New to FE, and have some questions!

[Bubblegoose]

Hi Guys,

I have always liked watching people race boats around ponds and lakes, and have been an avid RC enthusiast for many years. I decided to span my RC reach to boating as I have all other bases covered.

Here is a list of what I have purchased so far:

HK Genesis cat (semi rtr)
ZIPPY Flightmax 5000mAh 4S1P 20C x2 (bought specifically for this boat)
HK-310 3 Channel 2.4ghz FHSS Ground Radio
Turnigy Aquastar 120A Watercooled ESC w/Prog
Turnigy nano-tech 5300mah 2S2P 50~100C Hardcase (bought for my RC car, but also can be used in series for this boat)
HK's 435 Metal prop
HK's 440 Metal prop
As well as a bunch of other stuff like silicone wire, heatshrink, new XT60 connectors for everything.

I have setup the boat as best as I could, however when on it's maiden voyage, it emitted some strange behavior, but as I am in unfamiliar waters *ba doom tish* I am not sure what is causing the behavior.

Firstly, it seems to sit quite low in the water, I have attributed this to the batteries I have chosen weighing more than the boat can handle.
The second thing it does, is when I go 1/10th throttle, the boat goes along quite nicely, I give it a bit more stick and it picks up speed. I then give it some more from about 1/4 to 1/2 throttle and it starts to kind of slow downm, and looks and sounds like the prop has stopped pushing water, to rather milk-shaking it. like someone has thrown an anchor on it. but once I ho above half throttle up to about 3/4 it jumps up on plane and blasts along. It's very stable in turns even sharp ones, but if I don't give it full stick out of the turn it tends to bog down and looks like it's treading water for a bit until it jumps on plane.

Could all of this be attributed to too much weight, and it riding too low in the water? When I say low, I mean, the rudder is basically fully submerged when the boat is in the water.

Another problem I have had, is that the rudder water pickup does not seem to work, I couldn't see any water coming out the side outlet, and when I got the boat back to shore after a minute or so of driving, the tubes had only a drop or so of water in them. Could this also be attributed to the ride height in the water? I have seen where others have had to modify their rudders, making the inlet wider, so I might try that as well.

Anyway, thanks for reading! And hope you can help!

[Chilli]

It's kind of hard to assess the problem without knowing more about your set up. It could be weight, but I doubt it. It could be prop, CG or hardware set up or a combination of everything.

What motor is in the boat, what KV and what size is the hull?

A picture of the transom and the interior might help also.

Water coming out of the outlet can be hard to see while running. I disconnect the cooling hose from the rudder, fill my mouth with water and blow it through the cooling system. Then I'll connect back to the rudder and disconnect the hose at the other end and blow. This helps me check if the cooling system is clogged and if there are any leaks. Low tech but it works.

BTW- Taking a while to get a boat set up is something most of us have experienced. Especially when it's your first boat. Knowing how to set a boat is part of the learning process. The more experience you get, the easier it becomes. When you get the boat running right, it will be worth it and you'll be grinning from ear to ear. So don't get discouraged!!

[Bubblegoose]

Thanks for all the info mate. sorry no pictures just yet, Will get around to it soon though. although hobby king has a few pics of it with specs

I took it for a drive yesterday after work, and I tried with one 5000mah 4s lipo (so about 450g worth) right up at the front of the boat hatch. rather than two (almost a kg of battery) in each hull straddling the motor/esc.

While it sits a little higher in the water, I'm not sure if it made much of a difference really, it still sat relatively low in the water.

Onto the second issues I noted earlier. It still had this issue with less weight. However if the boat is stationary, and I pull the throttle on 100%, it shoots off (with a bit of a jump) like a rocket right up to full speed with no hesitation. If I give it about 20% throttle and then hammer it, it almost sounds like it's running out of the water (like the motor/ prop sounds very unloaded), and then after a second or so it just goes *bang* and takes off (kinda like doing a burn out in a car I guess). but all the way up till about 50% throttle, even if I am slow at applying throttle, it still moves quite slowly, then once you go a bit faster it just comes alive.

