Natural Speed - SailNet Community

   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 > Out There > Cruising & Liveaboard Forum > Living Aboard
 Not a Member? 


Reply
 
LinkBack Thread Tools
  #1  
Old 04-10-2008
Junior Member
 
Join Date: Feb 2008
Location: Warren Ohio
Posts: 24
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
SURV69 is on a distinguished road
Natural Speed

I read an article in a boating book years ago about what was called a boat's "natural", speed . . . not to be confused with hull speed.

My boat, at the time had a "natural" speed of about 2+ knots.

If I remember right, the "natural" speed was a speed at which the boat could move with virtually no effort to keep it going once it reached this "natural" speed.

If I retire to a boat, as I hope to, I plan on using the idea of "natural" speed on excursions that will allow . . . hopefully saving a lot of fuel.

I have never been able to relocate this article, although I've been looking for years and was hoping someone here might know about this "natural" speed or the formula to determine it.

If I remember right the weight and beam pretty much determined the natural speed.
Reply With Quote Share with Facebook
  #2  
Old 04-10-2008
L02314564's Avatar
Itz That Eazy!!!
 
Join Date: Jul 2007
Location: NW Louisiana
Posts: 82
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
L02314564 is on a distinguished road
I googled "Natural Speed" and came upon a research paper that mentioned the formula. I can't paste the link because I dont have enough posts yet so I have included the quote. Hope this is what you are looking for.

Ed

"When talking about hull design it is important to consider the natural speed of a boat. The natural speed is simply the speed at which a boat will easily travel though the water without the use of excessive external forces. In order to assess the natural speed of a boat this equation is applied: take the square root of the waterline length which is the measure of the waterline on a boat. This formula will give the boats' natural speed in knots. To then convert nautical miles (knots) into miles per hour, multiply by the knots by 1.15. For example, a boat with a 25 ft water line will have a natural speed of 5 knots or 5.75mph. "

EDIT: hs.riverdale.k12.or.us/~hfinnert/exhib_04/bryang/paper/paper.html#naturalspeed
Reply With Quote Share with Facebook
  #3  
Old 04-10-2008
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,291
Thanks: 0
Thanked 9 Times in 9 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
Of course, that formula probably doesn't apply properly to multihulls, since most of the formulas are designed for monohulls only.
__________________
Sailingdog

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Share with Facebook
  #4  
Old 04-11-2008
Senior Member
 
Join Date: Jan 2007
Posts: 286
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
byrondv is on a distinguished road
Anyone else think the term "excessive external forces" is just a tad bit ambiguous?

Seems like it would be talking about an inflection point on a force to speed graph - but just before that we would be using less force...
Reply With Quote Share with Facebook
  #5  
Old 04-11-2008
Hunter
 
Join Date: Mar 2007
Location: Pensacola, FL
Posts: 20
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
SVSnap is on a distinguished road
Quote:
Originally Posted by byrondv View Post
Anyone else think the term "excessive external forces" is just a tad bit ambiguous?

Seems like it would be talking about an inflection point on a force to speed graph - but just before that we would be using less force...
Is it where force to speed becomes exponential vice linear??
__________________
Thanks!

Hunter
"Benvolere"
Catalina 30 Tall Rig
Alameda, CA
Reply With Quote Share with Facebook
  #6  
Old 04-11-2008
Senior Member
 
Join Date: Jan 2007
Posts: 286
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
byrondv is on a distinguished road
lol - good point. Guess I was reading it wrong
Reply With Quote Share with Facebook
  #7  
Old 04-11-2008
Senior Member
 
Join Date: Nov 2002
Location: New York
Posts: 5,399
Thanks: 0
Thanked 14 Times in 14 Posts
Rep Power: 14
bubb2 has a spectacular aura about bubb2 has a spectacular aura about bubb2 has a spectacular aura about
Natural speed, I never heard of this however every boat that I ever sailed had a "sweet spot." This would be be where everything fell in to place. One of the boats I am most familiar with has a water line of 25 feet. At 10 kts of wind I can get mid to high 5's of boat speed out of her. This works out very close to what the "formula" says it should be. To push the boat speed to the mid 6's I would need wind in the 15 kts range. That is a 50% increase in energy and only 15% increase in boat speed.

