Twin 6S rigger - Done!

[mm123521]

Finally done -- It will hit the water in another 3 hours.

Build thread: https://forums.offshoreelectrics.com/...40-inch-rigger

6S1P 5300 MAH Gens Ace batteries
CC2018 Motors (1800KV) spinning at 40000 RPM
Wire drive with 447 props.
44 inches long, 26 inch wide.
Weighs 13.5 pounds RTR
Finish is clear polyeurothane over plywood.

I hope this thing works? With a homemade hull, homemade turnfin, etc. -- it is highly probable that it will blow off or suck down or something will go wrong.
If the hull works correctly it may go between 80 and 90 MPH.
The no slip speed is 98 MPH
The 15% slip speed is 83 MPH
The 10% slip speed is 88 MPH

Mark
Homemade: turnfin, motor mounts, struts, wire drive, water pick up's.
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[mm123521]

Pictures:

I believe these motors are rated at 3500 Watts - Thats 9 horsepower in a 13.5 pound boat!

Check out my hull inspector!


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[mm123521]

More Pictures

Check out the turn fin, it's home made from polished stainless steel plate.
It is non-adjustable. If it is set on the wrong angle, it can only be bent.
It was precision aligned and precision bent, so I am hoping it works.
If you look real close, you can see horizonal scribe lines - those are my bend lines.
The boat was setup on a 3/4 inch thick, flat, alluninum plate and the lines were scribed from the surface of the plate, so I know they are perfectly parallel to the hull.

If it doesnt work, I have a second turn fin blank ready to bend.

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[Rumdog]

Let her rip! Gimme some vid!

[Jedi Master]

Wow, this should be an awesome first run.....

[mm123521]

Rumdog, & Jedi,
First run went good and bad.

BAD,
I wasnt paying attention and a cooling hose was up aganst the coupler. It rubbed through and flooded the hull.
Darn it -- an amateurs mistake!

GOOD,
It ran fast, straight, and flat -- no hopping, no blow overs, no flips.
I am used to running a 71 MPH SprintCat, and this rigger scares me, it's so fast.
When you get off the throttle, it coasts forever, before it drops off plane.
No GPS on this run, but I am sure its in the high 80's.
Acceleration is spectacular!


The water was half way up on the motors for 30 minutes -- how do I dry out the motors?
Electronics were mounted high and seem to be OK.

Mark

[Jedi Master]

Sounds like it went well, except for the mishap. I've flooded a lehner motor before. Didn't let it dry out completely, but got as much of the water out as I could before giving it a good blast with silicon spray. Then I ran it slowly to clear the rest of the water with more silicon sprayed in to keep the parts coated. I'm no expert, and my method may not be the best but I figured it would not do the motor any good if I let it dry out on its own. I replaced the bearings and it ran like a dream.

Would love to see some video!!!

[v-spec]

I'd just spray the motors down with corrosion x or similar. Wish you had a video!

[mm123521]

I'll get this thing dried out and make a video run tomorrow, after work.

Mark

[Fluid]

Yes, shake out as much water as possible, then FLOOD the inside with CorrosionX - or even WD-40 - until it pours out the screw holes. Corrosion inside the motor can lead to motor failure if the bearings seize or chinks of rust get thrown into the windings. A few $$$ investment in water displacement chemicals is well worth it.

A suggestion - paint the rigger a bright color so it is easier to see. I ran SAW riggers with natural finish like yours, but it is too easy to lose sight of a fast boat under many light conditions. Bright yellow, orange or even white will help to take the "fear factor" down a notch.

You do realize that you don't have near enough prop pitch on that thing don't you? Try some x648s or Prather 235s....

.

[mm123521]

Fluid,

Yes that has to be the conclusion. --Bigger props!
Step one was to see if the hull was balanced , both hydrodynamicaly and aerodynamicaly.

It's hard to believe that a rigger runs correctly on the first time out??!!
I did not expect this!
This thing was built with dial calipers, toolmakers squares, etc. - a precision build.
The wood components were all machined out perfectly square, not just cut on a saw.

It sticks to the water like glue and there is plenty of excess horsepower, so bigger props are next.

The fear factor comes from running out of lake too quickly!

The instructions for ZipKits riggers (my sponsons are modified from a zipKit 45 rigger) specify a slight sponson toe-in, but I set this one up with zero toe-in?
What does toe-in do for you??

Joe from ZipKits, said his riggers should stick to the water at over 100 MPH.

On the first run, the boat would not turn. There was only an inch of rudder in the water.
Next run, I put a longer rudder on (2.5 inches in the water) and now it will make a 175 foot diameter turn at 1/2 throttle.
The CG is only 1.5 inches behind the turnfin center. I think i need to move the aft battery back to increase this distance and help the turning.
The next step is to get rid of the counter rotating props as you sugested.

