Race Prep on my Crew Hull

[longballlumber]

Alright gang,

As I mentioned in another thread, I wanted to document my steps for preparing my new Crew for club racing this year. This is my attempt to do for you what Darin has done several times for the community here. I am not sure I can do the same justice that Darin does, but I will give it a try.

Nothing new in these first few pictures, but here are some shots of my hull. From the 3 feet (or less) that I was taking pictures, the finish looked good to me. I found it to be acceptable giving the price point of the boat and what you get. I did find what some others would call blemishes, but nothing that bothers me too much. After a day of heat racing, loading, and unloading in the car I am sure that it will get dinged up eventually…

[longballlumber]

Before taking everything off of the boat I did take a picture of motor alignment to the stuffing tube. I would prefer this to be better aligned, but I will address this at a later date when I start putting things back together.

I then proceeded to remove all of the hardware and all of the components. I do this because, to me, it’s easier to work with the bottom of the boat without banging the strut and the rudder. It also keeps the motor clean from debris and dust from sanding. I left the cooling lines that go thru the transom in the hull, because they can be difficult get back thru the transom after they have been removed.

[longballlumber]

In light of stock flex shaft concerns I am going to replace the stock shaft for a Hughey brand flex, but I will be using the stock strut bushing. First thing I did was clean up the end of the stuffing tube (the end were the strut bushing slides into). This isn’t a real big deal, but I sanded the tube end to get rid of any burrs or sharp edges created when it was cut to length. The other quick thing I do is run my Xacto knife (#11 blade) around the inside diameter (ID) of the stuffing tube end. This, again, will get rid of any burrs and put a slight chamfer on the ID making the bushing easier to slide in and out. You can also use the Teflon tubing to aid in this by pushing it from the motor end all the way thru to the strut end. This will help remove any large objects. I also clean out the ID with a Q-tip and make sure no small metal shavings are left over. You might be able to send a Q-Tip all the way thru using a 3/16 flex shaft (no Teflon) as the pushing tool. Again, no rocket science here.

Next is the strut bushing itself, first I clean the outside diameter (OD) of the bushing using some green scotch bright pad. Again this knocks down any burrs and sharp edges left from the machining process. I keep working the OD with the scotch bright until the bushing will SMOOTHLY insert into the stuffing tube and SMOOTHY pull out with no major sticking. After the OD is taking care of I move to the ID. I run a 3/16 drill to remove any burrs or sharp edges, and then Q-Tip to clean. I then slide the bushing onto the stub of the flex and make sure it rotates nicely without any snags. In this case it was like butter. If it did have a problem, I could also take the scotch bright pad to the stub end of the flex. BE CAREFUL, you don’t want to make the stub out of round. As long as you’re using a scotch bright pad and not too much elbow grease you should be ok.

[longballlumber]

For those of you who don't know... Hughey flex cables are the best in the business!

Ed and his brother Dee, were the pioneers of many RC boating inventions/improvements. Many from this board know Ed as a record setting FE boater from the brushed motor days. However, before playing with FE boats he was a very accomplished Nitro racer along with his brother.

[longballlumber]

Next, I moved on to the ride pads. Like ALL boats the ride pads need some attention. As you can see, they were concaved a little. In order to do this correctly you will need a FLAT sanding block and a couple different sanding grits. I started with 120 (I think), but that is only to get things started and the majority of the area flattened out. Once I felt the ride pad was getting close to being completely flat, I switched to 220 to finish up. Couple of notes here; let the sand paper do the work, you don need to “force” the removal of material. It may take you a little longer, but it reduces the possibility of sanding more angle into the ride pad. Remember, YOU ONLY WANT TO MAKE IT FLAT not change the angle.

I found the inside edges to be satisfactory for me. While I won’t say they are “sharp”, they are in pretty good shape. I had originally considered putting new ride pads on the bottom using 1/32 G10 fiberboard. That would really allow me to get edges nice and sharp, but it would require more time and a little more work. After seeing how well the edges were coming out of the mold, I figured it would be OK for now.

This is all I have for now... I will post as I make progress.

Thanks
Mike

[Doby]

For those of you who don't know... Hughey flex cables are the best in the business!

Ed and his brother Dee, were the pioneers of many RC boating inventions/improvements. Many from this board know Ed as a record setting FE boater from the brushed motor days. However, before playing with FE boats he was a very accomplished Nitro racer along with his brother.

Bushings on backwards, 3rd picture:laugh:

[longballlumber]

Bushings on backwards, 3rd picture:laugh:

HA.... Also no drive dog installed yet...... It's coming.... :thumbup1:

I was just checking the fit!

Later,
Mike

[longballlumber]

Alright, I have a few more updates. I’ve done more work here and there, but never found time to get it posted...

