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Jan 25, 2020, 03:17 PM
RELAX. You'll live longer
785boats's Avatar
Marcos.
That's fine. Adjusting the rudder like that is part of tuning. Rudder castor adjustment is a valuable tool in tuning a hull.
If the transom pops up & skips in the turn, driving the bow down, then tucking the toe of the rudder forward helps plant the transom & lift the bow in the turns. If the nose comes up in the turns, then laying the rudder back slightly can help pull the nose down.
I like my rudders tucked forward slightly on most of my boats.

Proboat 26.
Whether or not the stinger is at 90 degrees to the transom is not a concern.
All angles for tuning the strut are always taken in relation to the keel.
As Marcos has stated, the transom on this boat is laying slightly backwards. if the strut was set at 90 degrees to the transom there would be too much negative angle on the strut.

Cheers.
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Jan 25, 2020, 04:19 PM
Recoil 26 Pilot
ProBoat_26's Avatar
Quote:
Originally Posted by 785boats
Proboat 26.
...As Marcos has stated, the transom on this boat is laying slightly backwards. if the strut was set at 90 degrees to the transom there would be too much negative angle on the strut.

Cheers.
Okay, thanks. I guess I didn't read that part earlier.

Jan 25, 2020, 10:08 PM
RELAX. You'll live longer
785boats's Avatar
No worries mate. I do that all the time.
Jan 31, 2020, 09:34 AM
Boaters are nice people.
Hi Marcos,

As you found out, the transom on the Arowana isn't at a 90 angle to the bottom, so the rudder is toe in.

I didn't like that for our Arowana's, so there's a wedge to make the rudder shaft at a 90 to the bottom.

Regards, Jan.
Jan 31, 2020, 10:55 AM
Registered User
Thread OP
Quote:
Originally Posted by pompebled
Hi Marcos,

As you found out, the transom on the Arowana isn't at a 90 angle to the bottom, so the rudder is toe in.

I didn't like that for our Arowana's, so there's a wedge to make the rudder shaft at a 90 to the bottom.

Regards, Jan.
Hi pompebled,

I thought it was just mine, but it must be a flaw in the shape of the boat.

thanks
Jan 31, 2020, 10:58 AM
Registered User
Thread OP
Hi guys,
After further adjustments, my Arowana rc boat makes the turns without jumping.
I was not very happy with this boat - the self righting system does not work - even with a 600 gram battery next to it.
I needed to add another 230 grams of weight ...
But after many adjustments it was fine (in the turns).
Last edited by MarcosAC; Feb 20, 2020 at 10:24 AM.
Jan 31, 2020, 05:53 PM
Boaters are nice people.
Quote:
Originally Posted by MarcosAC
I thought it was just mine, but it must be a flaw in the shape of the boat.
Hi Marcos,

It isn't a flaw in the boat, but a result of how the mold was designed; having the sides of the boat slanting outward a little helps in getting the laminated hull half out of the mold easier than if all sides would be 100% vertical.

We as customers have to deal with the slanted outward transom.

Regarding the running attitude; from what I see in the video's, the propshaft exits the hull too deep, making it rise out of the water very high, there's very little rear end of the hull in the water to keep it planted.
The trimtabs (and propshaft angle) do their part pushing the bow down, so the boat runs rather wet, in stead of having the nose slightly up, running on the last few inches of the hull.

In a race situation where six to eight boats churn the water into a world of ripples and small waves, you would not have a chance against boats that run a lot less wet, you would not be fast enough.

When the Arowana with factory installed floodchamber first came out, I asked the seller to provide a video showing the boat selfright after a flip. He never responded to my concern that the floodchamber was way too small to make it work without adding a massive amount of lead...
Do you have a picture of how things are placed inside the hull?

Apart from the running attitude issues, you're being conservative on the prop size; with 1900Kv on 4S you're barely running 23000 rpm under load.
To get up to speed you'll need a bigger prop (introducing torque and propwalk issues due to the low exit of the propshaft), or run on 5S, which would get you about 28000 rpm under load.

6S is also an option, but I would prop down to a 42mm in order to keep the boat on the water...

And again: running so slow, there's no reason to back off the throttle when making wide(!) turns, once dialed in (and properly set up), the Arowana can handle turning at full throttle.

Regards, Jan.
Jan 31, 2020, 06:18 PM
Registered User
Thread OP
Hi pompebled,

I plan on running in 5S or even 6S when I get to the final configuration.
In the first video I was running in 6S but the boat was very unstable in the corners, it was an error in the configuration of the trim tabs.
Follow the photos you asked for. This was the first boat I mounted on the hull, I didn't have much idea, so I followed the configuration of TFL Pursuit.
The first installation was with the battery in the center. In this configuration, even with 400 grams of lead, self righting system does not work.
Now the battery was on the side, with 5 plates of 55 grams of lead each.
Feb 01, 2020, 11:59 AM
Boaters are nice people.
Hi Marcos,

Thanks for the pictures, nice clean build!
Did you add glasscloth to the joints of the mounting rails?

274 gr of lead is a lot of dead weight to ship around, our Arowana's have 50 and 65 gr of lead, positioned as far to the left rear as possible, see the pictures.

On my Arowana the 50 gr sits inside the floodchamber as far away from the center line as possible, the remaining 15 gr sits on the outside, not as pretty as having the lead inside, but I left it there after the selfrighting tests.
On my son's hull I had even less time before the next raceday, so all his lead is on the outside. Again not pretty, but who cares if you win races...