Mark

[LarrysDrifter]

You might want to try ABC 1816-3 counter rotating props. They are 45mm x 1.6 pitch. My cat, which I know isn't a rigger, pick up A LOT of speed over X447's.

[mm123521]

LarrysDrifter,

I was looking at exactly that prop a few days ago.
It retains the advantages of counter rotating props.
They are kinda expensive, I think they are about $30 each.

Larry; how much speed do you think you got?
What motors are you using? KV and # of cells?

2.88 inch pitch @ 40,000 RPM = 109 MPH -- no slip
Thats 92 MPH @ 15% slip
And 98 MPH @ 10% slip

Hummm -- bumping up aganst 100 MPH!!!

Thanks!
Mark

[Fluid]

Twin riggers do not like counter rotating props. This has been well known for decades - no one races twin riggers with CR props. These boats just will not turn well at all with CR props. Yes you'll have some prop walk with LH props, but you will be able to turn. 175-foot diameter turns is not even turning IMO.

A more real-world estimate of speeds with 2.8" pitch props - assuming you have a long enough straight - is closer to 90 mph. Still hauling. More speed needs more pitch. Don't be frightened...


.

[mm123521]

Jedi,

I had a can of "Liquid Wrench" Silicone spray that had a damaged spray nozzle, so I drained out the pressure and emptied the liquid into a plastic container. I soaked the motors in the silicone liquid for 20 minutes. Now the motors are hanging by the wires, draining.
Tomorrow, I'll reassemble the motors on their mounts and cooling jackets.

Thanks!
Mark

[LarrysDrifter]

I didn't realize that about counter rotating props on a Rigger, but it makes sense. I've never owned or ran a rigger. I think, if you want to make SAW passes, the counter props will work well, but as Jay said, use standard rotation props for good turning. I think the ABC props I suggested are de-tounged. I could be wrong. I run them on a 32" twin cat with 2800kv 540's on 4s each side. It's been a while since I ran X447's and the ABC's in the same day, so I'm guessing the difference was between 5-10 mph. It seemed like the boat just didn't "like" the 47's. Maybe they loaded the motors too much not letting them reach full rpm. It really "woke up" with the ABC's and has run a best of 81mph on GPS. I'm merely suggesting another set of props that worked well for me and give you another option for props. OSE has ABC's where you can pick what pitch you want on certain props. Some go up to 1.8, so you might want to have a look at those too. www.rocketcityracing.com has generous assortment of ABC props too.

[Chris Harris]

I'm thinking your turn fin may not be big enough if your intent is to run ovals. That is a lot of weight hanging on that fin in the turns. Your boat is about the same size and weight as a gas rigger and they run turn fins that have more suface area than the one your using. It doesn't necessarily have to be any deeper but I would double the surface area. You might have to look at rudder placement as well. Usually riggers have the rudder off to the right hand side and further back from the transom. Cool project though, I can't wait to see some video.

Chris

[ksm2001]

Congrats Mike, very nice build indeed. That's some horse power under the hood, I cant wait to see some video also

Ken

[mm123521]

Chris,

Today I called Joe P. from Zippkits (they sell the JAE line of riggers).
He said the same thing as you -- the turnfin is way too small and the boat is slipping sideways faster than the rudder can scoot the stern around the curve.
I am not ready to give up on counter rotating props just yet, although it may be necessary as Jay states.

Joe is sending me a turnfin that is sized right for this boat and HE WOULD NOT TAKE ANY MONEY FOR IT !!!! WHAT A GUY! ZippKits forever!!

Joe is also saying that slips in the range of 8% to 9% are obtainable with his setups -- If that is true with my rigger, I could be close to 90 MPH right now -- this is yet to be seen (I would feel lucky if I could achieve those numbers). I gotta get a GPS run going, soon.

Mark

[Brushless55]

this is cool!
I've thought about doing a JAE 45 and running twin CC1520's on 8s

[mm123521]

Brushless:

Gees! thats 47,000 RPM!! I wanna see that!
Can you cram all those motors and batteries in a 45?

=======================================

OK, I put the boat back together after drying it out.
Taped it up the hatches, threw it in the truck, and down to the lake.
The GPS said 82MPH --

Now come the excuses!! I didnt get a good long run, the radio was only getting about 400 foot range. It looks much faster?!
82 is just under the 15% slip speed for this setup.

This is the first time that I used this RX -- Next run will be with a known good RX.

I tried 2 full speed turns and it goes right around the corrner! I got about a 60 foot diameter "U" turn.
This boat wont make a tight, low speed turn, but it makes nice full speed turns?
Maybe this makes sense, because the ski's are like long striaght rudders and at low speed they are in the water and high speeds they are above the water???

Anyone out there with a JAE rigger? Is this the way they are supposed to work?

Boat ran flat, smooth, and striaght.
It would make nice, gentle, full speed, left turns -- about what you would expect.

The boat came back dry this time.

