Steering a Hydro

[Jeff Cowey]

I am gathering hardware for a twin wing hydro. I wanted to know if there is advantages of mounting the rudder off to one side or can it be mounted behind the prop? Would you lose speed with the rudder trailing the prop? Would the boat spin out in tight corners? Most pictures I have seen the rudder is offset. Also if it is offset should it be ahead of the prop or beside it?I have a Pro Boat 1/8 Hydro and I moved the rudder to the right side so it would carry more speed through the corners. This worked but it doesn't turn left as well. Who wants to go left anyway.

 

[Larry K]

I am gathering hardware for a twin wing hydro. I wanted to know if there is advantages of mounting the rudder off to one side or can it be mounted behind the prop? Would you lose speed with the rudder trailing the prop? Would the boat spin out in tight corners? Most pictures I have seen the rudder is offset. Also if it is offset should it be ahead of the prop or beside it?I have a Pro Boat 1/8 Hydro and I moved the rudder to the right side so it would carry more speed through the corners. This worked but it doesn't turn left as well. Who wants to go left anyway.

Hi Jeff - looks like your post is getting alot of hits but no response! I think the flood-gates will open once somebody throws something out there just because there are several ways to approach this topic & some guys have very strong opinions about it. Let's start the fray with some observations. On full-scale hydros of yesteryear, rudders were offset to use propwash to get the boat to go in a straight line w/o "dog-tracking". On those boats you will notice a "crook" in the tail-fin for the same reason. They figured out early on that prop-walking and torque reaction were forces that had to be dealt with. As boat design improved & corner speeds increased, rudders were moved further to the outside of the turn. I think the reason this works is because those guys are trying to get 6000lb boats to turn 180deg @ 150 plus & the way to make that happen is to pull the back towards the outside of the turn & get the nose pointed the other way. Most every boat on the circuit does it that way. I've even heard a crew member say they'd put the rudder clear past the right end of the transom if they figure out how to keep from tearing it off the boat. One of Jim Harvey's boats had ruddrer brackets on both sides w/ a drag link set-up for aesy change-over. I think they still ended up w/ it on the right. Now, I know physics is physics but I think we're dealing with some differences with scale models. In the past 20 yrs I've seen any number of full sized boats blow over in the turns & I can't help thinking that if the rudder was on the inside of the turn, that couldn't happen! Since speed vs weight & skid-fin & rudder sizes etc are all different on scales let me run this by ya. I put the rudder to the right & keep the angle from the rudder post to the skid fin @ 18deg or more. You're right - it won't like left turns much & you may have to deal with that, but it will go around the turn like it's on those proverbial rails. Also take time to make sure the rudder post is perpendicular to the waters surface with the boat @ riding attitude. You don't want to spend your time trying to dial out a problem that should'nt be there in the first place!

Good Luck - Larry K

 

[Ron Olson]

If you need a simpler reason to offset the rudder, it makes it a lot easier to remove the flex cable for lubing and to swap props.

 

[Jeff Cowey]

Thanks Guy's

That steers me in the right direction.