Arowana 32" self righting hull

[Old School]

the 4050 i have is a 2310 kv.

Sorry, but I am now looking at running 6s (two 3s batteries mounted fore and aft) so am thinking around 1330kv.

[rol243]

i would be working on something in the 1500 odd kv range running 6s. sometimes it pays to go that little bit higher in size .

[Old School]

!500kv would give me around 33,000 rpm. No doubt my son would much prefer that. OSE store showing nil stock for the 1570kv.

[rol243]

would it be easier for you to buy the 1570 kv from rcbb ?

[Old School]

would it be easier for you to buy the 1570 kv from rcbb ?

Pricewise about the same once a cooling jacket is added, although he only has one instock I believe.

[Old School]

Building two hulls at the same time is both time consuming and expensive. This shows progress to date with the second hull to the same stage. I am up to the point of affixing the longitudinal rails and completing the install of the stuffing tube. The images show a simple jig I set up to get the shaft square to the motor mount.

Those attempting a self righting boat may I offer one suggestion, before affixing the top plate on the chamber ensure the vertical plates are water tight. In this hull it was easier to affix the top plate of the chamber before fitting the sideplate, however, finding the source of a leak, right at the front of the chamber proved troublesome, being nearly 0.5 metres from the transom and almost totally dark inside.

[Old School]

I am currently fitting the equipment to the transom and have a question regarding the offset of the rudder. I am using an OSE rudder assembly and a Speedmaster stinger. When fitted, the propellor aligns with the trailing edge of the rudder.

I am thinking of offsetting the rudder mount centreline 55 mm to the right side of the transom vertical centreline. When the rudder throws full travel to port the rudder trailing edge neatly tucks in front of the propellor so little chance of contact but to ensure adequate clearance I was thinking of using an offset of 55 mm, although it does place the rudder a little far to the right side of the transom (aligning with the outer edge of the right side trimtab). Is it detrimental to offset the rudder too far to the right away from the prop centreline? Due only being able to fit one turn fin, most likely the boat will have predominantly right turns.

[rol243]

What i have found with mono hulls is having the rudder blade slightly behind the prop is better for handling than having the rudder before the prop. another thing to be carefull of is if the rudder is before the prop or even in line with the prop and you should make contact with something in the water which would kick the rudder blade back at the bottom thus making contact with the prop [ OUCH ]. you can position your rudder half way between your stinger and turnfin, just to the right of trim tab.

[Old School]

Many thanks. I will position the rudder further to the right than planned to get more clearance from the prop.

[Old School]

First static flip test on my son's hull in the bath was a success. The hull simply will not float upside down and flips immediately back upright. I was concerned that my additional float chamber may not have had enough volume. The second hull is about one day behind this hull.

The test was carried out minus the ESC as I was unsure of the watertight integrity of the hull fittings and even though waterproof to one metre I did not wish to chance fate. The ESC will mount forward beside the foremost battery and simply requires cable ties to secure.

The CoG is about one half inch forward of "ideal" but I do not think on a 32 inch hull that it should cause too much concern. The loop of water tubing on the transom is merely to seal off the through hull ferrules for the test.

[Old School]

I do not expect much runtime as the flood chamber intrudes on battery location and as the batteries need to be offset to port, space limitations mean that a 3s front and rear is the maximum as there are height limitations as well enclosing within the hatch. The motor does not help either as it is a TP Power 4060 1350kv running 6s (2 off 3s 65C - 130C discharge). The prop in the photograph is a CNC 442/3. I do not know if this will remain on the hull. I need the torque of a three-bladed prop to get the hull up on plane to empty the flood chambers after self righting.

The ESC is a Hobbyking 180 amp model, which given the potential current draw of the motor may be operating on its limit. I do not wish to over prop the boat to limit potential amp draw.

Apart from painting the hull, the only work required is to plumb the cooling lines, fit cooling outlets and RC antenna mount, attach the receiver and cable tie the ESC to its mounting. This project has given me a few headaches, the most notable being not knowing if the hull would self right. The original flood chamber as supplied on the hull was too small and leaked like a sieve. Given that the hull cost me around $130.00 including airmail postage I cannot complain. Now I need to concentrate on the second hull (my boat). This will be identical with the exception being a TP Power 4050 1330kv motor running 6s.

[rol243]

looking good. you can always give the hull a toss in launch like the glow and gas guys do with there hulls, this will get your hull up on the plain easier if needed. If your doing another mono how about offsetting the stinger / strut to starboard side by approx 3/16 to 1/4 inch as this helps to compensate motor / prop torque so then you should be able to place a battery pack on each side of motor eare for a good balance / cog.

[Old School]

I am not concerned with a normal upright takeoff onplane when initially launched , but when the boat flips the port side of the boat will be underwater with the flood chambers full. I do not really see an issue as the TP motors should make easy work of it. Just being a little overly cautious as this is a learning experience for me.

The self righting ability of the hull requires a port side bias to facilitate the flipping. Thus more weight needs to be placed on the left. A longitudinally stable boat may not self right unless it has a grossly oversized cabin/hatch (look to all the current self righting rescue craft used by the Coast Guard and RNLI organisations). The original Arowana 26" hull had an ugly oversized hatch to help the boat self right. I am extremely pleased with the self righting ability of this hull. The second boat already has the stinger mounted on the centreline and hopefully should self right exactly like this hull. The flood chamber does intrude on the internal hull space and this determines battery size and placement.

[rol243]

so have you run this hull yet ? or is this the 2nd hull ?

[Old School]

This is the first hull. I only installed the stinger and rudder assembly last night and did a static flip test this morning in the bath tub. The other hull is almost completed, just need to install the rudder and cooling lines.