Need Help With Boat (OTP)

[jamiekulhanek]

Due to the abundance of small dams popping up everywhere in my suburb, I thought it was about time i built a smallish boat using recycled gear.

So i picked my weapon (only aeroflyte kit left on the shelf):

The length of the boat is 39cm, and it s 18.5 cm wide.

The colour scheme and rear wing are horrid, but I plan to change the rear wing and give it a gloss white paint job, with blue pinstriping on one side only. At current I have it 60% built.

I also bought an 8″ prop shaft with a 30mm 3 blade prop, but i m thinking the 30mm prop is a tad big.

The guts of this are gonna be from a Mini Z;

-Mini Z pcb with 18 FETs Watercooled.

-JK Racing F1 motor Watercooled (FA130) (plenty powerful)

-Steering servo for rudder

Others:

-2 AA Lion 3.6v cells (1500 Mah i think, dunno, rcmart is down atm)

-Fuse

-Water rail/plumbing.

The calculated weight for this craft is 250g-300g

I am just wondering if anybody has any tips or suggestions before I tip $$ into a hole in the water?? Im hoping for about 25 km/h or so.

Cheers

[PandaBear]

Those boats aren’t that small, usually ends up 4x the size of the box.

You’re getting old JK… wouldn’t have expected saying this to you but definitely you’ll be needing MORE POWER. 🙂

Don’t know what it is with boats, but they usually need 2X the power of the same sized car so even overkill is never enough. Try something bigger like in a 540 size. :smiley16: And 10 cells. :p

And try to build all your onboard radio gear into a airtight tupperware box, silicone seal all the holes that wires come out of.

[jamiekulhanek]

The boat is actually smaller than the box!! Trust me i built it!!

The motor I am using puts out 15x the power of a stock Z motor, so i think that should be sufficient.

There is no room for a 540 or 10 cells.

Getting Old?? Huh?? Me??

[PandaBear]

40cm… isn’t that size of a 1/10 shell??
Must be a BIG box!! 🙂

Hmm… 1/10 shell… upside down… 👿

Ferrari Enzo catamaran? 😀

[jamiekulhanek]

It’s a long narrow thing, has very little water contact whatsoever, and if the donk I put in it isn’t powerful enough (total weight of craft 250-300g) which it should be, I’ll just add more Li-ion cells!!

14.4v on an FA 130!! Worth a try.

Wills, I think you would have some trouble in the model aircraft world, you can’t make a plane from bricks ‘n’ mortar, then shove the biggest donk you can find in it and expect it to fly nicely.

Building light is the key with planes, and i guess with boats too.

[PandaBear]

Haha… yeah, the planes we flew in the 1970s were “conventional”. Although I’d usually end up using too much epoxy and be quite a few grammes overweight. 😀

So we just stick in a OS40 instead of OS25, 60 instead of 40 etc.

Weight not that strict on a boat though.

This guy that I was buying my shrinkwrap from, he showed me this huge battery pack he made out of about 40 subCs. It was a huge stick 2x2x10 over 2 feet long, weighed 2kg+.

His boat was about 1m hull, running some Aeveox motor.

[jamiekulhanek]

Quote:

Haha… yeah, the planes we flew in the 1970s were “conventional”. Although I’d usually end up using too much epoxy and be quite a few grammes overweight. 😀

So we just stick in a OS40 instead of OS25, 60 instead of 40 etc.

Weight not that strict on a boat though.

This guy that I was buying my shrinkwrap from, he showed me this huge battery pack he made out of about 40 subCs. It was a huge stick 2x2x10 over 2 feet long, weighed 2kg+.

His boat was about 1m hull, running some Aeveox motor.

Damn, that must have been a seriously powerful boat.

When i used to be in the launceston model aero club (never flew outdoors, as my dad was always too busy to help me get into flying)

anyway, a bloke from Germany named Martin Webberschock who was the world champ F5B pilot came to our club, to show us his toys, though they had HUGE price tags, they were still toys!

His F5B had about a 2m wingspan, about 15cm chord and was made from carbon fibre….everything was CF. You could actually sit in the middle of the wing with the ends propped up and it would support yor weight, though nobody tried.

The plane had a 28 cells and pulled around 100A current. The cells only lasted a few cycles.

Anyway, this thing was incredible, the sound of it doing a pass at almost 400km/h was a blast.

It could climb 600ft in around 2-3 seconds, just incredible.

[oldtamiyaphile]

I agree that a 130 is too small. Build it light (much lighter than the kit, use thinner wood etc) and maybe you might get away with it.

Consider this; the stock motor is a 180, if the ESC can support ~7amps, you could run a Speed 280 and be done with it. Should be easier to find a motor coupling and drive shaft too.

My VAC II is about 600mm long, 250mm beam and runs a 540 on 8 cells, though it is heavier (mostly to support the motor and batts), it’s running a much larger motor on more volts.

My 130 project boat is only ~160mm long! (but running a single lipo).

[jamiekulhanek]

Dude i’m running 7.4v/22×1 motor with neodymium magnets/ 9×1 ESC watercooled, it aint a stock Z setup.

You might be right though….I am sticking with this motor as I need to test its durability.

[PandaBear]

Come to think of it… the family DOES have some watercraft powered by a stock 130…! 😀

Its this thing:

tam70153 Submarine Motor Torpedo Type in Waterproof Case

Performance wasn’t very memorable… 👿

[jamiekulhanek]

You aint getting my point….i’m not using a crappy 130!!

My 130 is close to the power of a basic 540, though it needs a much smaller prop or a gear drive to work as its all revs.

In a boat that weighs around 300G (1/5 the weight of a 1/10 car) It might be ok.

A 540 WILL NOT FIT IN THIS BOAT, NEITHER WILL A 6 CELL PACK!!

I might get away with a speed 400, and I may go to one of them soon as they have similar power to my 130 motor, but would be less strained and more reliable.

The ESC should be capable of passing many amps, as there is a copper waterpipe soldered to the FET stack, so the FETs should run 15 degrees or so.

The cells I am using are 2 Li-Ion 3.4v 1800mah Hewlett Packard’s which cost 3.90 US each.

[PandaBear]

If you’re after some fancy small motors, maybe check inside some Battery Toothbrushes.

Got cheap ones from Colgate etc selling for $10-15, all of them have 180 or similar motors in them which might come handy.

(180 is like a longer 130.)

[oldtamiyaphile]

I think a 400 is going to be too heavy again. A 280-300 would be best. I remember years ago just sitting a 540 in one of those boats and it couldn’t carry the weight. Sure, a 400 is smaller, but not by that much.

[PandaBear]

Boat ESCs RC HYDRO

[jamiekulhanek]

Quote:

If you’re after some fancy small motors, maybe check inside some Battery Toothbrushes.

Got cheap ones from Colgate etc selling for $10-15, all of them have 180 or similar motors in them which might come handy.

(180 is like a longer 130.)

Wills, i’ve been down this same road, and sorry, but the internals just aren’t up to it. Nylon instead of ceramics etc. No good for running big power. I don’t like wasting money on shit….unless there is a specific motor you are talking about.

Those watercooled ESC’s look quite cool….

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