Hopping in turns

[keithbradley]

I have a Supervee 27 that Im trying to get to steer better. I have used the boat for mostly SAW type runs in the past and now Im trying to straighten out the handling charecteristics when turning.
The problem Im having is the boat hopping when turning. Even at lower speeds, and turning in either direction, its hopping every time I turn. The boat didnt always do this, but I have had several different motor/esc/battery combinations and at this time I am running a leopard 4074/sf 120 an 4s2p lipos. Its pretty heavy and sits down in the water pretty good. I'm thinking maybe the extra weight is having an affect on the boat's horizontal attitude when turning and the rudder is lifting the boat. I will probably try a few degrees negative rudder caster next time I take it out (Its around zero now, maybe even a degree or so positive when the boat is at ride level).

It seemed to get MUCH worse after this crash, so Im thinking it may have knocked the rudder further into positive:

http://www.youtube.com/watch?v=x9c1QQnQXok&feature=related

Any other ideas on this?

[Fluid]

The boat is heavier and faster, you probably need larger turn fins. Hopping is one characteristic of too small fins.



.

[m4a1usr]

What prop are you running? Something with lift? A 4074 is big for that hull. Like Jay said the fins, but since its happening in turns and not speed related can you hear the prop loading and unloading? Maybe stinger angle? Depending on how far over the hull is leaning in the turn the stinger angle changes. I.E. they are adjustable up and down. Granted you would have to be at 90 deg to have a neutral setting but just throwing that out for thought. CG?


John

[keithbradley]

The boat is heavier and faster, you probably need larger turn fins. Hopping is one characteristic of too small fins.



.

Any reccomendations on turn fins? I know TOO MUCH fin can cause problems too, but I would like to get this thing dialed in to take turns at hgih speed. I assume at least some of this has to do with the rudder, because its ALOT worse now than it was in that video, and nothing else has changed other than that crash.
I have been thinking about a couple good fins though. I'm sure it would help.

[Brushless01]

http://www.offshoreelectrics.com/pro...prod=ose-80049

[keithbradley]

What prop are you running? Something with lift? A 4074 is big for that hull. Like Jay said the fins, but since its happening in turns and not speed related can you hear the prop loading and unloading? Maybe stinger angle? Depending on how far over the hull is leaning in the turn the stinger angle changes. I.E. they are adjustable up and down. Granted you would have to be at 90 deg to have a neutral setting but just throwing that out for thought. CG?


John

x445 prop, CG is at about 28%. As far as the prop loading/unloading, yes. It's literally hopping out of the water sideways. I am definitely getting lift from somewhere, and I'm getting a lot more than I was last time I ran it with the same prop, motor, batts, ect. Im getting hop taking corners at a "barely on plane" speed. Maybe 10mph.

As far as leaning in the turns, it isnt really even getting the chance to. It just hops out of the water with little lean at all. Thats why Im thinking maybe the rudder caster changed I know it hit hard on the rudder in the last crash. It sheared the ball off of the steering mount (obviously that has been fixed now).

I know the 4074 is a little big for the hull, but thats nothing new for me. I have a tendancy to go a little big on everything. Bigger is not always better, for sure, but I do like the freedom to move up to a bigger hull with the power system I have if I want to. Also this setup runs nice and cool and run times have been great so far. At this point I would just like to see if I can get it to run well enough where I can run an oval at speed. It runs quite well on 3s2p as well and if I could run an oval flat out on 3s I would be happy. 4s I cant always run a straight line flat out so I dont expect miracles there.

[m4a1usr]

Im getting hop taking corners at a "barely on plane" speed. Maybe 10mph.

As far as leaning in the turns, it isnt really even getting the chance to. It just hops out of the water with little lean at all. Thats why Im thinking maybe the rudder caster changed I know it hit hard on the rudder in the last crash. It sheared the ball off of the steering mount (obviously that has been fixed now).

I'd put the hull on a table letting the keel rest on its surface, let the rudder hang over the edge. Put something under each side to level it as best you can. Then put something under the nose until only the last 6 or 7 inches (measured from the transom) of the keel are in contact with the table top. That should be the natural ride angle of this hull. See where your trim tabs are adjusted. They might need to be adjusted. Now you should be able tell the leading edge angle of the rudders face. I like mine neutral in almost every mono I own, yours might need tucked in towards the transom. You certainly dont need any lift it sounds like.

This would also be a good time to see where your turn fins are adjusted. They should not be lower then your keel. Adjusted like that they are nothing but drag in the water. Turn fins are just that. Needed in a turn, not in the straights. You know all the basics but remember. Do one thing at a time. Test. If not fixed move to the next. Certainly listen to what Jay has to say.

John

[Gerwin Brommer]

Are you 100% nothing changed (positon-wise) after the crash ??
Looking at a supervee, I can imagine the turnfin changed position, as it has only 1 bolt in it, and not even an washer , etc etc etc.

[keithbradley]

Well I just got back from the lake. Wish I had some video to post of the sv27 now but only got the camera out for the DF40.
I put a little bit of negative caster on the rudder and it seems Im back where I started before the crash if not a little better.
It still hopped a little, but mostly because the water was a bit choppy today. I will be ordering a new set of turn fins soon. I think that will help out a lot on this boat. I'll probably get a better set of trim tabs for it too as the stock ones are pretty mickey mouse.
Thanks for the help guys. Your opinions and advice are very much appreciated.

[Brushless01]

http://www.offshoreelectrics.com/pro...prod=ose-80049

Try these work great gets rid of the hopping !!

[andym]

Hopping in turns is also a sign of pos on rudder, this causes lift in the turn. I like a few deg of neg on rudder ( end towards keel) helps keep em pinned in turns. Look at everything one thing at a time and you will find it.