Where to keep the outboard gas can - Page 5 - SailNet Community
Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.

LinkBack Thread Tools
post #41 of 43 Old 04-21-2006
Join Date: Mar 2006
Location: subject to change
Posts: 1,264
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Kinda puts the rest of this discussion in perspective, I think.

Thanx for a tip I hope never to have to use ;-)
eryka is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
post #42 of 43 Old 04-22-2006
Telstar 28
sailingdog's Avatar
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 18 Times in 14 Posts
Rep Power: 16
a good defense...

Originally Posted by yachtvalhalla
Are you a cruising boat sailing in water infested by pirates as I have been doing for the past few years? If so you don't store the gas can .. you keep it in the scuppers near the cockpit with a flare gun handy. It's a plan to discourage boarders by opening the can, throwing it into the water in front of the pursuing boat and lighting it off with a flare.


While this may be an excellent defensive measure, or possibly an offensive measure if their boat is in the pool of gasoline at the time.... I won't say how many laws, international and US that it violates...
sailingdog is offline  
Quote Quick Reply Share with Facebook
post #43 of 43 Old 04-28-2006
Junior Member
HenkMeuzelaar's Avatar
Join Date: Feb 2004
Posts: 26
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Physico-chemical info

Throughout this interesting thread conflicting statements have been made with regard to the behavior of gases and vapors. Unfortunately, none of the posts seems to provide a fairly comprehensive picture. Of the top of my head; these are the fundamental mechanisms underlying the observed phenomena:

At low concentrations only the relative molecular weights of molecules in the gaseous state, whether representing permanent gases, vaporized liquids or sublimated solids, determine which gas/vapor is heavier or lighter. At high concentrations, however, nonideal behavior can occur if the gas/vapor molecules are "sticky" (e.g. because of polar groups) and start clustering to form "dimers", "trimers", etc. thereby multiplying their effective molecular weights by a factor 2, 3 or more.

The molecular weight of the two major air components nitrogen (~80%; MW=28) and oxygen (~20 %; MW=32) puts dry air in an average MW range somewhere between 29 and 30. Low concentrations of water vapor (MW=18) will lower that number whereas higher water concentrations may increase the effective average MW of air through the formation of dimers and larger molecular clusters. Of course, below the dewpoint temperature water vapor will tend to condense out again, & s.o. & s.f..

Normal gasolines contain only trace amounts of gases/vapors lighter than air; e.g. methane (mw=16) or ethane (MW=28) and are primarily composed of hydrocarbon molecules with anywhere between 4 and 10 carbon atoms plus small amounts of non-hydrocarbon additives and degradation products; probably putting the average molecular weights of gasoline vapors somewhere in the MW 80 - 120 range.

So in completely still air gasoline vapors will tend to sink to the bottom of any airfilled containers, lockers, cockpits or cabins. In practice, however, most open spaces aboard an operating vessel will have significant air movements because of mechanical disturbances (people moving, doors opening, fans running) or convective air movements induced by temperature (and thus density) differences. This is the reason we can often smell gasoline and other relatively heavy chemical vapors , even though we are not direcly sniffing along the ground.

For the same reason convective air flows and other types of air currents can easily bring so-called lighter-than-air gases such as methane or even hydrogen down into open cabins or near open galley flames, even if originally released well above such danger points.

Flying Dutchman

Last edited by HenkMeuzelaar; 04-29-2006 at 01:55 PM.
HenkMeuzelaar is offline  
Quote Quick Reply Share with Facebook

Quick Reply

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

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:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


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.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Forum Replies Last Post
Outboard motor controls waltzingmatilda Gear & Maintenance 3 05-05-2010 09:08 AM
Outboard: Buying, Type & Fitting omega001 Gear & Maintenance 11 11-10-2006 10:09 AM
Dingy Outboard Motor rclampitt Cruising & Liveaboard Forum 0 01-10-2003 06:38 PM
Permanent gas line fittings for outboard? BallastBoy Gear & Maintenance 2 04-08-2002 04:26 PM
Help with Mariner Outboard kokerj Gear & Maintenance 0 04-02-2001 12:28 PM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome