MHZ 54" catamaran help needed

[Toberi]

Had plenty different rc boat up until today. No pro stuff at all but having a proper interested. Setting up a "winter project" by puttning together a complete boat by myself for the first time. Bought a 54" mystic c5000 catamaran hull to start with. Now I'm investigating what motors i will use. I calculated i will need 2 pcs 300A ecs and MHZ is recommending me to buy their motors Scorpion 5035 760KV-7,4KW. Are really outrunners a good choice on this boat I'm building? I would need some help from some more experienced people please...

/Tobbe

[jkflow]

Motor really depends on what you want to run, how many cells 6S, 8, 12S?
Sounds like 12S with that kV rating. Any ~700kV rated motor will be fine.
What is your main goal? SAW type or just for fun?

I'd check this site for motors and ESC options, https://www.offshoreelectrics.com/
or just click on 'store' above

[Toberi]

Hi jkflow! Appreciate your effort in my struggeling... Naa I just like playing around, it's just for fun. I love torque more than top speed even in the same time it's cool to make a real brutal top speed rip. Yes my plan was 10s to 12s. I just bought ZTW SEAL BL ESC 300A that can run take 14s. The Scorpion outrunners that MHZ recommended me can do 12s tops. My tiny experience tells me the outrunners would be ok for the torque and also get me enough top speed. Several friends had some bad experience with cooling on the their outrunners, but that is quite long time ago. Maybe there is better stuff on the market nowadays? My main concern is that I can't find a single person or a Youtube video showing this kind of boat with outrunners. Just want someone to hold my hand before buying the motors hahaha. Feel like a complete newbie, no one to ask...

[Panther6834]

Still a newb where RC boat building is concerned (have built PLENTY of land vehicles)...but, personally, I stay away from out runners on everything except crawlers & drones. Cooling motors in a boat is MUCH easier (and better) with (traditional) inrunners.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Toberi]

Hmmm this is exactly what I was thinking. I'll stay away from the outrunners in boats...
Tnx for fast reply!!

[fweasel]

TP 5660 888kV, ZTW 300A V1 ESC, 10-12S is a good setup for a fast MHZ 138.

[Bande1]

ose had a discount sss 56123 500kv for $159. its rated for 9000w continuous. that'd be my choice. run 3 blade gas props on 10s-12s like a 2517 or so. big motor also helps balance the hull from a 12s pack. flier 400A esc.

[Bande1]

heres the motor

https://www.offshoreelectrics.com/pr...s-56123-v1-500

[Toberi]

Great input both of you, now I have something to dig into!

[vvviivvv]

Are you building a twin or a single? A 56123 is a huge motor and has no place in a mystic 138, 12s is also going to be a fair squeeze in a 138… if running 12s/ motor…

Motors 2/3 the size of a 56123 can push a 138 hull to 120+mph.

[Toberi]

I bought 2 pcs ZTW SEAL BL ESC 300A, supposed to end up a twin. You still think TP 5660 888kV can be a good choice? I'm more in to aggressivity than absolute super top speed, but of course I want a real descent top speed...

[fweasel]

The TP5660 888kV in a 138 on 12S is a known 110+ setup with an aggressive prop. Dropping down in voltage will tame the speeds. 56mm motors will have plenty of torque for hole shots and rapid acceleration of that's what you mean by "aggressivity". Be sure to use 1/4" flex cables and quality collets. The MHZ mystic hulls handle like wet dish rags until they're on plane and moving on top of the water, so a build like this will be best suited for longer straight passes, weather you're breaking the sound barrier or not.

[Toberi]

Thanks fweasel for your input! Hahaha yes aggressivity meaning hole shots etc, in lack of a better word. Wet dish rag...
Sure I can find a nice 56 mm inrunner!

[Panther6834]

The MHZ mystic hulls handle like wet dish rags until they're on plane and moving on top of the water, so a build like this will be best suited for longer straight passes...

Not trying to hijack Toberi's thread...so, of you prefer to answer via PM, go ahead (tho, I suspect, others reason this thread, and my question, might be 'interested').

If the MHZ Mystic is best suited for SAW, what large-scale cat hulls would you suggest/recommend for a twin "just for fun" pleasure/bashing boat? In other words, something with a strong/sturdy enough hull that can handle higher speeds (tho, it would never be used for top-end speeds), but is also designed to be highly maneuverable (ie. turns in both directions equally well, whether the turn is 'gradual', or somewhat (but not necessarily 'extremely') sharp?


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Toberi]

Hmm do I hijack my own thread by also asking? Good question... I live by the sea, not a lake. The small experience I have is the catamaran hulls is way better due to wind and waves, good stability. fweasel have a point on the instability on the flying part when it's actually in the air, I also had some experience on that. May it rest in peace...

[fweasel]

Catamaran hulls do not handle better in the wind and waves vs. a V-bottom mono hull. Cats hulls ride on a cushion of air with less hull is in the water, which is why they are faster than V-bottom monos and don't require as much power to push them along. The downside is that they are susceptible to blow overs, which can happen with too much speed, incorrect setup, or windy conditions. Waves, forget about it, cats don't like waves. V-bottoms do a better job of cutting through rough water and have less issues in wind.

I wasn't trying to start a debate about cats vs. other hulls. My main point was that the MHZ mystic cats in particular are a real handful to steer until they're up on plane and running on top of the water. Plenty of fun can still be had with one, even if it's not running on the bleeding edge of SAW performance envelops.

