Miss Canada III. New build log - RC Groups
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Nov 06, 2011, 12:12 AM
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Miss Canada III. New build log

I stumbled upon this Miss Canada III kit by Osborn Models at a swap meet a few weeks ago. The seller was firm on 50$ but after I researched what the kit costs new with my phone I decided to buy it. I knew nothing of Osborn kits or the full scale Miss Canada III. http://www.osbornmodelkits.com/httpd..._boat_kits.htm

Its been fun researching the history of Miss Canada III. You can read some here. http://www.thunderboats.org/history/history0410.html
The boat still exists and is on display at the Clayton Museum.

After I got the kit home it struck me as to how odd looking the Miss Canada III is but it represents an interesting period in the evolution of race boat design.

I've got about 4 hours into the build so far to get the boat basically framed up. 3 of those hours were just in getting the parts seperated from the sheet. Seems the laser didnt cut deep enough, only about halfway through the wood on that sheet. An exacto knife wouldnt cut it, I really needed a jigsaw to cut the parts out but dont have one, so it took a long time to remove each part. Holy arthritus that was a pain. Looks like most of the other sheets the parts will fall right off the sheet.

I glued the transom in upside down the first time like the dummy I am and had to cut it off and graft it back in place with some of the scrap wood and epoxy.
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Nov 06, 2011, 12:23 AM
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Also this is my first electric power boat, so I would like suggestions for power system.

I'd like a brushless setup, the instructions call for an .05 size motor. Whats a nice motor/esc/battery combo that will give scale performance but also have enough power to be exciting to drive? Thanks.
Nov 06, 2011, 09:35 AM
Boaters are nice people.
Hi Chris,

Welcome to the wet section!

Actually the instructions mention a motor ranging from a 05 to a 700 motor.
As you want to have enough power to be exciting to drive, I suggest you go with a 700 motor brushless substitute.

Prior to choosing a motor you'll have to decide if you're going for the scale (= subsurface) or surface drive hardware.

Subsurface means the max rpm is between 15.000 and 25.000 rpm, (the latter is very high IMHO), with a surface piercing drive you can go up to 30.000 rpm at the prop, again that's about the max I'd go for, more rpm equals small props and cavitation.

Next you need to know what Voltage you're going to use, this decides the KV of the motor.

Most brushless ESC's for boats that I know, have poor low end performance, meaning the motor will burst into life at about one third throttle, making pottering around an illusion and going in reverse a direct challenge not to submerse the boat due to the (too) high revs.

I have good experience with car ESC's, which are much smoother in the low end.
If heat build up should be an issue, the heatsink of these car ESC's can be replaced with a DIY watercooler made out of aluminium.
You'll need a drill press to be able to make it.

Let me/us know have more questions.

Regards, Jan.
Nov 06, 2011, 10:18 AM
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Thanks for the reply. After I found the kit, I bought the scale submerged drive kit from Osborn models for it. So I will be using that drive system.

Good to know about the marine esc's, I have seen what you are talking about with the low end not being very proportional. That was one thing the old mechanical speed controls did very well.

As for battery I am thinking of going with the old split 6cell packs or see if I can find a Lipo that will fit.
Nov 06, 2011, 02:30 PM
Spreckels Lake, GGP, SF, CA
craig_c's Avatar
we be watchin'
Latest blog entry: Ah, To be young again...
Nov 06, 2011, 04:55 PM
Boaters are nice people.
Originally Posted by vupilot
As for battery I am thinking of going with the old split 6cell packs or see if I can find a Lipo that will fit.
Just 6 cells NiMH isn't much in terms of runtime and performance if you're after
'scale performance but also have enough power to be exciting to drive'.

Most of my boats that size (and weight) are powered by 3S lipo at least, on 2S the boat will be rather sedate to drive.
4S will most likely give you issues with getting the lipo's in without compromising the CoG and with that the preformance.

What size prop was provided with the submerged drive?

A 36 mm outrunner on 3S KV from 1500 to 1800 with sufficient length (= torque) should be able to do the job.
If heat should become an issue, keep room for a watercooled motormount which will deal with the heat build-up.

Regards, Jan.
Nov 06, 2011, 08:06 PM
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Thanks, the drive came with an X431 prop.
Nov 07, 2011, 09:43 AM
SSMA #01M9382, AMA #137824
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I'm happy to see you get underway with this! Its going to be cool Chris!
Nov 07, 2011, 12:09 PM
Boaters are nice people.
Originally Posted by vupilot
Thanks, the drive came with an X431 prop.
Hi Chris,

I'm always struggling with that...; is the prop 43 mm in diameter, or 31 mm, or what?
Found it:
Diameter: 31mm / 1.22"
Total Pitch: 1.4x1.22=1.708
Shaft Size: 1/8"

That's a tiny prop for that size (and weight) boat, Surface drive props on my boats are 42 - 45 mmm submerged would be 34,5 - 40,5 mm.

