Check to make sure that you have all the necessary parts to build your OpenROV v2.5! If you want to be thorough, check the BOM to make sure you have all the parts.

The first thing we're going to build is the internal structure of the ROV which fits inside the ROV Shell.

To build the internal structure, we'll need several tools and materials:

Internal structure parts (15 pieces) (There are other acrylic pieces included in the kit, but those are for other parts and are not shown here)

Acrylic cement and applicator syringe

Sand paper (around 150 grit)

Paper towels

We'll start out by assembling the ROV handle

The pieces you got likely came with a protective plastic backing on them. You'll need to peel this off of each piece before cementing it to anything

Cement two of the three handle pieces (shown in the photos) together to make one thick stack.

Once the first two handle pieces are attached, add the third.

This is a good moment to fillet the handle (now comprized of three pieces) using sand paper so it will be nicer to hold on to once the ROV is built

Now, we'll attach the lateral shroud support to the handle and attach that assembly to the top piece of the internal structure

After assembling the pieces, add cement to any areas that have not yet been bonded

Now we'll move on to the motor mount section of the internal structure. Cement the three pieces shown together so that all interfacing surfaces are bonded.

Be sure to apply cement to the bottom of the horizontal motor mount as this part has to withstand a lot of strain when the motor bells of the port and and starboard thrusters are being removed or replaced.

Once the first three pieces are bonded together, the second Axial Shroud Support can be added.

Now the Bulkhead piece can be added.

Be sure to get cement between every interfacing joint.

Once the Bulkhead is secured, the Bulkhead Brace can be attached. Be sure to areas around the outside tabs are cemented well, as voids may cause the tabs to break off more easily if the ROV is handled roughly.

The Bulkhead and Motor Mount assembly can now be placed down onto the Top Plate of the ROV.

Once again, be sure to bond any interfaces that have been created.

The Tube Cradle pieces can now be built. Two pieces are used for each of the two cradles. Just as you did with the handle pieces, it is recommended that you stagger the pieces in order to guide the syringe and cement, but be sure to align the pieces before the cement sets!

Place the Tube Cradle Assemblies into place and cement them to the rest of the internal structure. Be sure there is a good cement bond near the ends of the cradles as these areas will be under significant strain when securing the main tube later on.

You have now built the internal structure- congratulations! Now you can place the structure into the shell of the ROV and admire how pretty it is.

Let's cut the syringes! They are used as vent ports for the E-tube end caps. Here's what you'll need

Two BD [REF 309628] syringes

Vice

Hacksaw

Rag or cloth

Sandpaper [around 150 grit]

Hex wrench from kit or small screwdriver (for deburring) use a countersink if you have one

Remove inner plunger rod from syringe and set aside in clean place. The plunger rod will be used to seal the vent hole after assembly.

In the next steps you will be cutting the syringe in two places (indicated by the two red arrows)

Place syringe in vice with end protruding out

Cut off end just past where plunger stop is located

The part you'll want to keep is the piece that was between the two cuts. You'll also want to keep the white syringe plunger (we'll use that later). You can discard the very front part of the syringe as well as everything above the 0.15mL cut.

Slide the syringe further out from the vise and cut it at the 0.15 ml mark (which will be about 10mm back from the first cut)

repeat the last two steps with the other syringe

you should have two small pieces like in the picture!

Sand both cut ends of resulting pieces to smooth and square the edges

Use hex wrench or screwdriver to debur and remove particles from inside tube - you want to make sure the syringe plunger can easily re-enter the tube

Now its time to assemble the main endcaps! You'll need

Two cut-down syringes

Four 94mm diameter endcap disks

Two 90mm diameter endcap disks

Two 108mm diameter thick endcap flange disks

Acrylic cement

Acrylic cement applicator syringe

Paper towels

Remove plastic backing from a 90mm endcap disk (the small one)

Place a syringe piece through its center hole so that the disk is close to the small-hole-side of the syringe. (It’s supposed to be a very tight fit.)

Remove backing from a 94mm endcap disk and push the small-hole-side of the syringe into it’s center hole

Make sure that the small-hole-side end of the syringe is flush with the outside face of the 94mm endcap disk

Align the wire harness holes of the two disks

You can also find a video showing how to do these steps here: http://youtu.be/XCI5pkl50Vo

Insert the needle of the acrylic cement syringe between the two endcap disks with the needle facing downward and the bottom of the disks squeezed together

Inject acrylic cement between the two disks until about half of the disk area is wet (see picture)

Press the disks together against a flat surface on top of a paper towel.

