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Hi all, well i have my hands on a hk genisis. Running 6c , birdie 200 a , 2100kv motor . Its running fast and hot. I really wanted some ideas on a decent setup, ideal cg and trim( prop height).... I am not yet versed on the correct terminology so any explanations would be helpful. Eg sponson ?
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By 6c I think you mean 6s that's way too much rpm for a 2100Kv motor, you should be running 4s. That's why it's hot. What prop are you running on that? You want your rpm around 30,000 to work this out multiply your voltage by kv. Like my genesis is running 4s 14.8v and a 2000kv motor 14.8v x 2000= 29600rpm -
It is very likely the birdie will burn with your current setup, and potentially ruin your boat. (ask me how i know, nm don't ask) The ESC's build quality is poor and many have reported short lives or DOA - mostly with setups much milder than yours. I can point you to a thread that guides you through some improvements that can make the esc more reliable. Even then, it's more like a 100A esc than the advertised 200A. Sorry, I don't like to tell anyone their component isn't worth the risk. I'm just passing along what I've learned doing almost the exact thing you have.
Disclaimer: I hereby accept the potential loss of motor, ESC, entire boat, or credit rating, and forfeit all expectations of success.Comment
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It's a good old case of you get what you pay for. What do you want out of the boat ie 20-30-40mph long run times? The genesis prob isn't the best boat for a first boat. A turnigy 180 marine esc seems to be the choice of most here, me included and a Leopard motor although I run a turnigy XK-4074 2000kv motor and that seems to work well.Comment
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To try to answer your questions:
The sponsons are what your catamaran rides on. I've copied a pic I found that might help. It's from another member's post. Hope they don't mind. I've added comments showing where the rear of the sponsons are and an approximation of where to set the strut/prop shaft to start. (the dimensions are not me)
Gen transom.jpeg
Move the strut down to loosen up the boat. It tends to lift the rear. I found it less stable, but I had also moved my COG back (~28%). Moving the strut up drops more hull in the water. More stable for me.
Most suggest around 30% for the COG. This is 30% of the length of "wetted" hull. Measure from the front tip to the rear of the sponson. 30% of that length measured from the rear of the sponson gets you in the ballpark for COG. Each hull is different. I've read ranges from 25-35%. It also depends on speed, prop type, strut angle. COG needs to move forward with higher top speed to avoid spontaneous acrobatics.Disclaimer: I hereby accept the potential loss of motor, ESC, entire boat, or credit rating, and forfeit all expectations of success.Comment
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2100kv on 6s spells disaster. With that kv and the right prop and setup you should be able to achieve low 50s. If able run two 4s batts parallel for longer run times and cooler temps.white geico w/2200kv 3674 leopard 53.5mph 4s2p, geico w/ 1800kv outrunner 52mph on 4s2p, genesis w/2200kv castle 53.8 on 4s2p, impulse 31 w/2200kv castle, stock p1 and ul-1
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All the remarks included here so far are right on with this boat. 6S (22.2 volts) is too much for a 2100 KV motor. Trying to run 46,000 rpms is not near where the sweet spot is for your setup. 4S will make you very happy and your esc will thank you for it.
If you insist on running 6S find a 4082 around 1400 KV.Last edited by 1945dave; 06-13-2012, 01:04 PM.Comment
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Aside from everyone nailing the 2100kv and the 6c problem. Haven't seen you chime back in here bud.......I guess I'm left wondering what you are wanting out of this boat......set up can only follow after that is decided in my mindComment
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Well am still running the 6 s with better set up. its pretty fast but will definately take advice as stated because of the obvious over heating issue.Comment
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J, what prop are you spinning?Disclaimer: I hereby accept the potential loss of motor, ESC, entire boat, or credit rating, and forfeit all expectations of success.Comment
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J when will you take the advice as stated here? Some really knowledgable guys are spending their time trying to help you. Sounds like you are not reading or even trying to understand what we are saying to you. Everyone of us have full confidence if you are going to run 6S batteries with a 2100KV motor you can expect "the obvious over heating issue" to continue!!! Why do you think this does not apply to your situation? Drop down to 4S and you will be very happy. If you don't change the batteries to 4S your only other option is to change the motor to a lower KV rated motor. Failing to do one or the other and you will be melting something soon and spending even more money.
DaveComment
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Boy, I sure didn't want to get involved with discussing actual speed results regarding the Genesis. The problem J has with running 6S batteries and his 2100 KV motor if we plug in the numbers using the OSE speed calculator chart (see above link) you will find the theorectical no load rpm's for J's motor is 46,620 rpm's. Using the recommended M445 prop you will also see that the theorectical speed a boat setup like this could run 109 mph at 100 percent efficiency. At 80 percent efficency it is still 89 mph. So do I believe J is running fast you bet. The Genesis is no doubt a very honest 60 mph boat on 6S. I would not be surprised if J's boat ran in the low 60's. Yet for all the real expectations you can be sure J is not running much higher than mid to low 60 mph speeds. All the lost energy in not running 89 mph has to be lost in excessive heat. It may be a wonder we haven't heard about a burnt offering to the water god's.
DaveComment
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You have to take off around 20% slip on the prop in a cat hull + whatever the efficency of the motor is, on cheaper motors its prob between 70-80% efficent so theirs another 20-30% to add to the 20% of the prop slip.Comment
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I dont use the OSE calc but im sure it works out simular speeds, with the numbers ie kv,prop,hull type, slip,motor efficency i get 60-62mph.Comment
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