"China Walking" ????

[Terry Keeley]

Ron VanWagnen's wife Cheryl used to call it that anyway...

So for all you "one point hydro" guys, what causes chine walkin' and how do I stop it?

Getting my little Speedmaster 20 going faster and it just wants to rock from side to side and gets progressively worse unlesss I slow down. Tryed playing with the tabs and they can control it but it slows the hull down in the process.

Can I work the bottom? Add weight somewhere? Mess with the strut, chines, what? :unsure:

 

[Joe_Knesek]

Ron VanWagnen's wife Cheryl used to call it that anyway...
So for all you "one point hydro" guys, what causes chine walkin' and how do I stop it?

Getting my little Speedmaster 20 going faster and it just wants to rock from side to side and gets progressively worse unlesss I slow down. Tryed playing with the tabs and they can control it but it slows the hull down in the process.

Can I work the bottom? Add weight somewhere? Mess with the strut, chines, what? :unsure:

Terry of the 3 Speedmaster 20s I've built the only one that chine walks is the black one Emily races. The only difference in it and the other 2 are the tabs & lack of a turn fin. Obviously the turn fin is not doing anything but I think the Speedmaster tabs are too small and I've switched to Dave Prause's tabs. Since doing so, no chine walk.

By the way, I got the gears today. Thanks!

 

[oldlugs]

Terry of the 3 Speedmaster 20s I've built the only one that chine walks is the black one Emily races. The only difference in it and the other 2 are the tabs & lack of a turn fin. Obviously the turn fin is not doing anything but I think the Speedmaster tabs are too small and I've switched to Dave Prause's tabs. Since doing so, no chine walk.
By the way, I got the gears today. Thanks!

Hey Joe, where can I get hold of a set of Dave's trim tabs...?

Duane

 

[Joe_Knesek]

Terry of the 3 Speedmaster 20s I've built the only one that chine walks is the black one Emily races. The only difference in it and the other 2 are the tabs & lack of a turn fin. Obviously the turn fin is not doing anything but I think the Speedmaster tabs are too small and I've switched to Dave Prause's tabs. Since doing so, no chine walk.
By the way, I got the gears today. Thanks!

Hey Joe, where can I get hold of a set of Dave's trim tabs...?

Duane

Check Ebay.or call his dad.

 

[Ron Jefferson]

Terry: Just looking at the pics, I'd say the motor is too high

Rj.

 

[Ron Olson]

The Titan 21 that we had was notorious for chinewalking until I raised the strut up on it. I set the one on my Speedmaster 21 a little higher than normal when I built it and haven't had any problems with it.

 

[Rick Cesati]

Spoke with Dave Preusse this week He is building a new website. The tabs are on there.

www.CDrace1.com

Regards,

Rick

 

[Terry Keeley]

Ron VanWagnen's wife Cheryl used to call it that anyway...
So for all you "one point hydro" guys, what causes chine walkin' and how do I stop it?

Getting my little Speedmaster 20 going faster and it just wants to rock from side to side and gets progressively worse unlesss I slow down. Tryed playing with the tabs and they can control it but it slows the hull down in the process.

Can I work the bottom? Add weight somewhere? Mess with the strut, chines, what? :unsure:

Terry of the 3 Speedmaster 20s I've built the only one that chine walks is the black one Emily races. The only difference in it and the other 2 are the tabs & lack of a turn fin. Obviously the turn fin is not doing anything but I think the Speedmaster tabs are too small and I've switched to Dave Prause's tabs. Since doing so, no chine walk.

By the way, I got the gears today. Thanks!

Just got them now, jeez the mail's been slow lately, that's about 10 days to go the length of Lake Erie! <_<

Didn't think of the turn fin trick, even have one made up from when I built it, thanks!

Terry: Just looking at the pics, I'd say the motor is too high

Rj.

Knew I shudda made that unit a lay down... :lol:

 

[Joe_Knesek]

Terry I didn't see any difference in the handling with the added height of the gear drive. I only notice the difference in speed!

 

[John Finch]

Terry,

How ya been? Chine walk is caused by the prop. The prop turns counter clockwise as viewed from the rear of the boat, so the boat rolls clockwise. You knew that. Your just used to running riggers that have sponsons to control that type of thing. The answer is onefold..........Tabs don't stop it, they just slow you down. Strakes and fins can make it worse. The secret is.................. Move the strut a quarter inch to the right of centerline (give or take an eighth of an inch) where it exits the boat. Don't twist the strut or angle the direction of the strut. It will take a new stuffing tube, but do it! When the boat rolls in a clockwise direction the strut. being offset to the right of centerline is also lifting the right side of the boat. that lift from the prop WILL counteract the tourqe roll and you will loose no speed. Trimming a mono is like ballancing a marble on a razor blade. Ever done that?

Seriously.............that IS the secret given all other hardware and hull surfaces are true.

 

[Terry Keeley]

Thanks John, from the mono master himself no less!

