So I am just one boat ride in on a new to me catamaran. I've been up to 70 mph so far and I'm not sure if it really feels much different than a V bottom up to this point? Okay turning feels a lot different, but running straight maybe smoother but that's about it. My question is there an obvious point when you start to pack air or is it just a the faster you go the more lift ie gradual and hard to notice. I notice also that unlike my V bottom, which takes more and more TRIM the faster I am going, this catamaran seems to plane out about 40mph and take a couple nice bumps of trim and then even if I add 30 MPH it doesn't seem to want or need any additional trim at all...

The catamarans I've been on seem to get a loose feeling around 80mph. Beyond 90 the hulls start to feel like they're floating. Really cool experience for the boat to float above the chop.

What kind of Cat ? Full tunnel ? Center pod?
3600 Supercat around 95mph I can definitely feel the whole boat lift up when it starts packing air... boost goes down, I can pull back on the throttles and maintain same speed. I could tell even if I was blind folded.
Get some pointers on cats .. especially trim .Don`t go more than level, at lower speeds keep em in .
More trim will make em loose, dont pull back on the throttles if cossing wakes or if you lose control. That forces the bow down forcing more air in the tunel raising the a$$ end and possibly spinning out .
Mines on plane by 25 mph or less it`s hard to tell sometimes.
If you have Tabs use em to control the hop before they packs air .
Go faster .

Dont know what kinda Cat your on but there is no comparison in a V bottom to a cat ride , A real Cat doesnt need trim tabs AT ALL ....Stevie wonder would know the difference between a V & Cat ride

They'll usually hop a few times then take a set and be on rails. 36 Skater with 6s does it around 65mph. 70+ its floating and on rails. That being said, all cats are different. All of them. Period.
Take the Tres Martin course and stay safe.

It's a 38' Mares. I can go with the drives tucked in but I definitely gain some speed by trimming them up just a couple quick bumps I feel it get lighter and gain some speed. It's probably going to be irrelevant as I am going to be putting Arneson drives on the boat this fall, but I'm trying to collect as much data as I can now. And use the boat while we still have a nice warm Lake Michigan.

I have been in a few cats along with a 38 mares cat with the Arnesonson conversions with 750's in it , that boat never really climbed up and took off out of the water like the other cats did , almost like it was under powered or real heavy.

Sort of part and parcel to this but apples and oranges. My son's first boat (he was raised on my Force 235 with 502 and B&M 250). I took this out and ran it a lot to see if there were any ill manners he needed to be aware of, I found none. It does respond to an increase in RPM with corresponding speed very well but I am pretty sure it is not packing any air at 35 to 40 mph cruise. It does like a little trim but you can feel prop slip and reduction of speed if you give it much. The hull feels very efficient for just a 5.0 MPI with a top speed of close to 50 at 4800 rpm given its length and weight. It takes the chop and cruiser wakes much better than any deep V I have been in of a similar size.

Any hard rules or potential evil handling he should be aware of given its speed range? Medium to hard turn protocol at cruising speed? I sort of picked this boat out for him as a good starter and family boat, rides well is very roomy, and does not ride like a deck boat at all. I am hoping one of these days to drop a 383 in it.
https://www.splendorboats.com/deck-boat/240-platinum/

I guess I have a fake cat and Eddie Young who built engines for 3600 Supercats and hundreds of hours behind the wheel , he doesnt know what he`s taking about either when he says use tabs?
And neither does Nortech I guess , they just put on Tabs just because the boat didnt need it .
I can drive around at 60-70mph without hop by using tabs, bull$hit they don`t work
Good talk.

Take a chill pill Dan , theres a difference between trim tabs on a boat and the picnic table Dana monster tab needed on for example Eliminator 33s , been a quite a few cats that bdidnt need ANY tab at all like Jimmy Lees SKATER freedom carry on