Tunnel Tab?
 

I am looking for opinions on Tunnel tabs when used on 30 Spectre however all experiences are welcomed?
What are the different makes that will fit this application?
What is the down side to not having one?
Is a Tab necessary?
Are there Alteratives?
Approximate Price?

What nobody has an opinion?

I do know that there was a halfway decent thread on the...um...hot boat board. Look under cats.

I understand theres a New
Flex tab that make the
Re-Entry a lot smoother,
Best hope some of the Cat
Men can give you some Help
Mike J.

SOMEBODY HELP!!!!!!
 

I AM CURIOUS ABOUT THIS AS WELL...
HELP....HELP....HELP....HELP......HELP.....HELP:co nfused:

tab
 

I only have exp. with Skaters, 28' and 32' both (2) eng. outboard.
I see no reason to have a tunnel tab, or tabs at all. (2) of my friends both have 30' Spectre's, one a outboard, and the other one a Inboard. neither have tabs, and we have discussed this option many times, neither think their boats would benifit, I have run a 28' Skater with a Tunnel tab, and the added weight at the stern hurt the balance. These are just my thoughts, and I am not as expert on Spec. by any means, KenP has a 30' and he is the man to speak to.
Philip

How would the the weight throw the balance off? From my understanding most tunnel tabs use fixed turnbuckels. Maybe 10lbs each? :confused:

The flex tabs are really nice.

They are composite in design, cored with some kind of nomex felt encapsulated with either Kevlar or S-glass. They are flexure plates that behave much like a cantilevered beam with a point load near the end. The plate's don't hinge on a single point like most tabs and are do not act infinately rigid.

The plates curve and flex hyperbolically, giving way to a revolutionary way to create precise control surfaces with a more pronounced boundry layer that reduces shocks and improves the boundary layers....Great for 'intelligently' adjusting to pressure loads and changing angles of attack both hydrodynamically and aerodynamically.

We've done a lot of work on similar control surfaces on some up and coming military aircraft. The numbers prove the design.

I saw a few cats with these tabs in Daytona. I think they are working. ;)

I have a 30' Spectre I/O with the tab offered by the factory. I am glad I have it. It allows you to dial out any mid range porpoise you might experience with your boat. I run it completely up at top speed and completely up at low speed. If you want to go really slow (20MPH) and stay on plane-use the tab and you can.

Hope this helps.

Sonny

I need a tunnel tab for my Chris Cat to eliminate the porpoise that starts in the high 90's. Dueclaws had talked to George Linder the designer of the Chris Cat about this problem on his Cat on a post some time ago. George recomended the tab. Does anyone know if Duelaws has installed the tab on his cat and or, if it works well? The tab is supposed to add aft tunnel compression as the cat tries to balance out hydrodynamics/aerodynamics

The AO is slightly different that the Chris Cat but not sure of the exact specs but the Chris weighs a bit heavy to the AO. Also I am running #2 speedmasters with a Factory high X demension that makes the Chris run pretty flat until she packs some massive air.

Hey you guys,get a V ,only kidding cats rule !!!!!!! tripps

So are most of you guys thinking K-planes or a fixed tab?

Yep Baja is correct.
Flex tabs I know of are
Composit, And "well are being tested".
They can be adjusted both remote or Manual.
They prevent TRIP of the
Bow.
Mike J.

tunnel tab
 

tunnel tab from gc offshore

Above is a pic of tunnel tab from Keith Nunez's 30' Shadow Cat of Gulf Coast Offshore powerboat club.

Organ
 

The Arneson tabs Unfortunatley have not performed well on the Spectre. Sonney is correct, the center tab comes in handy if used with CAUTION!! a great many "roll overs" are caused by inproper use of the tab. In my opinion both you and Speed should consider stepping up to the plate on this option. Just listen carefully on how Jay instructs you to use it.

Maximus

Too Old, perhaps I is, perhaps I aint. ;) There's never a simple answer to such a complex question. :D ;)

In any event, a picture is said to be worth a thousand words...I just looked through all my Daytona pictures, but I was disappopinted to find that I didn't take any stern shots of these tabs.

