SailNet Community - Reply to Topic

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation > How to tell how thick the fog is...
 Not a Member? 

Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


Thread: How to tell how thick the fog is... Reply to Thread
Title:
  

By choosing to post the reply below you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Message:
Trackback:
Send Trackbacks to (Separate multiple URLs with spaces) :
Post Icons
You may choose an icon for your message from the following list:
 

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Additional Options
Miscellaneous Options

Click here to view the posting rules you are bound to when clicking the
'Submit Reply' button below


Topic Review (Newest First)
09-24-2012 06:19 PM
Bene505
Re: How to tell how thick the fog is...

Quote:
Originally Posted by Maine Sail View Post
I often use my plotter cursor to a known object I can barely see..

Like here where we could almost make out this island if we looked closely. As you can see we are at about 411 feet away so roughly 400 feet of vis.

That also shows how good it is to have the radar overlay on top of the chart platter. Very nice.

Regards,
Brad
09-24-2012 06:11 PM
Maine Sail
Re: How to tell how thick the fog is...

I often use my plotter cursor to a known object I can barely see..

Like here where we could almost make out this island if we looked closely. As you can see we are at about 411 feet away so roughly 400 feet of vis.

09-24-2012 05:44 PM
jackdale
Re: How to tell how thick the fog is...

Once your in it look for land or a vessel that is just visible and then use your radar to measure the distance.

In my experience your depth perception goes all to heck in fog. And so can your sense of direction.

Current weather conditions on Wx often describe visibility. That is actually not that current.
09-24-2012 04:53 PM
Bene505
Re: How to tell how thick the fog is...

Quote:
Originally Posted by MedSailor View Post
Right now I'm reading SailNet and listening to the sound of fog horns from ships. In our area we often get morning, or all-day fog, especially in july-october.

I've had times where I can see a wall of fog, and I wonder what my visibility will be after I sail into it. Once I sail into it, I continue to be able to see a mile. I sail on and my visibility remains a mile.I've had other times where I've sailed into a wall of fog and my visibility was 1/8 mile and stayed that way.

Is there any way to tell what your visibility will be once you sail into "that fog bank over there"? Will it be 1 mile once your in it or pea soup?

MedSailor
You might want to try looking at the top edge of the fog bank as you approach it. You can see in the way the sky color/whiteness changes how much thickness of fog there is at different angles into the fog there. (I've never tried that, but when in the fog, I do look at the sky color straight up - and up at an angle - to determine the height of the fog bank. This as more for flying than for sailling.)

Regards,
Brad
09-24-2012 03:22 PM
AdrenalineJunkie
Re: How to tell how thick the fog is...

Another way to look at it, if you sail into fog at 6 knots and someone is coming at you at 6 knots from the opposite direction, you have about 30 seconds to see each other before you collide if visibility is 1/8 mile (15 miles in 60 minutes or 1/4 mile in one minute closing rate,) not to mention fog can be denser in one spot than another ie visibility could get worse before it gets better. Makes radar (and knowing how to use it) or staying out of the fog seem like a good idea IMHO. Barges and other large vessels often travel much faster than 6 knots and the bigger they are the larger the radar shadow they have in front of them.
09-24-2012 02:40 PM
MedSailor
Re: How to tell how thick the fog is...

Quote:
Originally Posted by treilley View Post
Tough one. Maybe contact boats in the fog via VHF. AIS could help here by identifying a boat in the area without having to call all boats.
Actually, I kind of cheated and did just that. I don't have AIS (though I realised that it would be helpful here) and I called boats that I "assumed" would be out there where I was trying to go.

First I tried "Vessel in the northern end of the Rosario strait" -- No reply.

Then, since there are about 5 ferries that all go through this one area I called "Washington state ferry in the vicinity of Thatcher Pass." --Instant reply and fog report.

Strictly speaking, not how you are supposed to use your VHF though, calling ghosts in the fog.

MedSailor
09-24-2012 02:32 PM
Tim R.
Re: How to tell how thick the fog is...

Tough one. Maybe contact boats in the fog via VHF. AIS could help here by identifying a boat in the area without having to call all boats.
09-24-2012 02:19 PM
MedSailor
How to tell how thick the fog is...

Right now I'm reading SailNet and listening to the sound of fog horns from ships. In our area we often get morning, or all-day fog, especially in july-october.

I've had times where I can see a wall of fog, and I wonder what my visibility will be after I sail into it. Once I sail into it, I continue to be able to see a mile. I sail on and my visibility remains a mile.I've had other times where I've sailed into a wall of fog and my visibility was 1/8 mile and stayed that way.

Is there any way to tell what your visibility will be once you sail into "that fog bank over there"? Will it be 1 mile once your in it or pea soup?

MedSailor

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


All times are GMT -4. The time now is 10:34 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.