Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 18-08-2013, 14:20   #301
cat herder, extreme blacksheep
 
zeehag's Avatar

Cruisers Forum Supporter

Join Date: Jul 2008
Location: furycame alley , tropics, mexico for now
Boat: 1976 FORMOSA yankee clipper 41
Posts: 17,770
Images: 56
Send a message via Yahoo to zeehag Send a message via Skype™ to zeehag
Re: Keeping Watch at Night ?

the actual 10 min lead was a true 4 hour lead..lol during which there are flukey winds and all kinds of other warnings of doom. that is for severe tboomers.
how do i know--i was out in them for a year. timed them and saw what happens.

haystax bring slightly shorter warning, as is the strange extra big sea everyone calls a rogue--isnt a rogue--is a freeking warning sign. pay attention. means bigger seas are coming, and if you look towards direction from which the damn thing came, you WILL see haystax. the more immediate changes are more heard than seen. there are 15-30 min between cat making feline 500 on this boat and downpouring rain or blasting wind--both make ear pain for gatos, therefore warning is rowdy.
__________________

zeehag is offline   Reply With Quote
Old 18-08-2013, 14:41   #302
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Keeping Watch at Night ?

Mark I don't want to bore CF readers in an esoteric discussion of papers especially ones so old, but I think night illumination is important so I will address some of your conclusions. The rest of CF can skip the posts, there is no exam at the end .

Quote:
Originally Posted by colemj View Post
The second link was to a US Navy study that concluded that low intensity white light was superior to preserving night vision in submarines than red light at an equally useful intensity.
I don't agree with your above conclusion of the second paper. The official conclusion was:
There were no significant differences in the ability to see such targets after adaptation to red or white light.
They also stated:
Thus, although there is no question that maximum scotopic sensitivity can be shown to be better after adaptation to red than to
white light,

Lets look at the paper in more detail.

The test was conducted at relatively high levels of illumination with only 8 or 12 subjects depending on the experiment.

The experiments showed a superiority of red illumination not the other way around, but it was not statistically significant. (Not surprising given the small number of subjects and high luminance). The actual results were:

Experiment 1:
Red: 0.49
White: 0.46

Experiment 2:
Red: 0.125
White 0.111

Experiment 3:
Red: 31,195 yds
White 31,021 yds

I don't see anything to support your conclusions that white light is superior.

The third reference was I am sorry, just junk.

Statements like this show a complete lack of understand of the mechanisms behind red illumination.

"night-vision" could be preserved better by stimulating only *one* of the three photo-receptors (humans can see red, green, and blue, and have receptors for each of these three "primary" colors).
__________________

__________________
noelex 77 is offline   Reply With Quote
Old 18-08-2013, 15:03   #303
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 17,314
Re: Keeping Watch at Night ?

yeeeeees

Standing watch.

How about standing offshore. Well afoot eh?

Nonsense.

Sit some stand some, get the blood moving. Why lash.

b.
__________________
barnakiel is offline   Reply With Quote
Old 18-08-2013, 15:14   #304
Registered User
 
Wrong's Avatar

Join Date: Jul 2013
Posts: 1,702
Re: Keeping Watch at Night ?

Quote:
Originally Posted by barnakiel View Post
yeeeeees

Standing watch.

How about standing offshore. Well afoot eh?

Nonsense.

Sit some stand some, get the blood moving. Why lash.

b.
__________________
Wrong is offline   Reply With Quote
Old 18-08-2013, 15:18   #305
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by jackdale View Post

Agreed. Headlamps also free up both hands. I have stuck my small Maglite between my teeth, but that is not very effective.
Best things since sliced bread always wear is at night

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-08-2013, 15:22   #306
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: UK/Portugal
Posts: 20,203
Images: 2
Send a message via Skype™ to boatman61
pirate Re: Keeping Watch at Night ?

