View Full Version : Engine Installation Help

Thomas Garber
07-27-2001, 10:18 AM
I just took delivery of a used Yanmar 23 hp, and am working on the installation in my 1938 Malabar Jr., ZEPHYR. I have run a wire from the center of the stern tube through the engine compartment as reference for the axis of the drive shaft and transmission coupling. I also built a template of the motor with a hole excatly at the center of the transmission coupling, and coresponding hole at the other end of the template. The idea being, I can align the holes on the template with the wire through the stern tupe, giving me the correct orientation for new timbers and engine bed.

It's a tight fit, and I'm concerned any play in the rig will cause problems when I install the engine.

Am I doing this right? Is there an alternative procedure (other than hiring someone to do it)?

Ian McColgin
07-27-2001, 10:52 AM
That's one way. I've just taped a flashlight to the end of the tube. By the time it runs up to your template (very nice idea) it'll give a nice circle to spot your mark. I think it'll be a little easier than being sure there's no error in the wire being centered but you sound meticulous enough to do it either way.

Sail boats are tough to keep alligned. On Goblin I had both flexable mounts and flexable shaft couple. Pricey but took the curse out.


07-27-2001, 11:56 AM
Check out this month's "Professional Boatbuilder" magazine as it has an outstanding article on drive train from prop nut to engine mounts and all in between.

07-27-2001, 12:17 PM
The first thing you might want to consider is to get hold of or eyeball a copy of the "CATERPILLAR Marine Engine Application and Installation Guide. It contains alot of useful information about engine and transmission installations regardless of the size. Did you string this wire (piano I hope) thru the center of your stern tube/stuffing box from the great outdoors? Sounds like you did. Did you fabricate a disc with a very small centered hole in it which will fit or register snugly in the outboard end of your stern tube? Is the piano wire that is strung thru the hole in the outboard disc secured to some kind of weight (10-15lbs)? If there is an aft strut then you have to wire thru it first then thru the stern tube. If there are cutlass bearings involved remove them and measure off the tube or strut bore (this might not be your case). You can't accurately center your wire by measuring off of rubber, especially if your cutlass bearings are worn.Secure the inboard end of your piano wire to or thru a target of some sort (small piece of wood with cross hairs) which you can move around until your wire is centered thru the stern tube at which time you fasten the target to a bulkhead or temporary piece of wood fastened from one strucural member to another ahead of where your engine will live. The forward target can give you a reference point to go back to should you wish to get the wire the hell out of the way in order to do some work. The wire now gives you the axis of where your tailshaft wants to live happily ever after. With your nice templating work that you've done and the known offset for your transmission it sounds like you're in the ball park. Is there enough space left over to allow you to properly install the exhaust system? When you go to do the final alignment do it in the water (maybe you're there now)after the boat has sat for a few days with all of the gear and rigging aboard and at least 50% fuel,water groceries and beer. Good luck.

Thomas Garber
07-27-2001, 01:25 PM
I ran the wire (an old bow stay) thru the strut bore after removing the stuffing box and cutlass bearing, and aligned it with disks as RGM suggested. With a turnbuckle I was able to tighten the wire enough to hold the template without sagging. I guess this will work. Thanks for the recommendations. I feel like a babe in the woods with this.

Bob Cleek
07-27-2001, 06:18 PM
Come to think of it, this sounds like a good use for one of those new fangled laser levels, except that you don't have to pay the big bucks for the level or transit rig.(I learned they are expensive because they have to build them to take hard knocks in the trades and stay accurate... so they say.) You can buy them as penlight toys these days for maybe ten or fifteen bucks. At least I saw them at the mall for that. One nice thing about a laser beam on this application, you can work around and through it without it getting in your way like a wire. (Don't look the thing in the barrel, though... bad for the eyes.)

07-27-2001, 08:59 PM
Lasers are a lot of fun, no doubt about it, and they look cool. The only problem with them is that for doing alignments you can't measure to them or off of them, they're just too damn soft and squishy. That's where the inconvenient, almost always in the way stinking wire comes in handy. You can use a tape measure, pocket rule, dividers, tongue depresser or preferably a snap gauge to measure between a strut, stern tube or stuffing box bore and a wire. It doesn't work with a laser.

John B
07-29-2001, 04:48 PM
That's basically what I did ,Thomas .the template, ... a rod instead of a wire .The only comment I have is that the most critical part of the equation was getting the athwartships alignment right as a priority over the vertical alignment. ( less adjustment available in that plane.)

[This message has been edited by John B (edited 07-30-2001).]