Corky's Build

[Corky]

Next step after the paint has cured is to cut the rudder tubes to the proper length...Pretty simple procedure...Measure between the upper and lower rudder mounting tabs and shorten the tubes to a nice snug fit...In this case the nylon rudder bushings are 3/8 inside diameter and 5/8 outside diameter and the exposed "hat" has a height of 3/8 inches...Here's the quick rundown...Cut the 1/2 inch sch 40 aluminum tube allowing for the 3/8 nylon hat at each end and use a fine {220 grit} to make a nice smooth mating surface for the bushing...

On a side note the hole in the bushing is a touch too big for my 304 stainless rudder rod when I tried them without being installed in the rudder...But, after the bushing is installed in the rudder the hole is actually too small...I took a small section of the stainless rod and ground it to a point then cut a flute {parallel notch}...I chucked it up in a drill then worked it into each bushing for the exact fit needed...At this point the rudders fit perfectly in their positions...

That leaves the rudder rods and how they will be fastened...The top and bottom of the rods will get threaded...The top of the rod gets a stainless nut run down until seated against the thread land then welded in place so it can't back itself off from vibration...The bottom will get a stainless locknut {nylon locker} so the rod can be removed if needed in the future...I probably could have used a nylon locknut at the top also but I just don't want to worry about it coming off at a bad time{which is anytime really } so welded it is...

Here's another small detail I'd like to share...Most rudder rod failures seem to happen on the threaded portion...Snapping off after the threads create a stress crack between them...With that in mind these rods have no threads at or in past the mounting tabs...All solid rod through the bushings,past the mounting tabs and then a stainless washer on each end before the threaded portion where the nuts are both run down to the thread lands...End of the thread stress riser problem and a tight fit to keep the cage and rudders in check even with a hard hit...

First pic is the rudder mating surface prepped and sprayed with an etching primer...Next up is the installed bushing itself...Third is the 304 stainless rod getting threaded....And lastely a pic of the top rudder stainless nut in it's place before being welded ....

[Corky]

And finally the rudders are installed on the cage...All mating surfaces are an excellent fit and they move with very little effort...Nice and smooth swinging them through the range of motion...These look so much better compared to a flat sheet IMO...And I'm glad I took the time to make these up....Next up is the rudder stick and linkage !!

In the meantime here's some pics of the rudders on the boat !!!

[aerokirk]

Nice work on the rudders Corky ... you should have nice smooth airflow across them. Looks like your hot wire worked pretty good! The foam cores should be a good alternative to internal ribs, mine have performed great and they're really light weight.

[Corky]

Thanks Ted, Mine are relatively light...I should weigh them and see where they are...The 1/8th inch thick insert and end caps added a little but overall they'll do fine...

[Corky]

Here's some details on the rudder linkage...I used 3/8-24 grade 5 bolts for the threaded ends...I welded a nut to the bolt for the end cap duty.... The heads on these bolts slipped into the 1/2 inch conduit with a little help from the hammer...Welded them up then dressed the welds so I can use a wrench on either end for the rod ajustment...I used both left and right handed 3/8-24 stainless rod ends so I can simply turn the bar to adjust the length...The coupler on the one end is a hardened adjuster that has both left and right handed threads so there's plenty of adjustment if I need it...Right now the rudders are set with 1 inch less on the leading edge than the trailing edge so I won't have any "flapping" under power....The prop tip closeness {to the linkage}is an illusion from the angle of the picture...

[Corky]

And while I was working back there I welded the rear navigation light bracket on the cage...The LED light sticks up just enough to give the 360* coverage around the boat....

[Corky]

Now we've come to the steering phase of the build... Decisions, decisions...Want to start a debate just mention which type of steering you like on an airboat and that'll fire up the conversation quickly...Here's what I've found that nobody really tells you about.... I had to do countless hours of research and ask all the right questions to make an educated decision....Since this hull has some high sidewalls there's two choices I could have made...

First up and very popular would be the teleflex steering cable...Smooth operating and an easy fabrication just make the stick and attach the cable between the rudders and stick...The only variables are where the cable get attached to both the rudders and the stick...Here's what I've found about using the teleflex cable...The useable cable travel is around 6-8 inches depending on the brand...All the local companies around here that had a shot of making me one up could only get around 4-6 inches of travel max.. I'm thinking this would be the "PTO" cable I keep hearing about being adapted to our needs...

So...For those of you who are contemplating using the teleflex cable you need to make sure your rudder's teleflex cable attachment points swing within that 6-8 inches of travel...That's alot of rudder movement from side to side condensed down into that few inches of travel on the cable...Even for our minis...I'm not sure what that ratio comes down to but it seems very steep....Ever see those beautiful manufactured aluminum rudders and wonder why it had that "clover leaf" at the bottom for multiple attachment points front and sides ??? Yes, that's why...You need those side mounted attachment points to get you within the swinging range of the teleflex cable...

