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Old Mar 24, 2007, 03:24 PM
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My PsychoCat build thread (catamaran)

Hi all,
long time since I was here last. Was a frequent poster at the AP forum 2yrs ago(?). Well this time I am going to get my almost 2yrs old PsychoCat boat ready for the summer. I am hoping that someone here can help me out with general boat building tips because this hull came without any instructions. Got some pics from the manufacturer on how to mount the rudder but thats it. I'll be posting pics here asap.

PsychoCat:
60cm long, 23cm wide, 600gr heavy.

It is going to be a LiPo + Brushless configuration. I've been thinking on using the Mamba Max 5700 + Barracuda 125 ESC on LiPo 3s1p 11.1V. Is this setup realistic? The manufacturer recommended Lehner 1940/8 & Schulze 17/149 ESC on 18cells Nimh. Haven't found any good info on what that that motor & ESC exactly is. I have no Nimh experience. MM + Barracuda would be good cause I already own the MM and I have used Castle Creations products for two years and I like them a lot.

I have no previous experience in RC boats.

Pics of the PsychoCat 1
Pics of the PsychoCat 2
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Old Mar 24, 2007, 06:55 PM
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do you plan to race the boat? or just run it as a 'fun' boat? that motor is likely not going to be happy running on 11.1v. I'm planning to build a similar size cat and have been advised to run a 3000-3500kv motor on 8cells(nimh, figure 7.2 v under load). you'll prolly find that a kv rating of 2500-3000(on either an 540L or xl) better suited for the boat.
edit
just looked at the boat. while my german is non-existant(as is my speeling) I was able to see which motor they used... you'll be wanting an 'xl' size motor with a kv rating 2000-2500 for sport use, maybe 3000kv for racing.
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Last edited by Rex R; Mar 24, 2007 at 07:02 PM.
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Old Mar 25, 2007, 05:40 AM
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Hi Botmund,

You might ask Jan Nicolas on the http://www.rc-raceboats.de/shop.shtml shop.
Tell him what you want to run/use and I'm sure he will come up with an alternative for the Lehner.

Write English, no problem.

Regards, Jan.
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Old Mar 25, 2007, 11:50 AM
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Hi pompebled,
thanks a thousand for your previous help!

I am planning to race just for fun. I like speed a lot so I'd like something that can go fast if the weather permits (too much power is enough).
Is the MM + Barracuda too much for this hull? It would produce somewhere close to or above 1000W. How does XL size motor compare to the MM (540 size)?

So, I'll refine my question. Is the MM + Barracuda at all possible for this hull? Will the motor burn up (it does get terribly hot when using in cars)? Meanwhile I'll email the shop as suggested to hear what he recommends.

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Old Mar 25, 2007, 12:18 PM
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imo the mm is way to hot a wind a motor for use without a gearbox. on 11v it will be trying to turn better than 62000 rpm!! the xl motors will produce a bunch more torque and run cooler(albeit with less rpm), and reduced amp draw(more runtime). same size dia but longer(iirc about 70mm). hth
rex
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Old Mar 25, 2007, 01:21 PM
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Quote:
Originally Posted by Rex R
imo the mm is way to hot a wind
I understand. Ok I'll look into some other motor alternatives then.
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Old Mar 25, 2007, 05:47 PM
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google 'hacker nemesis' brushless motors. run about $50-70 USD. I think you would want 2500 kv (6xl) not sure on the number of turns), on 11.1v. on the other hand the cc baracuda 125 is a fairly good value. couple of items to get for your boat; water jacket for the motor & cooling kit for the speed control
edit
finedesignrc lists nemesis blue; 540 9L $60 usd, 540 6xl $70 usd. either of those would work nicely(imo).
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Old Apr 18, 2007, 09:38 AM
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Rex R, thanks for the tips. I decided to go with the recommended setup Jan at www.rc-raceboats.de. Big thanks to him for his explanations and his advice on what this hull can handle.
I decided to use my 3s1p 3700mAh LiPos that I already own to cut costs. They will be connected in series. If all goes well and I like the boat I will upgrade and buy two "5s1p something" LiPos.

