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Sep 04, 2019, 10:44 AM
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Jansvast's Avatar
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I have installed the rudder today! She looks fantastic. I also applied one last coat of resin around the seam, with the rest of the boat masked off. I really like how she is coming together. Im now waiting for the 3100kv motor (rated for 17v and 45a), 70a flycolor esc, program card and a cooling jacket.

Will a 4mm Flex shaft be an overkill?.

Jan
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Sep 04, 2019, 01:35 PM
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Jansvast's Avatar
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Look at that beautiful flex shaft assemby i found! It comes with a strut, prop, stuffing tube, teflon tube and a hydrodynamic nut too! And for just 24$! Nice!

https://m.aliexpress.com/item/328648...Q1567621650562
Last edited by Jansvast; Sep 04, 2019 at 01:51 PM.
Sep 04, 2019, 02:48 PM
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Bear in mind that uses a 2 piece shaft assembly & maintenance is not so easy as a 1 piece flex shaft. With 1 piece shafts you simply undo the coupling & pull the shaft out for cleaning & re greasing which need doing often. The one you show you have to remove the strut assembly from the boat to get the flex out so you also loose any settings you had on the strut & need setting up each time, also to clean & re grease the stub shaft in the strut you must remove the prop & drive dog to get the stub out of the strut.
Sep 04, 2019, 03:13 PM
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Jansvast's Avatar
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Thanks for pointing that out! It is a deal-breaker for me... Luckily i found this

https://m.aliexpress.com/item/328616...Q1567627778474

https://m.aliexpress.com/item/400013...Q1567627545682

Some more items (so i can find them)
Coupler
https://m.aliexpress.com/item/330131...Q1567628469192
Last edited by Jansvast; Sep 04, 2019 at 03:23 PM.
Sep 05, 2019, 01:00 AM
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Jansvast's Avatar
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Im sure i have asked enough dumb questions in this thread allready, but i have 2 more

1 - what size of prop (2 or 3 blade)would suit this motor on 3s and 4s (im guessing something around 32 - 35mm, no idea abot the pitch)

2. Is it safe to run a 2845 3100kv on 4s (it is rated for 17v, a fully charged 4s is 16,8), or should i go for 2800kv?

I hope its not too annoying for you
Last edited by Jansvast; Sep 05, 2019 at 02:54 AM.
Sep 05, 2019, 03:01 AM
Boaters are nice people.
Hi Jan,

1) Props would be indeed in the 32-35 mm range, pitch 1,4, something like this:
https://nl.aliexpress.com/item/32993...chweb201603_53
As it's a metal prop, it needs to be sharpened and balanced, or the vibrations will destroy your bearings and rip the drivetrain apart!
If you don't want to do this, stay with plastic props.

2) The motor will run fine on 4S, but having over 50.000 rpm unloaded is a great strain on a budget drivetrain and the wear will be high, specially if the prop isn't perfectly balanced.
Even when the peak Voltage has dropped to 14,8V, you'll still have about 36000 rpm at the prop which is considered a lot.

Chances are the hull can't cope with those rpm and the boat will be undrivable, literaly.

As an example: I have a 50 cm stepped monohull which is powered by an ADS 400L 3700Kv watercooled outrunner, turning a Ų34,5 prop. On 2S I can barely run full throttle if the water isn't smooth, no ripples, turning 24000 rpm under load...
Offcourse I tried 3S too; the boat was undrivable, full throttle was impossible without flipping it within a few metres. This set-up ran 32000 rpm under load.

Your boat has a very steep deadrise, so even 32000 rpm under load will prove to be a challenge to keep it on the water.

Run on 3S, or get a lower Kv motor.

Regards, Jan.
Sep 05, 2019, 03:45 AM
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Thank you very much! That is just want i needed The prop shaft comes with a 32mm 3 blade, so i will try that first. I do not plan to run 4s regularly, im just curious to see how much power it would have. I will go with the 2800kv version, just to be safe. Its ordering time!

Regards Jan

Edit: id love to sharpen and balances a prop!
Last edited by Jansvast; Sep 05, 2019 at 03:58 AM.
Sep 05, 2019, 05:14 AM
Just Plane Nutts
AirDOGGe's Avatar
4mm dia. is a bit large for that boat. The 17' RTR boats run 2.3mm flexs and my 24" Barb XL and my similar sized infinitys use 3mm. 4mm will add a lot of unnecessary weight, and with the larger dia. prop shaft you may have less options of finding the correct prop sizes.


This low cost 2.3mm set-up with 3mm prop shaft from Volantex might be what this boat needs: https://www.ebay.com/itm/Volantex-V7...YAAOSwB3pbcq9h

This shaft/ stuffing tube assembly has to be used with this strut, which provides some useful adjustability of prop height and thrust angle: https://www.ebay.com/itm/NEW-Volante...75438be61caa3d


This is what it all looks like installed...pretty clean:https://www.pcmshop.com/17046-thickb...-v792-2-bl.jpg
Latest blog entry: My You-Tube channel
Sep 05, 2019, 05:28 AM
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Jansvast's Avatar
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I dont feel like a bit of weight is an issue for that boat. On Aliexpress i found a lot of smaller props for 4mm too, so that wont be a problem either. And yeah, i also like the look of the aluminium stinger i found Are you sure the volantex strut will hande 4s, too? The stuffing tube is stainless steel and pre-bent, so i cannot be sure it would fit well.

Thanks for reply anyway.

Jan

Edit: bought! Now we wait..
Last edited by Jansvast; Sep 05, 2019 at 01:08 PM.
Sep 07, 2019, 12:59 AM
Registered User
I personally would be running this hull on a 2s set up as anything larger will be an overkill.
Sep 07, 2019, 03:15 PM
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Someboby pls explain rules of weight ballancing boats like this mono hull. Or share link with information about it that will be greate.
Sep 07, 2019, 04:20 PM
Boaters are nice people.
Quote:
Originally Posted by SerfRider
Somebody pls explain rules of weight balancing boats like this mono hull.
https://www.rcgroups.com/forums/show...5&postcount=10

Regards, Jan.
Sep 08, 2019, 09:30 AM
Closed Account
Quote:
Originally Posted by SerfRider
Someboby pls explain rules of weight ballancing boats like this mono hull. Or share link with information about it that will be greate.
Monos need the cog to be between 28-32% of the length of the boat measured from transom , so its length multiplied by 28% = ... so for instance a boat of 32" would have cog of 8.96" that gives a cog of 28% .to get that cog you need to have all hardware on the transom and place all components inside and move things around to get the correct cog , also dont forget to test it with the hatch on . Once happy fix things in place .
Sep 09, 2019, 03:08 PM
Registered User
Quote:
Originally Posted by Apache Kemosabi
Monos need the cog to be between 28-32% of the length of the boat measured from transom , so its length multiplied by 28% = ... so for instance a boat of 32" would have cog of 8.96" that gives a cog of 28% .to get that cog you need to have all hardware on the transom and place all components inside and move things around to get the correct cog , also dont forget to test it with the hatch on . Once happy fix things in place .
Thanks! But what about left and rigth ballancing? I have seen more boats with esc and battery on one side. But if my mono doesnit have flip tank should i put same weight to the left and right side of hull?
Sep 09, 2019, 04:24 PM
Registered User
Boats use extra weight to the port side to counter prop torque roll, this is why you see some boats with the battery on the port side. This is also on boats that have no flood chamber, most boats that have a flood chamber also rely on the battery fitted as far over to the chamber as possible to assist with self righting & also counter prop torque roll.


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