ABS hull stepped
 

Hi,

I currently have a 26" catamaran unstepped hull, and i would like to know if i could make it into a stepped hull and if that would gain any speed.

So if its possible what would be the easiest way doing it?

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RE: ABS hull stepped
 

hi,

im not all that into catamarans but i believe that stepped hulls on catamarans would not be all that useful.
do not take my word for it as im not sure about it, but catamaran hulls work differently that deep vee or flat hull boats in their handling.

dave

RE: ABS hull stepped
 

it should help it get out of the water better possibly increasing speed but im not sure

RE: ABS hull stepped
 

Steps can help a cat considerably - if they are done right. They reduce wetted area while providing a positive method to maintain the correct aoa. My 12-cell stepped cat still holds the NAMBA P Offshore SAW record.



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RE: ABS hull stepped
 

got rpm, can u send us a couple of pics of your hull set up, cos its interesting even for me :D

thanks

dave

RE: ABS hull stepped
 

The SAW cat was destroyed during a crash at 80 mph but I have a shot of the top. I'm attaching a pic of the typical step design used on commercial R/C catamarans. The "secret" is to have the steps at a slight aoa relative to the bottom of the sponsons. 2-4 degrees is good depending on the boat's speed, the faster it is the lower the aoa. I just used two steps on my SAW cat.

Video of 75 mph passes in 2004 with 14 NiMH cells and Hacker motor. http://www.crumbgrabber.com/06lasawv...rqoffshore.wmv

RE: ABS hull stepped
 

hi again.

referring to what i have said before. i was watching tv today and there was the xcatamaran racing and i was trying to catch some idea of how the hull designs were. i noticed that most were stepped. i also noticed the steps started round about underneath the cabin. i have managed to find you a photo of one of these cats in the air and you can see what i mean. but as for actual designs or a better photo i have tried to search online for them but so far i have returned nothing. anyway, hope this helps you out or at least gives you some idea. if i find out anything i will let you know.

http://www.grantscustomrigging.com/p...hlRacing_6.jpg

dave

RE: ABS hull stepped
 

some more pics.<a href="http://www.rcboataholic.com/images/hulls/catamaran.jpg">


http://www.rcboataholic.com/images/hulls/catamaran.jpg</a>

http://www.rcboataholic.com/images/hulls/Cat-hull.jpg

RE: ABS hull stepped
 

Ok thanks, so any ideas on what materials i could use to make it stepped? :)

RE: ABS hull stepped
 

one more thing
stepped hull needs additional power from motor. If you havent much power then stepped hull works worse to unstepped.

RE: ABS hull stepped
 

could you send us a picture of your boat?? maybe i can get some idea from the pic as to what would be the best thing to step it with

promising nothing but i am trying :D

dave</p>

RE: ABS hull stepped
 

btw, what engine setup are you using??? just out of curiousity. tnx :D

RE: ABS hull stepped
 

In reality just the opposite is true. The reason that European monos are usually stepped is because it allows the racers to run longer using less powerful motors. This fits in with the racing rules that were in effect prior to BL motors and LiPos. The reduction in wetted area and the additional lift provided by properly designed steps means less power is needed to run the boat. It does take a bit more power to get on step, but once there properly designed steps will reduce the power requirement to stay on plane.



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RE: ABS hull stepped
 

Got RPMyou are right of course
but i mean something else
When the power not enough then weted area will bigger, the sponsons and steps will be weted. When increasing power, when steps will dry and when get profit from steps work.
In other words - before you get profit from steps you should spend much power.

RE: ABS hull stepped
 

Just to quickly answer the question about how to do it.
I have seen it done on a mono where the hull was just cut three times to make a rectangle, then pushed inwards and fixed in place.
It would be a bit more complicated on a Cat but if you made a template it could be done quite quickly.

RE: ABS hull stepped
 

Well it will be powered by a Aquacraft EP1 outboard, so not exactly fast/powerfull, but i will put a 600 motor in it with 8,4volt battery.

It is this boat, the sponsoons are basicly small V's with one side of the V longer than the other.<a href="http://modelmarvels.com/page65.html">http://modelmarvels.com/page65.html


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RE: ABS hull stepped
 

So Rull/RPM are agreeing. You need to get to a speed where the water is "hard" enough for the water to not bleed into the step. Once you are there the steped boat will become more efficient. At this point the step will begin to open and "inject" water under the trailing wetted surface and further free the boat from the surface. I think this is less significant on choppy water where the lake surface is essentially doing this for you. On calmer water this is a must for stable speed. I think after seeing the boat I share Rulls concern that the effort might be wasted. It would still be a good learning experience. But I fear at 15 mph or below the excercise will be futile. I would guess at 20+ your effort will begin to pay off. (these are "educated" guesses).

RE: ABS hull stepped
 

Ok then i think i won't do it, thanks for the help anyway. :)