Perversity in boats?
 

I've noticed something strange. I had suspected it for sometime but just
a little while ago my suspicion was confirmed. We had sailed to a small
island and moored in the only cove. Chart indicated no hazards, just
sand with small shell bottom. Dropped the anchor (Sarka) in about 4m of
water and laid out about 6:1 rode as per usual. The depth under the keel
indicated 5m. Went to bed. During the night I woke up with a strange
feeling of uncertainty. Perhaps the boat's motion had changed but
nothing obvious. Peering into the blackness, the loom against the stars
indicated we had not moved. Nevertheless, the feeling did not go away. I
flipped on the depth sounder and it read 4m but then started to chnage
-then 3.5 then 3.0 then 2.5 and that is when I reached for the engine
key. But it stopped rising at 2.3 and we need 1.8m. With little tide
left all would be well. As I watched it slowly increased again. I
deduced that we were ever so slowly swinging over an uncharted rock.
Intrigued I snorkeled out in the morning (Brrrrrr) and saw the rock. We
had laid just enough rode to place out keel right over the center of a
2-3 m wide rock platform with sand and deep water all around it.

Now why did we just end up over a rock? My suspicion is that boats seek
out rocks -is this possible? If so, why do boats seek them out?

Did I wake up because the small swell was accentuated as we swung over
the rock and I sensed it in my sleep?

Any similar experiences?

Cheers

Perversity in boats?
 

It's obvious you went over a seamount or a rock.

Just as helicopters and planes can go into ground effect you went into
shallow water effect.

Back when I was a bubblehead, one relied on this sense greatly.

BC

"Navigator" wrote in message
...
I've noticed something strange. I had suspected it for sometime but just
a little while ago my suspicion was confirmed. We had sailed to a small
island and moored in the only cove. Chart indicated no hazards, just
sand with small shell bottom. Dropped the anchor (Sarka) in about 4m of
water and laid out about 6:1 rode as per usual. The depth under the keel
indicated 5m. Went to bed. During the night I woke up with a strange
feeling of uncertainty. Perhaps the boat's motion had changed but
nothing obvious. Peering into the blackness, the loom against the stars
indicated we had not moved. Nevertheless, the feeling did not go away. I
flipped on the depth sounder and it read 4m but then started to chnage
-then 3.5 then 3.0 then 2.5 and that is when I reached for the engine
key. But it stopped rising at 2.3 and we need 1.8m. With little tide
left all would be well. As I watched it slowly increased again. I
deduced that we were ever so slowly swinging over an uncharted rock.
Intrigued I snorkeled out in the morning (Brrrrrr) and saw the rock. We
had laid just enough rode to place out keel right over the center of a
2-3 m wide rock platform with sand and deep water all around it.

Now why did we just end up over a rock? My suspicion is that boats seek
out rocks -is this possible? If so, why do boats seek them out?

Did I wake up because the small swell was accentuated as we swung over
the rock and I sensed it in my sleep?

Any similar experiences?

Cheers

Perversity in boats?
 

Fiberglass and wood boats are magnetically attracted to buoys, pilings,
and rocks.

--
"j" ganz @@
www.sailnow.com

"Navigator" wrote in message
...
I've noticed something strange. I had suspected it for sometime but just
a little while ago my suspicion was confirmed. We had sailed to a small
island and moored in the only cove. Chart indicated no hazards, just
sand with small shell bottom. Dropped the anchor (Sarka) in about 4m of
water and laid out about 6:1 rode as per usual. The depth under the keel
indicated 5m. Went to bed. During the night I woke up with a strange
feeling of uncertainty. Perhaps the boat's motion had changed but
nothing obvious. Peering into the blackness, the loom against the stars
indicated we had not moved. Nevertheless, the feeling did not go away. I
flipped on the depth sounder and it read 4m but then started to chnage
-then 3.5 then 3.0 then 2.5 and that is when I reached for the engine
key. But it stopped rising at 2.3 and we need 1.8m. With little tide
left all would be well. As I watched it slowly increased again. I
deduced that we were ever so slowly swinging over an uncharted rock.
Intrigued I snorkeled out in the morning (Brrrrrr) and saw the rock. We
had laid just enough rode to place out keel right over the center of a
2-3 m wide rock platform with sand and deep water all around it.

