Reply
 
Thread Tools Display Modes
 
Old 03-21-2015, 10:12 PM   #21
Guru
 
Capt.Bill11's Avatar
 
City: Sarasota/Ft. Lauderdale
Country: USA
Join Date: Apr 2014
Posts: 5,422
Quote:
Originally Posted by twistedtree View Post
I beg to differ. Our Grand Banks was a planing hull and definitely benefited when on plane.
Your on plane speed is not the same as a SF running 30+ knots.
__________________
Advertisement

Capt.Bill11 is offline   Reply With Quote
Old 03-21-2015, 11:11 PM   #22
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 3,187
Quote:
Originally Posted by Capt.Bill11 View Post
Your on plane speed is not the same as a SF running 30+ knots.
No, 20 kts.

The trade-off, as I understand it, is that to optimize for lower speed you would use larger fins to gain more lift. But at higher speeds, those larger fins mean greater drag.

To optimize for higher speed you would use smaller fins to reduce drag. Getting enough lift at speed is not an issue - the fins move very little compared to slower speeds. But at lower speed the smaller fins will reduce effectiveness.

So you can have both, but you still need to decide what tradeoffs you are going to make. I went with larger fins for effective stabilization at 6-10 kts, and accepted the greater drag at 20kts. But the impact on top speed was negligible - maybe 1/2 kt.

Re Andy's point, on boats that have a larger speed range, ABT fits a shaft speed sensor so the system knows how fast you are going, and it automatically adjusts accordingly. No tuning is required. My Nordhavn has the speed sensor too, though it's not as important to have as on a faster boat.
__________________

__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





All times are GMT -5. The time now is 09:11 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012