Now, at the control stick end...You need to find the happy medium between the short throw oversteer stick and the long throw out of your seat to turn situation...

My second choice for steering is the direct rod type steering... The rod type steering gives a better feel for what's going on with the rudders than the teleflex cable and also usually has a longer range of motion...The downside is it's harder to fabricate and getting the angles and throw lengths correct is time consuming....

The sub-categories for this are the three popular choices crowsfoot,dogleg, and bellcrank...

Crowsfoot is basically a direct link to the rudder using a straight,unbent link from the bottom of the control stick back to the "crowsfoot" on the rudder...Used where there's no height adjustment needed between the two...Seems deckovers use this alot...

Dogleg has the control stick link between the stick and rudder bent so it meets the "dogleg" fulcrum usually in the back,top corner of the hull...The height and width adjustments are made through the control stick link between the stick and dogleg...This style needs alot of room for the working range of that bent rod to move front and back..

Bellcrank is a vertical standpipe that is attached usually at the transom rear corner and uses lever action top and bottom to transfer the swinging motion from the low control stick height to the higher rudder working linkage height...

I ended up going with the bellcrank steering system...Here's why...First, I like the feel and working range of the rod type steering...Secondly, I've set mine up to make the steering smooth and very easy even under full power... The rudders themselves have a 7.5 inch span between the pivot point and the linkage{the actual rudder measurement minus the attaching "foot" is 5.5 inches}...That gives me a whopping 11.5 inch arch from stop to stop measured at the linkage attaching point...This translates into a much easier movement of the rudders under power compared to the teleflex cable...The control stick is set up with a little over 2:1 ratio for leverage{bottom of the stick being 1/2 the distance as the top section above the pivot point}...Heim joints are stainless steel as well as all attaching hardware...

To condense this info down.... The stick has a throw that's comfortable without needing to "lean into" the hard turns for most normal situations but does have the ability to travel "stop to stop" for some serious spinout activities if need be... The travel is very smooth using the argutto bearings on the stick and the bellcrank...Each rod has an adjuster so it's just a matter of turning the rod to lengthen/shorten it if need be...And lastely if I have this figured out correctly the effort needed to turn the rudders should be very comfortable even under full power...


OK enough of the info and reasoning here's the steering system pics to this point !! There's still a few gussets and small detail items to be added but you can see the main system parts...

[aerokirk]

Hi Corky,
Again, nice work there ... I've just got a couple of observations. I see that you've decided to have the stick on the right side and not the left which I've seen on many builds before. Generally though, when you push the stick forward (regardless of which side it's on), the boat should turn to the right and when the stick is pulled back, the boat should turn to the left. I see that yours is rigged opposite of that!? Was that intentional? I did the same on my first airboat but when I transitioned to my new boat I had a hell of a time remembering which way to move the stick since I built that one to the standard directions. Not saying there's a right and wrong way, just an observation.

Secondly, regarding your statements on using the teleflex cable, you can (and I did) get a cable that has an 8" travel range. My distance from the rudder pivot point to the cable connection is 6" and I have more than enough rudder travel in either direction. When I turn the boat at a slow speed, it will turn on its own radius, in fact, it will actually back up a bit in the turn. There is very little aerodynamic resistance to the turned rudders at any speed so I wouldn't concern myself with control pressures with the minis.

[Corky]

Hi Ted,

Good observation and thanks for asking... I figured I'd go into more detail if anyone cared to ask about the right handed steering....First, I'm left handed so it feels more natural to have the stick on the right...I set up my old mini on the right and did'nt even think about which side most are on{that one steers in the reverse pattern also}....I've been running heavy equipment for over 30 years and can adapt to different controls rather quickly so the "push right,pull left" standard stick was in fact in my mind but not a major concern...

After some thought....I did'nt trust the "Z" bar style where the bellcrank and control stick link remain on the left and the upper control stick is on the right they just did'nt appeal to me and bending the control stick kept going through my mind with this style of steering......That brought me back to all components on the right side.... The bellcrank just would'nt have enough room to clear the prop to my comfort level if I moved it inboard leaving the levers as they are...I could have spun the bottom lever facing the outside of the boat{thus "correcting" the throws} but then the control stick link between the two would have been on the outside,near the bottom of the sidewall which would surely be in the way.....So I took "the easy way out" for the right handed steering and just mirrored the left hand design with the control movements ending up like I'm accustomed to...

