Offset Drivelines in 1/8 Hydroplanes

[John Finch]

Hey John,

Guess we should add Historian to our resumes also - Har, Har !!!

First radio I bought for boats in 1970 was a Kraft 3 channel using KPS-11 servos. The last update to Kraft servos I recall was the KPS-20H. I believe I was still running this radio when I left Norfolk in 1970. In 1987 I was running Futaba

S-29 and S-131 for throttle and rudder.

These old servos may have been in the 47 oz/in torque range - down hill and down wind.

I was curious as to the torque used in a Friend's helo the other day - he said for me to grab an output arm and he would show me. I think those servos are in the 200 oz/in range and digital. Servo power is no longer an issue.

Here's a pic of the rudder assembly we had available back then. And a pre radio hydro that belinged to a Friend.

My Scale and Sport 40 rudders are on the right also. Shafts down the hull centerline. CHEERS !! Bob

I remember those Norfolk days like they were yesterday. Frank, rest his soul, built some really nice Lauterback hulls using wood veneer and he let me use his garage to work on my boats. My first model boat was a 1/8th scale roundnose with a red head Mckoy airplane engine modified for a boat with a Octura cool clamp for cooling. I have a video, which was originally an 8mm film of that first boat running at lake Trashmore in 1968 before Mount Trashmore was built. My rudder was made in the metal shop at the Naval Air Station by a friend of my Dad's. I didn't know Octura or Marine Specialties existed. We didn't have the internet and there were no books to learn about the hobby. That is why I wrote those three books. To get more people in the hobby and make it easier to find boats and parts. Wow how things have changed!!!!!

 

[John Finch]

I'm about to start setting up a sport40 boat. So,.. if I understand all this correctly,.. a good recommendation would be to,

-center the engine in the hull

-use battery weight to keep the left sponson down, (lifted from torque)

-maybe add a shim to the strut to keep the boat from pulling into the course. This helps with SAW speed reducing rudder input to keep it straight.

Anthony,

Everyone has there opinion as you know. What works for one might not work for another. I would ask the manufacturer or someone who has your particular hull. Not just anyone, but someone who's boat works really well. Seeing is believing, not what someone says on line. I have seen boats that worked really well on line but sucked big time at the lake. It is all relative. With that said.......i would start out with it set up just like you said if you don't have other input. Then, if you have to hold a lot of left rudder to keep the boat straight I would start changing things ONE THING AT A TIME. Keep in mind.........the sponon that hits the water the hardest will make the boat veer in that direction. I am sure that is part of what Doug is doing with shifting the strut to the left of centerline. I would rather add a couple of ounces of lead on the left sponson if needed.

The rudder mounted on the right of centerline will help push down the left sponson. It will also make left hand corrections easier without blowing the boat off the water. If the rudder is kicked back even the slightest it will lift the transom and the prop will walk the boat to the center of the course. So the rudder as well as the strut depth plays a lot in controlling prop walk. Etc. Etc. As you already know. There are so so many variables and so many ways to counter issues that I think it best to start simple and take the issues one at a time. I like to add a bit of a wedge to the right sponson sometimes to counter torque. Maybe 1/2 degree more than the left sponson AOA. Of course unsharpened props and oversized props cause prop walk but we are talking hull set up right now. Too small a rudder will let the boat walk to the right because as you said.....the rudder is what keeps the boat from walking right. I have found that setting the rudder with the right side parallel to the center line of the hull with the left side of the wedge hitting the oncoming water to be the best rudder centering. I would set the rudder in that manner and then start adjusting other things ONE AT A TIME to pull the boat into harmony with the rudder. Make the boat go straight and not crab.

The hard thing about a scale boat, unlike the versitility of your rigger, is getting the weight enough forward so that the boat does not blow off the water yet have enough weight on the prop that it doesn't get high out of the water and walk the boat into the course. Don pinckert told me one time a long time ago, and it is so true............if the tail is higher than the nose the boat will not blow off the water. Do it by making the strut deeper rather than letting the prop ride high out of the water. Also keep in mind the higher the tail is off the water the less AOA on the front sponsons. I am rambling now.....got to get back to work.

Hello John, while we see the same on a lot of settings, this is one that I have questions about. Setting the right side of the rudder blade so that it is inline with the center line of the hull is adding a lot of left trim into the rudder. In my experience, this makes a boat flighty. I know that you have ran very fast using this setting. Maybe the flighty boat is quicker in record trials.

I like to have the center line of the rudder blade parallel to the centerline of the hull with other settings, turn fin, strut set for the boat to pull just slightly to the left (8 to 10 feet for the length of the straightaway) when the rudder blade is neutral. Then when the rudder is trimmed to make the boat go straight it settles the boat down on the water. This is what I like for heat racing anyway.