Sorry folks but all this bollocks about lights is getting silly... its dark.. no moon and I've been on deck a couple of hours and need a coffee... so I'll do a 360 scan... nip below and put the kettle on... need light to make sure the sugar and coffee don't go on my feet... 5 minutes maximum... shoot may even knock up a sarnie while the kettles boiling... back on deck and I can make out the horizon after 3 minutes... if there's a light on it somewhere... I'll find it even quicker.
As to newbie crew knowing their lights... parrot fashion repetition of memorised flash cards is one things... seeing the real thing and calculating the headings is something else... so newbie crew WILL get tested and cues if needed before they'll be trusted at night... I get totally pissed of with being woken 1/2 hour or so into a nice sleep coz some dickhead cant tell stars low on the horizon from a ship..
__________________


Born To Be Wild
boatman61 is offline   Reply With Quote
Old 18-08-2013, 15:29   #307
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by boatman61 View Post
Sorry folks but all this bollocks about lights is getting silly... its dark.. no moon and I've been on deck a couple of hours and need a coffee... so I'll do a 360 scan... nip below and put the kettle on... need light to make sure the sugar and coffee don't go on my feet... 5 minutes maximum... shoot may even knock up a sarnie while the kettles boiling... back on deck and I can make out the horizon after 3 minutes... if there's a light on it somewhere... I'll find it even quicker.
As to newbie crew knowing their lights... parrot fashion repetition of memorised flash cards is one things... seeing the real thing and calculating the headings is something else... so newbie crew WILL get tested and cues if needed before they'll be trusted at night... I get totally pissed of with being woken 1/2 hour or so into a nice sleep coz some dickhead cant tell stars low on the horizon from a ship..
+ 1. That's what happens in real life.

Always why I ask newbies to wake me.

I should say even my own posts can come across as absolutist. But I'm not like that. I modify everything depending on conditions and the known skill levels of the crew.

Recently did a delivery with two friends both of whom are very capable skippers. No standing orders , Sleep was blissful.

Dave .
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-08-2013, 15:40   #308
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,359
Re: Keeping Watch at Night ?

Quote:
Originally Posted by boatman61 View Post
Sorry folks but all this bollocks about lights is getting silly... its dark.. no moon and I've been on deck a couple of hours and need a coffee... so I'll do a 360 scan... nip below and put the kettle on... need light to make sure the sugar and coffee don't go on my feet... 5 minutes maximum... shoot may even knock up a sarnie while the kettles boiling... back on deck and I can make out the horizon after 3 minutes... if there's a light on it somewhere... I'll find it even quicker.
As to newbie crew knowing their lights... parrot fashion repetition of memorised flash cards is one things... seeing the real thing and calculating the headings is something else... so newbie crew WILL get tested and cues if needed before they'll be trusted at night... I get totally pissed of with being woken 1/2 hour or so into a nice sleep coz some dickhead cant tell stars low on the horizon from a ship..
Yep. It's amazing how lighting schemes start to make a lot of sense after you spend some time observing the real thing. A freighter starts as a dim speck... obscured most the time by seas. Then... yes it's a white light that's really there. Pretty soon you can see the taller steaming light in conjunction with the bow light... and suddenly you know which way he's going and can make adjustments as necessary....then you can finally see some color on that bow light.... pretty cool really...
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline   Reply With Quote
Old 18-08-2013, 15:50   #309
Registered User
 
Wrong's Avatar

Join Date: Jul 2013
Posts: 1,702
Re: Keeping Watch at Night ?

Quote:
Originally Posted by Cheechako View Post
Yep. It's amazing how lighting schemes start to make a lot of sense after you spend some time observing the real thing. A freighter starts as a dim speck... obscured most the time by seas. Then... yes it's a white light that's really there. Pretty soon you can see the taller steaming light in conjunction with the bow light... and suddenly you know which way he's going and can make adjustments as necessary....then you can finally see some color on that bow light.... pretty cool really...
If you can't see the 'city lights' from most ships before they are on the horizon, you have a problem.
__________________
Wrong is offline   Reply With Quote
Old 18-08-2013, 15:50   #310
Registered User

Join Date: Mar 2013
Boat: 45' CC ketch
Posts: 332
Re: Keeping Watch at Night ?