Doing good, thanks, but I find this little Speedmaster more challenging than my hydros at times. :lol:

You'd mentioned that before and I should have done it over the winter but didn't. It doesn't show on this hull until about 55 so it doesn't bother me for heat racing. Guess I'll bit the bullet and do it now. B)

Funny thing also is that it tends to want to lean on the left side when I run it fast, don't think it's cause I'm holding left rudder but it might be. I have the tank on the left side at the CG, maybe it's too much? What about the rotation of the motor with the gear drive? The motor turns clockwise when viewed from behind...

Would different props walk more or less, even if they run the same speed?

 

[John Finch]

Sharper props cause less torque roll. Fuel on the left side can make it lean that way, but the real problem is when the boat does china walk the mass of the fuel going up and down makes the china walk turn into a down right disco dance. Always keep the weight in a boat as close to centerline as possible.

Banking to the left happens as you really air out and there is little boat touching the water. When you get going that fast and loose the rudder then lifts the boat. The further the rudder is to the right, the more it lifts the right side of the boat. Moving the rudder closer to the centerline of the boat will reduce that lift. Again......it only happens when you have a very fast and light running boat. I know all yours are light and fast, so look at moving the rudder more to the center of the boat.

It's the prop that causes the tourqu roll. I can't see the engine rotation having much effect. Torque can be a good thing: When I ran counter rotation props and engines on my riggers I stopped counterotation because there was no torque to hold the turnfin in the water when going thru a turn. With counter rotation if The boat lost grip of the turnfin in the corners the boats would roll over. With singles and twins with both props turning counter clockwise when the boat breaks loose in the corners, the torque slams the right sponson and turnfin back into the water. So torque is not always a bad thing.

 

[Ron Jefferson]

Still think the motor and tank are in the wrong position. Engine 1 to 1.5 inches up in the boat and the tank in the side also up higher won't be fixed by moving the strut over to one side of the hull.

Knesek... Height of the motor makes a huge difference in any boat so don't try to tell me it's not an issue. And, that having the motor up higher is a good trade-off for speed. That's just silly.

I still haven't seen a substantial difference in top speed to a gear drive set-up in a little mono. Throttleability or torque maybe, but not top end. Unless of course I missed something being out of the hobby for 1/2 a season.

Rj

 

[John Finch]

Still think the motor and tank are in the wrong position. Engine 1 to 1.5 inches up in the boat and the tank in the side also up higher won't be fixed by moving the strut over to one side of the hull.

Knesek... Height of the motor makes a huge difference in any boat so don't try to tell me it's not an issue. And, that having the motor up higher is a good trade-off for speed. That's just silly.

I still haven't seen a substantial difference in top speed to a gear drive set-up in a little mono. Throttleability or torque maybe, but not top end. Unless of course I missed something being out of the hobby for 1/2 a season.

Rj

We used to mount our engines high back in the late 1970s and early 1980s so the boats would stay leaned over in the corners. They didn't chine walk as a result. I agree with Knesek. What terry has is a faster than designed boat, which takes faster than designed measures. No the strut moved to the right won't cure his tank being on the left, but how much fuel is in that small 20 tank anyway. Ron has a good cure. Raise the strut, the boat will settle into the water, and it will be controllable at 48 to 50 mph. What Terry has is a real balancing act at 55 mph. I don't think he wants to settle for 48 mph and no china walk though. If you do, Terry. Just raise the strut.

I had a 20 mono that was clocked at 77 mph a month before record trials a few years back with no china walk. KP and I got the record at 65 mph, because the weather was terrible that weekend. Been there done that. The rudder was less than an inch from centerline because to the right the boat ran flat on its left side. Terrys rudder is way to far to the right to run excess of 55 mph and not lean to the left no matter where the tank is.

Been there done that.

 

[Ron Olson]

John, guess where I learned that at? Yup, one of your books!

 

[Joe_Knesek]

Still think the motor and tank are in the wrong position. Engine 1 to 1.5 inches up in the boat and the tank in the side also up higher won't be fixed by moving the strut over to one side of the hull.
Knesek... Height of the motor makes a huge difference in any boat so don't try to tell me it's not an issue. And, that having the motor up higher is a good trade-off for speed. That's just silly.

I still haven't seen a substantial difference in top speed to a gear drive set-up in a little mono. Throttleability or torque maybe, but not top end. Unless of course I missed something being out of the hobby for 1/2 a season.

Rj

Ron I'm not sure how you came up with 1.5 inches of increased height but the fact is the motor is less than a 1/2 higher then a conventional setup. Since you do not have to worry about getting a belt under the flywheel. The collet is nearly touching the bottom. I also reduced as much weight as possible from the drive and as a result, the boat is still under 5 pounds.

As John confirmed, the height of the motor does not cause chine walk. The larger prop is likely the culprit.

 

[Mark Stein]

Terry, Thats what made me retire the 3D .40 mono. It was so violent at the end of the straight I wasnt ever sure if was going to turn or turn over. I might have to pull it out again and make a few changes

If you can keep that Speedmaster standing up straight it going to be a rocket for sure.