You could try a number of things to get the extra lead down:
- Move the lead to the inside of the floodchamber against the outside wall of the hull; more distance from the center line, so a bit less lead required.
- Extend the volume of the floodchamber by adding a bulkhead that creates a triangle between where the mounting rail mets the transom and the floodchamber wall at the hight of the last slot in the deck, see picture.
This is a tricky operation, as you'll have to make cardboard templates, before you can cut the epoxy sheet to size.

The extra volume will make less lead necessary and will make the Arowana recover faster after a flip.

Questions: when your Arowana is upside down, does she turn back up over the side, or over the transom?
Does your Lipo fit between the mounting rail and the floodchamber wall, upright if need be?
Where does your Arowana balance?

Regards, Jan.
Feb 02, 2020, 09:03 AM
Registered User
Thread OP
Quote:
Originally Posted by pompebled
Hi Marcos,


Questions: when your Arowana is upside down, does she turn back up over the side, or over the transom?
Does your Lipo fit between the mounting rail and the floodchamber wall, upright if need be?
Where does your Arowana balance?

Regards, Jan.
Hi Jan,

I was wrong to say 5 x 55 grams, in reality it is 4 weights of 55 grams = 220 grams (check the images for the 4 weights - above).

Questions: when your Arowana is upside down, does she turn back up over the side, or over the transom?
This boat was not made for self-correction. It is very bad, with a battery smaller than 5S/6S I need to stay on the accelerator trying to throw it to the side to correct itself. It is a terrible boat in this situation.
I believe it turns by the large weight on the side, not by the water inlet. Your water chamber is very small and all pierced above, I believe that does not make a difference. Without the extra weights it won't turn.

Questions: Does your Lipo fit between the mounting rail and the floodchamber wall, upright if need be?
No

Questions: Where does your Arowana balance?
30%

-------------------

I just bought this boat thinking about self-correction. I was not concerned with performance, I wanted a 90km boat with correction. If it weren't for that, I wouldn't have bought it.
Unfortunately I don't know how to work on the fiber, so it's impossible to modify your camera (in my case). I also did not do any fiber reinforcement, I did not find anyone in my city willing to work with fiber reinforcement.
Another problem: This boat was having numerous leaks. It was necessary to close numerous holes in the water chamber and around the hull
I made the repairs with epox.
Feb 02, 2020, 09:16 AM
Registered User
You can enlarge the floodchamber using some thin plywood you epoxy in and just reinforce with fiber. Make a paper template first
Feb 02, 2020, 03:36 PM
Boaters are nice people.
Quote:
Originally Posted by MarcosAC
This boat was not made for self-righting. It is very bad, with a battery smaller than 5S/6S I need to stay on the accelerator trying to throw it to the side to correct itself. It is a terrible boat in this situation.
I believe it turns by the large weight on the side, not by the water inlet.
Hi Marcos,

It is most surely advertized as a selfrighting hull! I agree with you that with the small volume floodchamber, it will never work without adding a lot of weight.

Quote:
Originally Posted by MarcosAC
Your water chamber is very small and all pierced above, I believe that does not make a difference.
What? The floodchambers in our Arowana's are amongst the largest that will fit in a hull this size, they hold 2,5L of water!

Still a bit too small to selfright without adding a bit of lead and an extra tube running from the bottom of the floodchamber at the front to the other side of the boat, to make sure all the air can vent out (and water will enter) the floodchamber.

The holes on deck are to allow the air to rush in after the boat has flipped back up and moves forward again.

Quote:
Originally Posted by MarcosAC
I just bought this boat thinking about self-righting. I was not concerned with performance, I wanted a 90km boat with self-righting.
Another problem: This boat was having numerous leaks. It was necessary to close numerous holes in the water chamber and around the hull.
I made the repairs with epox.
If you can make repairs with epoxy, you can also work on the hull to alter the floodchamber shape and content.

Keep in mind there are virtually no selfrighting hulls in this price segment, maybe a couple of RTR, but those are rather expensive.

If you've browsed through the huge Arowana thread on this forum: https://www.rcgroups.com/forums/show...-MONO%2A%2A%2A, you might have guessed this hull is a DIY project; you need to reinforce the hull prior to installing motor and hardware. You would also know that the tiny factory installed floodchamber would not work without adding lead, or adaptation.

No worries, you'll get there eventually...

Regards, Jan.
Feb 02, 2020, 04:26 PM
Registered User
Quote:
Originally Posted by pompebled
an extra tube running from the bottom of the floodchamber at the front to the other side of the boat, to make sure all the air can vent out (and water will enter) the floodchamber.
Wow i never thought about that. Much nicer than drilling holes for sure!
Feb 03, 2020, 07:41 AM
Boaters are nice people.
Quote:
Originally Posted by Jansvast
Wow, I never thought about that. Much nicer than drilling holes for sure!
Hi Jan,

The tube was added after the holes were made; it turned out that there was air trapped in the front of the floodchamber when the boat was upside down, preventing it from turning back up.
The tube allows the trapped air to escape.

In hindsight, I should have used a larger diameter, as it takes more time for the air to vent, than I would like, when racing, before the boat starts to turn back.
You can not make up for the runtime lost while floating upside down...

Regards, Jan.
Feb 03, 2020, 09:03 AM
Registered User
Is there an advantage for the tube opposed to just drilling a 2mm hole where the air gets trapped?


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