The Warship was the first diesel release from Bachmann to incorporate both a decent mechanism and a fundamentally accurate body. Unlike it's more recent siblings, however, it's not DCC-Ready so the decoder needs to be hard-wired in, but it's an extremely easy job as there's plenty of free space inside the loco.
Photo 1
All you need. The loco, a couple of screwdrivers, a decoder (in this case the Lenz LE1025A) with the supplied double-sided sticky pad, a pair of cutters, superglue and some offcuts of timber or card. Also you'll need your soldering outfit and a craft knife or wire stripper - not pictured because they're not very photogenic! If your loco is a new one then it's probably a good idea to test-run it before proceeding in order to check everything is OK.
Photo 2
The Warship body is easily removed by undoing two screws (circled in red in the photo) with a cross-head screwdriver. Don't undo the other screws sitting temptingly towards the middle of the loco - these are not the screws you're looking for. Keep the screws somewhere safe as, not suprisingly, you'll need them to secure the body once you've finished.
Photo 3
Once the screws are removed the chassis should literally fall out of the body, it's not a tight fit in the slightest. You should now have unrestricted access to the small circuit board where you'll solder the DCC decoder. For later reference the front of the loco (or number 1 end as it's known) is the end where the circuit board is and not the end where Bachmann have fitted the crew figures - after the conversion your loco should move in this direction when you tell it to go forwards.
Photo 4
The circuit board with it's selection of interference suppression components is not required for DCC, but can be a useful place to connect a decoder, so I left it in place. Some of the surplus parts need to be removed first, however.
Photo 5
Unscrew the circuit board, turn it over and snip off the two coils shown in the photo. Replace the circuit board and unsolder the short red and black wires that connect it to the motor terminals - make sure you leave the other wires in place as they supply the power from the track. Finally snip off the round-ish orange capacitor shown in the previous photo, if you do it at this stage after removing the wires it's that little bit easier.
Photo 6
In order to provide a place for the decoder to sit I've superglued a couple of small pieces of thin wood (actually P4 point sleepering) across the chassis, but you could just as easily use offcuts of cardboard or even plastic. Make sure you don't obstruct the locating hole (circled in red in the photo) for the body mounting screw and the corresponding area on the other side of the chassis or you won't be able to get the body back in place.
Photo 7
Fix the decoder in place with the supplied sticky pad as illustrated, making sure it doesn't obstruct the body fixing points shown in the previous photo. With the circuit board to the left hand side as in this photo, solder the grey decoder wire to the motor terminal nearest to you and the orange decoder wire to the terminal on the far side of the motor. Then solder the black decoder wire to the side of the circuit board nearest to you and the red decoder wire to the far side. You should be soldering your wires to the points where the Bachmann ones are already connected, but don't worry about the fact that you might be joining red to black and vice-versa. The colour of Bachmann's wiring is not meant to match the wires of your decoder, in fact sometimes it doesn't even match similar models in the same range.
I've taped up the 5 unused function/lighting wires on the decoder - I'll be fitting lighting to this model at a later date but for the time being I want to keep them tidily out of the way.
Photo 8
Before putting the body back on the chassis it's as well to check that everything is working. The safest way to do this is to put the loco on the programming track and try and read information from the decoder - the instructions for your particular DCC system will tell you how to do this. If all is well (and I've never yet had a problem) then pop the body back on and secure it with the 2 screws. Note that the end of the loco with the circuit board should be the front and Bachmann have placed the crew figures in the rear cab. If you want to move the crew to the other end of the loco just pull out the cab interior mouldings and swap them around.