I remember remarking "Hey, those are interesting tabs" to Dean about these exact flex tabs in question. I saw one actuate to about half-down and they do flex to a pronounced curved shape. I'm certain they work well in transitioning airflow and compressing it at the stern exit. From the way they felt, I'd imagine that they are more forgiving in an abrupt water impact...They will bend to absorb shock.

Hi:

Where is Rich Luhrs????? He and Puff the Magic Dragon are trying to find Little Jackie Paper.......... for Tunnel Tab advice, something about "painted wings and giant strings".....:p

IMO tunnel tabs should only be used by highly experienced cat drivers..........never in rough water (the will trip and stuff you in a heartbeat).....and VERRRRRY gradually. (slight adjustments make big corrections). Personally, I don't like most of the designs in that they begin at the transom, rather than up in the tunnel where the effect on c/g is greater.

Finally, these tabs are meant as tunnel compression adjusters only, not as water deflectors, so the light weight ones make the most sense.

T2x

Eliminator runs tunnel tabs on their race boats. I know Jerry May lurks on here all the time; maybe he will come out of the closet to help us on this issue (again). Come on Jerry – you can do it!

T2x and Philip, got a question for you two. I ran a lot faster with three bladed props (83mph vs. 77mph) before the blowers. But it was real difficult to get on plane. Think I could run bigger three bladed props with the blowers and add tabs for getting on plane?

Philip – did you read my thread about running into a guy out here last weekend that knows you? Guys name was Joe Aviara (sp?).

T2x – Puff the Magic Dragon? Dude, you are oldddd!!!!

Tunnel tabs? I would never consider using them, especially on a pleasure boat! Really just asking to hurt a good customer and his family and that is about all, and this also seems to me like a “band aid” so to speak for a poorly balanced or designed boat! If it needs a tab watch out

Parting thoughts on the flexible after plane. Now just how would you begin to calculate the Bending modulus, Flexure strength? Needed oh I know we pick a flipper from the shelf Wrong!! But let’s see we could develop a simple stress-strain curve using air! Worse case jersey air is heaver Joke BTW! But what happens when good ole water which is in the order of 800 times the mass hits our protruding “Flipper”?? Oops this could happen close to the mount bad very bad or at the tip it would make a big difference and then its Dive mask time with a windshield wiper? Quick answer here it doesn’t take a whole lot of force to trip a boat ! so it’s always better to have one that’s properly designed to begin with. Especially when talking Catamaran come on if the builder cannot balance or do the tunnel air pack work I would run!!
:) :)

Tunnel tabs, just asking for trouble.

I never used the tabs on my 36, they did not even work eventually took them off.

If the boats balanced right you dont need them.

Curtis

Flashback-
I never added the tunnel tabs to my Chris Cat. Keith Nunez (Hot Pursuit) thinks that they should be on the boat and he likes him on his Shadow, but I'm hesitant. You can contact me via email to discuss if you wish.

Tabs
 

I agree a well balanced boat is the best solution. but for an outboard boat in paticular with fuel tanks allready installed whats the options? My 30 motion with 300pro maxs does porpise at cruise speeds, more so on flat water. so I also am considering a tunnel tab. Does anybody know who is making that flex tab ? are they all custom made?

Proroc
 

Rolf at Proroc makes his own Tunnel Tabs and being a Spectre dealer, he might be a good person to talk with about this...

Steve 1

The application I am questioning would be for a pleasure boat. However the intention was to cancel some of the negative effects of cats at lower speeds. The objective in this application is to help keep the boat planeing at lower speeds (20mph). To keep porpoise down during intermediate speeds to greater broaden the range of speeds available but still maintain enjoyable ride quality. Ideally to have a boat that will have good ride quality across a very wide range of speeds. However I am not certain that this boat does need to have one at all on it.

Question Spectre 30 owners what are your experiences?