Most people are right handed and the bellcrank is usually on the left.....I'm suspecting that's why "the standard" stick movement came to be clocked to the left side rudder movements....

And you're correct some teleflex brand cable do have the 8 inch travel...The PTO adapted cables{that could have been made up locally} have less travel.....I guess I was overthinking and overestimating the forces involved with turning the rudders on this mini and simply wanted more control over the movements in a given stroke of the stick with the least amount of effort which I'm sure I accomplished....

Converting back to a standard pattern with the teleflex cable and right handed stick I assume would be simply routing the cable around to the left side and attaching it as you would normally...Too bad the bellcrank is'nt that simple...

So the short answer is I'm left handed and wanted the steering set up like my old boat I have now... The susquehanna river is LOW now and to be honest I'd only be using the small, old mini when the river is this low and I {or anyone else}won't get confused with the controls jumping between the two..

Too bad we are'nt closer to each other I'd let you take mine out when its done so you could try the bellcrank style steering it feels very smooth with the argutto bearings and heim joints!!

[dr.peck76]

Hi Corky,
I always echo aerokirk's comments on the quality of build! Very nice craftmanship. I would also agree with him on the forces in play with the steering linkage. I have used a direct rod type linkage as well in the "dogleg" style you outline. The fulcrum point of my linkage is a simple triangle plate. A hinge on one corner with power and reaction linkages on the other two. It seems the ratio is quite large as well with my set up but with the aero-foil shape of the rudders I've never thought of the control lever to feel heavy. JMO . I'll post some pictures on my build thread for those interested. Anyway's, you are complete and I'm sure it will work more than well.

You must be getting excited for some water time, you've got all the big parts done now....

[Corky]

Thanks for your words of encouragement, insight and experience with the steering linkage Dr.peck76 it's appreciated ...I was trying to look at your build a while ago to see what you did for your steering but could'nt really make out your linkage system...Thanks for posting what you've done for your build I'm sure it will help others also....I have to admitt I am getting a little excited especially after the rudders/linkage phase is over and I'm looking at the next step...

I'm going to deal with the gas peddal, cable, and figuring the best brackets to attach the cable to the 084 engine as my next step.... I want to keep it simple if possible....As with everything else there's so many ways to get the results needed...All the 084 builds seem to do their own throttle bracket/lever layouts even though we're using the same engine !! But hey that's the fun of it!!

[dr.peck76]

If you have a chance to peek at my steering linkages. I used the same idea for my throttle linkages, a triangle plate to change the direction of force. Because my engine already had an adjustable throttle cable,(which was way too short) I fabricated a coupler to it and used stainless steel tig wire between the pivots. Because the force is always pulling (force against spring), if figured I didn't need a really rigid link.

The only tricky part with triangle plates is to ensure they are set-up in the proper position of the arc of travel. I know it took a couple attempts at my first one before I fully understood all the factors involved. I'll get some picture of my set-up on that as well.

[Papee]

Hi Corky,
Again, nice work there ... I've just got a couple of observations. I see that you've decided to have the stick on the right side and not the left which I've seen on many builds before. Generally though, when you push the stick forward (regardless of which side it's on), the boat should turn to the right and when the stick is pulled back, the boat should turn to the left. I see that yours is rigged opposite of that!? Was that intentional? I did the same on my first airboat but when I transitioned to my new boat I had a hell of a time remembering which way to move the stick since I built that one to the standard directions. Not saying there's a right and wrong way, just an observation.

Secondly, regarding your statements on using the teleflex cable, you can (and I did) get a cable that has an 8" travel range. My distance from the rudder pivot point to the cable connection is 6" and I have more than enough rudder travel in either direction. When I turn the boat at a slow speed, it will turn on its own radius, in fact, it will actually back up a bit in the turn. There is very little aerodynamic resistance to the turned rudders at any speed so I wouldn't concern myself with control pressures with the minis.

As for the steering. The stick is set up for your natural movements. Picture this, hold your hands up like you are steering in front of you, now turn to the right. Yes you turn the wheel to the right. Now, hold that steering wheel like you have you stick mounted to the left then turn right again. You will be turning right or if the stick was there pushing the stick forward. Now do the same thing with your fake steering wheel but this time like your stick is on the right side. You are turning right but if you picture the stick there you would be pulling back on the stick.

Another way to think of it is when you twist your body to the right, if your stick is on the left you would be pushing on the stick. Now go through that same motion with the stick on the right. When you look or twist right your arm is pulling back on the stick.

I know it sounds backwards but it really isn't.

