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Hydro-Cat that's exactly what I had in mind when I looked at the pictures!
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Good Grief Simon, you have given your poor little cat a 'low bottomy'
Graham.
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Can't wait to see how she runs! great idea, wouldn't have thunked it myself no matter how much I scratched my head or scribbled on the plans... Great to see the uninhibited!"Look good doin' it"
See the fleetComment
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ED.We often think the same way !
Graham It took about 2 days of thinking and 10mins with a knife to do that.
Jesse You want to know how it runs ?? So do I, but I am on duty for the next few days so no pond time. The suspense is killing me.
Here are a few possible bottom profiles I have sketched up for discussion.
Please place you vote for a,b,c or d and why you think so.
If you have any further advances then please shoot me the idea.
I can make "stick on" pads for experimenting with of various widths.
Keep in mind there is still the dihedral on the front ones. That can stay or be built out and flattened if required.
I have sheets of balsa and a lot of time so don't be afraid to make suggestions. I will try most things twice.
See it....find the photos.....sketch it it....build it........with woodComment
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My vote goes for AComment
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A could be a lot faster, as it is turning your cat in a hydro... The consecutive steps on a cat bottom are usually made to break the surface tension and get it to ride on the back ones. I would say probably B, but with a longer tip, so it touches the front step. If you leave it like this, the space will probably create a nice vacuum, making the boat super stable, but slowish... On second thought, maybe D placed under CG and lengthened to touch the front step.Comment
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Cornel Your input is well appreciated and I have noted what you say.
I need your kind of input so that I can continue to work with unusual ideas.
I now have another approach. I am 2 steps ahead of myself now as I have not even run it on the single step yet.
If I go with the traditional 3 step look, do I have them all inline, as in the all the steps touch the table. Or do I go for a raised rear step like I have seen on one cat (the Baby Freya if I remember right).
I can see that raising the rear step is similar to rocker in a mono-hull.
Is this a way to go. ??
Below is a simple scetch showing the idea.See it....find the photos.....sketch it it....build it........with woodComment
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It could be a better approach. If you make the steps gradually smaller, this will lift the whole boat to run on the front ones and prop, with the others keeping the hull glued to the water. I was looking on different pages about this, and they all seem to do gradually smaller steps...
Take a look at http://www.hydromarine.de/ , look for the drifter xl, nice profile pic...Comment
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Simon, I don't know very much about cats but from what I have seen, the idea is ride on the rear sponsons only (reversed version B)...:::::::::::::::. It's NEVER fast enough! .:::::::::::::::Comment
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Jan You are right, the best of them seem to run on the rears. Some run on all.
To get onto the rears I assumed it was set higher up and induce a small rocker effect and thus allow it to get onto the rear pads.
(reversed versionB) I am not sure what you see here. If you suggest that the middle or 2nd pad is too be lifted too then I can understand that.
I am keen to see if there is "rocker" in the ride pad line from fore to aft.
Pad width and dihedral (usually none) can come later.
This is fun and I have not even cut any wood yet !!See it....find the photos.....sketch it it....build it........with woodComment
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take a look at this, it is quite clear how the steps are going. They also seem to be rounded, not flat... plus the strakes...Comment
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Not sure about the rocker effect, I always thought it would be the air lift, CG plus the strut setting that defined where the ride would be. I believe that the forward sponsons' steps are for positioning the hull so air can flow under and the strut/CG would keep it from too far back.
Then again, like I said before, I am not very knowledgeable of Cats principals.:::::::::::::::. It's NEVER fast enough! .:::::::::::::::Comment
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Hi Simon
I would go with the 3 step configuration, either with all at same level (A) or with steps getting progressively lower towards stern. Either way the trailing edge of all the steps should contact a flat surface.
For instance step 2 could be 1/8 inch lower and rear step 1/4 inch lower.
IMO if you just have the rear step lower you could induce porpoising due to rocker effect.
Graham.
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Check out the Baby Freya Cat, it runs like a 3 point hydro and is designed that way.
very sim to this catComment
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The intended speed of the boat has a lot to do with the hull design. My Kyosho Hurricane originally went about 12 - 15 mph with the stock setup and GP3300's in parallel (dual ST 360's geared 2:1). I then went direct drive with a 700SC and GP 3300's in series (20+ mph). Next I went brushless with a KB45 and 2S lipo's in series (35 mph). Although I gained quite a bit of speed the performance went down with each change. There is quite a bit more to it than steps or no steps IMO as this is a stepped hull. The first picture is with the 700SC and GP3300's, the second picture is with the KB45 and lipo's.IMPBA 20481S D-12Comment
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