If needed, the disks can be rotated against each other about the syringe to spread out the cement. Make sure the glue does not take hold while the pass through holes are not aligned

Use a paper towel to remove any excessive glue that beads up against the edges

If there are spots that did not get bonded with glue, applying glue to the perimeter of the disk in that area may help strengthen the attachment

After removing plastic backing, add another 94mm disk (bigger one) to the syringe on the other side of the 90mm disk

push the large-hole-side of the syringe into the center hole of the disk so that the two large disks sandwich the small disk

Repeat the preceding steps to cement the disk in place

Remove backing and place the 108mm diameter (thick) endcap flange over the most recently added disk (where the large-hole-side of the syringe sticks out)

make sure that the hole in the center is concentric with the syringe, and the cutout slot is also aligned with the wire harness hole

Inject acrylic cement between the flange disk and the outer 94mm disk in a similar way to how other disks have been attached

Clamp or press the parts together until the cement sets

Repeat the previous procedure for the other endcap set BUT MIRROR THE DIRECTION OF THE 108MM THICK FLANGE DISK

Now we're going to start building the battery tubes.

Our first procedure will be to assemble the aft battery tube endcap. You'll need the parts boxed in red.

Roughen a corner of the spring terminal adjacent to the smaller hole (the one that doesn't have a lip)

Put a blob of solder over the roughened corner

Cut four 1m lengths of 20awg stranded wire (two will be used now for the first battery tube and two will be used for the other battery tube)

Strip about 1cm of insulation and tin one end of each of the four wire lengths

Put one of the tinned wire ends through the smaller hole (without a lip) on the base of the spring terminal and solder it to the base (basically bend over the solder blob and heat to attach). (NOTE: The spring terminal will get very hot so it’s best to hold is with helping hands or pliers.)

Thread a second 1m long wire through the bigger hole on the spring terminal (the one with the lip).

Run the lead wires through the aft battery endcap inner disk (it’s the one with two holes that looks like a button)

Super Glue(not acrylic cement) the spring terminal to the inner aft battery endcap disk.

Align and glue outer and middle disks of aft endcap. It’s important that it lines up correctly - the nub of the middle disk accenting the hole on the outer disk.

Measure out 25cm of wire length passing through the spring terminal endcap. (Good idea to make a reference mark on the wire near the base of the terminal.

Slip the middle and outer disks over the longer length of wire. Both wires through the middle hole.

Double check that the wire is 25cm (once the disks are cemented together, it’s very hard to pull the wire in or out).

Make sure the inner, middle, and outer disks are concentric (visual). Then glue them together.

Next, we'll glue the disks for the forward endcap. This is where the motor bell comes in- we're going to use it as a centering pin

Slide the larger forward endcap disk (28mm diameter) over the motor bell. Then slide the smaller one (24mm diameter) on. It will be a very tight fit. Cement them together.

Take another large endcap and sandwich the smaller one. Cement it in place.

Attach and cement the outer forward battery endcap disk.

Sand a corner of the button terminal (any corner of the button terminal - on button side)

Using the same method as for the spring terminal, apply a glob of solder to the sanded area of the button terminal

Using superglue, fasten the button terminal to the forward endcap assembly (it should be against the circular endcap disk, not the flange disk that has nubs on it)

Okay, this is the part where we attach the rear endcap to the battery tube and pot the channel system in between the two. This part is quite a bit of fun!

First, sand the inside of one end of the battery tube.

Apply a thin bead of super glue along the rim of the sanded end of the battery tube.

Insert the aft (spring terminal) endcap into the sanded end of the battery tubes.

Here comes the best part- we're going to pot the battery tubes, forward endcaps, and the area surrounding the syringe in the main endcaps.

First, insert the tip of an E-90FL mixing nozzle into the hole on the aft battery endcap (which is now held with superglue against the battery tube).

Inject epoxy so that goes around both sides of the parimeter of the endcap, up through the root of the "T" slot, out to either side of the T to cover the wires, until it finally oozes out of the center oval hole.

Next, we're going to pot the holes on the forward endcaps. This will seal the holes from water intrusion.