Now why did we just end up over a rock? My suspicion is that boats seek
out rocks -is this possible? If so, why do boats seek them out?

Did I wake up because the small swell was accentuated as we swung over
the rock and I sensed it in my sleep?

Any similar experiences?

Cheers

Perversity in boats?
 

Navigator wrote:
I've noticed something strange. I had suspected it for sometime but just
a little while ago my suspicion was confirmed. We had sailed to a small
island and moored in the only cove. Chart indicated no hazards, just
sand with small shell bottom. Dropped the anchor (Sarka) in about 4m of
water and laid out about 6:1 rode as per usual.

Is "sarka" a type of anchor? How much scope do you let out to set the
anchor?

.. The depth under the keel
indicated 5m. Went to bed. During the night I woke up with a strange
feeling of uncertainty. Perhaps the boat's motion had changed but
nothing obvious. Peering into the blackness, the loom against the stars
indicated we had not moved.

??? Dang you're good, doing celestial navigation to within a couple of
meters by eyeball through the port.

Why didn't you take a bearing, or better a transit, on some fixed
objects on shore? That way you can really tell for sure if you've moved
outside your swing circle.


... Nevertheless, the feeling did not go away. I
flipped on the depth sounder and it read 4m but then started to chnage
-then 3.5 then 3.0 then 2.5 and that is when I reached for the engine
key. But it stopped rising at 2.3 and we need 1.8m.

I thought you said your depth sounder indicated depth under the keel?

... With little tide
left all would be well. As I watched it slowly increased again. I
deduced that we were ever so slowly swinging over an uncharted rock.
Intrigued I snorkeled out in the morning (Brrrrrr) and saw the rock. We
had laid just enough rode to place out keel right over the center of a
2-3 m wide rock platform with sand and deep water all around it.

Now why did we just end up over a rock? My suspicion is that boats seek
out rocks -is this possible? If so, why do boats seek them out?

The Finagle Factor: perversity of the universe trends towards a maximum.

Same reason why boats sitting around a start line in no wind tend to
magnetically drift together.


Did I wake up because the small swell was accentuated as we swung over
the rock and I sensed it in my sleep?

It's possible.


Any similar experiences?

Mostly, I've awakened at some change that I *thought* meant we were
dragging, but turned out to be harmless. Or fishermen putt-putting by in
the wee hours. Most recently, I woke up about 2 minutes before the turn
of the tide when we were anchored in a channel and swinging to the
current. I watched the boat swing around and settle down peacefully,
dozed lightly in the pilothouse for about an hour waking up every few
minutes, then went back to bed when it was obvious that nothing was
going to happen. This kind of thing is a sailors instinct and almost
everybody who cruises much developes it in some degree.



OzOne wrote:
We seem to become ultra sensitive when hanging off a hook.

Alternately, I was tied alongside a jetty a few years back, dropped
off to sleep and woke to find that I was neatly tied off ON THE OTHER
SIDE of the jetty.
I asked a local about it and he said that fishing boats sometimes use
that wharf to unload. He had helped them quietly move us around the
end and onto the other side without waking us.

Those guys were slick all right. They must unload pretty quietly too!

No mean feat with a 46' yacht.

OK, now you're bragging...

Fresh Breezes- Doug King

Perversity in boats?
 

Actually, the rise and fall of water over a shallow plug or area does cause
a "suction" effect and will pull you toward it.