My favorite cat hull for just general use is a single or twin motor 34" TFL Cheetah. That boat turns on a dime, sometimes too sharp if you're using too much rudder throw or too long of a rudder blade, and handles rougher water favorably, within reason.

[vvviivvv]

Not trying to hijack Toberi's thread...so, of you prefer to answer via PM, go ahead (tho, I suspect, others reason this thread, and my question, might be 'interested').

If the MHZ Mystic is best suited for SAW, what large-scale cat hulls would you suggest/recommend for a twin "just for fun" pleasure/bashing boat? In other words, something with a strong/sturdy enough hull that can handle higher speeds (tho, it would never be used for top-end speeds), but is also designed to be highly maneuverable (ie. turns in both directions equally well, whether the turn is 'gradual', or somewhat (but not necessarily 'extremely') sharp?


~ More peace, love, laughter, & kindness would make the world a MUCH better place

Tbh, a mhz mystic corners a lot better than a hpr, build it light and it will handle a lot better.

[Panther6834]

Tbh, a mhz mystic corners a lot better than a hpr, build it light and it will handle a lot better.

I was actually asking/hoping for multiple models to be suggested...but.....

My favorite cat hull for just general use is a single or twin motor 34" TFL Cheetah. That boat turns on a dime, sometimes too sharp if you're using too much rudder throw or too long of a rudder blade, and handles rougher water favorably, within reason.

Thank you...that answers my question. And, truth be told, the Cheetah is something I was already thinking, and considering...albeit as an eventual replacement for my Skater X2. At the same time, my previous question was in hopes of finding something larger...essentially, something 'like' the Cheetah, only longer & wider (ie. a "scaled-up" version in the 45-50" range, that is equally wider).


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Peter A]

Thank you...that answers my question. And, truth be told, the Cheetah is something I was already thinking, and considering...albeit as an eventual replacement for my Skater X2. At the same time, my previous question was in hopes of finding something larger...essentially, something 'like' the Cheetah, only longer & wider (ie. a "scaled-up" version in the 45-50" range, that is equally wider).

There is a Cheetah XL.

[Panther6834]

There is a Cheetah XL.

I had forgotten about that. Toberi, this is the answer to both of our questions. Whereas, most race catamarans have a length-to-width ratio of 3.5-4:1, and SAW cats can have a tail as high as 4.5:1, the Cheetah XL (at 39.75") has a wider, more stable, 2.66:1. By comparison, the DF Explorer 36 is 3.34:1, and the TFL Genesis is 3.79:1 (forget any of the hills from KVA...as I understand it, they're definitely on the "heavy" side).

I don't know why...but, for some reason, I still want to try building a twin jet-drive cat...just haven't found the 'right' hull.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Bande1]

best handling cats
rico hulls
AC hulls

[srislash]

best handling cats
rico hulls
AC hulls

Particularly the R42. Handles rough water very well and very predictable. This is mine with custom hatch
B5A393E9-1DE5-40EF-82BC-A7D2841F60C4.jpg

[srislash]

Hmm do I hijack my own thread by also asking? Good question... I live by the sea, not a lake. The small experience I have is the catamaran hulls is way better due to wind and waves, good stability. fweasel have a point on the instability on the flying part when it's actually in the air, I also had some experience on that. May it rest in peace...

If you are looking to battle in the rough seas, one would target lower speeds (30-40mph). So say build a 12s boat and run it on 6s on rough days. On nice calm ones you can rip it up and on rough you can play, and likely with a real good runtime. As long as 6s jumps it up on plane you’ll be good to go without having to worry about hitting the throttle to hard and blowing it over.

I have a couple boats setup in this manner

Shawn

[srislash]

Not trying to hijack Toberi's thread...so, of you prefer to answer via PM, go ahead (tho, I suspect, others reason this thread, and my question, might be 'interested').

If the MHZ Mystic is best suited for SAW, what large-scale cat hulls would you suggest/recommend for a twin "just for fun" pleasure/bashing boat? In other words, something with a strong/sturdy enough hull that can handle higher speeds (tho, it would never be used for top-end speeds), but is also designed to be highly maneuverable (ie. turns in both directions equally well, whether the turn is 'gradual', or somewhat (but not necessarily 'extremely') sharp?


~ More peace, love, laughter, & kindness would make the world a MUCH better place

A bit of a flat ride pad would help slow maneuvers. Hydro&Marine may have something, and MHZ has other offerings.

[Panther6834]

A bit of a flat ride pad would help slow maneuvers. Hydro&Marine may have something, and MHZ has other offerings.

My question (which the Op was also interested in) wasn't about building a "slower" cat...it was about building a more "stable" cat, which would also allow it to be more maneuverable.

Bande1 mentioned hulls from Rico & AC, to which you referenced the R42 from AC. After checking them out, as well as some others, I'm thinking either AC hull, as well as the M-1 Supercat XL from H&M are better choices than the Cheetah XL. I like that both AC hulls have a wider length-to-width ratio (ie. more stable) than the M-1...but, I'm now familiar with H&M's superior quality (H&M hulls are among the best you can buy), whereas I know nothing about AC.

At the same time, a 50"L x 17.3"W cat is longer than most anyone might want. I need more info on the R42, so I've emailed them. Bande1, if you're interested, once AC replies, I can PM you the info.


~ More peace, love, laughter, & kindness would make the world a MUCH better place

[Bande1]

AC hulls pretty much sweep the gas cat class in racing.