P-Ltd Cat flips over in turns

[dan06]

Hi guys, I would like your opinion on this:
I have a Hobbyking Apparition which is a fiberglass 32" P-ltd catamaran, my setup is currently the 2030kv UL1 motor along with two 4S 4000mAh 25C in parallel.
The problem i have is the catamaran is easily flipped over in turns, even at quite low speed i highly suspect too much weight (mostly coming from the batteries). Each battery weights 370g, i think it is too much so i want to replace them. For example, by two 4S 2200mAh 25C (210g) for a total weight gain of 320g.

But i am concerned about the capacity and mostly by the power output of the new batteries.
2200mAh x 2 @ 25C gives 110A. And the UL1 is rated at 50A max, so i should have a good margin right?

Do you think it is a good trade off or should i go ahead with higher C ratings or capacity?

Of course, any other option appreciated.

Thanks!

[Fluid]

The Apparition is a narrow, scale-like hull which will never corner well like a Motley Crew or Miss Geico, etc. Weight is not the issue, hull design is. Adding a LONG rudder will help, but it will never get around like a wider hull designed for turning.



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[kfxguy]

He beat me to it. I have one, it doesn't turn well. You'll need a different hull for turning. I'm sure like he said a longer rudder will help too.

[dan06]

1/ Ok so one option is to use a long rudder. What size is long for you?

2/ Also i can switch to a skeg strut, any feedback on that? Pro, cons?

[Chilli]

Long would be something around 140mm. You could try a skeg strut as I see allot of them in gas boats. Heck I have even seen a cat with a sport hydro turn fin bolted to the inside rear of the sponson. In the long run, these are just band aid solutions for a hull that wasn't designed to turn well at speed as Jay pointed out. If you are the type that likes to fiddle with things to see what improvements you can make, go for it. If you don't want to deal with it, consider getting a more appropriate hull that is designed to turn well.

[dan06]

This hull may not be at its best when turning, i can tell it has potential in straight away. I am sure it can be very competitive if improved a bit by using one option stated earlier.

[Rumdog]

IME, sketched struts mostly help with straightening a boat out that suffers from prop walk. The downside, of course, is that's keg is disrupting the flow of clean water to your prop.

[dan06]

I think the best to start is a long rudder, but i find 14cm very long!! On OSE i could find only 10cm rudders.
I will build a rudder extender in aluminum and glue it to my current rudder to see how it goes.

[dan06]

Ok guys, after a lot of researchs i could'nt find a long rudder compatible with my centered-mount system...

Do you know one which could be 140-150mm long and have this kind of mount: http://www.offshoreelectrics.com/pro...prod=ose-80057

I have tried OSE, ebay, Hobbyking,... nothing compatible. It's either with offset (mono or hydro style) or too short.
The blade style i want should have two horizontal screws, most of products out there are vertical screws...
Any idea about taking one and make it compatible?

My current rudder:

https://drive.google.com/file/d/0ByJ-pJPAI-FQZFMyUURIQ3R4TVk/edit?usp=sharing

https://drive.google.com/file/d/0ByJ-pJPAI-FQb3lpLWhFWnZvWTQ/edit?usp=sharing

https://drive.google.com/file/d/0ByJ-pJPAI-FQeTZsWmxkU1h0VVU/edit?usp=sharing

[siberianhusky]

Speedmaster has 2 center mount rudders with 6.25" blades.
You will not find anything that is a direct bolt on replacement, there is no industry standard for hole spacing, each manufacturer just puts the holes where they fit and they are different for each size of rudder.
Fill the holes in the back of the hull, drill some new holes and mount a new rudder.
Not sure you are going to achieve what you want to with this hull, you are fighting the design. Great boats for straight line speed, since these hulls were released there have been dozens of threads about trying to get them to turn right.
I gave up on a very high quality German H&M cat for the same reasons, blindingly fast in a straight line, would roll just about every time you tried to turn. One day I retrieved it about 8 times, put it up for sale that night. Was one of those long skinny scale type hulls. Sad when a box stock Motley Crew outperforms a hull that cost more than the entire RTR boat!