Fill the hole of the endcap until a circular bead of epoxy can be seen filing the indented part of the button terminal.

Do this for both forward battery endcaps

Finally, we'll apply potting around the perimeter of the syringes on the main endcaps.

Place the nozzle of the epoxy gun between the outer perimeter of the protruding portion of the syringe and the inner perimeter of the flange disk hole.

Slowly push epoxy out of the nozzle, again being careful to avoid getting epoxy into the nozzle hole.

In this section, we're going to attach longer leads to each of the three motors and waterproof their solder junctions with special adhesive-lined shrink tubing. It will be helpful to have the tools and materials shown in the photograph.

To start out, we'll need to remove the motor bells. In order to do this, we'll have to remove the c-clips that retain them by spreading the c-clips open and off with the outside edges fine-tipped needle nose pliers.

If you don't have any fine-tipped needle nose pliers laying around, a flat-head screwdriver can also be used, but this is a bit more tricky.

Now we're going to remove the shrink tubing that protects the lead wires that came with the motor.

When cutting through shrink tubing, be careful not to nic the magnet wire coming from the motor.

Start by cutting along the length of the outer shrink tubing.

Once the outer shrink tubing has been removed, cut a slit in the three pieces of shrink tubing surrounding each individual motor lead. The slit should extend from the leadwire-end of the shrink tubing to the solder joint that couples the leadwire to the motor, but not further.

With a soldering iron, heat each solder joint (which should be accessible through the slit you've made) until the leadwire comes off.

Once you've removed the lead wire, you should be able to pull the shrink tubing off over the remaining solder glob

Now cut nine 65cm-long lengths of 20awg stranded wire. These wires will be used as the new leadwires for each motor.

For each motor, you'll use three of the 65cm wires. Strip about 1cm of insulation from one end of each wire and tin with the exposed strands with a liberal amount of solder.

Solder the leadwires to the magnet wire ends from the motor. There should not be much overhanging wire past the solder joint, since the whole thing will need to be sealed.

Cut three 3cm-long lengths of black 3M EPS-300 (adhesive-lined) shrink tubing

Slide one of the 3cm lengths of adhesive shrink tubing down each of the newly attached leadwires. Make sure the shrink tubing is slid all the way down the leadwire and over the solder joint until it bottoms out at the stem of the magnet wire from the motor.

Shrink the tubing with a heat gun until the inner lining oozes out its ends.

Cut three 35mm-long lengths of the larger diameter blue shrink tubing and place one over the wire leads for each motor. The initial diameter of the blue shrink tubing will make a pretty tight fit over the three smaller pieces of shrink tubing, but with the right coercion, should be able to slide most of the way to the motor.

TIP: Mark the wires I II & III so you know which wire(s) to pull as it is VERY tight fit. Use silicon spray which allows the blue shrink to slide over the 3 wires

Once the new motor leads have been attached and the potting in the battery tubes has cured, a wire harness can be built which will eventually pass into the Electronics Tube through the ROV's port endcap.

The first step to preparing the wire harness is marking the point that will pass through the end cap on each wire lead

Using a permanent marker, make clear indications of the lengths shown in the diagram for each motor (42cm for what will end up being the port motor, 38cm for the vertical motor, and 35 for the starboard motor). Remember, this is to MARK NOT CUT at this point.

Tape labels about 5cm above (closer to the end of the wire) each mark with the respective position that motor will be. For instance, since the motor with a mark at 42cm will be the port motor, a label with a "P" written on it was used.

Just as the marks were made on the motor lead wires, make marks on the battery lead wires at 50cm (for what will end up being the port battery tube) and 43cm for what will be the starboard battery tube.

Label the battery tube lead wires in the same way the motor lead wires were labeled- flags with "P" (red) or "S" (green) about 5cm above the length mark. Also, it is a good idea to find the longer of the two wires coming from each battery tube and put a separate label on those wires indicating they are the "negative" polarity for that tube.

You'll know which labels are motors vs battery tubes because the motor will have three wires and the battery will only have two.

Now that you've marked the pass-through points on each wire lead, group all the wire leads (9 from the three motors and 4 from the two battery tubes) together so that their markings align.

Tape the bundle together a few centimeters above the markings so that the markings stay aligned.

Find the shortest leadwire in the bundle (it should be the wire coming from the button terminal on the port battery tube) and make sure that it's end is at least 18cm from its length mark.

