Brushless conversion of a Musculus toy boat

[seehuusen]

Hey guys,

Back in 2013 I converted one of the Baleanoptera Musuculus boats to a brushless setup.
This was my setup.
MOTOR:
XK3665-B-2500KV Brushless Inrunner
Shaft Adapter - 5mm motor shaft to 4mm Flexi Shaft
36 Size Adjustable Motor Mount with Water Cooling
Water Cooling Jacket for 36mm Brushless Motor

ESC:
Turnigy Aquastar 180A Watercooled ESC
Water Outlet Barb

Servo:
Metal Gear Digital Servo
Flex-Rod Boots
Servo Con-Rod for Boat Rudder

Running gear:
4mm drive dog
4mm outer tube
4mm threaded prop nut
4mm flex cable with end
4mm teflon liner
130mm Rudder dual pickup version
Stinger 70mm long 4mm adjustable
4mm teflon thrust washer
37 x 1.4 x 4mm prop

Here are a few build pictures :)

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I ran it for a fair while, before I managed to drown it on a trip to North Queensland... After that, I greased it up, and it got stowed away in the cupboard. Then I had a kid and as any parent know, time flies when you've got a kid...
So the other day I managed to dig the boat out, and I decided, NOW is the time to get this thing back in the water.

[seehuusen]

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I didn't realize the 5 image limit per post... This is the previous, V1 setup if you like :)

[seehuusen]

A week or so back, I took the whole thing apart

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Then I mocked up how I wanted the new layout. I recall having a fair bit of the front part of the hull riding in the water, not so much on 4S... But the weight needed to come back in my oppinion

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Another thing I wanted, was more space for foam, which I'll put in the front.
I also wanted somewhere dry to put my ESC and Receiver. I purchased a little tupperware container, which was large enough to hold my gear.

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[seehuusen]

I then started to mock up some sort of mount to hold the ESC.
I did this using cardboard from a carton of beer :D I liked it so much, that I decided to see if I could just wrap it in fibreglass and to be honest, it looks to have worked out nicely!

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I then decided that I should make a battery box as well, and applied the same method :)

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The servo assembly will be screwed in place, so that I can pull that out if I need to. The battery box will be velcroed onto the servo assembly.

[seehuusen]

Other things I've done to the boat in this V2 setup, is to lay an extra layer of glass on the transom. Although I never had any issues with strength, I never really trusted it to be completely leak proof (suspect it took water in from there)...
I've mounted the running gear now, and next up will be to mount the remaining bits in the hull.

I'm going to make a new hatch design for this boat, I suspect it wasn't the most waterproof hatch in the first place. Once that is done, I'll put the two hull parts together permanently.
I'll be using a different paint this time, as the silver paint looked authentic to the real model, but actually was extremely difficult to follow when on the lake.

Here it is in its old form, running on 3S
https://www.youtube.com/watch?v=60Xbekbq-7w

I'll add more as I progress with the V2 setup :)

Cheers,
Martin

[seehuusen]

I had to run some new waterlines because I moved the servo into the middle. After a bit of fiddling around I found the best way to route them and drilled some new holes on the right hand side.
The old holes in the middle will get blocked out.
I also finished the servo mount, and made a wooden block that I glued to the hull. This I could then screw the servo mount onto, which gives me the possibility to remove it, should I need to.
I managed to fill the servo up with marine grease as well as gasket goop the 3 servo pieces together (as in the servo case).

This is what it looks like right now
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I'll fit the servo horn and hook up the rudder today. If I get time this morning, I'll block the holes with fibreglass and bog it this afternoon.
Then I need to figure out how to modify the hatch system, as it doesn't seal properly.

Cheers,
Martin

[Make-a-Wake]

Hi, I love souping up cheapo boats, I did an NQD/Syma several years back, Still have it and its a blast, runs on 4s with a 3665.

I for one can appreciate the fun of building these................and the challenge of turning a 15mph hull into a 35 mph solid running boat.

Be sure to post some vid when you are done!!

[seehuusen]

thanks, I'll post something up for sure, got a gopro these days too, so it should be a bit better than the last one with a mobile strapped to the Tx :blink:

It's definitely the fun in taking a cheap as chips hull and turning it into something that is extremely fun that got me hooked on this. I've often thought about buying a better hull, but really just want to go down the scratch built road I think.