So now I have the following:
Feigao FG-36 10L 540XL (1668KV)
YGE 120 Navy ESC (with an all german manual )
In series 2 * PolyRC 3700mAh 3s1p 11.1V LiPos = 22.2V 3700mAh

What expoy should I use to glue the motormount/servoholder to the hull? I assume one uses the same stuff to seal the hole where the propshaft enters the hull.
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Old Apr 18, 2007, 11:55 AM
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methinks that most any 20-30 minute epoxy should work, though for the motor mount you might want to reinforce the epoxy with some lite fibreglass(this might be overkill), or silkspan.
edit
from the look of the mount, you could prolly omit reinforcing the epoxy since this mount will spead out the load better than the one I was thinking of.
edit
If you don't already have one, a thrust bearing is highly recomended for use with feigao's to keep the thrust load off the motor(and shoving the rotor out the back of the motor ).
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Old Apr 18, 2007, 04:52 PM
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Sneek, Netherlands.
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Quote:
Originally Posted by botmund
So now I have the following:
Feigao FG-36 10L 540XL (1668KV)
YGE 120 Navy ESC (with an all german manual )
In series 2 * PolyRC 3700mAh 3s1p 11.1V LiPos = 22.2V 3700mAh

What expoy should I use to glue the to the hull? I assume one uses the same stuff to seal the hole where the propshaft enters the hull.
Nice set-up, should (in theory) be capable of making you wet yourself at the first few runs at full throttle...

I would use only the 24 h epoxy to glue the motormount into the hull.
Tack it in place with a few drops of CA and use glasscloth and the epoxy mentioned to secure it crashproof.

Make sure to sand the area where the epoxy comes, also wipe it with Acetone to remove any grease.

If you only have the 30 minute stuff, you can use that, combined with glasscloth, but you'll have to temper it by heating up the joint, so it becomes tougher.

Heating up the cat's hull is tricky, so be careful not to overheat it.
Best use the 24h epoxy if you're not happy with pointing a paintstripper (heater) onto your boat...

Please show us some pictures of your progress.

Regards, Jan.
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Old Apr 18, 2007, 11:12 PM
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Ok so I need glasscloth and 24h epoxy and a "thrust bearing". I'll try and visit a boating shop this week for the first two but a trust bearing what is that?
Any online tutorials on how to use glasscloth and epoxy? Don't want to make any mistakes.
I will take a series of pictures hopefully this weekend that shows where to drill the holes. Because of copyright I won't upload DrPsycho's pictures.
I won't do the epoxy thing until I am 97.55% sure I understand how to do it.
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Old Apr 19, 2007, 01:02 AM
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couple of links for you
http://www.rcboataholic.com/hardware...%20bearing.htm
www.offshoreelectrics.com/categories.php?cat=14
1st one (with luck) should explain the thrust bearing(rest of the site has some good explainations also) 2nd link(offshore) leads to where you can buy some. hth
rex
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Old Apr 19, 2007, 02:03 AM
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Quote:
Originally Posted by Rex R
couple of links for you *snip*
Excellent, now I understand the idea! I'll definitely have one of those. Seems like a very cheap way of prolonging the motor's life/bearings.
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Old Apr 19, 2007, 02:13 AM
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Quote:
Originally Posted by pompebled
Nice set-up, should (in theory) be capable of making you wet yourself at the first few runs at full throttle...
hahahaha, yeah it might. Certainly if the boat flips considering the amount of money that will be put into it.
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Old Apr 20, 2007, 10:56 AM
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Today I bought epoxy and glassfibre cloth. The salesperson was so good that I also bought some kind of white powder to blend into the epoxy. For some reasons I did not understand what he meant that powder did or why I would need it. Well it set me back only 5e.

It says on the epoxy bottles 3hrs clamptime & 19hrs sanding time. I hope this is round about what you recommended pompebled. The cloth is 3m x 5cm. Should be enough I hope.

I won't be able to start this project this weekend as we are going away. Hopefully I'll be able to start drilling next week sometime. I will try and document each step as good as possible and come back with detailed pictures so that others might have use of the information.

edit:
Rex, is a thrust bearing needed here because the boat uses a flexible shaft. Isn't the tube where the propshaft runs the place subjected to the force the prop creates?
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Last edited by botmund; Apr 20, 2007 at 11:10 AM.
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