Trim the ends off of all the remaining wires so that they end at the same place as the shortest wire.

6 Auxiliary Wires: With the remaining 20awg wire, cut six 60cm long leads and group them together. These will be used as the auxiliary wires for connecting external devises to the ROV. The ends will be sealed with epoxy until ready for use. The new PMU sensor add-on uses 4 and two are reserved for I2C.

Note: Add additional wires for aux if you plan on tinkering later. Current build allows 24 Digital User Pins and 7 Analog Pins.

Pull one of the ends out from the coil of twisted pair "tether" wire and group it so that it is flush with the ends of the newly cut auxiliary wires.

Align the ends of the the tether and auxiliary wires with the ends of the motor and battery leads and wrap tape around the whole bundle. This tape cover will help guide the bundle through the mesh sleeve that will be used several steps later.

Thread the wire bundle through the yellow mesh sleeve until the sleeve is on the other side of the pass-through markings on the motor and battery lead wires.

In the next few steps, we'll be attaching the motors to internal structure.

To start out, we'll want to prevent the mesh sleeve from freying further, so we'll want to tightly wrap each end behind where the freying stops with electrical tape.

The freyed parts of the sleeve on the other side of the electrical tape wrapping can be cut off using scissors later.

Before mounting the motors, use the 1.5mm hex wrench to tighten the set screws on each motor. (We've found that these are often a little loose out of the box, and it's much easier to tighten them now then after the motors have been mounted)

Place the M3 screws in through the top of the motor mount, then, holding the screw in place with the hex key, place the motor on the internal structure so that the screw also fits through the appropriate mounting hole.

With the internal structure up-side-down and the motors facing toward you, the wire harness should go around the left side of the main bulkhead.

To fasten the motor, place a lock washer on the shaft of the screw as shown, then place a nut on top of that and hold the nut steady with your thumb. Tighten the screw with the hex wrench until tight. Pliers should not be necessary.

The motor with the shortest wire lead should go on the left with the structure upside-down (which will be the starboard side of the ROV), the middle-length wire lead motor should go on in the middle (it will be the vertical motor) and the motor with the longest leads should go on the right. It will be the port motor when the ROV is right side up.

Glue the two acrylic rings (motor shrouds) on to the structure.

The wire harness can now be inserted into the port endcap. Insert the wire harness from the flange end inward as shown.

Pull the wire harness through the endcap until the marks on the wires made earlier are flush with the inner plate of the endcap.

To verify that the wire markings are in the right place (so that the harness will not be too long or too short), position the endcap in its cradle and check that the mesh-covered part is slightly slack.

If the harness is not the right tightness, it can be adjusted. If this is done, you should make a new mark on the wire to indicate the appropriate place it should pass the inner face of the endcap.

In this step, we'll add the white flange cover to the the endcap. Position the flange cover so that its flat edge is aligned with that of the main flange plate.

Inject cement between the two plates in a similar way to how the other parts of the endcap were assembled.

After sufficient cement has been injected between the plates, push the assembly down against a table to spread the cement across the interface.

At this point, the flange cover for the starboard endcap can also be added in a similar way to how the port endcap flange cover was added.

Use a hot glue gun to create a barrier that will prevent potting compound from leaking out the channel when the endcap is potted.

We're now going to get ready for one of the most important steps of the entire kit-building process: potting the port endcap. To start out, you'll want to make it so the wire harness coming through the endcap is pulled stright upward so that it doesn't touch the edges of the hole it is going through

For the next steps, you'll want to find a place where you can clamp or otherwise hold the endcap down against upward tension on the wire harness. You'll also need something above the wire harness that you can attach a rubber band too. A desk with a hutch, the space below a table, or an empty shelf on a bookcase are all good candidates.

Wrap some tape around the wire harness to make its cross-section somewhat circular just above where the wire comes out of the endcap hole.

Tie a thread or piece of fishing line to the wire harness a few cm above where it comes through the endcap. A knot that involves several wraps around the harness will work better.

Secure the other end of the line to a rubber band that is positioned directly above the hole in the endcap. Before tying the line off, pull it tight so that the rubber band is stretching downward from the tension in the line.

