New scratch build 24" mono

[jfrabat]

Well, did a pool flotation test... I think the debate is over. Battery needs to be moved forward. Either that or stick the ESC forward, but I need weight forward... She floats with her but almost submerged.

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I also have a water leak somewhere (I think it is coming from the trim tabs). I have to get rid of that pronto!

[jfrabat]

Proceeded to carve out some flotation foam from the front. I did not need to touch any bulkhead, which is good.

ESC will now go to the front (there is still some foam over the ESC):

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Now battery will be centered, and servo moved slightly back for better movement:

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Overall, CG moved less than half an inch, but it makes a WORLD of difference in flotation stance

BEFORE:

20200522_163952.jpg

AFTER:

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Like this I am willing to give it a shot.

Now, one question: is it really bad if I make extensions to the ESC to motor cables? Otherwise I will need to disconnect them every time I take out the battery... Also, I could make them 6mm bullets on one side and 3.5 in the other and avoid any cutting of cables. But I do not know if a couple of inches here will result in more resistance or something along those lines (I doubt this motor will ask too much of this ESC, though, so, for this application, I could be OK, I guess!)

[Jesse J]

Alternating current in brushless motors is less affected by longer wires. Try to stay under 6”, 8” at most.
Where is center of gravity? Ya that drive is heavy and your boat is narrow.
I do use both steering arms, but you may be ok with just one.
Oh, and in case I didn’t emphasize, go very light on thread lock... I had to dremel out a few screws when I went to service the outdrive.

Did you run yet?

[jfrabat]

Alternating current in brushless motors is less affected by longer wires. Try to stay under 6?, 8? at most.

I need about 6 inches or so (maybe even less). I also made an extension for the battery (I made it 6mm male/female to XD60, but, OF COURSE, I used the wrong side of the XD60!!! Now I have to resolder!). By the way, the batteries come with XD60 connectors; since this motor is supposed to draw less amps, do I go with that or still switch to 6mm connectors? I take it that if the motors have 3.5" bullet connectors, XD60 should be OK, right? I was planning on keeping the XD60's...

Where is center of gravity? Ya that drive is heavy and your boat is narrow.

Right now, it is right at the start of the N (right after the I) of QUARANTINE. Moving the ESC to the front only moved it about a quarter inch. I am still behind the 33%, but now by about a quarter inch, and, if I need to, I can push the battery a bit further forward now (I got about one or 2 inches of room before I hit the ESC).

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This is where the ESC is now (this is before I glued the tray in, but it ended up in the same place):

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I know you cannot judge distance from the pic, but the ESC is about 2 inches inside past the bulkhead.

I do use both steering arms, but you may be ok with just one.

The way I have it set up, I will go with just one. I AM using a 3mm rod with a 20Kg servo (with swivel ball joint on one end and the outdrive's rod connector on the other), so there should not be any issues. Besides, I put the water outlet in the way of the second arm, so if I wanted to install it, I would need to re-drill some holes...

Oh, and in case I didn?t emphasize, go very light on thread lock... I had to dremel out a few screws when I went to service the outdrive.

Yeah, I will. I still got to open it up and lube it. Have not gotten there yet.

Did you run yet?

No, it is not finished yet. And we are still in lockdown here, although the parks will open on Tuesday.

Today I glued in the tray for the ESC (had an extra battery tray that fit just right!), which was a fun endeavor, as that whole tray is in the bulkhead ahead of the hatch. I used a velcro strap to keep the ESC in place, but if I ever need to remove it... well, lets just say I will be entertained for a day or 2!

I also glued in the battery tray and the servo mount in place. I took all the hardware off and remounted everything to try to fix the leak I had (which was substantial). I used silicone (I have conformal silicone for my electronics) around all the holes in the rear. I also used some gasket material to make a gasket between the outdrive and the mount, as the boat is not perfectly machined. I put some more silicone around that, and I still have a tiny leak, but now it is much more controlled. I located the leak (the outdrive mount), so I will go over it with silicone once more to seal it.

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I still need to make the extension from the ESC to the motor (which I will also use to go from 6mm to 3.5mm bullet connectors, as the ESC comes with 6mm and the motor with 3.5mm, and that way, I do not need to cut anything!), re-solder the XT60 (the right one this time!), and make the hole for the steering rod and install that and the boot (which will going into the boat as opposed to going out, like I have it on my cat). I need to seal and paint the rear hatch (I made the hole for the thumbscrew), and I also need to velcro the receiver to the hull, but that takes 2 seconds. But it is almost there now!