Next I started re-installing the motor mount. Instead of using the standard Phillips head wood/sheet metal screws, I replaced them with #4 x ½” button head sheet metal screws (w/socket head). I do this for a few reasons; the first and most important to me is being able to use hex keys for installing and removing, they are used everywhere else on the boat, and hex heads are more resistant to stripping out. The ½” long screws are a little longer than the stock and the major diameter is a little larger and seem to hold better. Even if you don’t change these, keep an eye on them, they will loosen up and start backing out after a few runs. Oh yeah, the button heads will minimize the chance of puncturing any lipos in a crash or flip.

[longballlumber]

Now that I have the motor mount installed, I turned towards the stuffing tube, flex shaft, and coupler alignment.

Recently, I have been replacing the Aquacraft flex couplers with the Octura brand. I feel the Octura’s run a little more true (less run out) for my liking. This is not to say there is something wrong with the stock coupler. As a matter of fact the one I replaced on this boat seemed to be fine. It’s just a personal preference for me, but not a must for everyone.

On a side note, aren't those cooling sleeves nice. I think they are the "cat's meow" :laugh:

[longballlumber]

As you can see from my first picture, I still have some alignment issues. My objective to get things lined up is so I can insert the flex cable thru the strut and it will push all the way into the collet without moving or tweaking anything. There really isn’t much for me to take pictures off. Once the motor mount was screwed back in, I a little CAREFUL tweaking/bending of the actual mount. I also took out the Teflon tube and inserted a solid rod (as close to the ID of the stuffing tube as possible) and use that as a lever to bend the stuffing tube. Be cautious here, you don’t want to compromise the bond of the stuffing tube in the hull.

You will need to check this often to make sure the motor mount hasn’t been tweaked after running a few times. A misalignment can lead to heat in the stuffing tube.

[longballlumber]

I then moved to the rudder assembly. On the prototype hull that I ran last year, it had a water pickup in the rudder. I actually prefer that set up rather than the brass tubing pickup bolted to the sponson transom. I just so happen to have several spare rudder assemblies so I switched mine out. Oh yeah, something that I forgot to mention earlier when unbolting the hardware. I decided to change out the metric stuff for inch. I went to Lowes and got an 8-32 tap and drill set. It worked awesome. With going to the 8-32 bolts, I needed to clean up the mounting holes on the brackets. I simply used my dremel with a 1/8” carbide cutting bit.

Since removing the current stock setup I had two holes in the sponson transom. I used a 1/8 drill bit and drilled out the existing screw holes. Once the holes are opened up, I used a 1/8” wood dowel, lightly tapped into the hole using some thin super glue to bond it all together. The last steps were to sand flush with the transom and put some epoxy over the wood dowels to protect from the water.

[longballlumber]

More...

[longballlumber]

Once deciding on the different rudder, I disassembled the blade, arm, and hinge. I then immediately reassembled making sure the rudder arm was 90 dgress to the blade and use medium locktite (Blue) for all three set screws. You don’t need a lot of locktite and you want to make sure you don’t get any on the end that touches the shaft you only want it on the threads. A little goes a long way here.

I also started the process of sharpening the rudder. I used a couple different bastard files, then a set of diamond lapping tools, and lastly my dremel with a scotch bright type material to finish it off.

When sharpening the rudder blade try and follow the entire surface of the machined blade. As you can see in my pictures I was removing material along entire machined surface, not just the leading edge. Take your time and try not getting into a hurry. I had more than an hour in sharpening this blade before I was done. I wouldn’t advise using power tools. You can ruin the blade very quickly.

[longballlumber]

The leading edge of the strut got the same treatment...

[longballlumber]

In the spirit of changing my hardware over to inch, I also changed the mounting bolts for the rudder assembly to the bracket. I also replaced the stock shear bolt with a nylon one.

[Steven Vaccaro]

Nice Job.

[longballlumber]

Now for the big one, this technique can be applied to any boat you need to cut a flex cable to the proper length.

First item is to address the position of the drive dog. I start by gathering a mix of props you “think” could possibly be used on this flex shaft and boat. I have an X440/2, X440/3, 45X55, M445, X447. The X447 may never be used, but it helps to make sure you have everything covered. Oddly enough, the hub for the M445 is longer than the X447 making it the longest. The X440/2 was the shortest. The goal is to make sure you have enough thread for all of the props, and mark where the drive dog needs to set. I mark the edge and I also remove the set screw and mark the hole for the set screw.

