HK Genesis tuning help!

[Sessholvlaru]

Hey guys. I'm new to the forum. Chris is the name.

So I have worked up my Genesis with a Leopard 4082 1,600 kV motor, Swordfish 240 ESC and 2 4S 5,000 packs in series (8S). X642 prop. This setup is based on several others I have seen, so I know that it works. However, their Genesis' seem rock steady at speed. Mine hops. Alot. To the point where the boat is actually leaving the water at speed.

I have tried: Moving the packs around. The guy who has this same setup and is doing 85 mph listed his c.g. (about 30%) and tried that. Still hops. I moved the packs around a lot and it made very little difference. I moved the strut further down and also tried angling downward (toward the water). This also made next to no difference.

The only thing I haven't tried is moving the strut up, as in the prop closer to the boat. Is this the key? Any other suggestions?

My video: http://www.youtube.com/watch?v=OyeleOEfpks

Guys vid whose setup I copied: http://www.youtube.com/watch?v=hQq5va2_Q-A

Note how much more stable his is. I'm not getting passed half throttle here. Please help, as this is getting very frustrating.

[tunnelvision]

Hey Chris,

Welcome to the boards! Search the threads, everything you need to know about setting up a Genesis is already on here.

However, here are a few tips that should help out a bit.
Set the CG at 27-30% from the end of the last ride pad on the bottom of the sponsons, not the centerline or overall length of the boat.
Next, lay the boat on a flat surface with the strut at the edge and prop hanging off. Set it flat and make sure the bottom of the last ride pads are touching the surface. When you look from the side the strut should be neutral with the propshaft slightly above the bottom of the sponson.

Hope this helps! Where in NJ do you run? I live near Princeton and go running almost every week.

[Sessholvlaru]

Thank you for your kind welcome.

I had searched the threads (I'm a regular on RCU for plane stuff) but really didn't come up with much.

The c.g. is right on the money, so that isn't the problem.

I adjusted the strut...is this what you were talking about? If so, the strut ends up about 1/8 inch higher than I had it. Maybe that will make all the difference!

Unfortunately I'm in West Caldwell, which is about 1.75 hours away from you. There isn't much in the way of boat clubs here so a buddy and me run in the local pond.

[HYDROJERRY]

yeah that looks about wright,, with the boat flat on a table the strut should be sitting flat on the table too,, but all must be level if the strut is low and making the boat sit up off the table the strut must be moved up so all is touching the table evenly,,thats your starting point then you can adjust it positive or negative angle as you test it in the water!!
Welcome to the site bro!!

[tunnelvision]

Yep, as Hydrojerry mentioned that looks good. Will be a good place to start. Let us know how it goes.

I do make it up to your part of the state every now and then. There are a few clubs up there I have been wanting to join. They run on Wednesdays and Saturdays. Anytime you plan on running shoot me a pm and we can meet up. Its about 75 t0 90 minute drive which I have no problem doing.

[martin]

I dont run cats but have seen a number of issues like this when running an inline rudder. I know a lot fit an offset rudder to cats to improve handling. Martin.

[Rumdog]

Raise the strut more. At least 1/8" above the sponson bottoms.

[Rumdog]

Also, 8s is a bit much with that motor.

[Sessholvlaru]

Yep, as Hydrojerry mentioned that looks good. Will be a good place to start. Let us know how it goes.

I do make it up to your part of the state every now and then. There are a few clubs up there I have been wanting to join. They run on Wednesdays and Saturdays. Anytime you plan on running shoot me a pm and we can meet up. Its about 75 t0 90 minute drive which I have no problem doing.

Thanks guys! I'm hoping to run it again after work today. I guess that the further I kept moving the strut down, the more it tried to push the nose down, hence the porpoising?

I had Googled around a bit and the closest club I found was in Mount Laurel, which is two hours away. Which club are you talking about?

[Sessholvlaru]

Also, 8s is a bit much with that motor.

Hi Rumdog. I will start with the strut flat, and work my way up.

This motor is rated up to 8S, and this is an all-out setup just to see how fast I can go. I plan on running it on 6S most of the time.

[v-spec]

Raise the strut more like others said. A friend had a Genesis do the same thing for weeks. I grabbed it raised the strut and it was instantly more stable on the water and faster too. I raised it about 3mm from bottom of sponson on a table.

[Sessholvlaru]

Raise the strut more like others said. A friend had a Genesis do the same thing for weeks. I grabbed it raised the strut and it was instantly more stable on the water and faster too. I raised it about 3mm from bottom of sponson on a table.

Thanks for the tip. Raising it 3mm's basically puts it as high as it can go. If the weather holds out I'll post more video tonight.

[Fluid]

Hi Rumdog. I will start with the strut flat, and work my way up.

As the strut is raised the hull will drop further into the water, helping to reduce the "hop". The CG will depend on the speed, prop depth and type, and the hull (they are NOT all the same). Do not assume that 27% is good, IME that is too far back . On my record-setting cats I run between 32-34%....but yours is a different hull entirely so it may be different.

This motor is rated up to 8S, and this is an all-out setup just to see how fast I can go. I plan on running it on 6S most of the time.

What the motor maker recommends as maximum voltage is pretty meaningless, it is meant for use in a gear box, not a boat. Even 6S is hot although not that extreme, just watch your run times and component temperatures. 8S is SAW territory and you will have to be careful not to burn things up. Only two passes then back to the beach to check the temperatures. You will need plenty of room to reach the 80s, a small pond will only be frustrating. I hope you have built the boat to survive a high speed crash (packs anchored with more than velcro, motor mount glassed down, etc.). You will eventually experience one.

A word to the wise - do not believe every video you see on line. You do not know how real it is, you don't know if what he said he used is actually in the boat for the video, you do not know that on the next run the boater blew up his ESC and packs. He may be lying, he may be mistaken, he may be 100% accurate - but it is not worth risking a lot of $$$ on a single video. Look around and ask questions, it could save you a lot of frustration and $$$.


.

[Sessholvlaru]

A word to the wise - do not believe every video you see on line. .

Thanks, but I am neither an idiot or a child. I am also very well versed with electric setups, just with airplanes and helis. If the video was not believable (you see the whole setup when he opens the boat) then I would not have spent several hundred dollars on the boat.

I appreciate your advise, but please don't insult my intelligence.

[Rumdog]

Sounded like good advice to me. You're the one who wants tuning help.