Micro Hydroplane Build Attemp - RC Groups
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Dec 23, 2004, 12:16 AM

Micro Hydroplane Build Attemp

Hi everyone, i'm usually on the airplane side of this site, but since i'm waiting on some aircraft parts to arrive, i thought i'd try my hand at a quick boat.for those of you who have read my other treads i've started, you know i love SMALL..lol..i love the budwiser boat you see in the hobby store, but at almost $300, thats way out of my budget..after some searching i found some plans for a simi- scaled hydroplane i got from the internet. i took the plans and reduced it to a smaller size of about 7'' in lenght, as to the 12'' it called for...i will try to post as much build pic.s as i can. the framing will consist of plastic sheets. this is easy to cut out with scissors. so here it goes...any help from any of you would be greatly appreciated..tom
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Dec 23, 2004, 12:49 AM
Useful Idiot
That Hydromite must be the basis of a lot of boats. Some people may even have built it as drawn
Dec 23, 2004, 01:53 AM
here's another pic. of the hull assembled..martin yes it is..i'm doing it smaller though..it's a good plan and very simple to construct
Last edited by thailandboy2; Dec 23, 2004 at 01:56 AM.
Dec 23, 2004, 01:56 AM
now for the start of engine work and skinning..tom
Dec 23, 2004, 07:27 AM
Fly like you stole it .

Hydro Mite

yes I have built one per the plans amd it is a blast to drive. It has just a speed 400
Dec 23, 2004, 11:17 PM
airbatic, what did you use for electronic to steer and speed control? i'm still debating on what motor to use, i'd like to try using the micro-sizer car parts with a larger motor of 30,000 rpms but not sure how the range would work on this set up..any ideas? my boat is only 7'' long and about 3'' wide, not much room for space..
Dec 23, 2004, 11:23 PM
o.k. alittle more progress on the body. as you can see in the pic.s i have added the outter side skins and bottom. also i carved a quick foam cockpit for the little budwieser.. it still need alittle more sanding and some touch ups. next i'll add the rudder and spoiler..
Last edited by thailandboy2; Dec 23, 2004 at 11:30 PM.
Dec 24, 2004, 12:27 AM
Useful Idiot
For the prop tube and rudder, unless you can adapt parts from an existing toy boat, you will have to make your own. I think the rudder details are shown on the plan. A 280 size motor is probably a better choice than a 12 V car motor, as getting 10 cells to fit would be difficult. Another option would be to use a servo motor with the electronics serving as a speed controller. A micro receiver and servo may just fit and would be a safer choice than the micro-car type for range.
Jan 10, 2005, 06:49 PM
Registered User
For prop shaft have a think about using brass tube and stainless steel bowden cable (bicycle brake cable)... This will allow the prop shaft to be bent in line. It's easier if you have a lathe to make the parts, but can be fashioned using a mini drill.

Jan 11, 2005, 01:48 AM
Useful Idiot
Here's a very bad image of something like Joules mentioned. The threaded part is a brass M4 screw with the head cut off and about half the threaded length filed down to fit into a 4 mm od brass tube. The cable is 2 mm stainless steel, fitted into the same tube with the help of scrap pieces of brass tube. The outer tube is notched for better lubrication and the set up has been used successfully with a speed 400 motor, with no signs of the epoxy adhesive failing. Using the 2 mm flex allows standard Graupner motor couplings to be used.
Jan 24, 2005, 07:26 AM
Purdue Engineering
Rocketman1092's Avatar
Where did you get the plans?
Feb 10, 2005, 12:59 PM
Maker of Sawdust
forresterace's Avatar

Hydromite plans

The Hydromite plans are available on two different websites-



The original hull size as designed is 16.5" long.

You are right, I have heard of just about every imaginable size variation of the Hydromite being built - from 7" up to a 44" gas-powered giant.

The biggest part of the problem in building a down-sized version is not finding a suitable motor, batteries or even driveline hardware. The toughest part is to find a suitably sized prop that will work efficiently as a surface prop. Once you go below 25mm diam. (even if you could find one), the efficiency as a surface drive would be dismal. You could always try to solder one up out of brass.

Good luck.

Doug Forrester
Forresterace Designs
Feb 13, 2005, 02:21 PM
Useful Idiot
You could try the Graupner 26 mm carbon props, which are threaded for 2 mm drive shafts, They can probably be worked down to 24 mm. Beyond that the only alternative that comes to mind are the many reduction gearings available for 280 size motors.
Feb 15, 2005, 04:52 PM
Registered User
beanoman's Avatar
Forresterace is absolutly right. the hardest part is getting the right prop. the only place i have found for decent, cheap props is from toys. for 10 to 20 dollars, you can pick up a toy r/c boat with two small props at walmart or toys r us. obviously they will also come with small motors, batteries, simple charger, and a reciever, although they will not be propo.
i am building a small boat also. it is five inches long, and a landing craft, so its quite boxy. it uses a 7mm motor, and is slightly overpowered.

for the seven inch hydromite, a 280 is a bit big, i think. if you are going to use a propo system, get a hs-81 servo, and use the motor and board from that. look here: http://www.geocities.com/patsmodels/lcm3/ you can see that two of those are powering a box, erm, landing craft more than twice as big as your racing boat. i would say a hs-55 for your rudder. i dont really know what you would want for your rx and batteries.
Feb 19, 2005, 08:45 PM
Registered User
Following this thread I'm now building an 11" Hydromite, I've already built an 18" one for EDF but never got the motor setup right... I've got most parts sorted out for this micro but I don't know what to do about the prop. My gear is:

Motor: Speed 280
Battery: 7xAAA Mi-Mh (800mAh, 5A)

I had the perfect prop from a Keil Craft Whisper kit but it threw a blade when I was trying things out for this boat. What I don't know is whether I should take something like a 29mm Graupner prop and trim it down, hunt for the right toy boat and knick it's prop or try to build my own.

How hard is it to make a prop that works well enough for a surface drive? What would be best to cast a prop with? Would bending a sheet of brass and sandwiching it between two bolts be sufficient???

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