[longballlumber]

Next, using a grinding stone in my dremel, I grind a flat spot on the stub shaft. This spot is just big enough so the set screw will have a flat surface to compress against. After installing the drive dog and confirming that all of your props fit correctly with ample amount threads I disassemble and use a permanent form of loctite. In most cases I would use RED, but I didn’t have any on hand, but I did have retaining compound. I a small amount of retaining compound on the shaft at the point the drive dog gets assembled and rotate so that it’s coated well. I also put some on the set screw and tighten everything up. I want this to be a permanent assembly; once together I don’t want it coming apart.

Oh, as you can see in the last picture, I put a slight chamfer on the leading edge of the drive dog using my belt sander... It's all about minimizing resistance in the water!

[longballlumber]

Now comes cutting the flex shaft to the correct length. As you remember before our motor alignment with the shaft/stuffing tube has already been set, make sure you have the flex collet loosened so our flex can travel all the way into the collet. Run your cable thru the strut and into the flex collet until it stops. What the flex shaft is getting stopped by is the motor shaft, meaning it can’t go in any further. With the flex shaft fully installed go the back of the boat and measure how much needs to be cut off. This is very important; when measuring, you will need to measure from the back of the strut to the leading edge of the drive dog. Mine was right at 4”. Hold on, because cutting off 4” off the flex shaft would make it too short. You want to take 5/32” to 3/8” off of that dimension. This will build in a preset gap at the strut. Remember the golden rule; measure twice and cut once and you can always remove material, but can’t add…

[longballlumber]

Now that I have the correct dimension and my flex cable marked, I use a cutoff wheel and my dremel to cut the flex shaft. I use my belt sander to clean up the cut end and put a chamfer on the end. Slide in the flex making sure it’s seated completely in the collet and check to make sure you have the proper gap!

Later this evening I will be soldering the end of the flex and finish getting this boat ready to run at tomorrow’s practice.

[longballlumber]

Nice Job.


Thank you Sir...

[Rumdog]

Great thread, Mike. Should help a lot of guys get their Motley's really ripping!

[longballlumber]

Great thread, Mike. Should help a lot of guys get their Motley's really ripping!

Thanks Rum, I appreciate you comments... Half the fun for me is actually working on the boats, not just running them.

[longballlumber]

Ok… I finally got things finished up last night. I needed to finish up the flex shaft. I know there are different theories on this but my preference is to solder the end of the flex. I use a Weller 200/260 watt gun (not an iron). Getting the end of the flex hot enough for the solder to flow can be difficult and the heavy duty gun seems to work ok. I am sure that some people use a torch, but that has its own set of difficulties. I also use Stay Brite brand solder. This stuff comes with its own acid flux and has a small amount of silver making it a little stronger than you typical 60/40 lead solder. Because of the small amount of silver it does have a higher melting point.

I mount my flex in a small vice. There are some nice V-groves the run length wise in the vice blocks that allow me to lay the flex cable in to hold, but it’s not so tight that I can’t rotate the flex too. This helps with cleaning and soldering.

First step is clean clean clean…. I first wipe down the end of the flex with acetone. Next, I use the acid flux (Stay Clean). It only takes a couple of drops as you rotate the flex. I keep a Q-tip on hand to help coat the flex. Remember this stuff IS ACID, so I keep a well dampened rag close by (water neutralizes acids).

Once you have the end of the flex cleaned I take the solder gun and start heating up the very end of the flex. It will take a little for the flex to get hot enough, but once it does I start feeding the solder along the flex. Don’t worry about how it looks. Make sure your solder is penetrating the cable. Once your satisfied let everything cool off.

[longballlumber]

Once cool, I took the soldered end to the belt sander again. Smoothed everything out and put a chamfer on the cable end… PREST-O BANG-O we are done with the flex!

[longballlumber]

Last couple of easy things… I reinstalled the servo, again, swapping out the Phillips head screws for more user friendly socket head sheet metal screws, and washers.

I will admit, I did cheat a little. I snagged my other AquaCraft Speed control and swapped it out with the new one. I wasn’t going to have time to solder on new 5.5 bullets last night. No worries, it’s the same controller.

It’s getting wet for the first time this afternoon after work!!!!

I hope everyone found one or two things useful in this thread. I will try and keep it up to date with my Eagle Tree Data. I am still working to understand using the Eagle Tree effectively, so bear with me…. Stay Tuned

Later :Peace_Sign:
Mike Ball

[maxmekker]

Great tread(even though I have a MG) Now go out and make a video :-)

[Grimracer]

Nice Job Michael..

Now that you have seen the boat from start to finish everybody has an idea of what, at this time, has to be done in mass market and what tid bits still need work.

The things that Michael brought forward here are the same things I do to my boats less replacing the screws and drive system.

Some day with the help of our great customers we will get each and every boat better and better..

Something you have to please take time to understand.. I have been "Racing" RC boats for over 20 years.. as easy as it might seem to "just do it right" meaning make it like Michael did, Its a balance of cost... To me all the little issues are HUGE.. but have to be taken as a bump in the road and as we continue, we WILL align!

