Joysway UH-1 Catamaran Model number 9112H

[fidelity101]

I'm new to electric boats, I've had a gas Warehouse Hobbies Team Enforcer Pro for a few years and thought I'd try my hand at electrics. I purchased the Joysway UH-1 (http://www.ebay.com/itm/231292164109) and it looks like a beautiful boat.

The good:
- Motor and ESC seem to stay very cool on 8S.
- Boat runs well on 6S wit decent speeds...I was using a 6S 5000mah pack
- Looks!...This boat just looks cool!

The bad:
- Hull quality. The boat fell apart when attempting to run the boat on 8S using two 4S 4000mah 25C battery packs. The boat failed BIG TIME as the seem gave way and the boat seemed to crumble. Here are some before and after pictures.
- Battery tray and CG. The battery tray will accept two 4S 5000mah packs but not much more. That should be enough for 4 minute run times. The hull comes out of the water quickly as the batteries are placed between the sponsons. I think this boat would benefit from two 8S 5000mah packs with one pack being placed over each sponson for some nose weight and improved run times.

Verdict:
- I would definitely buy another one if I could find a good price, but I would spend a few days adding carbon fiber cloth and epoxy on the inside and around the entire joint section where the top and bottom hull sections meet. The overall hull is approximately 1/16" thin and it appears that quick setting resin was the only thing used to hold the hull pieces together.

Here are the pictures I managed to take before and after the hull failure. I am still waiting to hear back from the ebay seller as to a replacement hull...they do not appear to be overly willing to help get me back in the water anytime soon.IMG_2017.jpgIMG_2016.jpgIMG_2020.jpgIMG_2023.jpg

[Doby]

so it just came apart while running, no crash etc? Not good if so!

[fidelity101]

Here is a picture of the damage after my first run on 8S.

IMG_2034.jpgIMG_2035.jpgIMG_2036.jpg

Also, to those of you who mentioned that upgrading the ESC would be a high priority, I was unable to verify it...sorry. The ESC was cold to the touch after a 4 minutes run with the 6S 5000mah 50C pack. After running it on 8S, the water flooding inside the boat did a lot of cooling for me...so it was hard to see if it got warm. :-(

I know that some Chinese products are better than others, but I'm really bummed about this entire experience. I really wanted to get into RC boating this weekend and my entire family (kids and parents) were impressed with the way the boat looked. They also laughed very hard when the boat failed and started to sink. They laughed even harder when I dove in, fully clothed, to prevent it from sinking any further. I was able to recover the hull and the canopy...so hopefully the electronics will work again (I'm giving them a few days to dry out)

I think I may have to buy another boat and return this one because the ebay seller is being very unfriendly and extremely unhelpful. I asked for a replacement model and they said "hahaha"

[Doby]

Was there any flotation in the hull?

[fidelity101]

It comes with an empty hull...I recalled from my gas days that using foam is a great way to provide cheap security so I used the tubes you can see in picture 4. I hot glued them inside the hull. That prevented the boat from going underwater completely...4" of the hull stayed above the water as it was vertical in the water so the battery tray was slowly starting to get wet. I dove in and "hopefully" disconnected the battery before any damage occurred.

The boat seller told me they've never had a single report of failure and said it was the way I drove it. Not sure why it fell apart at half throttle other than the extremely thin hull.

I am two days into my vacation and I've spent a few hours on the phone with eBay and asking the seller for help...I think boating it not in the cards anymore...really stinks

[fusion_m8]

Time to cut your losses and frustrations bro, not any hull can handle the physical stresses that 8s can dish out. Trying to repair a broken hull like the one you got is akin to glueing back a broken mirror, its never going to be the same. Salvage the electrics and get a good hull from the OSE shop, there are many on offer like the one below that can handle 8S and they are reasonable priced with customer service you know you can trust.

http://www.offshoreelectrics.com/pro...prod=aero-1127

If you are willing to settle for 6S, there is a more affordable hull on offer that has been proven to be a great performer:

http://www.offshoreelectrics.com/pro...prod=Aero-MM-2

[fidelity101]