Charles

Charles,

I was telling the story of Mike's electric boat on another thread and how I used a slight right rudder to keep the boat on the water in some rough water. It goes along with what you said about the little bit of left making the boat flighty. In this case the rudder was made a bit of right to neutral as I was driving it. Just wanted to confirm what you said about left rudder causing the boat to get flighty. I proved it out when I let the rudder go to neutral and the boat blew off the water after many laps of holding a tad of right rudder and not blowing off. I had forgotten when we talk on line that we can't always tell it right for every circumstance and all water conditions etc. Driving methods come natural to us long time racers who drive by watching the boat and adjust for water conditions. The more I think about it the more I think the guys with normal rudders (not modified like mine) are most likely better off with the rudder dead neutral. Tip to the guys who don't know...........if your scale gets flighty a quick right rudder adjustment on the wheel can sometimes bring the boat back down to the water where if you had not tripped the boat, it would have blown off the water. You have to be attentive to the ride of the hull.

 

[Charles Perdue]

John, we are getting closer to being in agreement.

The difference in the way that you and I are setting the boat up is, I keep the rudder dead straight and use the turn fin and strut to make the boat track slightly to the left. This is primarily for circle racing. That way the boat does not raise the left sponson and get flighty.

I only sharpen the right side of the turn fin (not needed for SAW) and this goes all the way, from the front to the back, making the turn fin shape a very narrow wedge. The left side of the turn fin is completely flat and kept parallel to the centerline of the hull. This helps some and the rest of the trim that is needed to make the boat track left is by twisting the strut just slightly, moving the front of the strut to the right.

I also keep the sponsons pointed straight forward. I do not want the running surfaces towed in at the front. This is not a wheeled vehicle where that is used to make it go straight without wandering. That is for rolling resistance to make it track. The reason that works at all on the boats is that when you tow in the right sponson you are angling the turn fin to the left.

Then I use the ever so slight right trim in the rudder (fractions of a degree is all that is needed) to make the boat go straight. This makes for a very smooth running and consistent boat. MAAaaaYBE

Charles

 

[carlnoki]

Charles, with what you just discribed on your type of set up, it seems you are fighting one input with an opposite input (so to speak)

to get the hull to track straight. To me that is counter productive. (if my reasoning is correct) All the rudders on my hydros (riggers ( i know)) have

all been on the right side and **** near straight down the centerline as far as angle in concerned. I hope I said this correctly. :blink:

 

[Charles Perdue]

Hello Carl, just the opposite, you have get everything working together. You have to counteract the prop walk and the tendency to turn right in some way. This is about the most efficient way that I have found to setup a boat and the actions and reactions not be fighting each other.

By the way, I run ALL of my rudders on the left and there is no RC boat on the water that that runs smoother or will out turn them, none. That is a big statement, but I stand behind it. Just ask anyone that has ran one of my boats or has seen one run.

If that does not start an argument, I do not know what will.

It is all in fun.

Charles

 

[John Finch]

There was a small book that came out many years ago buy Les Scruggles I believe his name was. It was a guide to setting up a scale boat. He mapped out measurements of the rudder to turn fin relationships, AOA, etc. I used it as a guide several decades ago. I believe the relationships put the rudder on the left. But then again......servos were weak and turnfins were small.

I agree with you Charles on the turnfin and strut for a heat racing boat as I have done the same on many a boat. I am having a hard time with the rudder on the left though. How do you make left corrections at speed with the rudder on the left? You know when you are racing someone is going to cut you off and you will have to make a left correction. ALL my scale boats have bolt holes on the left side of the transom where I had at one time mounted the rudder. ALL of them. Well, not all. I just bought a new one already built with the rudder on the right. Turn fin and strut like you explained on some of them but not all. The circus was done with sponson AOA and ride surface changes. On my riggers the struts are all straight and I use the AOA and sponson distance to the tub to offset prop walk. No toe in either. Turn fin parallel to tub cut like you said. Do you mod the sponsons like I did on the Circus Circus, or add weight to the left sponson, or cut the sponson bottoms to offset the ride surfaces. Is there something else I am missing to make the boat drivable to the left with the rudder on the left?

 

[Dasboatman]

Les Ruggles - - he was from Kent, WA.

John and Charles - topic started as "Offset drivelines in 1/8 Hydroplanes". We can confuse many Big Time if we start talking outriggers too in same thread.

John and I are both of the same opinion with the setup of Scale and Sport boats. Were we all talking about the same hull we would have something, but we're not. They are all different.