Mark

 

[Terry Keeley]

h34r:

Sharper props cause less torque roll. Fuel on the left side can make it lean that way, but the real problem is when the boat does china walk the mass of the fuel going up and down makes the china walk turn into a down right disco dance. Always keep the weight in a boat as close to centerline as possible.

Banking to the left happens as you really air out and there is little boat touching the water. When you get going that fast and loose the rudder then lifts the boat. The further the rudder is to the right, the more it lifts the right side of the boat. Moving the rudder closer to the centerline of the boat will reduce that lift. Again......it only happens when you have a very fast and light running boat. I know all yours are light and fast, so look at moving the rudder more to the center of the boat.

It's the prop that causes the tourqu roll. I can't see the engine rotation having much effect. Torque can be a good thing: When I ran counter rotation props and engines on my riggers I stopped counterotation because there was no torque to hold the turnfin in the water when going thru a turn. With counter rotation if The boat lost grip of the turnfin in the corners the boats would roll over. With singles and twins with both props turning counter clockwise when the boat breaks loose in the corners, the torque slams the right sponson and turnfin back into the water. So torque is not always a bad thing.

Thanks John, I knew if anyone could help it would be you.

So what I get from this is that the drag of the rudder lifts the right side of the hull at a certain speed counter-acting the reaction from the prop, in effect causing an imbalance of forces. In my case having 10 oz. of fuel on the left makes it worse because there's more weight on the end of the pendulum.

Sooooo, if the rudder causes the right side to lift at a certain speed, if enough weight is added to that side to keep it from lifting would that delay the onset of the "disco walk"? :lol: What if just enough weight was added to counteract the rudder lift, would the hull fly level at a certain speed?

What causes the walk back and forth? Does the rudder lifting and then unloading have anything to do with it? Kinda like flutter on an airplane control surface?

For a pure SAW mono would it be better to put the rudder on the left?

 

[John Finch]

h34r:

Sharper props cause less torque roll. Fuel on the left side can make it lean that way, but the real problem is when the boat does china walk the mass of the fuel going up and down makes the china walk turn into a down right disco dance. Always keep the weight in a boat as close to centerline as possible.

Banking to the left happens as you really air out and there is little boat touching the water. When you get going that fast and loose the rudder then lifts the boat. The further the rudder is to the right, the more it lifts the right side of the boat. Moving the rudder closer to the centerline of the boat will reduce that lift. Again......it only happens when you have a very fast and light running boat. I know all yours are light and fast, so look at moving the rudder more to the center of the boat.

It's the prop that causes the tourqu roll. I can't see the engine rotation having much effect. Torque can be a good thing: When I ran counter rotation props and engines on my riggers I stopped counterotation because there was no torque to hold the turnfin in the water when going thru a turn. With counter rotation if The boat lost grip of the turnfin in the corners the boats would roll over. With singles and twins with both props turning counter clockwise when the boat breaks loose in the corners, the torque slams the right sponson and turnfin back into the water. So torque is not always a bad thing.

Thanks John, I knew if anyone could help it would be you.

So what I get from this is that the drag of the rudder lifts the right side of the hull at a certain speed counter-acting the reaction from the prop, in effect causing an imbalance of forces. In my case having 10 oz. of fuel on the left makes it worse because there's more weight on the end of the pendulum.

Sooooo, if the rudder causes the right side to lift at a certain speed, if enough weight is added to that side to keep it from lifting would that delay the onset of the "disco walk"? :lol: What if just enough weight was added to counteract the rudder lift, would the hull fly level at a certain speed?

What causes the walk back and forth? Does the rudder lifting and then unloading have anything to do with it? Kinda like flutter on an airplane control surface?

For a pure SAW mono would it be better to put the rudder on the left?

 

[John Finch]

Terry. The best thing for the model is to not have counter act for forces. Having the tank on the left is something you don't Want to have to counter for at slow speed. Having the rudder full to the right is something you don't want to have to counter for at high speed. The ptoblem is this.............At different speeds different hardware either effects or does not effect the ride of the hull. So.................to make it simple, put all the hardware where the boat is comfortable at all speeds. Don't build a plane that you know will flutter. If you build a wing that bends under pressure a tail spin eventually becomes tighter and tighter as air speed increases making an uncontrollable spin to the earth unless you can slow down airspeed enough for the wing to straighten out. Then you can pull out of the dive. That's airplane terms for what is happening here. Just put the tank in front of the engine, move the rudder to the left until it is about 1/4 inch from the outside edge of the prop, Move the strut to the right a bit, and you are ready for top speed. If the boat is wild after that.....Raise the strut to settle the boat into the water for control. If that doesn't meet your satidfaction then there are trim tabs. As for mounting the rudder to the left of center for straightaway records...... NO. that would really make the boat lean to the right. The distance from the rudder to the transom also effects how much the rudder holds the bow down in the corners and the straightaway. As does the depth and width. Believe me.......a mono is an animal that can be balanced a number of ways. Making changes that work at 55 mph don't work at 60 mph etc. It takes a lot of experimenting or a lot of luck at high speed because the effects of the hardware change as speed changes.