wrote in message
...

On Jun 9, 8:06 pm, "Eisboch" wrote:

The Navigator had a Raytheon system on it that was calibrated for the
transducer location versus the actual hull depth.
It was accurate to 2.8 feet. Ask me why I know.

Eisboch

The simple guess would be that your boat needed 2.9? Good to see
you stop back in.. We have all been working very hard to keep it nice
while you were away...


Heh...

well, the boat drew 4.5', but with the programmed offset, I was good to
2'9". 2'8" meant I just went aground.

Eisboch

On Mon, 09 Jun 2008 19:50:06 -0400, RLM wrote:

On Mon, 09 Jun 2008 23:31:21 +0000, Short Wave Sportfishing wrote:

On Mon, 09 Jun 2008 11:04:13 -0400, wrote:


In a sailboat, the transducer would be mounted in the hull, above the
level of the top of the keel, so you would have 4-10 feet (depending
on how deep a keel you have) of water even with the keel scraping
bottom. Sounders usually have a "keel offset" setting to compensate
and tell you how much depth remains after the keel height is
subtracted.

I understand that - I'm not clear on the whole zero depth concept.

If the water's muddy and you can see the bottom that's the zero depth
concept or just use the acronym ZDC.

The sounder is the noise the hull makes scrapping in the mud.

That's kind of my point. Zero depth implies no water. If there is no
water, why do you need a depth finder?

On Jun 9, 8:26 pm, "Eisboch" wrote:
wrote in message

...

On Jun 9, 8:06 pm, "Eisboch" wrote:



The Navigator had a Raytheon system on it that was calibrated for the
transducer location versus the actual hull depth.
It was accurate to 2.8 feet. Ask me why I know.

Eisboch

The simple guess would be that your boat needed 2.9? Good to see
you stop back in.. We have all been working very hard to keep it nice
while you were away...

Heh...

well, the boat drew 4.5', but with the programmed offset, I was good to
2'9". 2'8" meant I just went aground.

Eisboch

ROTF!

On Mon, 09 Jun 08, Larry wrote:
What I always thought we needed was a sort of underwater "curb feeler"
like we used to put on the pimpmobiles.

On a sailboat, that's called a centerboard or swing keel.

Rick

On Mon, 09 Jun 08, gfretwell wrote:
Hard to beat a piece of PVC pipe in shallow water. Drill holes in it
calibrated to the top rail or gunwale so you can use it at night.
One hole 1 ft under the keel, 2 holes 2' below the keel ...

A paddle or an oar works too. And you can mark 'em if you'd like. Or
use the dipstick method: Dip, bring back aboard, stand it on deck and
see how high the wet part is, air dry, repeat ;-)

Rick

lid wrote in news:cior44h1c8m8672ml387rb0cm33rjkqb3h@
4ax.com:

On a sailboat, that's called a centerboard or swing keel.

Rick



On many sailboats, it's called the FIXED KEEL. It's our big curb feeler...
(c;

On Mon, 09 Jun 2008 14:55:54 GMT, Short Wave Sportfishing
wrote:

Now, with respect to zero depth performance - pardon my ignorance but
I'm curious why you would be running around in zero depth waters. Do
you have a deep draft sailboat or cruiser of some sort?

Measuring zero depth is relatively easy in a deep draft boat becuase
the transducer typically has more ping delay to work with, assuming it
is not mounted on the bottom of the keel. I find it much more
difficult in something like a dinghy that only draws maybe 10 inches.
I have trouble getting reliable measurements under 3 ft or so.

lid wrote:
On Mon, 09 Jun 08, gfretwell wrote:
Hard to beat a piece of PVC pipe in shallow water. Drill holes in it
calibrated to the top rail or gunwale so you can use it at night.
One hole 1 ft under the keel, 2 holes 2' below the keel ...

A paddle or an oar works too. And you can mark 'em if you'd like. Or
use the dipstick method: Dip, bring back aboard, stand it on deck and
see how high the wet part is, air dry, repeat ;-)

Rick


You boys don't have a lead weight on a length of marked rope so your
crew can call out soundings?

"HK" wrote in message
news
lid wrote:
On Mon, 09 Jun 08, gfretwell wrote:
Hard to beat a piece of PVC pipe in shallow water. Drill holes in it
calibrated to the top rail or gunwale so you can use it at night.
One hole 1 ft under the keel, 2 holes 2' below the keel ...

A paddle or an oar works too. And you can mark 'em if you'd like. Or
use the dipstick method: Dip, bring back aboard, stand it on deck and
see how high the wet part is, air dry, repeat ;-)

Rick


You boys don't have a lead weight on a length of marked rope so your crew
can call out soundings?



Can't get good help anymore!

On Mon, 09 Jun 08, gfretwell wrote:
Hard to beat a piece of PVC pipe in shallow water. Drill holes in it
calibrated to the top rail or gunwale so you can use it at night.
One hole 1 ft under the keel, 2 holes 2' below the keel ...

Phantman wrote:
A paddle or an oar works too. And you can mark 'em if you'd like. Or
use the dipstick method: Dip, bring back aboard, stand it on deck and
see how high the wet part is, air dry, repeat ;-)

HK wrote:
You boys don't have a lead weight on a length of marked rope so your
crew can call out soundings?

Actually, yes I've had one for as long as I can remember, stowed
conveniently where I might (or might not) be able to find it in the
bottom of some locker somewhere.. But the paddle dip method just seems
to happen when the situation arises (with a boathook as a close second
choice).

Rick