See for yourself, just watch the water over a shallowly submerged boarding
ladder, piling or rock. The structure truncates the wave structure
underneath the surface and only allows higher frequency components of the
wave to exist above the shallow, hence the faster waveforms in the water in
the decaying response waveform and the lower frequency components in the
forcing function. In other words, the water drains faster than it fills (or
has a different waveform) and a relative "vacuum" is formed.

BC


"Navigator" wrote in message
...
I've noticed something strange. I had suspected it for sometime but just
a little while ago my suspicion was confirmed. We had sailed to a small
island and moored in the only cove. Chart indicated no hazards, just
sand with small shell bottom. Dropped the anchor (Sarka) in about 4m of
water and laid out about 6:1 rode as per usual. The depth under the keel
indicated 5m. Went to bed. During the night I woke up with a strange
feeling of uncertainty. Perhaps the boat's motion had changed but
nothing obvious. Peering into the blackness, the loom against the stars
indicated we had not moved. Nevertheless, the feeling did not go away. I
flipped on the depth sounder and it read 4m but then started to chnage
-then 3.5 then 3.0 then 2.5 and that is when I reached for the engine
key. But it stopped rising at 2.3 and we need 1.8m. With little tide
left all would be well. As I watched it slowly increased again. I
deduced that we were ever so slowly swinging over an uncharted rock.
Intrigued I snorkeled out in the morning (Brrrrrr) and saw the rock. We
had laid just enough rode to place out keel right over the center of a
2-3 m wide rock platform with sand and deep water all around it.

Now why did we just end up over a rock? My suspicion is that boats seek
out rocks -is this possible? If so, why do boats seek them out?

Did I wake up because the small swell was accentuated as we swung over
the rock and I sensed it in my sleep?

Any similar experiences?

Cheers

Perversity in boats?
 

It's all explained he

http://www.soest.hawaii.edu/PubServi...fs/Eriksen.pdf

BC

Perversity in boats?
 

Rocks in your head, MC....actually, it was probably gravimetrical
changes...every time the boat wallowed over the rock, your center of gravity
changed and your inner perceptions, so finely tuned, registered the effect
and awakened you...this would not have happened to a lesser man, say...Doug?
But then, he probably doesn't have a propensity for finding every rock in
the ocean like you do....

--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

DSK wrote:

Navigator wrote:

I've noticed something strange. I had suspected it for sometime but
just a little while ago my suspicion was confirmed. We had sailed to a
small island and moored in the only cove. Chart indicated no hazards,
just sand with small shell bottom. Dropped the anchor (Sarka) in about
4m of water and laid out about 6:1 rode as per usual.


Is "sarka" a type of anchor?

Yes it is.

How much scope do you let out to set the
anchor?


Well, it depends on the depth. My rule is not less than 4:1. Often use
6:1 and if it's going to blow let out more still (combination rode).


.. The depth under the keel indicated 5m. Went to bed. During the
night I woke up with a strange feeling of uncertainty. Perhaps the
boat's motion had changed but nothing obvious. Peering into the
blackness, the loom against the stars indicated we had not moved.


??? Dang you're good, doing celestial navigation to within a couple of
meters by eyeball through the port.

Why didn't you take a bearing, or better a transit, on some fixed
objects on shore? That way you can really tell for sure if you've moved
outside your swing circle.


... Nevertheless, the feeling did not go away. I flipped on the depth
sounder and it read 4m but then started to chnage -then 3.5 then 3.0
then 2.5 and that is when I reached for the engine key. But it stopped
rising at 2.3 and we need 1.8m.


I thought you said your depth sounder indicated depth under the keel?


Typo -it's always reading depth under transducer.

Cheers

Perversity in boats?
 

Interesting idea. What if the wavelength is much longer than the
structure -does that have an effect?

Cheers

Bob Crantz wrote:

Actually, the rise and fall of water over a shallow plug or area does cause
a "suction" effect and will pull you toward it.

