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Re: T&T: Vecter Charts and Rocks - Coastal Explorer

RR
Ron Rogers
Tue, Feb 7, 2006 4:34 AM

Using CE's TerraServer aerial photo option, I zoomed in on Ram Island, ME
and believe that I am seeing all the rocks to which Jeffrey has been
referring. Jeff, could you check this observation? One of the rocks is
subtle and is better seen from a slightly higher elevation owing to
resolution issues.

A pretty neat temporary fix until NOAA releases the missing chart. I need to
make a CYA cautionary statement. There is no way for the user to know for
sure what the state of the tide was when the photo was taken so high tide
will make many rocks invisible (local knowledge would permit an intelligent
estimate. IMHO, the photo was taken near slack as the rocks are visible, but
several are submerged. I see a total of 6 rocks above the East-West line
passing through the buoy on the South side of the island.

Ron Rogers

Using CE's TerraServer aerial photo option, I zoomed in on Ram Island, ME and believe that I am seeing all the rocks to which Jeffrey has been referring. Jeff, could you check this observation? One of the rocks is subtle and is better seen from a slightly higher elevation owing to resolution issues. A pretty neat temporary fix until NOAA releases the missing chart. I need to make a CYA cautionary statement. There is no way for the user to know for sure what the state of the tide was when the photo was taken so high tide will make many rocks invisible (local knowledge would permit an intelligent estimate. IMHO, the photo was taken near slack as the rocks are visible, but several are submerged. I see a total of 6 rocks above the East-West line passing through the buoy on the South side of the island. Ron Rogers
JS
Jeffrey Siegel
Tue, Feb 7, 2006 1:50 PM

Using CE's TerraServer aerial photo option, I zoomed in on
Ram Island, ME and believe that I am seeing all the rocks to
which Jeffrey has been referring. Jeff, could you check this
observation? One of the rocks is subtle and is better seen
from a slightly higher elevation owing to resolution issues.

That's an interesting idea - I'd never tried it.  I compared a few satellite
images and it is amazing at how much difference there is.  Google Earth (the
free stand-alone software version) definitely shows the rocks although I
wouldn't want to navigate with the sloppy image that they have of the area.
virtualearth.msn.com definitely does not show the rocks.  The images on
virtualearth must have been taken at a calm, high tide time.

I put up a page showing 5 different samples of the area:
http://www.activemap.com/ramisland.htm

As reported on Panbo last week, the NauticPath charts show 12' in the area
of the rocks and don't display any rocks.  They probably got their data from
the USGS map after looking at all of these.

The rock that is especially bad is the one that is between the 45' and 33'
soundings on the NOAA chart.  That one is uncovered by 2' on a normal low
tide.  With 10' tides it means that for half of the day, there isn't 3' of
water above it.  Boats regularly slam into it.

The only safe ways to transit the area are:

  1. South of the rock.  It feels like you are very close (too close) to the
    shore but there is more than 30 feet of water along the area.  The land
    falls off very sharply although it always feels uncomfortable going through
    there because you end up very close to land.

  2. North through the 11' sy area.  This is also uncomfortable because the
    rocks on both side are charted but unmarked and there isn't a lot of room to
    navigate between them.

I've only gone through #2 with a small Whaler or when the rocks were
visible.  GPS error tolerance isn't good enough to do it with electronics.
With #1, you just stay close to land so you don't need a GPS.  I've gone
through that way many times.

There are safe ways to get to both sides of this area without tempting fate
and crossing these rocks.  The area north and northeast of Ram is a very
comfortable anchorage complete with sunning seals and a couple of bald eagle
pairs.

Nothing beats local knowledge...

================
Jeffrey Siegel
M/V aCappella
DeFever 53PH
W1ACA/WDB4350
Castine, Maine

> Using CE's TerraServer aerial photo option, I zoomed in on > Ram Island, ME and believe that I am seeing all the rocks to > which Jeffrey has been referring. Jeff, could you check this > observation? One of the rocks is subtle and is better seen > from a slightly higher elevation owing to resolution issues. > That's an interesting idea - I'd never tried it. I compared a few satellite images and it is amazing at how much difference there is. Google Earth (the free stand-alone software version) definitely shows the rocks although I wouldn't want to navigate with the sloppy image that they have of the area. virtualearth.msn.com definitely does not show the rocks. The images on virtualearth must have been taken at a calm, high tide time. I put up a page showing 5 different samples of the area: http://www.activemap.com/ramisland.htm As reported on Panbo last week, the NauticPath charts show 12' in the area of the rocks and don't display any rocks. They probably got their data from the USGS map after looking at all of these. The rock that is especially bad is the one that is between the 45' and 33' soundings on the NOAA chart. That one is uncovered by 2' on a normal low tide. With 10' tides it means that for half of the day, there isn't 3' of water above it. Boats regularly slam into it. The only safe ways to transit the area are: 1. South of the rock. It feels like you are very close (too close) to the shore but there is more than 30 feet of water along the area. The land falls off very sharply although it always feels uncomfortable going through there because you end up very close to land. 2. North through the 11' sy area. This is also uncomfortable because the rocks on both side are charted but unmarked and there isn't a lot of room to navigate between them. I've only gone through #2 with a small Whaler or when the rocks were visible. GPS error tolerance isn't good enough to do it with electronics. With #1, you just stay close to land so you don't need a GPS. I've gone through that way many times. There are safe ways to get to both sides of this area without tempting fate and crossing these rocks. The area north and northeast of Ram is a very comfortable anchorage complete with sunning seals and a couple of bald eagle pairs. Nothing beats local knowledge... ================ Jeffrey Siegel M/V aCappella DeFever 53PH W1ACA/WDB4350 Castine, Maine