Charging concepts (solar, outboard). Willl probably be leaving the
boat in the marina, and might not have shore power.
3. Battery monitoring. Since power requirements are low, I do not
want to spend a lot on expensive monitoring devices.



Google for "The 12 Volt Handbook", it will tell you all you need to know
about boat electrics.

Jim

--
Remove "nospam" from return address.

The book is a good suggestion, but I'm curious, how much output do you get from
the alternator of a 5 hp engine? I know that some 9.9 engines have a 12 Amp
alternator, but you don't get that unless you're running hard. Also, you have
to consider how often you'll run the engine, and for how long, etc. For
instance, if you have to power for a while to get out of a river, you may
generate enough to provide for a day's usage. And if you use it every week, not
much will lost to self discharge.

On the other hand, if you don't use it often, a small solar panel might be
better.

Also, an AGM battery will have a lot less "self-discharge" and is easier to deal
with on a small boat.



"Jim Thompson" wrote in message
...
I am refitting a 17' Siren sailboat that has a 5 HP outboard motor. I
plan to put a 12V deep cycle battery aboard for VHF, sounder, lights,
etc. Can anyone point me to any do it yourself websites that discuss
this issue in particular?

I am interested in findiing out more about:
1. Battery size (~120 Ah should be more than enough).
2. Charging concepts (solar, outboard). Willl probably be leaving the
boat in the marina, and might not have shore power.
3. Battery monitoring. Since power requirements are low, I do not
want to spend a lot on expensive monitoring devices.

Jim

I have lurked on this website for 5 years. I have been googling
extensively without finding any comprehensive discussion forums or
websites on this particular subject (small sailboat with or without an
outboard motor, but owner wants electronics on board), and I own The
12 Volt Handbook, Nigel Calder's book and several other marine
electronic references. I have extensively rewired our 30' powerboat
over the years. That's why I am looking for a comprehensive source of
information for this particular problem, ideally someone who has
already done such project recently. Technology has evolved very
rapidly in this specific area in the past couple of years. Hence my
question.

The specific case example that I am looking for is this:

17' sailboat.
Weekend/weekday sal****er sailing. maybe 1-2 nights overnight, some
nights camping out in the slip.
In-water at the marina slip between trips, with or without shore
power.
12 V DC power for:
VHF radio.
Sounder.
Nav lights.
Cabin lights.
DC socket for recharging cellphone, camera.

My thoughts so far a

1. Small 75 -120 Ah (?) pure deep cycle battery.
2. Charging system:
2a. Solar panel if not on shore power? Practical? Size?
2b. Shore power charger. Stray current not an issue if no metal from
the boat is in the water. Does not need to be heavy-duty, but needs
to be "deep cycle" aware.
3. Battery monitor: voltage, amperage draw, and maybe even one of the
Link type battery monitors that can estimate remain Ah, but cost
containment is and issue, and overkill is not in the specs.
4. Wiring: that's the easy part (AYBC specs, etc). The standard books
are fine for this, and the local boating stores sell all the products
I need.
5. I have no experience with LED nav lights, but there seems to be
plenty of info on google for that subtopic, and there was a good
thread on this newsgroup recently.

I am building my own case study for this application he
http://jimthompson.net/boating/Siren/Electrics.htm

Jim

On Wed, 04 Aug 2004 12:58:45 GMT, wrote:

For a 17 foot boat used as you describe, you don't need much of
anything. Buy a decent quality deep cycle (not dual purpose) 100 AH
battery, and don't worry about all that extra stuff. You don't need
it. Really. Your outboard will keep things topped up with little
trouble. Even your need for shore power is highly questionable. You
really don't have much of a load, there at all.

Thanks. How does one rig a Merc 5 HP 2-stroke to recharge the
battery? Is there simply a way to tap into its stator output?

Jim

The Mercury 5 hp "classic" has an optional alternator, maybe yours is already
fitted. The spec says:

"Alternator Amp: Optional 4-amp lighting/2-amp charging"
http://www.mercurymarine.com/mercury_5_classic

If you have to buy anything, consider a small solar panel first - that would
likely keep it topped up all the time, and will be useful in the off-season.

Get a handheld VHF. The builtin requires an antena and will be useless if the
cable or antenna breaks - an easy thing on a small boat. Unless you rig a
masthead antenna, your range won't be that much greater than a handheld.

A small Fishfinder, like a Ray 265 is a great depthsounder, with a consumption
of 2 Watts (4.5 with backlight on) so it can run all day on a few amp-hours.
You can glue a transom mount to the inside of the hull. People may suggest
fancy setups (mineral oil tubes, etc.), but for a thin glass hull none of that
is needed, just find a flat spot, and glue it in. If the "glue layer" is thin,
then silicon can be used - you might try that first anyway just to see how it
works. A more solid glue, like epoxy, is slightly better but permanent. And
why even consider mounting on the transom? - for a small sailboat you want the
sensor as far forward as possible.


With LED running lights, and a battery powered camping "lantern" down below, you
could probably go a whole season on a 100 AH AGM battery.



"Jim Thompson" wrote in message
...
On Wed, 04 Aug 2004 12:58:45 GMT, wrote:

For a 17 foot boat used as you describe, you don't need much of
anything. Buy a decent quality deep cycle (not dual purpose) 100 AH
battery, and don't worry about all that extra stuff. You don't need
it. Really. Your outboard will keep things topped up with little
trouble. Even your need for shore power is highly questionable. You
really don't have much of a load, there at all.

Thanks. How does one rig a Merc 5 HP 2-stroke to recharge the
battery? Is there simply a way to tap into its stator output?

Jim