See for yourself, just watch the water over a shallowly submerged boarding
ladder, piling or rock. The structure truncates the wave structure
underneath the surface and only allows higher frequency components of the
wave to exist above the shallow, hence the faster waveforms in the water in
the decaying response waveform and the lower frequency components in the
forcing function. In other words, the water drains faster than it fills (or
has a different waveform) and a relative "vacuum" is formed.

BC

Perversity in boats?
 

katysails wrote:

Rocks in your head, MC....actually, it was probably gravimetrical
changes...every time the boat wallowed over the rock, your center of gravity
changed and your inner perceptions, so finely tuned, registered the effect
and awakened you...this would not have happened to a lesser man, say...Doug?
But then, he probably doesn't have a propensity for finding every rock in
the ocean like you do....

So are you saying I rock?

Cheers

Perversity in boats?
 

MC asked: So are you saying I rock?

I have no personal experince of that...do you?

--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

katysails wrote:

MC asked: So are you saying I rock?

I have no personal experince of that...do you?


Modesty prevents me admitting it.

Cheers

Perversity in boats?
 

MC claimed:
Modesty prevents me admitting it.

And where did this new found modesty come from?
--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

It always been one of my many qualities.

Cheers

katysails wrote:

MC claimed:
Modesty prevents me admitting it.

And where did this new found modesty come from?

I'm just too modest to admit to modesty.

Cheers

Perversity in boats?
 

MC explained:
I'm just too modest to admit to modesty.

And so humbly stated....
--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

MC explained:
I'm just too modest to admit to modesty.

katysails wrote:
And so humbly stated....

And not only that, he knows absolutely everything there is to know about
old frigates!

DSK

Perversity in boats?
 

DSK sniped.

Perversity in boats?
 

You've "humbled " the Nav???????


Bwahahahahahahahahahahahaaaaaa



CM

"katysails" wrote in message
...
| MC explained:
| I'm just too modest to admit to modesty.
|
| And so humbly stated....
| --
| katysails
| s/v Chanteuse
| Kirie Elite 32
| http://katysails.tripod.com
|
| "Women and cats will do as they please, and men and dogs should relax
| and get used to the idea." - Robert A. Heinlein
|
|

Perversity in boats?
 

Mooron asked in disbelief: You've "humbled " the Nav???????

MC always stands humbled in my presence....

--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

"katysails" wrote in message
...
| Mooron asked in disbelief: You've "humbled " the Nav???????
|
| MC always stands humbled in my presence....

Indeed!

:-D

CM

Perversity in boats?
 

Mooron exclaimed: Indeed!

:-D

Indeed!!!!!!

--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

I actually I prefer to lie down!

Cheers

katysails wrote:

Mooron asked in disbelief: You've "humbled " the Nav???????

MC always stands humbled in my presence....

Perversity in boats?
 

MC admitted:
I actually I prefer to lie down!

Oh, my....now what am I to make of that??!?!?!
--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

"katysails" wrote in message
...
MC admitted:
I actually I prefer to lie down!

Oh, my....now what am I to make of that??!?!?!

Get a taller pedestal?

Seahag

Perversity in boats?
 

Haggie suggested: Get a taller pedestal?

No...a shorter one...that 7' piece of marble I've been standing on was
beginning to give me vertigo...will be much easier if he just lays down so I
can trade it in for a 3' model.....

--
katysails
s/v Chanteuse
Kirie Elite 32
http://katysails.tripod.com

"Women and cats will do as they please, and men and dogs should relax
and get used to the idea." - Robert A. Heinlein

Perversity in boats?
 

"katysails" wrote in message
...
| Haggie suggested: Get a taller pedestal?
|
| No...a shorter one...that 7' piece of marble I've been standing on was
| beginning to give me vertigo...will be much easier if he just lays down so
I
| can trade it in for a 3' model.....

WHY????

You could stand barefoot in the sand and have him smothered in granules of
penance! ;-)

CM