teach me about tunnel tabs...
06-07-2010, 02:37 PM
#1
Registered
Thread Starter
Join Date: Apr 2006
Location: Grand Lake (E-Dock Junior Varsity)
Posts: 3,017
Likes: 0
Received 2 Likes
on
2 Posts
teach me about tunnel tabs...
The boat Im considering has a tunnel tab on it and all the search function has revealed is negative reviews of them.
If everyone hates them so much, why do people add them on there and what is their purpose??
Are they a bandaid for porpoising or is it a cure for another problem?
I hear about how dangerous the boat can handle when the tab is down, so how do you run one?
Im a little lost on this. Ive heard that when the tab is down, it lifts the boat further out of the water and gets a higher top speed but the downfall of this is that you can't turn the boat with the tab down and if you forget to put the tab down after a run, it can cause a roll or nosedive.. Whats the mechanics behind this theory?
If everyone hates them so much, why do people add them on there and what is their purpose??
Are they a bandaid for porpoising or is it a cure for another problem?
I hear about how dangerous the boat can handle when the tab is down, so how do you run one?
Im a little lost on this. Ive heard that when the tab is down, it lifts the boat further out of the water and gets a higher top speed but the downfall of this is that you can't turn the boat with the tab down and if you forget to put the tab down after a run, it can cause a roll or nosedive.. Whats the mechanics behind this theory?
06-07-2010, 08:24 PM
#2
Registered
Join Date: Jul 2008
Location: lake charles LA
Posts: 387
Likes: 0
Received 0 Likes
on
0 Posts
We had a Motion and also a Spectre with a tab, never used them for the most part but would stop the 60-80 mph porpuse issue whe it was used. Hurt speed if it was down. Added stern lift if down.
My opinion only, it made for a small swim platform, about it
My opinion only, it made for a small swim platform, about it
06-07-2010, 11:51 PM
#3
Registered
Join Date: Oct 2009
Location: Madison, Wisconsin
Posts: 184
Likes: 0
Received 0 Likes
on
0 Posts
http://www.offshoreonly.com/forums/g...-porpoise.html
Here is a link that should help with understanding the dynamics of the catamaran design and a bit of info on tabs.
The quick explanation is the tab restricts the exit of the air collum and produces more lift and in turn less boat in the water= faster. the force is applied somewhat evenly throughout the tunnel. I cant answer for sure in regards to turning with a tab down but if you think about it this way, I need 50+ mph to "build an air rail" where it doesnt handle like crap. A tab should reduce this a little, making the low speed planning and turns nicer. A high speed tab down turn will more than likely be F&%$ wild! Very little boat in the water and turning=YEEEEEEEHAAAAAAAAAAA. But when have you ever had to crank it around at 70 or 80. OH dont forget about cross wind handling. I guess it would get blown around a bit more too.
DISCLAIMER! I do not have a tab on my boat, just logic and thoughts!
Here is a link that should help with understanding the dynamics of the catamaran design and a bit of info on tabs.
The quick explanation is the tab restricts the exit of the air collum and produces more lift and in turn less boat in the water= faster. the force is applied somewhat evenly throughout the tunnel. I cant answer for sure in regards to turning with a tab down but if you think about it this way, I need 50+ mph to "build an air rail" where it doesnt handle like crap. A tab should reduce this a little, making the low speed planning and turns nicer. A high speed tab down turn will more than likely be F&%$ wild! Very little boat in the water and turning=YEEEEEEEHAAAAAAAAAAA. But when have you ever had to crank it around at 70 or 80. OH dont forget about cross wind handling. I guess it would get blown around a bit more too.
DISCLAIMER! I do not have a tab on my boat, just logic and thoughts!
06-08-2010, 10:10 AM
#4
Registered
Thread Starter
Join Date: Apr 2006
Location: Grand Lake (E-Dock Junior Varsity)
Posts: 3,017
Likes: 0
Received 2 Likes
on
2 Posts
The tunnel tab on the boat Im looking at isn't a true tunnel tab, its actually two large bennett trim tabs spaced about 3" apart.. Not sure if that makes any difference at all...
06-08-2010, 12:14 PM
#5
Gold Member
Gold Member
Join Date: Jan 2007
Location: Tulsa, OK
Posts: 1,039
Likes: 0
Received 0 Likes
on
0 Posts
I drove a 36 Spectre that had a tunnel tab and with some negitive tab it actually picked up a couple of MPH due to compressing the air and creating more lift, and you could feel it, with that set up your talking about it will not compress the air, that boat must have a pretty good hop to it to throw on some bennetts. did you get rid of the Sunsation?
