Ok Cat Guys...need Some Help
 

Im building a smaller twin application fishing cat. I notice on the single application that there is a need for tabs..understood. On the twin application like a typical cat it corners relatively flat, and I have used this www.twintrimusa.com devise which makes her handle like a v bottom...really impressed with it. My question is do I need a tunnel tab like I see on some of the west coast cats.. what will they do to help if any..I imagine it settles ride or purposing. Looking for advice..

Thanks Jeff

Jeff,
You answered your own question... I would not add one unless it's needed. While they can solve some issues (see above), they can create others (possibly stuffing) if not used properly.

A Tunnel Tab Can Fill The Tunnel With Water Instead Of Air
And Turn The Bottom Into A Barrel Instead Of A Cat Then Barrel Roll

Tunnel tabs are generally a bandaid for an existing handling/ride issue or on some race boats can be used to squeeze some speed on the very top end of a spec class boat but you pay for it in the amount of skeg left in the water and the boats point of turning being shifted forward (both not good). I dont really see them on many race boats these days. Sure theres a few still out there but as far as an active surface they dont have a practical use. If you have one just set it an forget it, I've seen some use them to help plane but thats about it.

All this may not apply though in your case Jeff as your cat may not really "air out" like offshore cats and a tunnel tab may remain more of a wetted surface.

If its a porposing issue what about moving the center of gravity to combat the oporposing issue?

Thanks guys for the comments above. The boat doesnt really air out. Top speed is between 45-50. Moving cog is being considered since this will be the first twin application. Tabs are needed in certain water conditions on the single when there are more than 4 people on the boat. Just thought it would be nice if need be to have something in case there was porpoising. I guess try it first and can always go back if something is needed ...Thanks Jeff

Just ask AJ, he knows all about tunnel tabs:evilb:

Go ahead and add all the electrical work during the build.

What cha building Jeff???

They are generally a bad idea, but at those speeds I certainly wouldn't worry about it.