I was wondering is some sort of gimballed IR sensor with a proper controller/software, doing 360 degrees scan of the sea, would help detecting unlit boats. If it is unlit, does now show on radar, no AIS, then the only way to reliably detect it is a thermal signature. In the sea, any boat will have a different thermal sig from the water, and this can be used to alarm. It may even be not too much expensive, unless you use commercial FLIR stuff.
__________________
Sea Frog is offline   Reply With Quote
Old 18-08-2013, 16:09   #311
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by Wrong View Post

If you can't see the 'city lights' from most ships before they are on the horizon, you have a problem.
Dont get to sea much Wrong do we , most freight boats at night are not lit up like cities. Often there can be little deck lighting or usually accommodation block is at the rear with most of the lighting

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 18-08-2013, 16:27   #312
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: UK/Portugal
Posts: 20,203
Images: 2
Send a message via Skype™ to boatman61
pirate Re: Keeping Watch at Night ?

Quote:
Originally Posted by goboatingnow View Post
Dont get to sea much Wrong do we , most freight boats at night are not lit up like cities. Often there can be little deck lighting or usually accommodation block is at the rear with most of the lighting

Dave
Likely a Caribbean cruiser used to the 'Lobster Boats'...
Yo Mon... der be 5000 lobsters landed at South Beach....
__________________


Born To Be Wild
boatman61 is offline   Reply With Quote
Old 18-08-2013, 16:33   #313
Registered User
 
Wrong's Avatar

Join Date: Jul 2013
Posts: 1,702
Re: Keeping Watch at Night ?

Quote:
Originally Posted by goboatingnow View Post
Dont get to sea much Wrong do we , most freight boats at night are not lit up like cities. Often there can be little deck lighting or usually accommodation block is at the rear with most of the lighting

Dave
Even in the rare case when a ship may not throw so much light as to look like a city in the distance, I have never had trouble recognizing the white navigation lights on bow and stern far enough away to discern that first it is a ship and second direction of travel. Even in significant seas. What do you define as a "freight boat"?
__________________
Wrong is offline   Reply With Quote
Old 18-08-2013, 17:21   #314
D&D
Marine Service Provider
 
D&D's Avatar

Cruisers Forum Supporter

Join Date: Nov 2008
Location: Blue Mountains, Australia
Boat: now working Syd Harbour charters
Posts: 1,459
Re: Keeping Watch at Night ?

Quote:
Originally Posted by skipmac View Post
The problem with head lamps is that it is a natural reaction is to look directly at another person when you speak to them or they to you. With a head lamp you just blinded them.

Certainly handy when trying to work on something by yourself and you need both hands but not allowed on my boat for general use.
On most decent head lamps the angle of the lamp is adjustable...and, for most people (certainly the case here) the most useful angle is inclined down so as to be pointing to objects within arm's length in front. So it shouldn't always (or even often) shine into someone else's eyes.

Furthermore, for us nearly all night watch keeping is done solo, while the other 'crew' sleep. So for us there's very, very low risk of blinding anyone else.

Further still, if the head lamp is used on the red light (as it should be >90% of the time) it is significantly less blinding than the white light. We read (with interest, thanks! ) the articles and posts in this thread about 'the red myth', but it seems safe to suggest at least that a single red LED on a head lamp will have less impact on night vision than full white light from either the head lamp or a torch.

Finally and even accepting the risk of shining into someone else's eyes, that risk itself can be managed by the wearer of the head lamp simply taking care not to indulge the "natural reaction" and instead be always mindful of where your own lamp is pointed.

As already noted on this thread, head lamps are hugely handy tools. They are always there -- you never need to look for them when you need them -- and they leave both your hands completely free.

So for us, all weather head lamps are absolutely required wear for night watch keeping...and we keep spares.
__________________
D&D is offline   Reply With Quote
Old 18-08-2013, 17:25   #315
Registered User

Join Date: Nov 2007
Location: Probably in an anchorage or a boatyard..
Boat: Ebbtide 33' steel cutter
Posts: 3,537
Quote:
Originally Posted by jackdale View Post

How do you read at night without a light? I suppose a red headlamp might work.
Thinking about it I hardly ever do, very occasionally with red head torch but to be honest it doesn't work very well. I was wrong there.
__________________

__________________
conachair is online now   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 01:33.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.