I agree with you fusion. However, the hull isn't a complete failure...I should be able to fix it in a few evenings and add a significant amount of carbon fiber and fiberglass support to the entire hull. It will add weight, but it will be worth it in the long run. I'm also going to cut out the stock battery tray and make two more trays to the left and right of the stock tray location so I can run 8S 6000mah packs on each side for a total of 8S 12Ah power...which should give me a solid 12 minute run time. :-) What do you guys think about trim tabs on a catamaran? This boat will live to see another day and I'd rather spend time fixing it up than doing more search on finding a suitable replacement for the electronics I'd be pulling out of it. :-)

But then again, if this boat hobby is anything like the RC airplane hobby, I'll probably have 5-10 boats in my shop before the end of the year. :)

[fusion_m8]

That sounds like a good plan if you are able to repair the hull, as for myself I lack the tools and the expertise to perform such a repair if it were to happen to me. But seriously...8S??? That's a heck of a lot of power for any RTR hull to handle...

[fidelity101]

I think the total power (watts) divided by the total weight of the boat is a better indicator of performance. My friend has the Genesis and on 4S, it's crazy fast! I ran the Joysway on 6S 5000mah packs because I wanted to see how it ran and it did ok, I'm guessing it was in the 60-70A range, pushing approximately 1300 watts and it went about 20-25mph. On 8S, I was only able to test with 2x4S 4000mah 25c packs but it was much MUCH faster. The amp draw was probably closer to 100A at WOT and I was never able to see max speed because the hull failed during the test. The hull on the joysway is so thin that once the gelcoat broke out of the way and exposed the fiberglass, I could clearly see holes in the fiberglass. There wasn't even enough resin in there to seal the fiberglass and the fiberglass was only a single layer. There is no way it can handle much more than 25-30mph in stock form because there just isn't enough support.

I really wanted to get a replacement but the seller was very much against it...so I'm going to look for other options. If anyone is thinking about getting a joysway hull, the price is definitely right if you have the time and knowledge required to fix it up properly. If I do end up with another cheap Chinese manufactured hull, I'll take some detailed pictures during the build process before the first maiden. :) To me, that seems like an easier option than buying a quality hull and installing the flex shaft, engine and ESC because I've never done that before and I'm much more confident in my ability to reinforce fiberglass than to try and correctly install running gear.

[fidelity101]

I just found out that atomikrc.com has these listed as "OUT OF STOCK" because 50% of all the boats had a split hull on arrival! The manufacturer never put a single layer of fiberglass over the seam and most of the boats were split when received by Atomik, apparently the United States distribution for Venom and Joysway. I wish I had known that information before buying this boat! I wish the person going by the ebay username "UJTOYS" would verify this information himself and stop selling the product until it gets fixed!

Does anyone know how to contact the Venom guys on this forum? I'd like them to verify this information. I'd also like to find a way to verify this information with ebay to force their user "UJTOYS" into honoring some sort of warranty or replacement.

[fidelity101]

IMG_2087.jpgIMG_2083.jpgIMG_2084.jpgIMG_2085.jpgIMG_2081.jpg

In case anyone is interested, here are the pictures of the inside of the UH-1. I think you could increase the thickness of the hull and make it work but this is one THIN hull.

[fidelity101]

New boat, before and after photos. I'm determined to make this thing run properly. New running hardware provided by Chris Fine. Replaced the prop, shaft, collet, ... Entire system. Stock prop was 60mm and new prop is 452 Octura...apparently 60mm is a bit big for an 8S setup on a 1050kv motor.

Before overhaul:
ImageUploadedByTapatalk1409494649.873867.jpgImageUploadedByTapatalk1409494669.822209.jpgImageUploadedByTapatalk1409494686.174544.jpgImageUploadedByTapatalk1409494707.858073.jpgImageUploadedByTapatalk1409494720.959324.jpg


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[fidelity101]

ImageUploadedByTapatalk1409494760.763120.jpgImageUploadedByTapatalk1409494774.597778.jpg
This stuff is pretty low quality! Wooden supports didn't even bond to this junk so the engine was very loose in the hull


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[fidelity101]