Use hot glue to block the outlet of the endcap pass-through so that potting compound will not leak out around the sides of the harness. Try not to get too much glue on the disks that will go inside the tube, and also make sure that the wire harness itself does not bulge up above the height of the large flange disk.

Keep the hot glue gun on and ready to use so that any hole is discovered once the endcap has been potted can be plugged. (This can be done by simply wiping off any escaping potting then filing that area with hot glue)

Start potting the endcap by inserting the mixing tube as far down into the pass-through as possible. You'll want to fill starting from the furthest-back point to avoid bubbles. Also, insert the mixing nozzle between the wires in the bundle to make sure there are no voids that are not getting filled.

Fill the pass-through hole to the rim (if a little spills over, that's no big deal- it can be wiped off or left as is)

Within the first 20 mins of potting, move the wire harness back and forth as well as up and down longitudinally (like a toilet plunger) to make sure potting compound is filling every void.

E-90FL starts to set up after about 90 mins, but it will take a day for it to fully harden.

Insert wisdom here.

While the E-90 is still fluid, you'll want to attach propellers to the motor bells for each thuster. Start by sanding the shaft of each motor bell using a medium-grit (we used 150-grit) sand paper.

Cut off three 4mm long pieces of the adhesive-lined shrink tubing that was also used on the motor leads. These will be used to keep the shaft concentric with the mounting hole in the propeller.

Slide one of the pieces of shrink tubing down to the root of each shaft and shrink it down until it is secure using a heat gun.

Place the tip of the mixing nozzle firmly into the hole of a propeller and the hole with potting compound until it overflows. There may be some air that needs to escape for the potting to fully fill the hole. It's okay for some potting to overflow onto the surface above the hole.

Using a rotating motion, press the propeller down against the motor shaft. You'll need to sort of screw the threading onto the shrink tubing on the shaft for it to go on all the way without scrunching the tubing.

Do these steps for all three motor bells and place them somewhere where they can point directly upward. A wire shelf or a crack made between two books can allow the bottom side of the shaft to be out of the way.

We're now going to build the Electronics Chassis (also known as the E-Chassis). For this, you'll need the 13 parts shown here (as well as an additional two blinder pieces that are not shown here)

Start by cementing the Endplate pieces to the Main Platform. Orientation is importent here: the large hole on the Main Platform should be in the upper right corner with center stand-off on Endplate pieces pointing toward you (as shown). This will allow the OpenROV Controller Board to fit on the right way.

Now attach the four Braces (two for each Endplate) to the E-Chassis. They should be able to fit in if inserted at an angle.

Next, cement the Servo Mount to the same side of the Main Chassis the Braces are on.

Now we'll start making the camera platform. Start by cementing the two pieces for the Camera Mount arms together. The round bases of each piece should end up being concentric, but to aid with cementing, it may be easier to stagger the pieces initially. Of course, be sure to align them before the cement sets!

Next, you'll want to cement the Camera Mount arms to the Camera Platform with the smaller of the two pieces on each arm facing outward.

Finally, attach the white blinders to either side of the camera hole.

Now it's time to attach the ESCs to the OpenROV Controller Board. In each ESC box, you'll find one ESC, two zip ties, and a bag with shrink tubing and double-sided adhesive. You'll want to keep the zip ties and bag, so put them aside for now.

We'll want to cut the thick lead wires from the ESC down to a length of 4cm (Don't cut the thin capacitor wires). To keep everything looking tidy when mounted to the Controller Board, it's best to start by cutting one of the lead wires to the right length, then use that as a guide to cut the others afterward.

Next, we'll want to roll each wire around between our fingers to make the cross section of the wires circular. This will be important later on (especially with the two power wires) for getting them to fit into the holes on the Controller Board.

Because each wire has a very high strand count (and thus the strands are very fine), we'll do a trick to prevent them from fraying. Using a soldering iron, heat the tips of each wire (which is not yet stripped) and apply a bead of solder. The silicon insulation on the lead wires should be able to take the heat.

You should end up with five wires that have small beads of solder covering their strands as shown.

You can now strip each wire. Strip off 4mm of insulation from each wire using a sharp razor (auto-strippers will not work well with the flexible silicon insulation and the short cut length).

The ESCs should now be ready to be mounted to the Controller Board.

The ESCs will ultimately be placed over the blank area of the Controller Board with the leadwires arching over to the holes they'll be soldered in. Look at the second photograph in this step to make sure you've got them oriented correctly.

