I recently used an ordinary car puller to shift the prop on my sons boat. It is one of those multiple choice jobs(4, 3 or 2 leg combinations). You can probably hire one.
Just make sure that the leg clawtips can get a good grip on the back face of the prop boss.
You may need to drill a bit of a dimple in the end of the prop shaft to provide location for the nose of draw bolt.
Loosen off the prop shaft nut but do not remove it. When the prop jumps free from the shaft taper the nut stops the prop dropping on the concrete.
Tighten up the draw bolt really firmly, then give the prop boss(between the root of the blades) a sharp clout with hammer and blunt bolster. If you haven't a bolster use a large open ended spanner. Place the outer edge of one jaw against the boss and smite the outer edge of the other jaw lustily. This causes the tapered hole in the prop to "spring" momentarily, unfreezing prop from shaft(this is an old engineering trick). You won't bend the prop shaft or do any mischief but by all means get a pal to hold something heavy against the opposite side of the prop boss if it makes you feel more comfortable.
One good thump should free the prop. When the taper sections part it usually sounds like a gunshot, don't be supprised!
Have fun, Rod.
One addition to this comprehensive posting. The forward edges of some prop bosses are rounded, or for some feathering or folding props there is a "bulge" at the centre of the length. In these difficult cases the puller feet don't grip the prop very well and slip off when the load is applied. A technique I have used for years is to put a long hose clip right round the puller feet, holding them on quite adequately.
Remember that if you resort to heavy hammering the load is being carried by the gearbox thrust bearing. This was not designed for this kind of treatment and it will not take kindly to it. The radial hammer across the taper, as described in the posting above, will have no effect on the bearings. I normally use two lump hammers, one from each side.
If there's an engineering firm nearby that uses a flame cutter / copier you can usually find offcuts that originate from the cutting of flanges. The hole in the flange creates a disk and you need two of these. Most firms would let you have a couple for free as it's so much scrap as far as they're concerned. You are looking for something that's 10 or 12 mm thick. Ask them to cut a slot in one of them so that the disk, which now will look like a very fat 'C', can fit over the shaft, behind (in front of?) the propellor. All you need now is a length of 10mm studding (bought from a hardware store and cut into three pieces) six nuts and six washers. Drill three holes in each disk so that you can join them with the studding passing between the blades. Assemble around the propellor, using two washers under each nut on the 'unslotted' disk; Tighten up gradually while holding this disk over the end of the shaft. Tighten some more and then give the aft disk an almighty wallop with a club hammer along the shaft axis (i.e. from back to front and not sideways). This will make the prop jump free. Sometimes, just tightening the nuts will also do the trick.
Maybe it sounds complicated but that's just me! There's really not much to it!
eerr wot appens to the bit that goes into the gearbox when you give the shaft this"almighty wollop"...all this ammerin and bashin...just warm it up a little it will come off in your hands(ware gloves or or somthin cos its ot..).
Nothing happens to 'the bit that goes into the gearbox' - or, more correctly, to the flexible coupling! The sheer combined mass of disks, propellor and shaft are more than enough to absorb the energy of the wallop and the prop releases from the taper well before the shaft can move forward. The blow does need to be sharp, though. Think of a karate master splitting tiles with his fingers. The sudden blow causes the tiles to snap before his fingers can hurt. You could cause more damage to the propellor if you overheat it like, say, with a blowlamp.
If you still have doubts try this: lay a decent length of galvanised water pipe (or a mild steel rod, if available) on the ground and see how far you can shift it with a hammer blow on the end....
Firstly this assumes that all boats have a flexible coupling. Not true, mine doesn't for one.
Secondly, the force required to indent an angular contact bearing is very small. Dropping a relatively small bearing, e.g. 3 inch, from a bench will put sufficiently large brinelling marks into it to cause it to fail in a short time. The energy involved is certainly less than that provided by a mighty blow with a lump hammer.
Thirdly, moving a heavy mass with a sharp blow is one thing, but transmitting that blow through a heavy mass is something else. Surely everyone has seen those desk toys with the five balls swinging on strings? The transmission of energy is virtually 100%.
The approved way to remove a taper fitting is to hit it radially, not axially, from two sides at once. If it was not overtightened in the first place it will often come off without the use of a puller.
If you read my inital posting you will see that I recommended using the bolster/ open ended spanner, placed on the prop boss BETWEEN the blade roots.
Unless I am mistaken, the only way the blow can be struck is radially.
1. The energy in the first ball (mass) only needs to pass through three balls (3 x mass) whereas the power from the hammer (mass < 2 kilos) needs to pass through the combination of 2 disks, propellor and shaft (mass = ?). I don't think that if I'm hammering a nail into a solid brick wall I would knock off the pictures hanging in the next room!
2. The blow from the swinging ball is NOT a sharp blow.
3. The three pieces of studding will already be under considerable tension (which you can calculate, if you really want to), linking the propellor boss to the aft disk. The sharp wallop is only sufficient to SUDDENLY add that little extra jolt required to break the taper bond.
4. You can still, if you prefer, hit the side of the prop between the blade roots - though how you can hit both sides on a 3-bladed prop is really beyond me.
4. I have a flexible coupling and my engine is on rubber mounts.
5. It works.
I've taken off literally hundreds of props, I use the puller and sharp rap on the boss with a hammer, method. I have also removed hundreds of steering ball joints, with two hammers to break the morse taper. Funnily enough I have only replaced about two thrust bearings in gearboxes, in a very long career, does this tell you something?