Small planing cats.

Absolutely nothing like the one in the link, but its small and its a planing cat that I built and sail.
From my sailing experiences I think small planing cats have lots of potential. Great fun.
My planing Cat
Cheers
Andy

Thanks for link. Interesting craft you've created. So how about telling us a little about your experience sailing it? How does it handle? How much wind does it take to get it up on plane? etc., etc.

That is pretty darn cool Andy! Nice job.

One could even buy a couple of larger used sailboards and mount a tramp between them.

I'm just amazed that no one is building a planing production cat though.

Thanks for the positive comments.

It gets up on the plane quite early. It will never be quick round a course due to the fact I only have a single rudder for minimal resistance, therefore has a fair bit of leaway when going into wind, but for blasting up and down on a reach it's a hoot!
See the link below for a fuller story
Planing Cat
Andy

The Paper Tiger is a boat sailed in Australia and New Zealand, not sure of the numbers still sailing, we had a good large fleet in South Africa but it just died out in the 90`s. A great 14ft single-handed boat, you could build it in plywood easily, weighed nothing and went like stink, I remember watching the PT sailors surfing waves passing Hobie 16`s down massive waves offshore Durban (I was on one of the Hobies being passed.) They definitely plane downwind, and sail on the chines well upwind.
Had one for a while, but moved on when the class died.
What a great little boat.

web page

There are still good fleets of Paper Tigers racing in Australia and New Zealand.

What about adding a small skeg so it doesn't slip so much- a kickup windsurfer daggerboard- I think someone might have said that - or a small strip rinning down the middle of the hull to take the brunt of beaching wear and tear and it might make take pressure off the tiller. Or are you just going to leave it as is?

John R.

Hi John
A long skeg may well be the answer.
However, I have stopped developing my cat as I am in the process of building my next contraption....I reckon I have found quite a fast hull shape so am making a much lighter monohull using the same hull shape but with hiking racks. I'll be experimenting with amas on each side to add a bit of stability. All up weight is on target for 35Kg using an 8 - 9 metre windsurfer rig and 16 guage alloy tubing for the racks.
Apologies for mentioning the word monohull on this great forum.
Andy

BLAS-FEMUR!

Burn her!

Hi folks.
Check out this video of a planing production catamaran from 1980. It performs well here in 15 knots of wind despite a poorly cut sail. www.mckeewildthings.com/video/itzacatbig.mov
you will need the latest version of quicktime.It's 40mb
There is a smaller 15mb version at www.mckeewildthings.com/video/itzacatsml.mov
The hull widths and planforms were chosen based on calculations of planing efficiency, not because they resemble a sailboard. Note than the hulls are canted at an angle to each other so that the leeward hull is at an effective planing angle when the windward hull is slightly lifted from the water. A later version was scaled up to 17 feet long and had two steps to reduce wetted surface, so that it's wetted surface when planing was much less than the craft in the video, but with a tornado sized rig.

For the record (and despite popular belief) the steps in planing hulls are not there to reduce wetted surface. They actually increase the lift available by increasing the amount of hull that is

planing

. This is not the time or place for a hydrodynamics lecture so you'll have to trust me on this.

Hi scarecrow. No need to have to trust you. You are correct that steps increase available planing lift. Having been a codesigner of the boat in the video and having built step hull cats, sailboards, water skis and speed boats as well as full size robotic whales and sharks I'm quite familiar with fluid dynamics. However steps can effectively reduce wetted surface area with an appropriate design, and as the boat speed increases, wetted surface is substantially reduced compared to a comparable length non-stepped planing hull. More planing lift yet less boat in the water.

The hydroplane [speedboat with sponsons forward] would have to be the epitome of this concept, yes?

Or airplane floats - consideration has to be given to various angles of attack and low drag at various speeds.

I couldn't agree more. I was probably over simplifying as a lot of people seem to think that the saving is in the hull area immediately aft of the step, rather than in the topsides etc.