Hull Speed - Page 3 - 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 > General Interest > General Discussion (sailing related)
 Not a Member? 


Reply
 
LinkBack Thread Tools
  #21  
Old 07-04-2007
Junior Member
 
Join Date: Mar 2006
Location: San anselmo
Posts: 15
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
slyrss3 is on a distinguished road
The CCA boats have long overhangs. So as the boat approches hull speed it sinks further into the bow wave. As it does this, the overhangs are submerged, increasing the LWL even more.
Reply With Quote Share with Facebook
  #22  
Old 07-04-2007
RichH's Avatar
Senior Member
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 2,699
Thanks: 9
Thanked 57 Times in 51 Posts
Rep Power: 15
RichH will become famous soon enough
The CCA design was simply a 'ratings rule beater' and although the effective waterline (hull speed) did increase with boat speed, those large overhangs also produced a pronounced 'hobby-horse' motion when in waves ... which tend to slow down a boat.
Reply With Quote Share with Facebook
  #23  
Old 07-04-2007
.
 
Join Date: Nov 2006
Posts: 10,855
Thanks: 0
Thanked 3 Times in 2 Posts
Rep Power: 12
Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice Giulietta is just really nice
but man...are they beautifull....
Reply With Quote Share with Facebook
  #24  
Old 07-04-2007
Member
 
Join Date: Nov 2006
Location: Beacon, New York
Posts: 652
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
Tartan34C will become famous soon enough
The long ends of the CCA style of boat also adds buoyancy in the ends and flattens out the buttocks at the ends which helps to keep you from being pooped while running. Also another characteristic of the style is narrow beam with slack bilges and a curve of area that is more symmetrical forward and aft then modern boats. Makes for a gentle motion at sea and promotes easy steering. In fact a lot of CCA boats will self-steer while very few modern boats will do this for more then a few minuets at a time.
All the best,
Robert Gainer
Reply With Quote Share with Facebook
  #25  
Old 07-04-2007
tomaz_423's Avatar
Senior Member
 
Join Date: Feb 2006
Location: Slovenia
Posts: 410
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 9
tomaz_423 will become famous soon enough
There is more than one LWL for each boat.
Some manufacturers even publish "static" and "dynamic" LWL.
When you are sitting flat in the water you can probably see that the stern is not touching the watter - there is some overhang. When you move (motor for example to eliminate heel from experiment) you can notice, than the faster you go the deeper the stern sinks and higher the water rises - extending the water length. Add heel and it is a bit longer again. Also the formula is not accurate for all boats. The narrow stern boats should use a bit smaller factor as the narrow stern can not support the weight of the boat even before the wave is at the end of the boat, so the stern sinks.
The boats with relative wide sterns can use larger factor because even when the wave is almost at the end of the stern it can still support the weight of the boat.
The factor is some sort of average for traditional design boats.

Of course very light boats with large sail plan are powerful enough to climb over their bow wave and start planning (most hi.perf. racers like America cup boats or Giu's boats), but than that is no longer displacement sailing.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Beneteau Oceanis 473

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

full time cruising
Reply With Quote Share with Facebook
  #26  
Old 07-05-2007
CBinRI's Avatar
Senior Member
 
Join Date: May 2004
Posts: 912
Thanks: 1
Thanked 0 Times in 0 Posts
Rep Power: 11
CBinRI is on a distinguished road
It has been my experience that hull speed is really just a useful guideline. I have been able to average higher than hull speed on some trips.
Reply With Quote Share with Facebook
  #27  
Old 07-05-2007
CapnHand's Avatar
humble pie rat
 
Join Date: Nov 2006
Location: Location, Location
Posts: 867
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
CapnHand is on a distinguished road
So with fresh water being lower density than salt water, boats will float lower in fresh water. This gives them more water line. Will hull speed be greater in fresh water than in salt water?
Reply With Quote Share with Facebook
  #28  
Old 07-05-2007
RichH's Avatar
Senior Member
 
Join Date: Jul 2000
Location: Pennsylvania
Posts: 2,699
Thanks: 9
Thanked 57 Times in 51 Posts
Rep Power: 15
RichH will become famous soon enough
Not due to density but freshwater has a lower absolute viscosity (and lower surface tension) than seawater ... therefore faster in fresh water.
Reply With Quote Share with Facebook
  #29  
Old 07-06-2007
pigslo's Avatar
Senior Member
 
Join Date: Nov 2004
Posts: 804
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 10
pigslo is on a distinguished road
But if they sink further in the fresh water, they will have a lot more wetted surface and slow down.
pigslo
Reply With Quote Share with Facebook
  #30  
Old 07-06-2007
Here .. Pull this
 
Join Date: Jan 2007
Posts: 2,031
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
Sailormann will become famous soon enough
When you sail fast boats (like a CS) in salt water you have to be careful because the boat moves through the water so fast that the friction makes the water boil and vaporise leaving salt crystals on your hull that slow it down....
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
Hull speed and wide sterns Jeff_H Boat Review and Purchase Forum 24 11-21-2006 11:58 PM
Speed Week Redux Dan Dickison Racing Articles 0 09-27-2002 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 11:15 PM.

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