I have been building WOF MHR 8255 hulls since about 1996 and they are all different. Only thing common was that the drive line has been on, or parallel to the hull centerline. Two hulls have the driveshaft 1" to the left (Port) of hull center line; one is 1/2" to the left of hull centerline, and two are right down the center. All of these hulls have dihedral on Port sponson, Right (Starboard) sponson has anhedral. All the rudders are on the right. The first hull of the bunch was a learning platform for Jack and I. The hull was started by my Father, and both Jack and I worked on the hull. Jack, armed with a die grinder made numerous changes to the center section airfoil and the sponsons - - there was snow in Jensen Beach, FL. Nothing seemed to make this hull decent. Jack finally ran this hull through the band saw - literally - to put it out of it's misery.

The next hull was Gus'. Painted as Executone and ran a solid shaft. Fair, but nothing to write home about. I raced this hull the remainder of 1999 after Gus passed.

At this point, Jack and I built our own hulls incorporating what we had learned from the first two. Jack's yellow Speedy (#1) and my Oberto are both very good race boats.

Each of these hulls has run a flat turn fin of Jack's design - tapered on the right side with the inside flat, with a portion of the rear of the blade milled away.

The last two hulls I built are both running curved under turn fins that have been tuned to the hull.

All turn fins are not created equal. Changes to shape, and trailing edge rake can make a big difference . If I could afford very thin Titanium turn fins and rudders, I would run those instead of the Speedmaster rudders I currently run.

When I first started R/C boating in 1970, we offset the drive shaft to Port 3/8" I believe. Through the years, this shaft offset has reduced to zero - straight down hull centerline. Radio boxes hav been aft of the engine, forward of the engine, and presently are to the left side of the engine in the hull center section.

In summary. What works for one boater won't work for, or please another boater. CHEERS !!! Bob

 

[anthony_marquart]

this is one of the best threads in a long time.. and just great since I am just beginning in sport boats.

 

[Charles Perdue]

Les Ruggles - - he was from Kent, WA.

John and Charles - topic started as "Offset drivelines in 1/8 Hydroplanes". We can confuse many Big Time if we start talking outriggers too in same thread.

John and I are both of the same opinion with the setup of Scale and Sport boats. Were we all talking about the same hull we would have something, but we're not. They are all different.

I have been building WOF MHR 8255 hulls since about 1996 and they are all different. Only thing common was that the drive line has been on, or parallel to the hull centerline. Two hulls have the driveshaft 1" to the left (Port) of hull center line; one is 1/2" to the left of hull centerline, and two are right down the center. All of these hulls have dihedral on Port sponson, Right (Starboard) sponson has anhedral. All the rudders are on the right. The first hull of the bunch was a learning platform for Jack and I. The hull was started by my Father, and both Jack and I worked on the hull. Jack, armed with a die grinder made numerous changes to the center section airfoil and the sponsons - - there was snow in Jensen Beach, FL. Nothing seemed to make this hull decent. Jack finally ran this hull through the band saw - literally - to put it out of it's misery.

The next hull was Gus'. Painted as Executone and ran a solid shaft. Fair, but nothing to write home about. I raced this hull the remainder of 1999 after Gus passed.

At this point, Jack and I built our own hulls incorporating what we had learned from the first two. Jack's yellow Speedy (#1) and my Oberto are both very good race boats.

Each of these hulls has run a flat turn fin of Jack's design - tapered on the right side with the inside flat, with a portion of the rear of the blade milled away.

The last two hulls I built are both running curved under turn fins that have been tuned to the hull.

All turn fins are not created equal. Changes to shape, and trailing edge rake can make a big difference . If I could afford very thin Titanium turn fins and rudders, I would run those instead of the Speedmaster rudders I currently run.

When I first started R/C boating in 1970, we offset the drive shaft to Port 3/8" I believe. Through the years, this shaft offset has reduced to zero - straight down hull centerline. Radio boxes hav been aft of the engine, forward of the engine, and presently are to the left side of the engine in the hull center section.

In summary. What works for one boater won't work for, or please another boater. CHEERS !!! Bob

Bob, you are absolutly correct, John has been talking Scale hydros and I have been talking riggers.

My Bad???

Charles

 

[John Finch]

Bob,

That photo of the bardahl transom is when I tried the hard shaft. Looks like the rudder was on the left at that time. It is on the right now. The hard shaft was way too noisy with the hard motor mounts. Yes I recognize that is my boat. Here it is today.....

Thanks Bob for getting Charles and I on the same page.

 

[RobertWurster]

Les Ruggles - - he was from Kent, WA.

John and Charles - topic started as "Offset drivelines in 1/8 Hydroplanes". We can confuse many Big Time if we start talking outriggers too in same thread.

John and I are both of the same opinion with the setup of Scale and Sport boats. Were we all talking about the same hull we would have something, but we're not. They are all different.

