It will be completely covered with resin and cloth, and have full length low profile engine rails!
The bottom ride surface will be laminated with light ply, all un-needed foam gets removed from the main hull!

Isuzudude, dont make me start another project!
Im already looking at a couple of pieces thinking about a small cat!

What kind of pieces? Whatcha got in mind? Come on...you can tell me

Thinking of a straight line cat around 40inch aka drag cat etc.
For when I can afford to splash out and buy a real marine rc engine.
I was going to modify some F1 cat plans to take our inboard motors!
Not sure still thinking!

Hey Oz,
Thinking, now that is dangerous. From what I can see with all your designs it should be something truly different and out of this world. I reckon you'll make it work well too.
Moofy

Dangerous is right!
And then I need pain killers to get rid of the headache!

Ok so I changed the overall design for the hydro!
Cut my profile from 1/8 ply last night and glued the 3" thick foam down on a flat suface with another piece of ply on top and a heap of weight and left it till this afternoon to give it some roughing out so you could see some of the shape that Im going with this time!
This is not the top for this one I just threw it on there for the sake of it!

Hi Oz,
Looking good so far, keep up the great sffort.
Have you tried any wind tunnel testing so far.You don't need a huge complex setup,
remember the boats are not that big,
Just use a good size fan (best is industrial otherwise a normal home fan will suffice, but turn it up full blast) with a fixed head so it does not rotate. Place some
wool tufts about 200mm (or 8 inches in foreign currency) on all leading edges,
longer sections require ATLEAST six, smaller ares ATLEAST three. You can also use
a smoke machine (party variety) if you have one. Carefully watch the tufts or smoke and where the tufts or smoke bends erratically aand flap, try to smooth that area out until the tuft or smoke has a smooth flow.
Try it, it does work. Rember it is not rocket science (Well maybe it is but it is not
too technical.)
Hope this helps.
Moofy.
PS remeber not to remove too much surface at once.

Funny you should talk about fans etc.
I spent the morning fitting a new 30cc Homelite engine to my airboat!
Then went and gave it a test run down the lake!

YOU GO BOOOOOOOOOOOOOOYYYYYYYYYY!!!!!!!!!!!!!!!!!!!!!!

Congrats with the homebrew hydro.

About the aero- and hydro dynamics Moofy is (almost) right.
It's not a rocket science. But it is close to.

The idea of the wool tufts is fine. But remember that when tufts lifts from an upper surface this means that an air-drag is occurring like on the wing of an aeroplane.
This in effect can make the hydro "lift off" and make it flip backwards at high speeds.
The opposite could also be the case. If wool-tuffs beneath the hydro, lifts away from the bottom, it could mean too much downforce.
So it's very much a question about getting the right balance by shaping the hydro with care at the front.

Anyway: Your project looks soo beautiful, and I would like to see more pics from the building process.
BTW: What's the size of your hydro?

Cheers!

Woodie.