Arrowshark 57" Fighter Cat FE Conversion

[JGZN]

Hi all,

This is my first post and also the first time attempting to do a conversion or build a boat myself. I will keep my works as detailed as possible to my ability. Because this is my first conversion, I will need lots of constructive input and/or advice to as to how i am gonna build it.

A little more about the boat:
It started life many years ago as an empty hull with it going the electric route with the single drive Neu 2215 motor.

Build thread over at our local forum:

http://www.daddyhobby.com/forum/showthread.php?t=39520&highlight=

Boat : Arrowshark 53" Fighter CAT
Motor : Neu 2215 2Y
ESC : Huayu 200A HV
Batts : Rhino 10S2P 9800mah 20C lipo
Prop : X455
Rudder servo : Blue Bird 13kg MG

Controlled by Spektrum DX3.0 Tx and SR3000 Rx.

He apparently hit close to 60mph with the above build back in 09'.

The boat was then sold to another local boater and it reverted back to gas. Then sold to another guy whom i bought from. He had it for about close to 3 months, then moved on to another hobby, and sold all his rc stuff. I happen to catch wind of the news, and quickly swooped it and grabbed it.

The pics are how it looked like when I first collected it.

[JGZN]

So now it is in my hands. I am gonna take my time on this as I have work and also my 1/8 nitro off road and 1/10 electric racing commitments at the moment. So I apologise if this gonna lay up for a period of time in between updates.

With closer inspection, the hull seems fine. The engine fires up as it should.

Why convert this to electric? Well, in the noise sensitive Singapore where I live, this is a major problem. After going thru scarce information in silencing the pipe, it's too much unnecessary work for diminishing gains. And the engine cutting out without any rescue boat is not funny at all(I happen to be alone at the quarry where we are unofficially allowed to play boats).

Took out some of the ugly stickers, gonna rip them all out and repaint it.

[JGZN]

"Begin with an end in mind......"
-Stephen R Covey

Ok, here are some outlined goals i have in mind to my point of having fun:

-No 3-5 min runtime. Looking at 15mins at least
-Glass water is only fun for this long. I am gonna bring it offshore when my bro goes on his offshore fishing trips and play with the waves at the beach front.

Thanks to OSE vast library of builds, I have found my source of inspiration

Many thanks to Algroove2000 for building this wonderful HPR. I am gonna follow closely to this electric setup. Will share the setup of my build later on
http://forums.offshoreelectrics.com/...h-Voltage-quot

[JGZN]

Referring to the data logs from Algroove2000 Castle Creations ESC, i can safely say that with that prop setup that he ran on(i am not sure what prop he used initially, any heads up on this?), each motor is drawing about 4500w peak.

I'll use that as an indicator to build a more budget friendly setup with some decent speed and most importantly run times.

One thing for sure, I will be utilizing 12s 1p 5000mah batts just like the HPR build.

Choice of motor:

This is closer to what the 4035-630 the HPR is using.
630kv*44.4v = 27,972 rpms

1) http://hobbyking.com/hobbyking/store...ize_heli_.html
600kv * 44.4v = 26,640rpm
A little pricey for me, but this is the closest to the scorpion

The below 2 is what i am looking at
2) http://hobbyking.com/hobbyking/store...ter_Motor.html
530kv * 44.4v = 23,532rpm
This is bigger than the 4035 scorpion. Looks more muscular for the intend job where bigger is better? hahaa.... Wouldnt mind stretching the budget for it, but is it necessary?

3)http://hobbyking.com/hobbyking/store...ter_Motor.html
510kv * 44.4v = 22,644rpm
This motor is the one I am leaning for. Is the rpm sufficient for sport running or is it too far off from the 630kv scorpion?

[kfxguy]

I know nothing about a boat build this big, but I'll be watching. I do have alot of fabrication and carbon fiber experience so if the need arises, I'll chime in.

[JGZN]

Questions......

1) Should I keep the rudder as it is? Seems ok to me.....

2) What struts fits into the bottom? Can some one point me a direction?

[JGZN]

I know nothing about a boat build this big, but I'll be watching. I do have alot of fabrication and carbon fiber experience so if the need arises, I'll chime in.

Thanks for your help! I'll definitely need those invaluable advices to cover up all the holes on the canopy and existing exits for the hardware later on!

[Adrianli]

Nice to see my old boat back in action.

[grsboats]

Strut looks ok but you can offset your rudder(to the right) for better turning this way you also minimze the water pressure on the rudder servo .Gill

[JGZN]

Strut looks ok but you can offset your rudder(to the right) for better turning this way you also minimze the water pressure on the rudder servo .Gill

I'll be removing the original strut and replacing it with a twin setup. I'll just keep the rudder as is it for now to reduce cost and work done.

[JGZN]

Nice to see my old boat back in action.

Hahaa.... When I re-maiden this fella, I'll surely need your help!

[JGZN]

Ok, some data which I have gathered so far.

From adrianli, the stock boat with the stock Zenoah 26cc in it does about 30mph with about 2.5hp.

2.5hp is about 1900w. A mildly modded Zenoah around 5.5hp(~4000w) @ 18k rpm. So using High Voltage as an example, 4500w x 2 = 9000w = 12hp!!!

So scaling back into my budget, around 6-7000w @ 22-23k rpm from the twin motor should put it into the 50mph easily. Theoretically, I should do 20 mins easy with a similar batt setup as Algroove2000's HPR.

I should be able to get away with a 120A HV esc because the HPR is peaking at 4500W @ 44.4v which is about 101A.
I'll use the same octura X457 and X457R or 1 prop size down to compensate for the additional 'whatever' drag that caused by weight or poor hull design. Besides, I'll be using a motor which peaks out @ 4000w and of lower rpm, so naturally, the amp draw will come down.

Please correct me if i am wrong....

[JGZN]

Skeg vs std struts

I was shopping around for struts and i came across skeg struts. It looks nice and upon further reading, it says that it helps cats to turn better? Is it true or quite baseless?

[JGZN]

Got some time and stripped out the engine and all its stickers. It looks so much better now.

IMG_20140819_230531.jpg
IMG_20140819_230545.jpg

[JGZN]

In the mean time, I have selected my power plants. I have come to realise that I can literally put anything and make it a rocket ship or have something for sport running, just the money part which is the limiting factor.

For my budget and to my understanding, I have bought the following:
2x Turnigy 510KV 44mm outrunners
2x Yep 120A HV ESC

With the above setup gonna run 12s1p 5000mah x2. The motors will be turning a x457 and x457R.

The above setup wont get me a rocket ship I know. Anything more than 120A HV the prices are also in the rocket range. So decided to limit my self to max 120a HV ESC and find a suitable motor for it.

IMG_20140816_230535.jpg

Bought me self a nifty prop balancing tool as well!