Upgrade pictures:
ImageUploadedByTapatalk1409494839.902877.jpgImageUploadedByTapatalk1409494858.156232.jpgImageUploadedByTapatalk1409494879.957619.jpgImageUploadedByTapatalk1409494898.624481.jpgImageUploadedByTapatalk1409494911.825892.jpg

More to come


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[fidelity101]

2 pound polyurethane foam in the hull and sponsons and sealed all air holes with west systems marine epoxy and filler.
ImageUploadedByTapatalk1409494965.398960.jpg
ImageUploadedByTapatalk1409495004.934992.jpgImageUploadedByTapatalk1409495015.051106.jpgImageUploadedByTapatalk1409495049.520614.jpg

Next step is to cut the new shaft and attach to hull. I'm going to remove that pressure fitted ball bearing inside the hull and replace it with the aeromarine system that includes the oil injection piece...it looks cool! Also purchased an aluminum engine mount, leopard motor and swordfish 200A 8s capable esc...I really hope the esc will hold up. Purchased a new battery tray from aeromarine do the life battery and servo will be sealed in the event of a flip.


Also going to add foam to the inside of the hatch...it sinks fast without foam...I know from experience.


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[fidelity101]

Is anyone following this thread?

Using West System Marine Epoxy and 104 filler (and some fiberglass cloth and milled fiberglass) I reinstalled the wooden assembly. I also wrapped the bottom of the servo tray portion with thick plastic previously purchased to protect the bottom of my RC Cars. Once the plastic was installed and reinforced, I used a fair amount of the epoxy paste to seal the 4 corners...hopefully resulting in a waterproof box.

Pictures below show the re-installation. Thank you Chris Fine for the 8mm to .250" collet and replacement shaft. The clear plastic tube covering the drive shaft was also replaced with copper tube with a teflon liner. I also used high temp RTV sealant to hold the copper tube inside the stock shaft tube as you can see in the last picture.

For anyone doing research on Joysway hulls in general, this is NOT a 56mm Leopard motor as I previously thought...based on the review of the Joysway Silverline by AtomikRC. I purchased the 56mm battery tray from OSE and it was unable to hold the motor at the correct angle and the back portion would have to be supported with an adapter plate as the stock motor in the Joysway UH-1 measures about 52mm wide by 105mm long. It appears to be a good quality motor, but it's an odd size. Does anyone know how to measure kv of the motor?

[785boats]

One of these should do the trick.

http://www.hobbyking.com/hobbyking/s...earch=KV+Meter

There is also the drill press method. As long as you know the revs of the drill, or can measure the revs with a tach.

1. Drive the motor with a drill press.

2. Measure RPM and voltage generated (by one phase).

3. Kv = RPM / (volts x 1.41 x 0.95)

Good work on the patch up job, bty. Thorough & methodical.

[jaike5]

I Think everybody ran for cover when you mentioned c.f.

Cheers, Jay.

[fidelity101]

c.f. - Carbon fiber? :) I had some cloth laying around and it seemed like a better idea than the fiberglass I had.

Check out the videos of the first run. I went with a new strut, shaft (.250 cut down to .187), shaft tube and prop (452 Octura) which was a perfect match for the stock ESC. I ended up using a swordfish 300A esc because I wanted data recording capability but i think the stock ESC would have worked with the current setup. The previous running gear was horribly out of balance and came with a 60mm prop which would have definitely pulled more amps and probably resulted in overheating or a melt down within a few runs on 8S. The new setup is using a .250 shaft cut down at the end to .187 and a balanced and sharpened 452 Octura prop. If anyone likes data, here is a picture of the graph when powering the Swordfish with an 8S2P 12400mah setup. Overkill for sure, but fun none the less.

Data run on 09132014.jpg

Also, I really didn't notice an improvement in performance when going from 8S1P 6200mah to 8S2P 12400mah and the run times were only about 50% more because because of the increased amp draw (because of the added weight) so I'll probably just stick with 5 minute run times on the 8S1P configuration.

First run: (2 x 4S 6200mah batteries)
Pulling 133A max
https://www.youtube.com/watch?v=m-L7xo5WK2k

Second run: (4 x 4S 6200mah batteries)
Pulling 142A max
https://www.youtube.com/watch?v=B1Oe3oWh2Bc