Removing a westerbeke diesel from a Gemini Catamaran

Gemini Catamaran
The maintenance side of sailing

It’s not ALL fun and games. But ask any cruiser and the definition of “cruising” on a boat and one answer you will likely get is “fixing things in exotic places” In this case this happened at home, but I suppose for some people Nova Scotia is an exotic place. Gemini Catamaran forum

maybe all over done, but being old, on the water and mostly without help, here is what I did and learned in the process of removing the Westerbeke diesel engine after repowering the Gemini with a 25HP Mercury outboard engine.

  • Disconnected all hoses and wires. 
  • I was fortunate, no bolts were frozen in place, none required beating on or even BP Blaster. (except drain plug with should have been brass, but that is another story, and in another post)
  • I started by removing the bolts from the engine mounts,  the front “big nuts” came off (that hold the engine to the mount) and the back little bolts came out (the ones that hold the mount to the boat) these were the ones that  were accessible. 

Removing engine from Gemini Catamaran

  • Then I took off the flex connector at the back of the transmission (the sillette was already off)
  • then I set up a frame, pictures below.  While you can’t see it very well what is actually holding the chain hoist is a 1 inch ID schedule 40 stainless steel pipe, which is about 1.5 inch ID.  This was roped to two of the stainless steel canopy support tubing for stabilization, not to hold weight. The frame was made with stuff I had lying around, 3×8 hemlock, that was previously used for a bridge, a deck and wharf. 
  • The Gemini Catamaran uses a diesel engine with a Sillette “sail drive” or drive leg. The leg was the problem on this boat, the engine was fine.
  • Put cardboard and plastic on the sole of the cockpit.
  • What you also can’t see very well is that the engine was not supported by ropes but by a 1/2 or 3/4 inch threaded rod that ran through the two engine lifting points, the rope was there just to hold the hook in the correct position on the threaded rod.  The rod took the weight. also the rod bent slightly in the process.  hard to believe this rig only ways 275 pounds. 
lifting frame
  • I lifted it off the front mounts and dragged the back mounts up with it. Once it was clear of the combing in the front, I removed the front mounting brackets, they may have cleared, but  it did not look good. I also removed the end caps of the heat exchanger.  the seem to stick out a little too much.
  • At this point because it was easy and I was going to do it at some point I removed the starter motor 
  • While this is specific to a Gemini Catamaran, much of the process will be the same on a lot of boats with diesel engines.
  • at this point I squeaked it out up over the combing, I had some boards on the cockpit sole and set it on the front engine mount brackets, which I put back on as I did not know if the oil pan would support the engine. so it was resting on the front brackets and the bellhousing mating plate.
  • It turns out the oil pan will support the weight ! so some of this was unnecessary. 
  • I removed the bellhousing and transmission, the rear mounting brackets come off in this process 
  • The bellhousing and transmission WILL just “slide” off the engine.  in other words there is nothing holding it there except a spline once you get all the bolts out around the bellhousing, BUT, “slide” is a deceptive term,  I had to pry pretty hard, and put a piece of wood in one side, pry open the other side, put wood in there, then go back and pry the other side. in a sense wiggle it back and forth using a pry bar. But the point is there is nothing holding it together (once the perimeter bolts are out) except rust/corrosion/ and maybe some kind of loving attachment after having been joined together like this for 20 years. 
  • probably unnecessary but I then removed the manifold and any other stuff that has hanging around.
  • I removed my lifting frame and cleaned up the cockpit as much as I could with the engine sitting in it.
  • I then connected my main halyard and a jib halyard to the end of the boom, and swapped the main sheet block and tackle top for bottom so the pulling was done from the boom DOWNWARD rather than from the engine UPWARD. I used a few shackles here and there. 
  • I then protected the seats tops and front of the seats (engine compartment) with wood, and rehosted the engine on to the seat (which was replaced by now) using the boom and main sheet. .  BTW the other come-along that may show up in a picture was never used, I thought I might needed it but did not use it.
  • I rehosted the engine on to the seat then pushed/slid it over on boards to the gunnel?, upper seat. Protected the side and top of that with wood. 
  • I then hosted up on to the upper seat and disconnected the sheet, and moved it to the other side of the canopy support tubing. 
  • Right at this time my neighbor showed up in his dingy to ask if I was still planning on taking the engine off the boat, what timing!!!
  • So he manned the rope (the main sheet) and lifted it the few inches over the combing and I swung the engine out over the floating dock. (The lifelines had already been removed). on to the 1200 pound capacity garden cart. 
  • see the Gemini Catamaran forum for details on this and many other Gemini owner’s projects. This is really a great resource in you are an owner of one of these boats particularly, but there is a lot of information for any boat owner. It is a members forum, currently no charge but there is a bit of a questoionng at the application to join to help cut down on spammers and trolls.
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