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HK gas engines for speed boat ?
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Dragevo View Drop Down
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Posts: 527 		  Quote Dragevo Quote  Post ReplyReply Direct Link To This Post Posted: 28/Dec/2009 at 10:24pm
Thanks for the ideas, guys. Smile
 
My next big concern is the power transfer. I'm thinking that a rubber/timing belt w/sprockets could work to run & gear up the prop shaft ?
 
Have a look at this cool boat : http://www.youtube.com/watch?v=NV9NdVwoCMI
 
The red tubes we see, are those for cooling ?
 
Edit : It seems that boat has a gearbox connected to the engine shaft. I wonder if those two prop shafts are counter rotating...? Should they be ?
 


Edited by Dragevo - 29/Dec/2009 at 1:22am
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Icepic View Drop Down
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Posts: 52 		  Quote Icepic Quote  Post ReplyReply Direct Link To This Post Posted: 30/Dec/2009 at 5:48pm
Jep the red tubes are for water.
Jep counter rotating props make it easyer to trim the boat.
The ebay offer looks like a cool homemade 52 ccm twin for a powerboat.
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Posts: 527 		  Quote Dragevo Quote  Post ReplyReply Direct Link To This Post Posted: 30/Dec/2009 at 11:32pm
Originally posted by Icepic

.
The ebay offer looks like a cool homemade 52 ccm twin for a powerboat.

 
 
Yes, cool - but kind of heavy. Ebay seller told me it weighs in at 6-6.5 kgs. Too much for my project, I'd rather go with two 26 cc's - at around half the weight.
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Posts: 254 		  Quote Mattyc Quote  Post ReplyReply Direct Link To This Post Posted: 03/Jan/2010 at 2:43pm
if your not worried about out and out speed then Get a single RCMK s254 evo and direct drive it dont mess around with gear reduction or clutches they only add complexity and more things to break. you will probably get 65-70k to a big mono with one engine if you keep the boat light and set up your surface outdrive properly

Twin motors i would advise against unless running counter rotating motors as the prop torque will make the boat handle like a pig

if you want a bit more pace you can get left and right rotating RCMK r254 engines.

I would not personally bother converting the aircraft engines in this day and age as the carbs are metered for lower rpm and the port timing is normally not optimum for boats as the aircraft motors run in a much lower rpm range with a canister style muffler. by the time you muck around watercooling it getting a tuned pipe, finding a collet to fit it, engine mounts etc you might as well have bought a purpose built motor - ie RCMK s254 or r254 or zenoah 260

the  Evo is Watercooled and made for the job 26cc and 5.03hp out of the box, put a QD hot pipe on it and bobs your uncle.

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Edited by Mattyc - 03/Jan/2010 at 2:51pm
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Posts: 1956 		  Quote Mustang Sally Quote  Post ReplyReply Direct Link To This Post Posted: 03/Jan/2010 at 8:38pm

I am  sure that HK could get us this:

 
Or this:
 
or a Turnigy version and at a reasonable price.
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Posts: 527 		  Quote Dragevo Quote  Post ReplyReply Direct Link To This Post Posted: 05/Jan/2010 at 10:53am
Thanks for the input, guys. I'd be happy to save weight, time & money on using direct drive engines.
 
So, I'm considering these engines now - which seems to be the same as those M.Sally linked to :
 
 
 
 
EDIT : Is this one worth considering ? :
 


Edited by Dragevo - 05/Jan/2010 at 12:16pm
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Posts: 254 		  Quote Mattyc Quote  Post ReplyReply Direct Link To This Post Posted: 05/Jan/2010 at 4:45pm
those motors are ok personally id buy the rcmk, like i did

http://cgi.ebay.ie/RCMK-S254-EVO-26CC-MARINE-BOAT-ENGINE-MOD-CYLINDER_W0QQitemZ350293497105QQcmdZViewItemQQptZRadio_Control_Parts_Accessories?hash=item518f1e9511
my 1.2 meter catamaran does about 55 mph at the moment and im still running the motor in using this motor.

the RCMK is a high performance race engine. The CY is good, but the RCMK has more power and is cheaper. the  CRCCPro is a chinese copy of a zenoah and only uses a 2 bolt cylinder.

the CRCCpro looks ok, but personally id stay away, go for the RCMK or the CY.

for instance - the RCMK evo here doing 72mph in a whiplash hydro http://www.youtube.com/watch?v=NcNZHmgmIeA
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Dragevo View Drop Down
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Posts: 527 		  Quote Dragevo Quote  Post ReplyReply Direct Link To This Post Posted: 05/Jan/2010 at 11:33pm
Thanks, Matty - it seems you know what you are talking about. Smile
 I will seriously consider those RCMK's.
 
While we're at it : How hard would it be to make an 'inliner' from two of those rcmk's ? What kind of coupler/connector is used to make the two come together in to one ? Are there other issues, as sync ?
 
Thanks.
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Posts: 1956 		  Quote Mustang Sally Quote  Post ReplyReply Direct Link To This Post Posted: 06/Jan/2010 at 6:36pm

I think the idea is to have two outputs with two propellors in stead of a single driveshaft.
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Dragevo View Drop Down
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Posts: 527 		  Quote Dragevo Quote  Post ReplyReply Direct Link To This Post Posted: 07/Jan/2010 at 4:53am
It seems that depends on who has got 'the idea'... Wink
 
This inliner has one output/one prop. Looks fast, and seems to be handling well. I guess a setup like this uses a bigger prop than a boat of the same size w/two shafts & props. I sure would like to know which setup is the faster one.... Smile
 
 
 
When it comes to hulldesign, I have the impression that outriggers are faster. The downside is that they don't look 'scale'.. So, I'll probably go for a cat.
 
Here is a 1.8 m cat w/ 4 Zenoahs (at least that's what the title says...)
I'm thinking it must be on the heavy side...?
 
 


Edited by Dragevo - 07/Jan/2010 at 4:55am
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