I have to admit, I've been eyeing off your avatar on every post you've made, what is it? does it have a build thread? I really like the look of that boat :thumbup:

[seehuusen]

I've blanked out the two old water cooling holes, though I still need to apply bog to blend them with the hull/deck.
At the same time, I sorted out the hatch. I've been pondering on this since I started out, as the boat had a tendency to take in water from the back/not be properly sealed.
This is what I came up with

Original hatch
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New secondary hatch
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The lip I made with fibreglass to hold the secondary hatch.
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I've not really come up with the exact way to hold it all down yet... Ideas greatly appreciated :)

I also installed the rudder and ran the servo actuator... Aaaaand, that reminded me of something I'd been annoyed with in the original version, the rudder is on an angle like so \ (not quite that much, but you get the point)...
That meant when turning one way, it was very forgiving, but turn left, and the rear would try to lift while the front would try to dig in... So I'm now going to pull it off, block out the old holes, then re-drill with zero angle on the rudder...
Sooo close, yet so far away :p

Also, as I'm in Oz, any of you good fellas have a picture of how you made your safety loop? I think I might head down to Brisbane for a run every now and then, and I believe they require you to have one.
I'm not paying 30 bux for one from the RC Boat shop...

Cheers
Martin

[Make-a-Wake]

I have to admit, I've been eyeing off your avatar on every post you've made, what is it? does it have a build thread? I really like the look of that boat :thumbup:

Its a 45" 1984 Dumas Scarab fiberglass offshore boat. I turned it into a 22 foot ski-boat scalewise with the interior and 12" Barbie and Ken riding in it.

[seehuusen]

that's sick! I like it very much :)

Edit: I managed to find it on YouTube, very nice in deed!!

[iop65]

you could save weight when changing that esc with something smaller , but are that xt 60 connectors?
prop should be bigger for that size boat + motor

tried a 40 mm yet?

[Make-a-Wake]

prop should be bigger for that size boat + motor, tried a 40 mm yet?

Its only 22" long

[Make-a-Wake]

Seehuusen, looks like the cog can go back a bit from the vid in the "old form", also could use trim tabs

[seehuusen]

I was thinking of adding trim tabs... is there a good way to make your own? For $12 I can get some, so it's not the money aspect of it...
What sort of size should I go for with my size boat?

Would turn fins be something that I should use for added stability? They just assist in the turns, right?

EDIT: Added size question re: Trim Tabs

[Make-a-Wake]

I'd suggest these

http://www.offshoreelectrics.com/proddetail.php?prod=ose-80077

Small turn fins will help too..........if you have room on the transom after the tabs

[iop65]

Its only 22" long

i stand corrected , thought it was around the 26"" mark

in that case : a 3665 with a 180a esc is way overkill

wouldn't a 2860 2700 -2900 Kv with a 60a /90a esc be a better option ? will spin that 37mm prop without any problems on 3s
and he surely would save some weight

[Make-a-Wake]

These smaller "toy" hulls are featherlight and the extra weight helps keep them planted, so overpowering and extra weight are a plus. I had a 2860 in my 27" toy conversion and had to add an 8 ounce sinker to make it stable, then it was slower, so I went with a larger motor too.

[seehuusen]

I'd suggest these

http://www.offshoreelectrics.com/proddetail.php?prod=ose-80077

Small turn fins will help too..........if you have room on the transom after the tabs

Thanks! :thumbup1: I started looking for some and found that size here in Oz from a local supplier, so I might just get a set. They were $12 pp


i stand corrected , thought it was around the 26"" mark

in that case : a 3665 with a 180a esc is way overkill
wouldn't a 2860 2700 -2900 Kv with a 60a /90a esc be a better option ? will spin that 37mm prop without any problems on 3s
and he surely would save some weight

Thanks, I do see your point, lighter and smaller gear would potentially yield the same sort of results.
I run something very similar to what you suggest, in my jet boat (NQD). I find that the motor gets lukewarm on that boat, and it is smaller and lighter.
Most ESCs I've put into the jet boat with that motor, tends to run a bit on the warm side. With one exception, a 120amp ESC. That and the fact that this ESC was recommended as close to bullet proof, was the reason I went that way.
Weight is obviously not an issue when you have about 1.2 furious electric horsepower in a boat this size haha

For this boat, I wanted something that would run cool, have power to push the boat up around 40mph, and do that, battery pack after battery pack... This is the reason I went a bit larger everything on this boat.
As a result, I can pretty much run anything I want prop-wise, and just worry about trimming the boat and running it.
In its previous state, it did run those types of speeds on 4S. Hopefully trimmed a bit better now, it would run that and a bit more :)

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I managed to blank out the old holes for the rudder, this was something I'd wanted to do on version 1, because it was on an angle, which led to some funky high-speed behavior, especially when turning left (lifting the back and pushing the front into the water)
I then added a bit of material to straighten the rudder mount a little, as the transom is curved (not that this has any major impact on the handling, though it does put the rudder rearwards a few mm).
Lastly, I drilled the holes on the right angle, and I'm happy with them now.