Insert the ESC leadwires into the holes on the Controller Board and solder them in place. You'll want your soldering iron to be at a fairly high temperature since there is a lot of metal to sink heat here.

Watch out for stray wire strands that don't make it into the Controller Board holes. These can be removed with small wire cutters or needle-nose pliers.

Once all the ESCs are soldered in place, it is recommended that any excess wire lead that protrudes beyond the solder joint be removed using diagonal cutters.

Now you have both parts of the E-Chassis and a controller board that's ready for external electronics. Nice job! Next, we're going to attach the lights and camera to the Camera Platform.

Start by soldering the two light panels together. To do this, you'll want to create a small solder blob on the pads on the far left and right of one of the light panels, then attach the leads from the other light panel so that the red wire you're attaching is on the same side as the red already-attached wire (and the same for black).

Apply a small amount of super glue between the two notches in the Camera Platform and place a light panel there. The light panel should be positioned so that its leadwires are aligned with one of the notches, and it should be centered vertically. Note: using velcro with adhesive backing here allows lights to be moved and serviced.

Now you'll want to take apart the Genius F100 webcam so it can be mounted to the Camera Platform. Start by pulling the camera off of its stand (a strong tug should do the trick)

Next, remove the plastic piece still attached to the camera by unscrewing the small Phillips-head screw that goes through it.

Using small zip ties (you'll have found two of these in each box the ESCs came in), attach the webcam to the Camera Platform as shown. You'll need to double up the zip ties in order for them to reach around the assembly.

You can use scissors or a diagonal cutter to remove excess zip tie material. You'll want the zip tie heads to be positioned so that they don't bump into the E-Chassis main platform when the Camera Platform is looking all the way up or all the way down.

Once everything is secure, you can set the Camera Platform assembly aside for later.

Now we're going to start mounting other electronics onto the Controller Board. The first part we'll add is the Homeplug Adapter board.

We'll use the communication PCB out of a Tenda P200 Homeplug adapter to allow us to talk Ethernet over our twisted pair tether. To start, we'll need to open the Homeplug adapter and separate the communication board from the power regulation board.

Use a large flathead screw driver to pry apart the case.

Keep in mind that one of the four walls of the case is attached to the top piece of plastic so it won't pry off the same way as the other three sides.

You'll notice that there are two circuit boards inside. We'll want the one that the Ethernet jack is attached to.

There are five connecting pins between the two boards- three in the front and two in the back. Clip these pins as close as you can to the power regulation board (the one without the Ethernet jack) to separate the boards.

If you can't get cutters into the board as shown in the picture, then you can unsolder the 3 pins on the power regulator side, as we will be discarding the power regulator board

If the length of any of the header pins is significantly longer then its neighbors, you can trim it down to be even with the others using a diagonal cutter. You'll want the pins to be similar heights so that they fit into the female headers cleanly.

Place the Homeplug Adapter Board onto the controller board so that each of it's two sets of pins fit into he respective female headers on the Controller Board. The Ethernet jack on the Homeplug Adapter Board should face away from the ESCs.

At this point, you can also plug the ESC servo leads into the 3x6 header labeled "J8". You'll want ESC 1 (Port) to be wired to D6, ESC 2 (Vertical) to be wired to D7 and ESC 3 (Starboard) to be wired to D8.

Now insert one end of the Ethernet Jumper into the jack on the Homeplug Adapter Board. You should hear or feel a click from the plug locking into place.

Place an M3 nylon screw through the bottom of the controller board in the hole adjacent to the AtMEGA chip. Secure the 23mm threaded nylon standoff to the shaft of the screw on the other side (the top) side of the board.

Place the BeagleBone Black down onto the large male headers built into the controller board.

Plug the other end of the Ethernet Jumper into the port on the BeagleBone Black.

Use an additional M3 screw to fasten the BeagleBone Black to the standoff coming out of the Controller Board

Attach the Controller Board to the E-Chassis using M3 nylon screws and nuts as shown. To Orient the board, note the cut outs on the E-Chassis are for the solder points on the Controller board.

From inside the box for the HS-81 servo, remove the two-arm servo control horn and cut off one of its arms using a diagonal cutter.

Also use the flush cutter to remove the corners from the cut-off portion of the horn. This will allow the arm to fit inside the hole cut out in the Camera Mount arm.

