Another way to explain is this...........Think of the transom as a pivot point. If the rudder is close to the transom and it lifts the transon as water hits it, it doesn't take but a 1/4 inch of lift to move the bow a full inch. Do you see that relationship. Like a teeter totter with a short end at the rudder and the long end at the bow. If you extend the rudder away from the transom it takes less effort ( there is more leverage as you said) to lift the rudder same 1/4 inch. BUT the 1/4 inch moved on the rudder now only moves the bow 3/4 of an inch. If you went nuts and moved the rudder away from the transom the same distance as from the transom to the bow, a 1/4 inch movement at the rudder would only give a 1/4 inch movement at the bow. There is so much force on the rudder when the boat is running that leverage is not needed to make the rudder have leverage. When you have leverage- you lose distance traveled on the other end. I know that's confusing, But I am having a hard time explaining it. Take my word for it. It works. A quick way to see it...... is to hold your boat by the deepest part of the rudder with the boat bow pointing at the ground. You will notice that when the rudder is close to the transom the boat hangs tilted toward the rudder. If you extend the rudder you will see the boat hang straighter to vertical as you extend the rudder further from the boat. Now imagine that happening while the boat is running.
Kicking the rudder back causes lift at the transom when cornering and puts more pressure on the bow. More pressure at the bow and less at the transom equates to spinouts and darty turning. Looks like your rudder is kicked back a bit. As for trimming a Seaducer.......I will admit......I am not your guy on that one.
John,
i see why my little mono hops in the turns now..great info as always..MT
I think I get what you are saying!
I was hoping to keep the discussion generalised rather than focus on a specific hull. I am trying to understand what happens on a mono in a turn as opposed to on the straights, getting back to my earlier question relating to the effect of strut depth being different in the straights and corners.
Ian.
Ian,
The thing is............the boat design has a lot to do with how well a boat turns. The keel is actually a big player in turning the boat as it has more affect in holding the boat in the turns than the turn fin. The chine angle, vee angle, and bottom hull design dictate what you have to work with. There are some hulls out there that are designed in a maner that it is not possible to make the boat turn linear turns no matter what you do on the hardware setup. Here are a few known facts that can help.
1. When the boat turns and leans over on it's side, the boat will slide to the outside while turning. Thats just centrifugal force. The keel keeps the boat from sliding into never never land. If the keel bites hard in the forward section of the hull and the rear of the hull lifts because of a deep strut or strut that is too long (has too much leverage), the boat will spin out or dart. That's where a boat with a forward cg can dart more than one that has a 30 to 31 percent cg. If the hull is a warped plane bottom it is easier to control the pressure points to control the pressure at different parts of the keel. When you have a non warped plane bottom every little non conformity has an equal and opposite reaction to water under the hull. Like a hook for instance can be good for trimming the boat for the straightaway but be devastating for control in the corners.
2. Trim tabs affect cornering and can be adjusted to make the boat turn tighter or with less sensitivity on warped plane hulls, but not on most non warped plane boats.
3. If the strut puts the prop too far back the boat will hop in the corners. Mostly nitro boats because the extra weight of the gas boats keep the transom planted.
4. Sometimes we forget about the servo power. if the boat tends to stay turning after you let up on the steering wheel, the servo is too weak to center. If the boat fades or gets less responsive halfway thru the turn the servo is too weak.
5. If the prop is too large it may walk the boat around at the transom. Try a smaller diameter prop with more pitch.
That's it for now, got to get to work.
If you click on the pics, higher res pics come up.