RumDog: Sorry no video -- called my boating buddy, but he was busy.
Mark

[Brushless55]

Brushless:

Gees! thats 47,000 RPM!! I wanna see that!
Can you cram all those motors and batteries in a 45?

Mark

Mark, I would need someone to make the tub wider so I can fit the motors and batteries

[mm123521]

Joe (From ZippKits) sent me not one, but TWO turnfins!!!!!!
He sent them via priority mail -- I cant believe they arrived so soon!!!

I installed one after work, charged batteries, taped the hatch, and off to the lake.

THE BOAT RAN GREAT!!!!!!
IT TURNS ON A DIME NOW!!!
Chris and Joe were spot on! The turnfin was just too small.
It has VERY predictable handling, and even makes nice, smooth left turns.

ESC's were cool, batteries were cool, and motors were cool.

Now its time to prop up!!

Thanks all for helping with their sugestions!!

Mark

[Jacked1]

Awesome!!!! :D

[Doug Smock]

Joe (From ZippKits) sent me not one, but TWO turnfins!!!!!!
He sent them via priority mail -- I cant believe they arrived so soon!!!

I installed one after work, charged batteries, taped the hatch, and off to the lake.

THE BOAT RAN GREAT!!!!!!
IT TURNS ON A DIME NOW!!!
Chris and Joe were spot on! The turnfin was just too small.
It has VERY predictable handling, and even makes nice, smooth left turns.

Now its time to prop up!!

Thanks all for helping with their sugestions!!

Mark

They just don't come any better than Joe! Chris either for that matter.
Cool project Mark, looking forward to some video.
Doug

[Chris Harris]

COOL! I'm glad you got her turning good now. That must be a sight seeing that thing rip around the corners at 80mph!!!

What props are you going to try next? Maybe a couple of ABC H-7's with some cup or maybe H-10's. They both have a bit more pitch than the 447's and a lot better blade design especially for hydros.

Now about prop slip. In theory you should be able to get better efficency with two props doing the work but prop design will have more to do with that. I think the 15% that your getting now is pretty good but you should be able to up it a little with better props.

Chris

[Steven Vaccaro]

Any video?

[mm123521]

Heres a video.

When the new, much, bigger turnfin went on the speed dropped to 70 MPH -- Darn it!
Notice the hopping -- that was not there before with the small turnfin.

The hopping goes away with the slightest right turn.
It may not show on this video - I have done a bunch of tweeking sense that video was taken.

ESC's, batteries, and motors all come back cool.
I get good run time, so It looks like the motors are running easy, but my slip is 29% -- very bad.
Maybe the props are running in non-smooth water and are not "hooking up"??
The hopping isnt helping.
Weight on the props is about 3.75 to 4 pounds. I wonder if the props have too much lift, tipping the boat down and causing the turnfin to "pull down".

How come it hops?
I have adjusted the angle of the turnfin.
I have adjusted the position of the rear battery to shift the CG.
I have tilted the struts down slightly, to get more prop imersion.
Nothing has worked

I put on a pair of non-counter rotating X452 props and it really messed up the handling.
It would take a 30 degree right turn when you hit the throttle - it was really hard to steer like that, so I took them off.

I have ordered a set of PropShop 5014 right and left, 3 blade, props. 50MM and 2.75 inch pitch. Maybe they will help?

GP/5014/3/LH/BR ----- £20.58
GP/5014/3/RH/BR ----- £20.58
Delivery: £8.55
VAT: £9.95
Total: £59.66 = about $100-- ouch!!!

These props are 3 MM bigger, and 3 blade insted of 2, and the pitch goes from 2.59 to 2.75 -- these have gotta buy me a little more speed.
I need to exceed 85 MPH (the record or our little lake is 85 MPH) -- That should be a modest goal for the installed horsepower, if I can get the hull to run correctly.


http://www.youtube.com/watch?v=lk21KVVfTxo
My 9 year old Niece was filming!!!

Mark

[Jeepers]

Little lake? you couldn't even get that boat to that speed on our lake!! wow that thing is quick!

OH and your niece films great!

[Chris Harris]

Was that still with the L&R X447's ? First down angle on the struts is only going to make the hopping worse. I would put them to neutral and see where that gets you.
Second when you changed the angle on the fin did you move the bottom of it toward the rear or forward? On curved turnfins the more you angle them back the more it will suck down the bow, conversly if you angle it too far forward it becomes a hydro foil and lifts way too much usually flipping the boat. The turnfin can be used to tune the ride attitude to get the nose up where you want it. It looked to me like it was running wet up front and tail high. If the turnfin was the only change from when you run it before the hop try angling the bottom of the fin torward the front a little bit at a time and see if you can get the hop out that way. (along with your struts to neutral) Beyond that you could give the props a bit of cup to take some lift away, but I would definitely try the simple stuff first.

Chris