There should be enough space for the trim tabs, I'd want to put them fairly close to the stinger, right?
If I went and bought some turn fins, could I put them right on the edge of the transom? and what size would be recommendable for a boat this size? smallest I can find is 55mm x 21mm.

Thanks for your input and interest, it's nice being able to draw on other people's experience :tiphat:

Cheers,
Martin

[seehuusen]

Made an order this morning for some 38mm x 32mm Trim tabs.

I'm not 100% happy with the rudder alignment, it is slightly on an angle. I'm considering pulling it off and starting over again, thoughts?
I drilled 4 holes for my hatch screws, it looks OK, but slightly overkill. So I might remove 1 and reconfigure the two front holes to 1 at the very front of the hatch... not sure if it is important enough yet though...
I won't be putting the deck back on the boat until the trim tabs have arrived and I've worked out the best way to set these up... Is closer to the stinger better or further out towards the sides the go?

[seehuusen]

minor update, I pulled my rudder off and re-drilled the holes for the screws.
I can now confidently say it is completely vertical :) The transom is curved as well as the deck being curved, it was extremely tedious to get right, fiberglass is good to clean up mistakes though ;)

I'm expecting the trim tabs to arrive today via the post man, could any of you fine gents let me know what is better, further towards the sides or closer to the stinger?

Thanks in advance,
Martin

[785boats]

I have one of those, but it's called the Dolphin. Same boat though, & it has a little outrunner in it. Haven't even run it yet. But the tabs are installed from the factory towards the outside of the hull. About 1/4" from the outside of the tab to the side of the hull. It's a very narrow transom & I will have to fit some turn fins on it as the boat doesn't have any fitted from the factory. I intend to try the Proboat 1500kv motor in it to see how it performs in our Restricted Mono class. Should be fun.
Where in Queensland are you? Anywhere in Brisbane?

Paul.

[seehuusen]

Hi Paul,

Thanks for the directions on the trim tabs. That's how I will install them then :)

I'm on the Sunshine Coast, I normally run my boat in the pelican waters canals, you can always find something flat to run on ;)
Mine doesn't like too choppy waters, despite the hull shape.
I am actually planning on a trip down to Tripple S boat club's waters in the beginning of April, do you run your boat there by any chance?

Cheers,
Martin

[785boats]

Yep.
That's my main scale/fun club. We are there every Saturday afternoon running fast boats too. Scale & sail & submarines etc are in the morning.

But this Saturday coming our Race club meets at Lakeside Raceway at Petrie. So most of us will be there instead of Boondall.

[seehuusen]

I was thinking about coming down 11th or 12th, so that might coincide perfectly :)
I do wonder, I don't have the safety power cut-off lanyard on the outside of my hull, well I don't have any on the inside either LOL What are the rules surrounding that?
What time do you run in the afternoon?

Back into the build again, I've installed my trim tabs as I read the suggestion above, we'll see how that runs on the lake.
Apologies for the terrible photos
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Additionally, I trimmed the stinger up to as much positive angle I could give it (moved prop up, should lift the nose out a bit better)
I'll control the ride via the trim tabs and stinger angle, although I do think I could need even more of an angle upward, so I might take some metal out of the stinger mount, where the adjustable screw goes.

Additionally, I found a crack along the deck and the hull, after my sneaky maiden voyage (without camera).
So I did this
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Now, I'm aware it's not super pretty right now, but a bit of sanding will see that blended in nicely ;)

I should have the boat on 4S tomorrow, but that is weather depending.
Additionally, the 4S batteries both report a cell with high voltage... Might be because they've been stored for a long period of time and getting old...
Someone told me to flog it and then re-charge it, that this might get them back on track... I'll try that and take my charger to the lake.

Cheers
Martin

[Make-a-Wake]

Trim tab placement is very good, deck of boat may have a touch of cancer or some condition..............LOL

How did the boat run in your sneaky maiden???

As for the voltage issue, discharge your batts then balance charge them. In some cases if they are way off..............I have actually charged the one cell that was low with charging pins into the balance plug. You can also discharge one cell this way

[seehuusen]

Thanks for the tip on the LIPO mate, I'll give that a shot, fingers crossed they're not dead...

The maiden was good, in the sense I managed to run to 3S batteries through it.
The rudder is MUCH better now, in fact I could increase the 55% limitations I had on there to 65% and will increase more on net runt. No more crazy weird turns, clean in both directions.
The stinger was a bit on the negative side, and I didn't realize before I was cleaning up and taking it all apart for a re-grease... This has been addressed now though.