Before mounting the servo to the E-Chassis, push the horn onto the servo and gently rotate it back and forth to its extremes. Adjust how the horn is placed on the servo so that its limits are in positions equivalent to the camera platform looking straight up and straight down (ish). The screw that holds the horn on is not really needed.

Loosely attach the servo to the E-Chassis using a set of M3 screws and nuts as shown. You'll need the nuts to be just barely threaded onto the screws at first so that the Camera Mount arms can be put into position before being secured. (Make sure the arm is centered - lined up with the camera mount semi-circle.)

Place the Camera Mount Assembly onto the E-Chassis so that the top of the webcam (the side without the webcam mounting stand tabs) is facing up with servo on the right when the camera is facing toward you.

Attach the arm on the side without a servo to the E-Chassis using an M3 screw and nut. Do not fully tighten as this screw will act like a hinge and should not create much friction.

After assuring the servo arm is seated inside the cavity of the Camera Mount arm, tighten the two screws holding the servo in place until they are snug.

Now it's time to do a bit of housekeeping. There are several wires coming from various places on the E-Chassis, and we're going to want them all to be plugged in and well organized.

To start out, you can get the capacitors attached to each ESC out of the way by tucking them under the ESC's leadwires as shown.

You'll want the switches from each ESC to be available for programming and calibrating each of them, so they can be placed alongside the BeagleBone.

Next, you can plug in the USB connector for the webcam. You'll want the cable from the connector to bend in the direction toward the DB-25 plug.

To keep the USB cable for the webcam out of the way, we'll wrap it around the main platform of the E-Chassis. Because the Electronics Tube will have to fit over the entire assembly, it's important that the wraps of cable are side-by-side and do not stack on top of each-other.

Depending on where the end of the doubled-up cable ends up (that seems to vary every time we build an E-Chassis) you can use the velcro strip that came with it, some tape, or a small zip tie to hold it in place.

The resulting bundle should lay flat against the E-Chassis platform, but be pushed to the side enough so that when the camera platform is pointing all the way up or down, the camera doesn't collide with the cable.

Next, plug the servo into the controller board. Plug into D-11 on the end of the header set. Remember, the "signal" line (the yellow wire) should go over the inner pin closest to the Beaglebone.

You can also plug the LED array into the Controller Board. The black and red wires go into headers "P1-" and "P1+" respectively as shown.

Once the potting in the main endcaps has cured, you can attach the DB-25 connector to the end of the wire harness.

Start by removing the tape that was used to hold the bundle together

Next, measure a distance of 17cm from the inside surface of the endcap, and cut one of the wires from the bundle at that length. Measure twice, cut once- you don't want the harness to be too long or too short by more than about 1cm!

Use the one wire that you've cut as a guide to cut all the remaining wires in the bundle to the same length

Now you can get ready to solder the DB-25 connector to the end of the newly trimmed wire harness.

Start by stripping off about 3mm of insulation from the end of each wire

Because each stripped wire will just barely fit in the solder cups for the DB-25 connector, it's easiest not to tin the wires before inserting them into their respective positions.

Look on the back of the DB-25 connector (the end with the solder cups) and identify pin 1 (labeled with a faint imprint in the plastic for the connector)

Use the guide shown to attach wires to the DB-25 connector. The guide is looking from the back of the connector - where the wires are being attached. Be sure that battery polarity is correct by measuring for continuity between the forward (positive) terminal in each pack and the other end of the wire it goes to.

You can put any of the ESC A B & C wires in any order in the connector. For example, it does not matter which of the Port motor wires go into pins 1 2 & 3

Once you've soldered all the wires from the harness into their respective pins, you can attach the forward battery terminals to each battery pack. This will be done in a very similar way to how the rear spring terminals were wired.

Start by sanding in the corner of each battery terminal and placing a large glob of solder there.

Using pliers (since the wire will likely get quite hot) hold the wire lead against the solder blob on the battery terminal and heat the terminal until it accepts the wire.

Hold the wire in place with the pliers until the solder cools and hardens.

You can also now attach the motor bells with propellers to their motors. You want the two aft props to be counter rotating- preferably so that the port propeller spins counter-clockwise (and the starboard propeller clockwise) when the ROV is moving forward.

You can now mount the internal components you've completed to the shell of the ROV. This is best done with the ROV up-side-down.