Regards

Grimracer

Go get em Buddy!

[wparsons]

How'd the maiden go?

[longballlumber]

Sorry,

I have been out of town for work. I will reply tomorrow about my runs last week.

Later,
Mike

[longballlumber]

Alright Gang,

Now that I am back from travel for work, I can give you some info on a couple of runs I did on my MC.

For starters, both runs were on 4S2P 4200’s. The strut was set to the factory settings and never changed.

I started with an Octura X440/3, this is the same prop that I ran on the prototype version of the MC all summer last year. I knew starting with prop what to expect. On this run I ran the boat for just over 5min. It was long than I thought and I WOULD NOT advise someone to run their MC this long with the X440/3. The batteries, motor, and controller came in hotter than I like at low 120’s. I prefer to keep things under 110*. The boat was running rock solid. The wind was pretty gusts nearing 20mph. I honestly expected to boat to be loose and flighty, but it never happen. Even when driving into a head wind. I am still working with the Eagle Tree System, so I am not going to post my graphs until they are visibly easier to read. On this run I was pulling in the upper 60 amp rage with a mid to low 40’s speed. Remember this speed was maintained over 5+ minutes. Towards the end of the run I was trying to get the boat to roll onto itself, buy doing an extremely tight and elongated figure 8. The only thing the boat did was spin out once. Otherwise, it would handle the tight turns and instant acceleration fine. I was surprised and happy all at the same time. Oh yeah, I forgot the battery position on this run. I ran the packs as far forward as possible, up to the motor mount.

The second run was with an ABC 45X55 (similar to the GrimRacer 42X55 only a tad larger diameter). I also moved the CG of the boat back by .75” from the first run by moving the batteries back in the boat. This run was just over 3 minutes. The boat was running a little lighter and with a little more speed. Even though this run the boat was running a little more lose, it didn’t have any indication of blowing off. I expect that I will be running this prop for Offshore heat racing. Temps were still a little higher than I like, but I feel that some prop work will help this. This 45X55 prop can be thinned and sharpened a little better. I may even remove some of the tongue. The temp on the motor and controller were in the low 120’s again, and the batteries were low 110’s. The speed increased slightly into the mid to high 40’s (47 mph max). My amp draw did go up slightly into the low 70’s.

I am really pleased with the first two runs. I have some work to do getting the temps and the amp draw a little lower.

Have Fun
Mike

[hobby_man]

what was the stock mph vs the modified boat mph?

[longballlumber]

Hello,

I wouldn’t necessary consider the boat “modified”. I would consider everything listed in this thread (besides replacing the flex shaft) a fundamental of getting a RTR boat TRULY ready to run. All of the information provided doesn’t necessarily provide a performance advantage as much as it lets you learn about the boat and makes sure everything fits correctly providing an enjoyable time at the pond.

Back to your question; I never ran the boat before creating this thread and going thru the entire boat.

Later,
Mike

[justski]

thank you very very much for this thread best i read so far ....

[pistol18]

Great thread, thanks for all the info and pics!!

I just picked up a used MC and it has the following eqipment:

seamonster 2300 kv motor
seaking 120esc
octura x438 prop
flipped motor mount
hyperion v3 4s 4200mah 35c single batt mounted across the back of hull between servo and esc

Boat runs decent(I'm coming from a rio 51 that was much bigger and ran 48 on gps for reference)
but does seem slow to get on plane. Turns on a dime though, wow!
I've read the grim 42x55 prop is a good choice for this hull, should I swap to that?

For the drive cable, I'm not sure if its stock or upgraded but will prob get the ose upgraded shaft when its back in stock.
Also, I don't see the bushing in the drive strut when I took the cable out to lube it? guess it was removed by prev owner?

Thanks in advance for the help!
Joe

[pistol18]

Anyone????

[Grimracer]

I suspect the reason we are slow to react is your setup and what the boat came with.. It would be a guess (edgamcated guess :lol:) but a guess none the less to (make you go faster?)

The first thing I would do is start over and from the basics.

Grim

[hobby_man]

Anyone????

what is the question?

My new MC stock went 34 mph out of the box.
I installed the Grim 42x55, re aligned a few things now its at 42 mph.
Lipo's are traxxas 2s 10000 mah, they weigh 1 lb each

To get my boat to go faster? Lighter Lipos will help for a mile or two, I have some on the way. Other than that 42 mph out of this boat is real good.

SPEED cost MONEY!

[pistol18]

Thanks for the replies! Please go here next:

http://forums.offshoreelectrics.com/showthread.php?37942-Help-rebuild-my-MC-after-esc-fire!