SailNet Community - View Single Post - HULL , BOAT SPEED
View Single Post
post #5 of Old 09-13-2001
wwilson
Chesapeake Sailor
 
wwilson's Avatar
 
Join Date: Jul 2000
Location: Herrington Harbor, MD
Posts: 579
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 16
 
HULL , BOAT SPEED

The calculation yields an approximation, but it should not be that far off. The more interesting of the two measurements you supply is the motoring in calm water example. That one precludes surfing or lengthening the effective LWL through angle of heel and thereby increasing theoretical speed. The first place to look is at the GPS measurement. Was there a favorable current running (tidal or river)? Remember GPS is measuring Speed Over Ground (SOG) not through the water which the calculation approximates. Also is the GPS measurement recent, i.e since GPS selective availability has been turned off (May 2000 I think)? Is your GPS a differential model using beacon or WAAS? The tighter geolocational accuracy of differential also yields more accurate velocity calculations.

wlw
wwilson is offline  
Quote Share with Facebook
 
 
For the best viewing experience please update your browser to Google Chrome