[Corky]

My old mini {13hp 14x4jon} originally had a steering wheel up front and you'd sit up there to steer... Only problem with that was A} the front seat/bow became the lowest point in the water if only one person was in there... You were safe after the rock cleared your feet the rest of the hull made it over... B} It NEVER went up on plane sitting up there {30 years worth of plowing the water}..One day just for laughs I sat on the back bench seat and push/pulled the steering cables and watched the steering wheel spin but something else happened...The bow came up and it came up on plane !!! It became clear what the boat wanted .... I moved the operators seat back where it wanted to be and fabbing up the stick on the right...It's always felt natural being "opposite" from what a left stick would do...

But what you're saying makes sense papee...The natural throw of your body compared to a steering wheel...Good analogy...

Another reason I wanted the steering to be easy and smooth was I plan on letting my wife drive this around if she wants to...While I had her in the seat trying out the stick movements I realized the step up to the platform was high for her{around 18 inches} and so I added a step on each side to get up there if you're walking around in the hull...These will make it easy for anyone who pilots the boat...

[Corky]

The next step is the fuel tank placement...I did'nt want it under the engine I feel that puts all the weight too far back for this build...So I moved the fuel tank placement up ,under the rigging, between the operators seat and the front seat...And here's the other problem I had on my mind{yep, overthinking again}...Knowing what I've gone through out here on the Susquehanna river I did'nt want the tank to sit completely on the floor...I've hit rock where it's creased the hull floor from bow to stern...Now with 1/8th inch aluminum you would'nt think I'd have the same problem but...I just don't want to take any chances...So the tank sits a few inches off the bottom {4 to be exact}...
This does two things for me...First the air can get under,over, and around the tank{the tank is still below the prop line} and I feel it has'nt significantly raised the center of gravity...
Secondly,now I can add an access door to the deck and fill the tank resting a five gallon fuel can on the deck while pouring it in !!! Another point to make is with this set-up all I have to do is simply open the door and look at the tank's built-in fuel gauge...I now have the ability to check the fuel level from the operators seat !! The fuel tank will get two straps holding it in place....Here's the pics showing the fuel tank and the new steps...I'll get pics of the access door this week and show what I'm doing...

[aerokirk]

As for the steering. The stick is set up for your natural movements. Picture this, hold your hands up like you are steering in front of you, now turn to the right. Yes you turn the wheel to the right. Now, hold that steering wheel like you have you stick mounted to the left then turn right again. You will be turning right or if the stick was there pushing the stick forward. Now do the same thing with your fake steering wheel but this time like your stick is on the right side. You are turning right but if you picture the stick there you would be pulling back on the stick.

Another way to think of it is when you twist your body to the right, if your stick is on the left you would be pushing on the stick. Now go through that same motion with the stick on the right. When you look or twist right your arm is pulling back on the stick.

I know it sounds backwards but it really isn't.

Makes sense to me too Papee ... I've just never seen a boat with the stick on the right. Now airplanes, on the other hand ...

[Corky]

Here's the aluminum fuel hatch pics during the fitting...This aluminum hatch is very light and the lid will get covered with the diamond plate aluminum decking so it will blend in with the deck...As you can see there's plenty of room to fill the 9 gallon tank and I can use the deck as a prop for filling it with a 5 gallon container... And as stated before I can check the fuel gauge with a quick peek under the hatch...

[Corky]

Here's something I ran into with the fuel system...I bought an Attwood universal fuel tank kit...It has a "new and improved" tank quick disconnect...Here's the package label..But, and you knew there'd be a "but" in here....The fittings are plastic which is'nt a deal breaker...And the O ring is a concern but still not a red flag....Here's the problem I see with this...Take a look at the pics showing the actual fuel orfices and you'll see the problem... That sure looks like a BIG restriction right where you don't want one !! I threw in the old brass barbed connector as a comparison...

It's a good thing this tank is getting mounted... The brass,barbed fitting will be used for this build and I'll try the "new and improved" fittings on my small airboat and see if it keeps up with the kohler engine on that one...

[Corky]

On a side note the actual fuel line has been improved since the last time I bought a kit...My old marine lines usually only last a few years until the plastic liner separates and collapses {it was literally paper thin with the old style} and you find out at the worse time which is usually moving along at a good pace and start to lean out...Here's the fuel line in it's newest,thicker form..It appears the liner is now thicker as well as the actual line itself...

[aerokirk]

Corky,I have the very same Attwood setup and there's been no concern with fuel restriction to the engine. My tank is just behind my seat on an aluminum framework very similar to yours and the squeeze bulb is within easy reach when you turn in your seat. The only thing with that new connector is that you need quite a lot of push to get it to seat on the male side. It's possible for it to look connected but not transfer fuel. I had this happen a couple of times but you can tell by squeezing the bulb as it won't get firm.