Genesis skittish at high speed

[Mattwarner]

Hi, having just finished a twin rivercat it's made me realise how badly my CF Genesis handles at speed, whereas the rivercat stays planted the genesis seems very light and almost chine walks, I've adjusted the cog but this just makes it plough/porpoise so I was thinking it must be the strut height, currently it's level with/maybe 1mm lower than the sponsons, to get it higher I need to put a touch more bend in the stuffing tube and grind the adjustment on the strut but first I wanted to find out whether you think I am on the right track? What happens if the strut is too high? The stingers on the rivercat are about 5mm from the bottom of the sponson

Thanks

[srislash]

That's exactly what I need to do with my Geico.Next time out.You're on the right track Matt.

[Prop-a-Gator]

What prop are you running, Matt? I'll be running my Daytona today. I'll record cog, strut height and angle. Maybe we can learn something together. I bet my Daytona is a lot heavier than your CF version, so not everything may apply. I ran my maiden with the bottom of the strut about 1-2mm above the sponsons and level with a 442 prop. It ran well, maybe a little wet or maybe 40ish mph really doesn't air out this hull.

There's a lot of Genesis experience on this forum, though I'm not sure I recall reading about what you're describing. Any video?

[martin]

Are you using the inline rudder or did you mod to an offset, a friend of mine was having this skittish problem where it would be excellerating quite hard & suddenly it would flick to one side.Also in fast turns it was easy to turn over where it was skitish in the turn, i said to fit an offset rudder & it cured these nasty habits to the point he could turn flat out quite sharply & the boat was planted. No more flicks in a staight line when excelerating either.

[ozzie-crawl]

I have not had a genesis hull but had a few single motor rivercats. they to become very squirrelly with a inline rudder. A strong servo and steering rod can help, but up over 55mph they still become very twitchy and still dont corner very well. as Martin says if you have a inline a offset will make a huge difference.

[Mattwarner]

Currently i have an X443 prop and inline rudder mainly because i set it up with a push/pull servo set up, Martin thats interesting you say about it flicking to one side as mine does the same especially at high speed, i am running a 4082 on 6s so should be getting 55ish but so far ive not been able to hold full throttle long enough to get close.

Ive also thought about running 6s2p to give a little more weight and maybe that will help.

Heres the setup:

[izcain]

I was right were you are about a month ago Matt. After raising the strut and moving the cog to about 33 for me and running a M445 from it cleaned itself right up!

I am going to change to an offset rudder though since I think it will work better as I begin to go faster then what I am currently running (gps'd 61.8) I believe I have pretty much the exact same setup as you right now Matt

[Mattwarner]

good to know!! how far up is your strut and what angle (if any) are you running, if you could post a pic that would be handy, and as for 33% cog what does that work out as inches from the rear sponson?

I read your post on your Genesis as you have the same setup 61.8 is great going! think i might get a M445 too.

[izcain]

If it makes any sense to you my strut has 2.5mm sticking up thru the center on the top part of the bracket. No angle up or down (neutral I would say). I will post a pic in a little bit that shows what I am talking about. I will remeasure the cog again tonight and let you know what I come up with in inches I forget now.

I am moving to a M545 and 645 right now to try out and see how fast it will go before I change esc's and start adding cells!

[martin]

My friends Genesis has one of the XK Turnigy 1600kv motors on 6s with i believe was an X444 & he got around 56mph.

[Mattwarner]

If it makes any sense to you my strut has 2.5mm sticking up thru the center on the top part of the bracket. No angle up or down (neutral I would say). I will post a pic in a little bit that shows what I am talking about. I will remeasure the cog again tonight and let you know what I come up with in inches I forget now.

I am moving to a M545 and 645 right now to try out and see how fast it will go before I change esc's and start adding cells!

If you look at the pic i posted my strut is already above the top of the bracket by at least 2.5mm and this was when the bottom of the stut was set below the sponsons, i am going to need to lengthen the slot in the strut to raise it any further

[izcain]

Where is your cog at right now?

I found too much and it plowed and to little and it was all over the place

[Mattwarner]

It's about 9" from the rear sponson

[Prop-a-Gator]

This is where my strut is. Not sure if you're running the larger 3/16 "conversion" strut. Mine is the Genesis strut. You can see I need quite a bit more than 2.5 mm above the bracket to get the bottom of the strut level with the sponsons.
DSC00728.JPG
My only issue is that it tends to turn right at speed. Prop walk? It also seems to run a little wet. I'll move the cog back a little. It was at 30% (9-3/4" from [edit] rear of sponson)
You guys are running bigger props than me. Does your torque roll affect you once on plane? My right sponson seems to run wetter than the left - though I haven't gotten really good video to replay.

[izcain]

My Cog is set at just a touch over 10 3/4 inches from the rear of the sponsen. it will plow water unless I bring the wheel a touch to the left, once you do that it airs right out and shoots straight! I imagine I will have to retune once I get the other props installed.