I have been building WOF MHR 8255 hulls since about 1996 and they are all different. Only thing common was that the drive line has been on, or parallel to the hull centerline. Two hulls have the driveshaft 1" to the left (Port) of hull center line; one is 1/2" to the left of hull centerline, and two are right down the center. All of these hulls have dihedral on Port sponson, Right (Starboard) sponson has anhedral. All the rudders are on the right. The first hull of the bunch was a learning platform for Jack and I. The hull was started by my Father, and both Jack and I worked on the hull. Jack, armed with a die grinder made numerous changes to the center section airfoil and the sponsons - - there was snow in Jensen Beach, FL. Nothing seemed to make this hull decent. Jack finally ran this hull through the band saw - literally - to put it out of it's misery.

The next hull was Gus'. Painted as Executone and ran a solid shaft. Fair, but nothing to write home about. I raced this hull the remainder of 1999 after Gus passed.

At this point, Jack and I built our own hulls incorporating what we had learned from the first two. Jack's yellow Speedy (#1) and my Oberto are both very good race boats.

Each of these hulls has run a flat turn fin of Jack's design - tapered on the right side with the inside flat, with a portion of the rear of the blade milled away.

The last two hulls I built are both running curved under turn fins that have been tuned to the hull.

All turn fins are not created equal. Changes to shape, and trailing edge rake can make a big difference . If I could afford very thin Titanium turn fins and rudders, I would run those instead of the Speedmaster rudders I currently run.

When I first started R/C boating in 1970, we offset the drive shaft to Port 3/8" I believe. Through the years, this shaft offset has reduced to zero - straight down hull centerline. Radio boxes hav been aft of the engine, forward of the engine, and presently are to the left side of the engine in the hull center section.

In summary. What works for one boater won't work for, or please another boater. CHEERS !!! Bob

Bob, you are absolutly correct, John has been talking Scale hydros and I have been talking riggers.

My Bad???

Charles

Some of use have been talking sp 20,40.LOL

 

[Dasboatman]

Hey John,

I knew you'd pick up on the pic, even if I cropped it a bit. I was looking for something for "Show and Tell" and didn't have anything of my own to show with an appropriate number of visible holes. We tend to believe things more after we try them ourselves.

I hear Steve now has the Fritz mold for your hull in West Palm. I wondered what had become of it.

I figured one of us had to attempt to keep the ranting of the three of us to one topic. My turn to play hall monitor I guess, Charles. I anticipate having a senior moment any time now. Har, Har !!! When the three of us have each played with the same subject so many times, I saw no need to have others attempt to Recreate The Wheel. Some will insist on peeing on that electrified fence just to prove, again, the result.

Run Fast, Turn Right my Friends. CHEERS !!! Bob

 

[Charles Perdue]

This has been a good discussion without "Untimely" interruptions. It really feels good not to have to put up with that crap.

Charles

 

[Don Ferrette]

This has been a good discussion without "Untimely" interruptions. It really feels good not to have to put up with that crap.

Charles

My my now whatever could you mean sir Charles? Are you missing your bestest buddy already?

 

[Dasboatman]

Hey Don,

I thought it had been exceptionally calm and peaceful here lately. It didn't dawn upon me what pestilence was missing until you posted. GA Scale won't have anything to do now!!! Har, Har !!! Gawd know he's not making much progress on his Sport 20. CHEERS !!! Bob

 

[Ray Sametz]

This has been a good discussion without "Untimely" interruptions. It really feels good not to have to put up with that crap.

Charles

My my now whatever could you mean sir Charles? Are you missing your bestest buddy already?

:lol: :lol:

 

[John Finch]

This has been a good discussion without "Untimely" interruptions. It really feels good not to have to put up with that crap.

Charles

My my now whatever could you mean sir Charles? Are you missing your bestest buddy already?

:lol: :lol:

Ray,

There is a lot across the lake from me for sale. 5.7 acres and has two houses on it. $380,000 takes it all. Perfect location on the lake to run boats. Come on down! I know you are ready to move out of New Jersey. Why not come here where you will have a bunch of boat buddies.

 

[Charles Perdue]

Sorry about the mixup there Mr. John. Most of the time, I am at work and I jump on and off of here without reading and rereading everything that is said.

Look at it this way, we covered a broader range of the boat type setups. (I am trying to wiggle out of this one)

Don, you really enjoy picking on me, don't you? Remember paybacks.......

Charles

 

[John Finch]

Charles,

I just get on line in spurts when the workload dictates myself. It is all good! As for Don.......it is what it is....Don's favorite words of choice. Gotta love him.

 

[Don Ferrette]

Charles,

I just get on line in spurts when the workload dictates myself. It is all good! As for Don.......it is what it is....Don's favorite words of choice. Gotta love him.

LMAO!! I'm just deeply concerned for my good friend Mr. Perdue as it seems he might be going through withdrawals.
Nuttin' but luv for ya Charles!