My gues is that propsize is for a 05 motor, as a 700 motor will pull a 40,5 without any issues.

Use the X431 for testing purposes and replace it with a metal one once this one has shed it's blades.

Keep the propshaft angle as shallow as possible, the picture on the Osborn site of the boat doesn't look good to me, specially if you install 'enough power to be exciting to drive'...

With an angle that steep the nose will be pushed down when full throttle is applied, giving you an 'adventurous riding attitude' at best and an undrivable boat in the worst case scenario.

On a side note, the hardware doesn't look to great either, more for static display than fast running...(and quite expensive too...).
I'd consider replacing it with better quality stuff, up to the task.

Once you've installed it and the boat has been run a couple of times, the rattle of bad bearings is a sign you'll have to rip out the stuffing tube and replace it with better stuff,
Better install quality right away.

Regards, Jan.
Nov 07, 2011, 02:04 PM
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Thanks for the thoughts. Yes the running gear was a bit salty, being new to this I just wanted to have all the parts I needed and it to match the instructions. I was suprised more parts were not metal.
I'll keep the shaft angle shallow as I can, I was worried about that too from the pictures. Do you think I should just plan on a 05 motor instead of a 700? I'd rather it be slow than porpoise or stuff the nose down when running.
Nov 08, 2011, 02:58 AM
Boaters are nice people.
Hi Chris,

A 05 motor has the same diameter as a 36 mm outrunner (or an inrunner for that matter, but you'll have to add a cooling jacket on an inrunner, making it thicker).

So, you'll have to decide what motor to use in order to establish the propshaft angle.

Some motor suggestions:
Mild motorisation:
A bit on the short side for my likings and only 350W, which will work fine in a light boat your size.(Don't use the ESC that's in this deal, the motor is available seperately too).

I'm running this one in both my stepped Xcalibur and my nonstepped ARPRO on 3S, turning a 43,5 - 45 mm Graupner prop in surface piercing drive, giving me 6-8 minutes of runtime on a 3S 3300mAh Lipo, speed is in the 28 - 30mph range, power 500W:

I have this one still in the box, but it has a twice the Oompf of the previous two, but also a higher power consumption:

I run all my outrunners on a watercooled motormount like this:

Made out of a flat piece of 6 mm thick aluminum with a hole drilled through the top with pipes glued into it.

This is a car ESC that will give you the smooth response you'll want:

I don't have the ESC mentioned above, but I do have a couple from this series:
They work very nice and the heatsink can be replaced with a custombuilt watercooler replacing the existing one with the fan.
This makes the ESC better suitable for a boat, as it'll deal with powersurges better and it's smaller without the bulky heatsink and fan.
Should you go for the last motor I mentioned, refitting a watercooler is a must.

Regards, Jan.
Last edited by pompebled; Nov 08, 2011 at 12:25 PM. Reason: Addition.
Nov 08, 2011, 09:29 PM
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Slow but steady progress.
Nov 09, 2011, 10:13 AM
SSMA #01M9382, AMA #137824
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If you keep this up, you are going to have a boat!
Nov 11, 2011, 04:24 PM
Boaters are nice people.
Hi Chris,

Having seen the pictures of the bottom both in this link:
And in the other thread, I'd go easy on the power installed; the reason is the stepped hull, which draws air under it when getting up to speed.

Overdo the speed and the rudder will stand in a pocket of air, rendering it useless.

I had similar experience with my stepped testhull of an Italian MTB; running on a 05 size motor on 8,4V on a 1:2,3 (belt)reduction, the boat would run as on rails with nice cornering, very quick and agile.
Changing the motor for a direct drive 700 Neodym on 12 cells NiMH, turning the same 40 mm X-prop, the speed was nearly twice as high, making the boat blistering fast and rudderless when at topspeed.

This is very bad for your heartrate when the boat is hurtling towards a brick wall with no functioning rudder due to the airpocket from the prop.
Only throttling down and hoping the boat will get off the plane and getting the rudder function back before you hit something could save the boat.

Mine still has a nasty flat spot on the nose from running uncontrollable into a 1:1 steel hulled cruiser...

The second (1700KV) motor I mentioned should be sufficient.

Regards, Jan.
Nov 11, 2011, 05:12 PM
Sharky1dk's Avatar
Flatnose...... ouch not really good

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