rudder tube and shaft ending below waterline

[s vernon]

I wonder how people feel about very short rudder tubes that terminate below the water level.

I know it can be done and I had one way back when, but not now. I feel it is too risky. Too much chance for a leak problem. I am surpised to see that this is the current recommended way to build an EC12 for everyone including beginners building their first boat.

I generally put a long tube and rudder shaft on there and make my long "tiller arm" Z shaped to make the ends level with the servo and the rudder arm.

Scott

[John Hulsberg]

<font size="2"><font face="Arial">Are You up early, or out late,Scott![:D]

For what it’s worth as a newbie, I’m building mine now; I poured over the plans for quite a while and ended up with a 1½ inch stuffing box with two 3/16 “ bearings silver soldered at the ends. My thoughts were that the space cleared back there would be useful if I had to re-attach the back stay or deck/hull repairs.

I used a very similar tube on my old Star when I put the rudder shaft mounting block in sideways. I never had a problem even though the Star’s rudder is exposed and unprotected (not the case in the EC-12). I used heavy kosmoline grease in that boat, which I won’t use again; it stained the hull (now clear, water/dust resistant PTFE bicycle grease).

I’ll be curious if others have documented a real leak problem. You won’t need the “Zâ€

[Capt. Flak]

My new boat has the short tube. Works great. No leaks at all. Follow the instructions on the building site and you will be fine.

Joe Walter #24

[Rick West]

The short rudder sleeve has been on the building site for a year and just recently updated. As noted there dual grease bearing seals are installed on the shaft. This has eliminated leaks from the shaft as long as it is maintained.

The boat I used this year on the East Coast has this and water was not a problem from that source. The hatch is more of pain and I will be fixing that this winter on the new boat that is being used to update the documentation for the building site.

...94

[jack wubbe]

You dont have to worry about long or short rudder tubes if you use gears from www.servocity.com The servo mounts back near the rudder post and has a top gear that meshes with a gear on the rudder shaft. I have been using this system for over 2 years and zero problems. No push rods, no bell cranks, its back out of the way, no leaks and very little rudder lash.

[PaulP]

Jack
Servo City is a very interesting site.

Did you just buy the gears from them or is there a specific model you are using? Can you control the backlash of the gears to minimize slop?

Paul

[jack wubbe]

Paul

I have used both 48 and 32 pitch delrin gears with no aparent differance. The backlash is very little if the tolerance between gears is close. The servo I use is a HS-5645-MG which is hi-torque and 90 deg. rotation. The degree of rudder rotation can be controled by the number of teeth on each gear.

Jack

[PaulP]

Jack,
Do you use one of their glass filled servo mounts or just mount a gear on the servo, a gear on the rudder shaft then mount the servo to the crossbeam?

Have any pictures?

Paul

[Pink66]

Scott I agree with you totally. Every rudder I ever built was sent out with a 3 1/2" long tube for two reasons. The first and obvious one is so that top of the tube when installed will be above the waterline. Why have to worry about bearings, grease and maintenance when plain old physics takes care of the problem. None of my boats are built any other way.

The second not so apparent reason is so upper brace for the rudder tube is farther away from the rudder/hull joint thereby giving the tube a longer moment arm to resist the torque and pressure induced by the rudder servo/arm wanting to push the top of it around under load. Especially with the high torque servos we are using for rudders. Jack's gear theory does about the same thing.