When I do a turn with a radius of about, 3 meters, even if I give it full throttle, a slow squeeze, a fast squeeze etc, it still just mashes water for a good second or so and then if I have enough throttle it will take off.

As I am new to boating, this might just be what they are like? and I have to learn to hammer it hard and then stay above 50% throttle? and just try to do bigger corners to not lose speed?


Also, on a side note. My HobbyKing ECO 6-10 Battery charger died last night I had been previously doing a liberal charge the first time of the batteries at 2 amps (which is about 0.5c), however after seeing plenty of people charging these batteries at 2C with no heat or issues, and the charger advertising it can dish out 10A I have it a try. Charged the battery fine, however when I went to do a second battery it said "connection failure". Which was not the case, it said the same thing for the battery I knew worked as it just charged it, and tested as working (on each cell) with a battery meter. It is my only charger, so I will have to wait till I can afford to buy a decent one...

[Flying Scotsman]

These words of wisdom from Nautiboyz are very valid.....I might suggest a prop problem.....Did you sharpen and balance it?...Do you know your CG position?....also welcome to the wacky world of FE boating.

Douggie

It's kind of hard to assess the problem without knowing more about your set up. It could be weight, but I doubt it. It could be prop, CG or hardware set up or a combination of everything.

What motor is in the boat, what KV and what size is the hull?

A picture of the transom and the interior might help also.

Water coming out of the outlet can be hard to see while running. I disconnect the cooling hose from the rudder, fill my mouth with water and blow it through the cooling system. Then I'll connect back to the rudder and disconnect the hose at the other end and blow. This helps me check if the cooling system is clogged and if there are any leaks. Low tech but it works.

BTW- Taking a while to get a boat set up is something most of us have experienced. Especially when it's your first boat. Knowing how to set a boat is part of the learning process. The more experience you get, the easier it becomes. When you get the boat running right, it will be worth it and you'll be grinning from ear to ear. So don't get discouraged!!

[Chilli]

Thanks Douggie.

BG, I think some of what you think are problems are normal for FE's. These boats do sit low in the water when at rest. The rear shouldnt be totally submerged but having most of the transom under water is not uncommon. Your second problem sounds like the prop ventilating and thats also normal. Most FE's will just churn the water at 1/4 throttle. Once she gets on plane and the prop bites, then the boat will take off. Remember these are small surface drive props and they spin really fast. Only half the prop is in the water when the boat is on plane.

Your CG should be somewhere in the neigborhood of 28-33%. Thats measuring from the back of the sponson forward. If your bow is digging into the water at full thottle, you need to move the batteries back a bit. Having the CG to far forward increases the load on the motor increasing heat and amperage draw. It can also cause the boat to submarine if it gets airborn. If the CF is too far back, then the boat can run nose high, porpoise or the bow will bounce up and down. When the CG is right, the boat will run level to slightly nose high. if the boat catches a small wave and gets a little air, the hull should for the most part stay level. Now........this is what makes a newbie want to tear his hair learing how to tune a boats ride. Just about everything I describe can also be affected by, prop, strut height, strut angle, rudder lenght, rudder angle, trim tabs. You adjust one thing, and it may throw off something else. Thats why you must only make one at a time and make it small.

This probably makes you want to get a car.

[sanyijr]

Hey Nautiboyz,

I did just get my nitro car going.... That is well put, to start with. That is why you need to have at least two types of R/C vehicles. I have gone from elect. cars to gliders to boats back to gliders to nitro cars to boats again. Now I run all of them here and there, so I never get frustrated enough to pull my hair out.

BubbleGoose, good luck on your setup. Boating is super fun once you have a solid setup!!!

[Chilli]

I just got into planes myself this past year. It didnt take long to get another...and another. I told the wife I'm for cross training for boat racing. Also got my son a T-Maxx for Christmas since he got good grades. He's been wanting a nitro truck for two years. My basement is better stocked than most hobby shops.

[Bubblegoose]

Thanks for all the reply's. I have a lot to test out it seems! I cant do much until I get a new charger, so I might not post back with anything for a few weeks. I have a prop balancer, and although it's pretty balanced, it's definitly not sharp. I tried the stock plastic/composite prop, and it isn't very sharp, and it yielded similar results.