This holds true wither boat is under sail or power. For instance my boat burns a 1/4 gallon a hour of diesel at 5.2 kts, if i push it up to 6.5 kts i am burning 1/2 gallon a hour.

Other sailors I know refer to it as being in the "groove."

Last edited by bubb2; 04-11-2008 at 06:48 AM.
Reply With Quote Share with Facebook
  #8  
Old 04-11-2008
Senior Member
 
Join Date: Aug 2006
Location: wherever
Posts: 5,256
Thanks: 8
Thanked 17 Times in 16 Posts
Rep Power: 10
xort has a spectacular aura about xort has a spectacular aura about xort has a spectacular aura about
Quote:
Originally Posted by L02314564 View Post
I googled "Natural Speed" and came upon a research paper that mentioned the formula. I can't paste the link because I dont have enough posts yet so I have included the quote. Hope this is what you are looking for.

Ed

"When talking about hull design it is important to consider the natural speed of a boat. The natural speed is simply the speed at which a boat will easily travel though the water without the use of excessive external forces. In order to assess the natural speed of a boat this equation is applied: take the square root of the waterline length which is the measure of the waterline on a boat. This formula will give the boats' natural speed in knots. To then convert nautical miles (knots) into miles per hour, multiply by the knots by 1.15. For example, a boat with a 25 ft water line will have a natural speed of 5 knots or 5.75mph. "

EDIT: hs.riverdale.k12.or.us/~hfinnert/exhib_04/bryang/paper/paper.html#naturalspeed
How is this different than hull speed?
Reply With Quote Share with Facebook
  #9  
Old 04-11-2008
TrueBlue's Avatar
Señor Member
 
Join Date: Oct 2004
Location: Narragansett Bay
Posts: 4,853
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 12
TrueBlue is a jewel in the rough TrueBlue is a jewel in the rough TrueBlue is a jewel in the rough
Quote:
Natural Speed
. . . and I thought Surv69 was announcing a new source for "natural" adrenaline boosters - legal speed!

After all, his moniker suggests he's a Woodstock survivor. (g)
__________________
True Blue . . .
sold the Nauticat
Reply With Quote Share with Facebook
  #10  
Old 04-11-2008
hphoen's Avatar
"Nevis Nice"
 
Join Date: Apr 2003
Location: Virginia
Posts: 224
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 12
hphoen is on a distinguished road
Quote:
Originally Posted by bubb2 View Post
Natural speed, I never heard of this however every boat that I ever sailed had a "sweet spot." This would be be where everything fell in to place. One of the boats I am most familiar with has a water line of 25 feet. At 10 kts of wind I can get mid to high 5's of boat speed out of her. This works out very close to what the "formula" says it should be. To push the boat speed to the mid 6's I would need wind in the 15 kts range. That is a 50% increase in energy and only 15% increase in boat speed.

This holds true wither boat is under sail or power. For instance my boat burns a 1/4 gallon a hour of diesel at 5.2 kts, if i push it up to 6.5 kts i am burning 1/2 gallon a hour.

Other sailors I know refer to it as being in the "groove."
Bubb,

From 10 kts to 15 kts is a 125% increase in energy. Kinetic energy increases with the square of the windspeed. That would reinforce your point about fuel consumption, which you said doubles from 5.2 kts to 6.5 kts.
__________________
Hud
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Speed Week Redux Dan Dickison Racing Articles 0 09-27-2002 08:00 PM
The Need for Speed Dan Dickison Racing Articles 0 10-03-2001 08:00 PM
Speed Sailing Overview Dan Dickison Racing Articles 0 05-16-2001 08:00 PM
Hull Speed Demystified Steve Colgate Learning to Sail Articles 0 06-10-2000 08:00 PM
Hull Speed Demystified Steve Colgate Buying a Boat Articles 0 06-10-2000 08:00 PM


All times are GMT -4. The time now is 08:22 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