So all in all, it's still fun, it still runs wet, but hopefully the changes will sort that out for the next run ;)

[Make-a-Wake]

Put your cog at 28-30% from transom..............

[seehuusen]

The missus was out, so I snug off for another test run. I'm glad I did actually, it ran extremely wet with the new trim tabs, after adjusting them up as well, I got it running OK, but still drawing more amps going by the heat of the battery.
It's very stable now with the tabs though, I think it's an improvement, but just need to adjust the boat to be out of the water more...
I need to take some material of the rudder post, I need a bit more adjustment from the trim tab under the rudder, and the screw is hitting the bottom post for the rudder...

Also, batteries were shocking... I'm not sure if leaving them was such a good idea... 2 of the 2200mah 3S were great, the rest (1x 2200mah 3S, 1x 2650mah 3S & 2 x 2650mah 4S) were all really crap. I'm hoping giving them a run and deflating them a bit today, followed by another balance charge will make them come good... Actually, I'm thinking I might get 2 x 3000mah 2S batteries and run 4P2S (? is that what it's called?), run them in series anyway, for 4S power but with a battery on either side of the hull...

Cheers,
Martin

[Make-a-Wake]

Ok..................so hopefully you are checking your cog.............all you are talking about is your tabs and screws and stuff. If the cog is way off it doesn't matter. What is your cog from transom? That will help you.

[seehuusen]

I re-checked my COG, and the numbers would add up to me needing to adjust the stinger and trim tabs...

Boat is 520mm long

No Battery 140mm COG from transom - 26.9%
2.2A 3S 130mm COG - 25%
2.65A 3S 125mm COG - 24%
2.65 4S 115mm COG - 22%


So my COG is way back on the boat, there's no other reason to my mind why it would have to be change... If anything, my understanding is that it needs to be moved forward, in an ideal world?

Cheers,
Martin

Edit: Make-A-Wake: didn't see your post suggesting to check COG, thanks for the input, really appreciated mate :) So the above numbers is very close to what I got when I started out with the rebuild, hence why I talked about the stinger/tabs... What do you reckon mate?

[785boats]

I was thinking about coming down 11th or 12th, so that might coincide perfectly :)
I do wonder, I don't have the safety power cut-off lanyard on the outside of my hull, well I don't have any on the inside either LOL What are the rules surrounding that?
What time do you run in the afternoon?

Martin.
On the 11th we will be at Boondall all day, from about 8:00am till around 4:30pm. Come & have some fun.
The safety loop isn't necessary at Boondall. Only at our race club at Petrie. So don't sweat on that.

I should have the Dolphin running by then so we can run them together.
I've just fitted a pair of small turn fins. Not much room on the transom so I had to use the outside trim tab mounting screw for one of the turnfin mounting screws too.
Here's a pic of the fins added. All the other hardware came with the boat.
And a pic of the little 1500kv motor that comes with it. Interested to see how that little motor runs. I feel it will be a bit under powered as this boat of mine is made of some pretty heavy glass, for its size.

[Make-a-Wake]

Shouldn't be running wet with those cog's. Paul can help you with it when you go visit him I guess.............til then maybe move it forward a bit just to test.

[785boats]

I agree.
With the COG that far back boats usually get very flighty.
If there is negative angle in the stinger, that could be causing the boat to run wet.
Check the angle of the stinger with a straight edge along the keel & adjust the centerline of the stinger to have a bit of positive angle, ie prop end up a bit. About one degree or so to start. It may need more. But test that first.
Same with the trimtabs. Place the straight edge along the hull under them & make sure they are not angled down. Actually I would angle them up as far as possible until you get the setting of the stinger right & the bow is not running wet. Then bring the tabs down if needed.

[seehuusen]

Thanks for your input guys :tiphat:

I've got the stinger sitting at pretty much zero degrees, and that is at it's max up position... I've re-adjusted the trim tabs, and will take the boat out again in an hour or two (waiting on a couple more batteries to finish up)
I'll report back :)

[seehuusen]

ohhhh yeah! now we're talking :)
On 4S it screams for that little boat, stability is right there on the edge, prop/motor twists the boat on too much punch on the throttle :D
Gotta trim the trim tabs down a touch to see what that does for stability, but it is looking much better!

Thanks for your help guys :)

Paul, I'll certainly get your input on it when I pop down next Saturday.


Vid to come...

[785boats]

No worries Mate.
Sounds like all you need now is some small turn fins for the corners.

[Make-a-Wake]

You need to possibly lower the port side trim tab 1-2mm as that is the side that drops...............not both tabs

[seehuusen]

thanks for that suggestion Make-a-Wake, I'll try that out on my next outing :)