HPR C5008 185cm prop size dilemma... Any suggestion???

[PETERPAN]

I just recently bought a HPR C5008 185cm all carbon fiber hull from Switzerland and yes it did cost me an arm and leg but what is a guy without toys???? This bad girl will be powered by 2 Lehner 3060/10 and 2 12S/3P 4000 Lipos. I'm kind of new to RC power boating so I'm having a dilemma on which prop size to use as my "starting point prop". I know every boat has it's own "favorite prop" so I wanted to use my starting point prop as a guide to finding the favorite prop. Ideally I want to go with a 3 blade but I'm totally lost on diameter and pitch. Anyone familiar with big euro cat please help?

[Boaterguy]

I don't know how well a 3 blade will perform on a twin cat. You could go with 5 Bladers for a scale look, but two blades will be your best bet.
I don't know good dimensions for props, someone will most likely be able to help

[ManuelW]

Hello Peterpan,

when I read what you write I would not think about props but about getting enough flotation. Imho 12S3P per engine is WAY too much for the boat. Normally a 12S1P 5000mAh 40C Lipo is enough, for longer runtimes maybe a 12S2P 4000mAh Lipo is okay but 12S3P is an overkill.

Best regards,
Manuel

[johnson22456]

Octura x457 right and left should put you where you want to be as far as speed goes. You could start with a x450 r&l but that's probably not enough prop for a cat that size. You could have a set of x457s cut down to 55mm or so. The only bad thing about twins is your limited by what props are available. Abc has some bigger props with higher pitch you might want to look at also.

[ManuelW]

maybe most important question is: how fast do you want to go?
LMT 3060/10 on 12S is not a really hot setup in my eyes, still enough power to achieve some serious speeds. And which ESC's do you want to use?

best regards,
manuel

[PETERPAN]

Thank you Boaterguy!!!

[PETERPAN]

I apologize for the slow reply. Been very busy with work. I will follow your advice and go with 12S1P or 12S2P lipo. I'm also about to purchase some props from the Prop Shop. Do you have any recommendation on prop size and pitch? THANKS AGAIN!!! Say hello to Hanspeter for me!!!

[PETERPAN]

Fast as possible... with all the money I already invested into this project my as well go crazy!!!! What is a hot set up to you??? Like I mention before I'm very new to power boating so I'm kinda lost I see a lot of ppl using scorpion brushless motors. Is that a better choice? I'm planning to use Schulze fut-xxl-40.333WK.

Best Regards,
Peter

[PETERPAN]

Thank you johnson22456. I will take your advice seriously in consideration. How about 3 blade props? Thanks again!!!!

Best Regards,

Peter

[LarrysDrifter]

The props Johnson suggested are 3 blade.

[PETERPAN]

Thanks LarrysDrifter.

[6BOOST]

Hi Peter,

I am in a similar position to you having just purchased a 67" MHZ Mystic and being relatively new to rc boating (coming from gas cars), I would have liked a HPR but after numerous emails over 2 weeks with no reply I gave up. Anyway the 3060/10 is a 700kv motor, so 12s is only 31000 rpm, which imo is low unless you just want to do some sport boating, it is however far below the capabilities of these motors and the video's you see of guys doing upwards of 165klm are doing 40-50000rpm. another thing to keep in mind is that the lower the voltage, the more the amperage, the higher the voltage the lower the amperage. So those motor's propped up hard might pull 300 or so amps on 12s, and 150 amps with the same load on 24s, much less heat. 60000rpm is too hot for your application, but you get what I mean.

I would be looking at something between 15 and 18s, I have gone with 3s batteries for my LMT3080/7's (similar kv) so that I can step up in 7500rpm steps from 15-18 and 18-21 for saw purposes. This will bring your heat down and your speed up and put less strain on the esc's, if you were on 18s with 46000rpm and 9000 watts of power draw your only looking at 135 amps, this brings your battery requirements down to 5000mah 1p 45c, you could even get away with less for short run times, but 5000 would give you decent run times, similar to running 5000 2p 45c at 9-12s, similar total battery weight, more rpm and speed, less heat, win/win =P

As far as props go the 457's will probably be ok but maybe start with 50's and work up. For the amount of money you have invested some data logging might be a good idea like eagle tree or similar, it's only about $400-$500 tops for a decent amount of sensors and full system to keep an eye on temps, rpms and they have just released a 300amp sensor as well. Any good prop guy out there like Andy Brown or similar can cut down a 457 for you if you need something in between a 50 and 57, I'd get on the water with a 50 and get used to it and then see how your temps and speed go.

Best of luck with the build and happy boatings=)

6BOOST

[6BOOST]

Forgot to add that naturally you need a esc that will handle high voltage, there are a number of them available these days, swordfish and fightercat do some, the fightercat ones have a 200a 16s already released and a 24s 200a on the way.

6BOOST

[ManuelW]

Hello,

seems as I need to write a bit of a longer post.

@boaterguy: Please don't get me wrong at all but as far as I read your posts up to now I'm not 100% sure if you should try to give prop recommendations on such a FE setup in a 185cm Mystic. These things are no toys anymore and a little mistake or wrong recommendation can cost quite a sum. This means by giving recommendations you also have a certain responsibility in my eyes. PropShop 5 blade props look nice but I wouldn't recommend them at all except for display or show purpose. At the moment 3-blade props is the maximum I'd run on the boat.

@ PeterPan:
As far as I understand you already have the LMT 3060/10 engines at home? When used with 12S Lipo each you'll get around 31.000rpm at a maximum efficiency of nearly 96% at 170A, resulting in a power output of 7500W. This means enough capabilities for your boat, with an Octura X457 prop which should be fine you should be driving a bit over 130km/h. For higher speeds this setup won't have any problems later on using 2x 13S Lipo which should give around 140km/h. Another setup idea would be maybe a 3060/9 on 12S1P 5000mAh 40C per motor. With the X457's you could be around 145km/h. The Schulze 303/333 is a good ESC but quite high priced and also heavy. If possible you could also try to get a pair of Schulze 40.160's of the old series, they should do the job quite successfull. For the Scorpions, the 5035 MHZ Edition is quite fine but you may get troubles with the 240A Swordfish when using more than 10S or bigger prop. But this is just what I've seen from others, I've never tried them. For further contact you can also write me an email!!

@6Boost:
A MHZ CT04 with 2x 3080/7 and 18-21S lipo for SAW purpose.... PLEASE could you be so nice to take a video of the test run? I'd also consider to take at least 2-3 big garbage bags to the lake, you might need these

And as a general recommendation:
Please be aware of high-voltage or careful. 12S lipo is okay, 14S lipo is hard on the edge but I think with more than 14S you may just play with your life. A 16S set of charged lipos can be around 67V, wouldn't recommend or try to touch both poles at the same time. If someone really knows what he does this might be okay to take the risk, but as a general recommendation?

Best regards,
Manuel

[6BOOST]

Sorry Manuel, I was obviously too blazé about running higher voltages, and assuming someone with a boat worth more than $10000 would educate themselves as to it's running and safety, I guess it's something I took for granted in posting having an electrician as a father.

I Will post video's of all my projects when I get more time away from work, having only had 4 days off this year including weekends rc comes second. Engineering 2000+hp fuel injected turbo race cars from scratch in house, I can assure you that nothing will be coming home in garbage bags, not every "noob" is incapable of those things that most only dream of

6BOOST