head of the river cat hull thread

[bustitup]

In my opinion dont even think about 7xl's you are asking for HEAT problems
If your are commited to Feigao use 8 or 9xl or something in the range of 2000kv to 2100kv if you are using 4s on each motor

I started my twin drive build yesterday. Going along the lines of Killerdave`s build with 2 4cells lipos and octura X442`s (counter rotating) but with 2 7XL motors.

Got the outdrives mounted (from tough racing) and then found out I`ve bought the wrong size stuffing tubes - awesome!

I haven`t got the esc`s sorted yet but I might go for 2x himodel 200amp(modified with water cooling). I already have an ETTI 150 (which is easily the best esc ever owned) but its cheaper to buy 2 himodels than one more of these.

And now I have a question, there are 2 types of himodel 200amp esc. The 4-8cell version with bec and the 3-7cell version with no bec. I have already fried one of the first type (which ran very hot even with water cooling at 118amps) and have another one ready to try. Is there any reason why the 3-7cell version might be better, I`ve noticed that quite a few people use them?

[Simon.O.]

My cat is only a bit bigger than the HOTR and i have a single 7xl on 4S to a Graupner carbon K40, similar to a x440. That is plenty enough power to send this hull nuts on the water.
Twin 7xl's would be a lot of overkill for the hotr. Doable but not advisable.
Graham D has the 36"Jolly and said it was insane on twin 8xl's and now has twin ammos to 442's
If I were to twin my cat or indeed a hotr i would look to SV motors or even L size cans.
Twin XL's is a lot of weight and a lot of power.

Your boat, your money and your call.

[lomdel]

You guys doing twin HOTR builds. Please post some pics of the motor-mounts....

[bustitup]

You guys doing twin HOTR builds. Please post some pics of the motor-mounts....

Lexan

https://www.rgcbuilders.net/mar8.jpg

[Alfa Spirit]

My FSD Shenzhen Feisuda Electrical Machinery 540 XL

http://www.5imx.com/shop/5imx-product.asp?productSort=369

[ray schrauwen]

Thats a 6XL wind. I would go to 5mm plugs for the Amps they will pull. Plus the soldering job on FSD and other chinese motors is not so good...

Running 3S or 4S?? 4S would be quite a hot setup depending on props...

[ray schrauwen]

You guys doing twin HOTR builds. Please post some pics of the motor-mounts....

HOTR sells a mount just for mounting twin cat motors, in 380 size or 540 size. They are made so you can get the motors out easier than what you see in Lexan.

For the price, they are a steal.

[Simon.O.]

Thats a 6XL wind. I would go to 5mm plugs for the Amps they will pull. Plus the soldering job on FSD and other chinese motors is not so good...

Running 3S or 4S?? 4S would be quite a hot setup depending on props...

IF that is a 6XL I would not advise that as a good motor for this Cat.
I have a 6Xl in my rigger where low wind motors are just ok.
I have a 7XL in my cat that is a little bigger than a hotr and would really rather have a 8XL but the 7 is what I have.
A 6XL in this cat will be a grenade on anything above a X440, you are welcome to try it but not with my packs and esc.
If you are buying from new then go for a 8xl as a minimum.

For those looking at twins in the HOTR, twin XL cans is a waste of money as far as I can see. Go with a pair of L cans or a pair of AQ SV27 setups to 442 CR props.

[Rull]

yea
I'v decided to use double 540L motors with 10 winds on 4S li_po or 11 winds on 5S LI-po. Of cause Octura 442 L and R props.
I will add holes to front and rear lid to avoid demagnetization.

[tomstoys2]

Seems like a lot of twin cat builds. I'm going to be building one this winter as well. Just received my MHZ 840mm(33") Mystic hull. Went with the Carbon/Kelarl. I have been struggling as well with what motors to use. Based on the size of this hull, battery placement will be tricky. I'm not looking to build a record breaker. Not going to race it, just for fun and show. A lot of the time I won't have perfectly calm conditions. I would like to run 2-4s but I don't know if 2s each is possible. Based on some recommendations, I am leaning twards twin 540L 11L or 12L motors. I was thinking Etti 150 Navy's. Better to go overkill with the ESC's right? I was also concidering the Seaking 180A's but I'm not sure if it's worth it to save $100 at this point. I figured I could always upgrade motors. Most of these items will be Christmas gifts as well.
I'd like to run 2s's for each sometimes but I don't know if that's going to pull to many amps.
I'll post some pictures of the hull this week. I love the lines of the Mystic.
Went with the MHZ outdrives as well. I parted with a lot of toys to save up for this.
I know this is a HOTR thread but I think the hulls are similar enough for a comparable twin build. I start a new thread soon for the Mystic.

[Simon.O.]

540L size is the right way to go.
2S will not give you the power you need unless you have insane amps. You will need to go 4S or more per motor.

As for ESC you can easily go with the mystery 200A units, I use them and they are fine if they stay dry. Depending on your loads you may even get away with 100A per side.
A 10L on 4S to a 442 setup as twins should draw around the 100A mark.
150 or 200A esc will give you plenty of headroom.
A 11L is even lower and will deffo be fine on 100A units.

I know Graham.D. has 100A xpowers running his ammos on 442s in his 36" Jolly and that thing hauls.

[Rull]

Guys
when you make reinforcement of hull what damage you want to avoid? What place of hull may be broken? Is it area of motors mount?
At the weekend I thinked to lay a few layers of fiberglass. But desided that new leyers will not good glued to old layers. So I may simply add some weight without true reinforcement.

[Tuslow1]

Hello all, I've been trying to read this thread but the kids and wife have proven to make it totally impossible to read 19 pages of anything. I wanted to read the thread to avoid asking repeat questions. So could you guys give me a quick overlook on the best backyard pond setup???
So far I have the hulls coming, 2 of them.
I'm waiting on Steven to get in the black inline strudders.
I'm wanting to go 8XL, 4s2p with a X640 and X642 props.
what I'm looking for is what is the amps on these setups because I'd prefer to have 120 Hydras over the China 200 models but don't know if the amps will blow the 120's and what kind of speeds can I look foward to? I'm wanting atleast 50 mph and 5 to 7 minutes of funtime.
Thanks for any and all replys...

[tiqueman]

According to FeCalc, On a Hydra 120, 4S2P 8XL, your over Esc amps on both props. With that said, it was in the low 50s. Maybe a 9xl w/ that esc. But even still, on a 642 your pretty close to max amps. And mid/ high 40s. Again, this is FeCalc info, dont shoot the messenger.

Oh and run times on the 8xl were just under 5 minutes... 9xl +/- 6 minutes

[ozzie-crawl]

for that speed and run time i would look at a 6s 1p setup