How dry is too dry? - Page 3 - SailNet Community
Reply
 
LinkBack Thread Tools
post #21 of 24 Old 10-11-2008
baDumbumbum
 
bobmcgov's Avatar
 
Join Date: Jul 2007
Location: Windy Wyoming
Posts: 1,126
Thanks: 0
Thanked 36 Times in 35 Posts
Rep Power: 9
 
Quote:
Originally Posted by Stillraining View Post
isn't there is a huge storage facility for aircraft in the desert where the humidity stays around 10 %? also in furniture building you want your wood well below that level even so I fail to see how this would hurt a thing..Ill gander a guess that the wood used in boat construction is below 7% moisture content..IMHO
Uh ... ambient relative humidity is different from MC of interior woodwork. Which is measured as percentage by weight. All that cellulose to deal with, you know. Hardwoods are air-dried from 25-35% MC (full saturation) to around 15-18%; often (tho not always) they are then kiln-dried to 6-8% MC. That drives off all the free and some of the bound water. Here in the desert, it stays there more or less year round; in damper climates, wood will creep back up toward 15%. In difficult climates, like Michigan or West Texas, MC of interior woodwork will fluctuate between 6 and 12% on a six month sine wave, driven by but lagging a few months behind ambient humidity. That's a real bastard to cope with. That's the sort of long-period, large amplitude swing I'm warning Faster to avoid.

Certain woods, like mahoganies (true and Phillipine), don't much care. They have low absolute movement and low T/R ratios (tangential to radial movement). Other woods like maple or beech are high in both and are likely to distort if subjected to large changes in ambient humidity. Wood-veneered panel products can be exceptionally damage prone, as the veneer is thin and highly stressed during the manufacturing process; it is then bonded with inelastic glue (typically urea resin) to a core that may have very different movement properties. The result of multiple large moisture cycles can be severe surface checking or even failure of the glue bond.

Upshot: stability of the environment is more important than damp vs dry climate. Actually, the very finest woodworking belongs to Japan, in part because it is cool and damp there year round. Highly conducive to fine assemblies using air-dried woods.

Buccaneer18, Grainnia
SJ21, Diarmuid
Albin Ballad 30, Fionn
bobmcgov is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #22 of 24 Old 10-11-2008
Handsome devil
 
Stillraining's Avatar
 
Join Date: Jan 2008
Location: LaConner,Washington
Posts: 3,477
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 10
     
Thanks for the lesson..
Stillraining is offline  
Quote Quick Reply Share with Facebook
post #23 of 24 Old 10-13-2008
Senior Member
 
Join Date: Mar 2008
Posts: 890
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 8
 
Quote:
Originally Posted by anthony11 View Post
I recently saw a boat for sale that included two units kinda like this:



It was the driest boat I've ever seen, no musty smell, the bilge was spotless and looked like it'd never seen a drop of water in 23 years. Now that I've seen the apparent results, I wonder why everyone with shore power doesn't use one.
I used to build a product for the greenhouse industry with a keyboard on it. Greenhouses are extemely humid, and our machines did the watering! We sealed up our keyboard really well. To test them we put them in bucket of water with a brick holding htem down for a week. They'd come out completely dry. Put them in the greenhouse and aftera month they'd have a couple of ounces of water in the them and everything was badly corroded! Up on the machine itself was an electrical enclosure that was ws nothing more than a fiberglass tote turned upside down, no gaskets at all around the bottom edge. No water, no corrosion EVER, even after years in the same enviroment that killed a half dozen attached keyboards. We finally figured it out.

At night the greenhouse gets cool and real damp. The sealed keyboard breathes in through the strands of wiring in the cable attaching it to the other electrical enclosure. It condenses in the cool keyboard enclosure, because there is no heat generated by only switches. When it warms up during the day the condensed water doesn't get pushed out. Over a month you collect a lot of water. the other enclosure has power supplies in it. Thermocouples inside and out recorded that it is always about 10 degrees warmer than ambient, night and day. The higher temperature keeps the moisture out at all times, and guarantees it won't condense.

The little unit you pictured is nothing more than a 90 watt heater, that will keep the boat warmer than the surrounding air even on a hot summer day, and especially at night. 90 watts is way less than a humidifier draws, and it will work just about as well, as you found out.
GaryHLucas is offline  
Quote Quick Reply Share with Facebook
post #24 of 24 Old 10-20-2008 Thread Starter
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,563
Thanks: 110
Thanked 317 Times in 302 Posts
Rep Power: 10
     
An update to this story.... we've been using this dehumidifier for a month or so now... yesterday we managed to get out for a bit after our mainsheet modifications and noticed that one of our sliding doors is suddenly about to fall out of it's upper track... normally the door is too tall to fall out on its own, of course. It seems to have shrunk that 1/8" or so.

I think we'll set it for its lowest setting for a while rather than constant duty.

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Faster is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

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:
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:
OR

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.




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
Dry Ice mman30 General Discussion (sailing related) 16 09-13-2008 01:10 AM
How to dry clothes at Sea? Traveling_Jim Cruising & Liveaboard Forum 12 04-22-2006 07:39 AM
dry rot repairs jsutor Gear & Maintenance 0 10-13-2004 03:41 AM
Using Dry Ice Sue & Larry Gear and Maintenance Articles 0 09-02-2001 08:00 PM
Discovering the Dry Tortugas Sue & Larry Cruising Articles 0 03-12-2000 07:00 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