I am installing a Lewmar Horizon 600/900 horizontal windlass on a 27
foot power boat. The users manual says to use #4 AWG marine grade wire
from the battery to the solenoid to the breaker to the windlass and
back to the battery. The wire leads on the windlass are #10 AWG.

I know the concern here is with voltage drop to the motor but the cost
of the #4 wire is huge. Rather than following the general guidlines in
the manual does anyone have a better way of calculating exactly what
gauge wire would be needed for this installation?

The total run from the battery to the windlass and return is 72 feet.

Don

Wire size is a function of amp load and distance. The #10 leads on the
windlass are only about 2' long so they can carry 50 amps with a voltage
drop of only 2%.

With 50 amps on a 72' run #4 is the absolute minimum size you should use.
Even then including the windlass leads you will be close to 10% voltage
drop. Using #8 you would loose more than 20%.

How are you routing the wire to use up 72' on a 27' boat?

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Don Mahony" wrote in message
...
I am installing a Lewmar Horizon 600/900 horizontal windlass on a 27
foot power boat. The users manual says to use #4 AWG marine grade wire
from the battery to the solenoid to the breaker to the windlass and
back to the battery. The wire leads on the windlass are #10 AWG.

I know the concern here is with voltage drop to the motor but the cost
of the #4 wire is huge. Rather than following the general guidlines in
the manual does anyone have a better way of calculating exactly what
gauge wire would be needed for this installation?

The total run from the battery to the windlass and return is 72 feet.

Don

Don Mahony wrote:
I am installing a Lewmar Horizon 600/900 horizontal windlass on a 27
foot power boat. The users manual says to use #4 AWG marine grade wire
from the battery to the solenoid to the breaker to the windlass and
back to the battery. The wire leads on the windlass are #10 AWG.

I know the concern here is with voltage drop to the motor but the cost
of the #4 wire is huge. Rather than following the general guidlines in
the manual does anyone have a better way of calculating exactly what
gauge wire would be needed for this installation?

The total run from the battery to the windlass and return is 72 feet.

Don

We got round this by using the engine starter battery and positioning it so
that it was as close to the windlass as possible (up forward) but still had
enough power to operate the starter. Easy on a 50-footer, but I don't know
about your 27-footer (storage space for the battery).

Dennis Pogson wrote:
Don Mahony wrote:
I am installing a Lewmar Horizon 600/900 horizontal windlass on a 27
foot power boat. The users manual says to use #4 AWG marine grade wire
from the battery to the solenoid to the breaker to the windlass and
back to the battery. The wire leads on the windlass are #10 AWG.

I know the concern here is with voltage drop to the motor but the cost
of the #4 wire is huge. Rather than following the general guidlines in
the manual does anyone have a better way of calculating exactly what
gauge wire would be needed for this installation?

The total run from the battery to the windlass and return is 72 feet.

Don

We got round this by using the engine starter battery and positioning it so
that it was as close to the windlass as possible (up forward) but still had
enough power to operate the starter. Easy on a 50-footer, but I don't know
about your 27-footer (storage space for the battery).



As a variation on Dennis' approach, some
folks will place a relatively small,
dedicated battery near the windlass. A
battery that will supply 50 A for a
minute or two need not be very large.

Voltage drop is all but eliminated. This
battery can be connected to your regular
(starter or preferably, house) battery
using wire as small as number 16, since
it will generally carry only small
currents needed to restore energy lost
by use of the windlass. Routing is
certainly easier.

May not make sense in a particular
installation, but can be less expensive
in others.

Good luck.

Chuck

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Don Mahony wrote in
:

The total run from the battery to the windlass and return is 72 feet.



Precisely why the wire is #4 for the long run. #10 is fine for very short
distances, like inside the windlass.

Shhh....don't tell anyone I told you this....#4 wire from the car stereo
shop, or even #2, is LOTS cheaper and works just great!

400% profit doesn't make it work better....(c;

Also try welding cables, which come in these smaller sizes #2 and #4.

Tell your yachtie friends you only used the most expensive "marine grade"
wire from the finest chandlers on the planet....so they don't snub you on
the dock.

Thanks for the reply Glenn.

The batteries are on the port side down in the engine compartment. To
come from there to where the breaker and control relay is located is
15 feet. From the breaker I have to go back down to the bottom of the
boat and gradually up to the bow where the windlass is located. :-(

I wonder if it is possible to run the chain from the bow through the
cabin and mount the windlass at the battery? Just Kidding! :-)

Don

On Mon, 19 Jun 2006 06:52:31 -0400, "Glenn Ashmore"
wrote:

Wire size is a function of amp load and distance. The #10 leads on the
windlass are only about 2' long so they can carry 50 amps with a voltage
drop of only 2%.

With 50 amps on a 72' run #4 is the absolute minimum size you should use.
Even then including the windlass leads you will be close to 10% voltage
drop. Using #8 you would loose more than 20%.

How are you routing the wire to use up 72' on a 27' boat?

Sorry, but this option is not possible with our configuration.

Don

On Mon, 19 Jun 2006 12:10:54 GMT, "Dennis Pogson"
wrote:

Don Mahony wrote:
I am installing a Lewmar Horizon 600/900 horizontal windlass on a 27
foot power boat. The users manual says to use #4 AWG marine grade wire
from the battery to the solenoid to the breaker to the windlass and
back to the battery. The wire leads on the windlass are #10 AWG.

I know the concern here is with voltage drop to the motor but the cost
of the #4 wire is huge. Rather than following the general guidlines in
the manual does anyone have a better way of calculating exactly what
gauge wire would be needed for this installation?

The total run from the battery to the windlass and return is 72 feet.

Don

We got round this by using the engine starter battery and positioning it so
that it was as close to the windlass as possible (up forward) but still had
enough power to operate the starter. Easy on a 50-footer, but I don't know
about your 27-footer (storage space for the battery).

I was considering this option as the price is a lot lower than marine
grade and my son is in the car sudio business. Have you or anyone else
actually used this wire in this application?

Don

On Mon, 19 Jun 2006 13:54:38 -0400, Larry wrote:

Don Mahony wrote in
:

The total run from the battery to the windlass and return is 72 feet.



Precisely why the wire is #4 for the long run. #10 is fine for very short
distances, like inside the windlass.

Shhh....don't tell anyone I told you this....#4 wire from the car stereo
shop, or even #2, is LOTS cheaper and works just great!

400% profit doesn't make it work better....(c;

Also try welding cables, which come in these smaller sizes #2 and #4.

Tell your yachtie friends you only used the most expensive "marine grade"
wire from the finest chandlers on the planet....so they don't snub you on
the dock.

Don Mahony wrote:
I was considering this option as the price is a lot lower than marine
grade and my son is in the car sudio business. Have you or anyone else
actually used this wire in this application?

Don

On Mon, 19 Jun 2006 13:54:38 -0400, Larry wrote:

Don Mahony wrote in
:

The total run from the battery to the windlass and return is 72 feet.


Precisely why the wire is #4 for the long run. #10 is fine for very short
distances, like inside the windlass.

Shhh....don't tell anyone I told you this....#4 wire from the car stereo
shop, or even #2, is LOTS cheaper and works just great!

400% profit doesn't make it work better....(c;

Also try welding cables, which come in these smaller sizes #2 and #4.

Tell your yachtie friends you only used the most expensive "marine grade"
wire from the finest chandlers on the planet....so they don't snub you on
the dock.

As conductors, marine grade and
non-marine grade wires are generally
indistinguishable. Some of the
differences are temperature rating,
flexibility (i.e., number of strands),
type of insulation (e.g., imperviousness
to chemicals such as gasoline and diesel
fuels), and most importantly, tin
plating. Marine wire is tin plated
because it is widely thought that it is
less corrosive in a marine environment
than unplated copper wire.

I have not yet encountered a judgment
that unplated wire is better. You might
want to do a search on Google Groups on
the subject. The issue has been
discussed before.

Can't say anything about speaker cable,
but I believe some automotive cables are
tin plated. They still don't match
marine wire specs but some boaters have
been satisfied with them.

Chuck

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Glenn Ashmore wrote:
Wire size is a function of amp load and distance. The #10 leads on the
windlass are only about 2' long so they can carry 50 amps with a voltage
drop of only 2%.

With 50 amps on a 72' run #4 is the absolute minimum size you should use.
Even then including the windlass leads you will be close to 10% voltage
drop. Using #8 you would loose more than 20%.

How are you routing the wire to use up 72' on a 27' boat?


It may be useful to put some reference
points into the analysis.

With a 20% reduction in voltage, a DC
motor would probably see a 20% reduction
in torque, a 20% reduction in rotational
speed, and a 44% reduction in power.

If the expected load is still met with
these reductions, there should be no
problem. The motor will not be damaged
by running at a 20% reduction in
voltage, but the wires may not be too happy.

It is also worth keeping in mind that 50
amperes is only going to be drawn when
the motor is producing its maximum power
output. This should be a relatively
short-duration situation, particularly
since must of us use swells to break an
anchor loose rather than windlasses.

Just stirring the coals.

Chuck

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