Push or Pull for Rudder control - Wild Thing Mono

[Curtis Beaumont]

Hey Guys,

I have been mounting the hardware I am going to run and noticed that I could put the rudder linkage on either side of the rudder, so I got to thinking, what is best? I would think that I would want to pull on the linkage through the oval and so I would want the linkage on the right side of the rudder. I took a look a t a bunch of boats, including my own Revolt 30 and it is a crap shoot. The revolt is a push rudder linkage.

Is there a reason for one over the other?

Now that I am thinking about it, it looks like John has it mounted on the right side from the photo of the transom in the original build article. This is a plans-built boat, not the new ML kit.

Thanks,

Curtis

 

[BobBonahoom]

Curtis,

I have never paid any attention to this in building, but now that you bring it up, it makes sense to pull the rudder through the turn. Simply because the pushrod is less likely to bend or bow. I noticed that John mounted his so the arm was inside the turn radius so that he was pulling on the linkage. Historicall, IMPBA boaters put the rudder on the right and with normal bracket mounting, they would be pushing the rudder. NAMBA boaters were usually on the left, hence pulling the rudder. In all these years I have never heard anybody comment on which is better and why.

By the way, I told John that I was dissapointed in how heavy my 21 ML Wild Thing kit turned out at 5 lbs 13 oz. He said the weight was good! Unlike hydros, he mentioned that people usually must add weight to monos to keep them on the water. The ML kit is the best I have ever seen in terms of quality of the wood and accuracy of fit. It came with a laser cut building jig. The boat turned out straight and true. GG was right on at 9.5" from the transom w/o fuel. Now we just need to get rid of the 10 feet of ice on the pond!

Bob

 

[John Finch]

Bob,

I have run both push and pull on the rudder. Sometimes it takes more strength to bring the rudder back to neutral than to make the boat turn because the boat naturaly wants to turn right and the prop is dragging the transom to the left. If you have a boat that comes out of a corner and wants to keep turning into the course when you straighten the steering wheel it is usualy that the servo is not strong enough to fight the prop pulling the transom around. The boat wants to stay in the turn. With the wild thing you are ok either way but I would use a servo like the hitec 645 mg on 5 cells for 133 inch ounces of torque for good control.

 

[BobBonahoom]

Thanks John,

I am using a Savox 1256 Titanium gear servo. This can do 277 inch ounces. Probably over kill, but I had it in the spare parts box.

 

[Samuel Hagan JR]

Would push or pull rudder act the same on hydro as to a mono?

 

[glenng]

Push rods are longer on hydros so I prefer they pull.

 

[John Finch]

Glenn has a good point on the larger hydros. My twin inline and sport gas SAW boats run very large props with 8 inches of pitch. When I let off the throttle too fast at the end of a run the prop acts as a brake and pulls the transom to the right really hard. If the rudder linkage is a push the linkage rod will bend. I have seen it on the mono SAW boats too. I know my situation is an extreme condition, but sometimes the extreme situations tell a more dramatic story. You have to let off the throttle fast when the bank is approaching at 300 feet in less than two seconds. Example.......when i set the twin SAW record i bent the linkage twice, bent the rudder bracket once, broke the sevro arm twice, and finally ripped out the servo. Lots of brake and break all in one day. Because the props are so big I have no choice but to do a push to turn or the props would hit the rudder. On the wild thing the props are so small this problem will never be seen. Push or pull according to where you can mount the servo for the best straight line to the rudder.

 

[glenng]

Well JC on a ten speed, Someone agreed with me

.

. On a .21 mono it would not be a big difference but when you step up to larger boats or Hydroplanes with longer pushrods The story changes. I make my own push rods from carbon fiber with tool steal ends. My own sport 40 seems to be right on the edge with a 645MG so it will be swapped out for a 200 Oz airtronics swrvo.

 

[BobBonahoom]

Glenn,

How do you attach he tool steel ends to the carbon fiber? Is it a carbon fiber tube? Can you tell use where you get the steel ends and the fiber?

This is good stuff.

Thanks,

Bob

 

[glenng]

Bob, the carbon fiber tubes were 5MM dia. and I bought them on e-bay quite a few years ago. they came with 4-40 all thread ends but I did not like the threads going thru the pushrod boots so I made my own by threading some pieces of S-7 tool steel with a die and die holder in a lathe. The ends that slid into the tubes were roughed up with 40 grit, cleaned and JB Weld was used. Never had one pull apart.

 

[BobBonahoom]

Glenn,

Perfect, that is what I will start doing.