One last pic showing off the hardware!

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[jfrabat]

A bit more progress... Servo is now connected to the outdrive.

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The rod is still hitting the top of the hole when I turn right, so I have a little finessing to do still. But it is all in now. Also did a pool test (now with the boot on and the silicone in place) and I got no leaks.

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I just noticed it looks like water inside, but that is actually resin... No water got in at all.

[jfrabat]

OK, I fixed the rod rubbing issue, but I need to strengthen the servo mount hold. The servo is strong enough to rip the epoxy (when I had rubbing), and it did. I am thinking of epoxying supports like this:

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The good news is that the outdrive is steering well... I made a video in my pool... I still got no power (until I make the ESC to motor extensions), but I need to wait for the bullet connectors to arrive first.

[Jesse J]

Balsa might not be strongest option, you have any basswood or ply you could use?

[jfrabat]

Not really. I have some 3/8 (might be 1/4, not sure) ply, I could try that...

[jfrabat]

Servo mount was epoxyed back un place and plywood additional supports have been added. Not my prettiest job, but it should hold!

[jfrabat]

Here is the picture:

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And here is a video of it working this morning:

https://youtu.be/xTAf_aOtN1g

Looks like the correction worked; the servo is stable.

[jfrabat]

Bullet connectors finally arrived... And it turns out, either the motor does NOT come with 3.5mm, or I got sent the wrong size in the 3.5mm package. Because, most certainly, these bullet connectors are smaller than what is on the boat (actually, they are the same size as what comes in my Aquacraft Minimono). Anyway, I looked in my drone stash, and I had 3 female connectors of the right size! So we are READY TO RUMBLE!

These are the extensions I made:

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And this is how they look in place (or how the DON'T!):

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Of course, I HAD to try the boat out in the pool, and this is where I screwed up... My son was filming me as I made a hole in the vinyl pool! You can see that here:

https://youtu.be/pLT-9dNeR2k

Oooops! Boat is fine, by the way... The pool took all the damage.

As far as speed, I think acceleration is significantly slower than the cat, but I am hoping it will pick up speed in long runs. As for turn fins, I think I can get without, but we will see once we actually run the thing for real!

[jfrabat]

By the way, I am seriously thinking getting a new radio for this boat. I am using the same Tactic basic radio that cam with the Minimono, but I think I am going to need something a bit more sophisticated for this. For instance, something that (1) records endpoints, (2) remembers channel reversals, and (3) has an exponential function, because this boat gets a bit squirrely once on plane with the steering. I was planning this boat for my son to use, but he is going to have his hands full, I fear!

I would give him the cat, but that one I think will be too fast for him. But who knows; he may end up driving better than me! LOL!

[jfrabat]

Finally got around to running this bad boy... First off, the boat bobs up and down (see video). I am not sure if it is a balance issue or a driveline angle issue (I am inclined for the latter, but maybe both!). For the run, I pushed the battery as far forward as it would go, so it may be a bit heavy in the front.

I ran it easy, mostly at around half speed. I did give it a couple of runs at full throttle, but was mostly running at half throttle. At the end, the boat would not turn (it was locked into to a left handed turn). Then, I lost throttle as well (you could hear the motor, but no action from the boat). I figured I had lost my prop, so I waited for the boat to float to shore.

Once we recovered, I noticed we did have a prop. The issue (I would find out when I got home) was actually worse; it seems Steven was right to warn against using a 4S. In my first run, I stripped the gears on the drive!

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Looking deeply back at home at the problem, the issue is that the gear was not meshed properly. So that is something I will have to take care of once I get the new shafts for it, which I need to take care of now (edit: Already ordered from OSE!)... Oh, and the cause of the left turn lock? I forgot to put Loctite on the bottom bolt of the direction system (it has two bolts, top and bottom; bottom one is gone!). Good news is that at least the cat ran like a dream!

Here is the video of that first run, so you can give me some advice on how to fix the bouncing issue:

https://youtu.be/ewgDD9TAwEo

What is my issue? Drive angle? Center of gravity too far back? Or too far forward? Or a combination of these?

[Jesse J]

Hey there, looks like your video is private.. can’t watch it. Try changing to public.

[jfrabat]

Try it now