What brand cats are true tunnels?
i know skater, mti are who else?

To my knowledge, there is no "dictionary distinction" between tunnel hulls and catamaran hulls. Generally speaking, a tunnel hull must have "roof" structure between the hull portions, while a catamaran can be either connected or open (such as the trampoline cats used in sailing).
In powerboat lingo, a tunnel USUALLY applies to a stubby upright air-packing hull (think Formula One outboard) while a catamaran USUALLY is the term used for longer, lower air packing hulls.
But outside of the bench-racing circles, there is no technical diagram that distinguishes a hull to be "strictly" one or the other.
It is generally left up to the hull designer to label it however he wants to

Even within either classification, you can find dramatically differing examples.

Symmetrical hulls vs asymmetrical hulls..
Half-hulls vs 75% or full hull sections.
Stepped hulls vs non stepped.
Flat chines vs sharp chines.
Wide tunnel vs narrow tunnel..
Deep tunnel vs shallow tunnel..
Extended bows vs fully enclosed bows.
Canard assist or not..
Descending tunnel or flat tunnel.
No-fly venting vs none.
Pads, notches,, reliefs... the list goes on..

So reword your question to be more specific and let's try to give you a good anawer..

M

My question would be how insurance classifies the different hull types.

No pad cats. Like an eliminator or dcb

You mean "Center POD" cats, don't you?....

Yes.. which cat brands are not center pods

American Offshore
Chris Cat
Awesome