Rout the wire harness through the opening in the main bulkhead on the starboard side of the ROV.

Place the internal structure into the shell and allow the tabs of the internal structure to click into place.

Move the two battery tubes so that they are resting forward of the bulkhead. This will position them in the correct place once the threaded rods are put in.

Add one non-locking M5 nut to each end of each threaded rod, about 1cm in from each end.

The two battery packs are wired in parallel to the OpenROV Controller Board.

Place three fully-charged 26650 batteries in each tube, positive end forward.

Close the tube and secure it with an extra 157 O-ring.

Using a digital multimeter, measure the voltage across each battery tube at the DB-25 connector. You should have around 12 volts dc.

The batteries can be left in the battery tube safely and without being drained because the OpenROV is turned "on" by plugging the mini-USB cable into the Topside Adapter. (We will do that later).

Insert one threaded rod into the rear-most set of holds on the bottom of the shell and the other rod either all the way forward, or the second hole in from forward.

Attach locking nuts to the ends of the threaded rod. The locking nuts are the ones with the white nylon inserts inside of them instead of just being all metal.

Use reusable zip ties to secure each of the two battery packs to the shell. The battery pack with the longer leads should go on the port side.

Use flush cutters to cut off excess zip tie, but leave about 5mm extra on each so that it is easy to reattach the batteries with the same zip tie later.

Now your ROV is about ready for it's first power-up! You'll need to put the latest software on a microSD card that will go in the BeagleBone Black. The latest image can be found on our Github page

Now we can build the Topside Adapter. Warning: Test Assembly Before Gluing. It is very important to start by taking apart the second homeplug adapter (just like you did earlier) and positioning it in the front panel of the Topside Adapter Box. It's important to make sure the box isn't put together inverted (mirror image)!

Do not cement the top panel (the one that does not have a hole cut out of it) as this will give you access to the box later. Instead, we will tape it in place after finishing the assembly.

Cut 6 x 7cm lengths of 20awg wire.

Solder three three wires into the three holes on the USB REG board. The stripped wires make a tight fit into the holes, so you may need to remove a few strands from each.

Use a flush cutter to trim off excess wire.

To keep the other ends of the wires from shorting with each other on the Homeplug adapter side (which you'll wire to next) place 10mm long pieces of shrink tubing over the wires coming from the "+3.3v" and "GND" pins on the USB adapter. You can shrink this tubing over the header pins on the Homeplug adapter after the next step

After adding shrink tubing, solder the "+3.3V" and "GND" wires coming from the USB Reg to the middle and outer pins in the three-pin header on the homeplug adapter respectively. (Wiring diagram on next page).

Solder wires onto the remaining three pins (one close to the Ethernet jack on the 3-pin header, and two on a separate header toward the back of the board)

Solder the two leads from the 2-pin header respectively to the "+5v" line coming from the USB REG and the left over pin (GND) on the 3-pin header. It does not matter which wire from the 2-pin header attaches to the 5v supply or the ground.

Pull the two sets of joined wires through the each hole on the back of the topside adapter using pliers.

Solder the two sets of wires to each pin on the terminal block.

Use hot glue (or better yet super glue) to secure the terminal block to the back of the case. The terminal block should fit flush against the back panel of the homeplug adapter.

The USB REG fits into the case so that the USB connector fits into the hole cut out for it on the same panel as the RJ45

After the hot glue has hardened, you can attach the tether from the ROV to the terminal block on the homeplug adapter.

You're now almost ready to do your first power-up on the ROV! Insert the DB-25 connector attached to the wire harness into the reciprocal connector on the Controller Board. You may have to wiggle it around a bit to fit under the USB plug for the webcam, but it should go in without needing to unplug anything.

Plug the one of the Ethernet patch cables that came in the Homeplug box into the Topside Adapter and into the Ethernet port on your laptop.

Plug the USB cable that came with your BeagleBone into your computer and get ready to plug the other end of the cable into the port on your Homeplug adapter.

Plug the USB cable into your topside adapter and look for lights on the Homeplug board in the Topside adapter to turn on. They should go through a startup sequence but then all be lit after several seconds (but the middle light may blink rapidly)

Look at the controller board and verify that the green "PWR" LED is on. You should also see one sold red LED and one blinking LED which were used to test the board during the QA process before being shipped.