Arowana 32" self righting hull

[rol243]

So is it necessary to use more weight on the port side of hull so the self righting works ? i would have thought when the chamber fills with water , the hull then flips back over.

[Old School]

Theoretically it is the weight of the water that flips the hull upright, however, other factors come into play like supplying enough water to flip the hull plus the bouyancy of the cabin which helps. From what I have seen self righting hulls are not weight bias neutral and offsetting batteries is needed.

[Old School]

One down (just needs painting) and now one more to finish. The first boat is now structurally completed and bench tested. I just need to add a hatch lock for security.

[rol243]

Don,t forget a Turn Fin.

[Old School]

Don,t forget a Turn Fin.

I was leaving it off for storage as the thing is like a sharp knife wanting to stab everything.

[martin]

Most self righting boats with flood chambers also need weight offset ( batteries normally but sometimes esc also ) to the port side to self right. Sometimes you also need to add stick on weights to the outside off the flood chamber to fine tune self righting.

[Old School]

Then there was two. Basically identical except my son's boat has a TP 4060 and my boat a TP 4050. Both running 6s. I have a 442/3 prop on my son's boat and a 'grimracer' 4255 on mine as that is what I had handy. When I get to test, if I like the 3-bladed then I will purchase another for my boat.

[rol243]

Mirror image. does certainly look that way but i must say you have done a fine job on these hulls. well done.

[Old School]

Many thanks. No mirror image, look to the different props. There were some trying moments especially in sealing the flood chambers. I have a bare Pursuit hull that I am thinking would make a fine self-righting hull (same hull as the Arowana, but different deck). For that one I will seal each wall as it is added so that I can access the forward section of the chamber. With the two Arowana the additional flood chamber had a carbon fibre lining and as it was pitch black inside it was difficult to see to seal it.

[Old School]

Bringing up an old thread that I have finally progressed after several years of neglect. Due to life commitments and a lack of enthusiasm after an extensive build programme with about five or six boats built at the time I finally got back onto this project. The mirror image boat that I built as well, I shipped off to my son but he reported that while a beast of a boat (TP Motor 4060 running 6s with I believe a three bladed prop around 44 mm), it did not reliably self right itself after flipping.

I decided it was now time to revisit my boat and hopefully overcome the resistance to righting itself. As supplied from the manufacturer the float chamber is woefully inadequate, essentially being less than half the volume needed to self right itself. Added to that the stock factory chamber leaked like a sieve. I taped up the hatch and flipped the boat over in a half full bathtub and noticed that air seemed to be trapped in the additional inner chamber that I had fitted. The two chambers are interconnected so I had thought that the inner chamber would bleed out through the holes in the underside of the hull linked to the outer chamber. I determined that additional holes were needed to vent both chambers and reduce the chance of an air pocket forming and thus inhibiting the ability to self right.

The end result was that even with both chambers vented of air, the hull would not go the final 1 - 2 cm from the vertical position to turnover and correct itself. The slightest finger pressure was all that was needed so I tried various lead weights in the rear of the outer chamber to determine the minimum weight needed to self right the boat. The weight needed was around 100 gm estimated. The boat then self righted itself every time. Unlike other self righting boats I have seen which take a few seconds to correct, this hull is unstable when inverted and immediately corrects itself.

While the boat was in the bathtub I decided to test its propulsion. The motor is a TP Motor 4050 1330kv "Y" winding running 6s with a 42/55 Grimracer two-bladed prop. This was the only prop that I had left as in my show of disinterest in the hobby I shipped off all my spares for my son to use as he is a keen devotee of fast electrics. With barely any throttle input the thrust was as much as I would comfortably trust my arm strength. I was amazed at the power of this setup. Because of very restricted space in the boat there is only enough room for two 3300 mah 3s batteries attached to the inner wall of the inner chamber, thus with a powerful motor I guess a runtime would be barely 2 - 3 minutes, but I believe an exciting runtime. A plus is that the hatch is easy to tape up so battery changes would take very little time.

The hull is still available from the manufacturer but be advised the stock float chamber is woefully inadequate plus will probably leak into the hull. A lot of work would be needed to make a self righting hull that reliably corrects itself. This thread details much of what I did to get to the stage of a reliable self righting boat. I must apologise for the gross misuse of "Miss Geico" stickers. Following is a link to the manufacturer.

https://www.littohot.com/collections/hulls/products/32-rc-ep-epoxy-fiberglass-deep-vee-arowana-mono-2-anti-turnover-racing-boat-hull-white

[ray schrauwen]

That looks really nice. I believe the hull was suited for a 3S 1 pack setup with a smaller motor in order to have proper weight in order to get it to self-right.

What is the quality of the hull like? I owned one of those years ago but not a self-righting one. The gel coat was really easy to crack on it.

Looks like you did a really nice job on it.

[Old School]

Ray,
the hull was well made with an excellent gelcoat. I decided to not even paint it. I cannot believe it was three years ago that I was building it.