Yea, you are right. I always 'assumed' it was MHHW, but the Pilot clearly
say MHW. It seems like MHHW would make more sense out here.
(sorry for the multiple posts earlier - Outrage acting up).

Paul
"otnmbrd" wrote in message
.net...
Coast Pilot 7, says MHW, unless otherwise stated.
You need to check your chart or Particular Coast Pilot, etc., if you
have any doubts ..... For instance, I believe the Mississippi river,
above a point will use "river stage".
If in doubt, G use the one that gives you the least clearance.

otn

Paul L wrote:
I think it's mean MHHW (Mean Higher High Water) on the Wesy coast, not
MHW.

Paul L

"Steve" wrote in message
...

Ok, now that I have had time to compare NOAA charts with the
reproductions
in the Maptech portfolio, I see that vertical clearance is from MHW
(mean
high water), as stated in the title block of each NOAA chart.

It seems Maptech 'washes out' the title block as they copy and crop the
charts for their book pages.

But, that still leaves me with the question: How do you calculate or

adjust

the stated Vertical Clearance when all you have is a chart and a tide
table.

In my example; The charts show a vertical clearance of Hood Canal
Bridge,
east span, as 55 ft and the tide table shows a height of 8 ft at the
time

I

want to pass under it. My mast height is 54' 7", including the VHF
antenna...

Do I need the NOAA tide tables or can this be calculated from the
usual,
locally reproduced, convience tables??

I realize, after the fact, that there would have been sufficient
clearance
yesterday, but there may well come a day when I arrive at the bridge at
something slightly higher than MHW.

Steve
s/v Good Intentions