Next voyage, I will try with a sharpened metal prop, I will also try with the batteries further back. in the boat (I will test the CG and get it to about 30% from the sponson (that's the back of the boat that the water is in contact with correct?). And I will let you know how it goes. I think it may be a case of weight too far forward now you mention it, as that might just cause it to be getting up on plane slowly, meaning I need to give it more throttle till the prop bites. And now you have said it, it does actually seem like that's what's happening.

The reason I put the weight forward in the first place, was the water looked as though it was going in the outlet for the water-cooling and I thought it should be above the water. I now realise that's a stupid idea I had in my head, as even if it was under the water, it wont get water in the boat!

Thanks again! Will let you know my luck in due time.

[JIM MARCUM]

Ditto all of the above. Tuning an FE boat can be a bitch. But it's a great feeling when you get it right.
Here are a few thoughts.
1. Set your CG as above (27-30%).
2. Set your boat on a flat surface and adjust your prop shaft so it's sitting flat & inline with the hull bottom. Raise/lower the prop strut to do this.
3. Buy a better charger. I like this one at http://www.hobbyking.com/hobbyking/s...dProduct=10327. JIM

PS: A lot of us R/C guys could open a hobby store with our collections. Just don't tell the wife how much money you spend.

[Bubblegoose]

I had one last fully charged battery (4S) and so I decided today to fix some of the possible issues and see how I went. I sharpened, balanced and polished the prop. I also moved the batteries back about 8cm back on the battery supports. I only had one battery connected, but I threw another in just to balance the weight. got the CG low and at 30%.

It seems these were good starting points, and while not 100% happy with the ride, I think the CG being where it is was worked a lot better than My previous attempt. Not sure if the prop modifications made a lot of difference, but it was hard to tell as the way I approached driving the boat was a lot different. It performed well.

The last real issue I have is water cooling. Everything is super hot inside, just after a short run. And there is no water in the hoses (I would expect there to be some). It might just be the lines are too narrow in diameter, but it takes a fair bit of pressure for me to blow water through so no wonder it's struggling.

What would be my best option? Put in a new prop spray water pickup? increase the tubing sizes (and someone modify the barbs on the esc)?

cheers for all the great advice so far. Much appreciated.

[cuppa]

If it takes a lot of pressure to blow water through the cooling system it could be that you have either a blockage somewhere in the system or a kinked cooling tube.

You can check that you do not have a blockage by getting disconnecting the existing tubing and then plug a length of tubing into the individual components one at a time (motor, esc, pickup and outlet) and blow through it to see where the blockage is.

Cheers
Jon

[Bubblegoose]

Yeah I did check that after the first run. It just seems that every part is adding a little bit more resistance. Each part on their own is fine, and there are no kinks. But when I add a little bit more, it just builds up more resistance.

When I first got my ESC, two barbs were completely blocked off (thankfully one on each side) they were almost 100% filled with red locktite. I was able to use some wire and push it out.

I'm not really a novice when it comes to water cooling systems. I'm an extreme overclocking enthusiast, and have build and used many water cooling systems, mostly LN2 or phase though. So I know my way around a watercooling loop. The only difference with the boat is it's open and not closed!

[pompebled]

Hi BG,

The lack of flow on your cat can be two things, if you don't count blockage of the barbs; the slit in the rudderblade needs to be elongated forward, so the waterflow actually reaches the vertical hole and the water gets pushed in.
Secondly, the Chinese tend to go overboard on the length of the silicon tubing; shorten it as much as possible, without kinking it and replace the long stretch from the inlet on the rear to the ESC with Ø4 mm aluminum pipe, this will drastically reduce the drag in the system and give you more than enough waterflow.

Regards, Jan.

[Flying Scotsman]

How hot is super hot?....battery, motor and ESC temps are what if read with an infrared temp gauge?

Douggie

[properchopper]

Re watercooling flow ; It's best to run a flow & leak test on a fresh build. I made a goodie to screw onto the faucet aerator (or you could make a squeeze-bulb thang). Blowing air will give you a false reading unless you have a complete blockage as in your T-120 [which JUST happened to a buddy's new T-120 btw - oops Turnigy ]

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