33 inch rigger handling very twitchy

[RC boat addict]

I am wondering how to reduce my riggers turning ability mechanically I have reduced down the travel on the remote but this increases the turning circle at slow speed too much. does moving the turn fin forward make it more stable? currently my turn fin trailing edge is right at the COG.With the fin mounted there it can turn in its own length at full speed. this is a severe test for the strength of everything.
Thanks for any help
James

[Ch.Lucas]

Hi,
mounting the turnfin more forward will give a higher momentum to rise the turnability. The riger will be more nerveus , possible the turn circle will be smaller , sometimes to small making a turn in. As closer the turnfit is to the c.g. it is more neutral , the rigger can hang on this stable point . To increase the turn ability you have to rise the turnfin size , deep. Also the ruder size helps . But all this will have higher drag and slow down topspeed. Possible a aktiv turnfin will help. Like a ruder a servo can give a better angle of atace , this is not limited only to the ruder. You can place different fins and you can make them all stearable. Have a closer look at fighter airplane. They have many flaps and ruder options to get highest turnability.

Happy Amps Christian

[RC boat addict]

I would have thought moving the turn fin forward would be like increasing the wheelbase on a car and making it less twitchy (more stable) At the moment where it is it only takes the smallest amount of rudder angle for it to hook into a turn I have no play in the steering parts at all.the turn fin starts it bend right at the point where it contacts the water,I am not sure if this is right I looked at other riggers to see if this is the correct depth.
Kind Regards James

[T.S.Davis]

Riggers require very little rudder input typically.

In yer head think about how a claw hammer works to pull out a nail. The end of the hammer handle is where the power comes from to pull the nail. If you make the handle longer on the hammer it pulls the nail much easier. Same is true for your rudder. Imagine your rudder is at the end of the hammer handle. Now make the handle longer.........gives that rudder more leverage to turn the boat. So moving the fin back on the boat makes the pivot point closer to the power (rudder). Makes the lever shorter. It has less leverage. Think claw hammer but cut the handle in half. Now try to pull the nail. Tougher to do. We've made the handle less powerful.

In theory of course. Every boat is a little bit different. This works on sport hydros too by the way. Little shifts this way or that can make a boat turn different.

[RC boat addict]

Ok guys I moved the fin forward 2 inches
(problem solved) I think you were right the fin going forward makes more leverage which just meant a weaker servo might do the same job but moving the fin forward took away the twitchy handling just like lengthening the wheel base on a car. The way I see it is I increased the wheel base. Imagine a one hundred foot long ship it will take longer to turn than a 20 foot long boat the turning radius is longer on the ship. Now imagine if the turn fin on the ship is at the front the radius of the turn is the length of the ship(100 ft) if the fin is in the middle of the ship the turn radius is halved. I did not want my rigger to turn sharper( less radius) i wanted the opposite.