SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Changing prop underwater

8K views 16 replies 7 participants last post by  Faster 
#1 ·
I've just ordered a new Campbell Sailor prop and is thinking of doing the swap underwater (with scuba gear of course). I've thought through the work processes and tools needed (bag to hold clotter pin, spanners, 2-claw bearing-puller<for removal of old 2-blade>, hammer, shaft-key ...).
Any advise from those experience in this ? e.g. should I engage into gear to lock the shaft when doing the swap? ..can hammer the old prop hub to free it? will the new prop go in freely or require some effort? should the prop shaft hole be grease? etc...

Ken
h326, SV Millennium 2
Singapore
 
#2 ·
I'd say definitely lock the shaft - you'll have enough difficulty using the puller underwater as it is.

I'd suggest you tie something on the old prop - they can "pop" off the shaft with some force and it might go for a swim if it turns out to be on real tight. Maybe leave one nut loosely on the shaft as a preventer....It's a good spare. When you use the puller stay to one side - don't be in the line of fire.

You might give the end of the shaft a good smack once the nuts are loose - this may pre-loosen the taper fitting, but use a soft hammer or a brass drift so as not to damage the threads.

The new prop should go on easily if everything is clean. Some never-sieze shouldn't hurt.

Since its a 326 it hasn't been on there for 20 years, so things should go OK - but it's a much easier job to do on the hard.
 
#4 ·
Once the puller has tension on the prop, tapping on the shank of the prop will break the corrosion between it and the shaft. Light tapping for a slightly prolonged period is best; you're breaking corrosion, not rearranging the metal. Place the retaining nut flush with the end of the shaft (protects the threads) and give the end a whack while under tension. If it doesn't come loose, put more tension on the puller and resume tapping on the prop.
 
#5 ·
you;'ll also need another pipe wrench to put on the prop shaft to prevent it from turning. Form experience, I've found that putting it in gear won't help. (much)
 
#6 ·
cardiacpaul said:
you;'ll also need another pipe wrench to put on the prop shaft to prevent it from turning. Form experience, I've found that putting it in gear won't help. (much)
hmmm, ok, I'll consider that. I assume you mean that when push-comes-to-shove the prop will turn even if its in gear. two spanners, a pipe wrench, puller and a prop, I don't think I'll need much weight to be negative buoyant.
Thanks for the info.
 
#7 ·
Please don't put a pipe wrench on the prop shaft. I normaly use a 2x4 or other wood block and put it between the blades and the cutlass or blade and the hull. I applaud your drive to change prop without a pullout. Try to have someone at hand who is experienced in changing props. ps putting any modern marine transmission in gear without the motor running will have no effect on the prop shaft turning as they are hydraulic transmissions. Like the automatic in your car.
 
#8 ·
bmunse, when I sail, to prevent the prop from spinning (and making noise) I put it in reverse gear. that holds it from spinning. so I assume this would in some way prevents the shaft from turning as I loosen the nuts. I'll be doing this underwater with scuba ...alone.
 
#10 ·
By alone I hope you mean you're the only one in the water - but that you will have a buddy on the boat/dock to assist and monitor your safety.

Some transmissions will lock the shaft, but only to an extent as Jones indicates. The pipe wrench is a bit brutal but will avoid stressing your strut if you need to put a lot of torque on the puller. Blocking the prop against the aperture or hull may transfer the forces to the strut.

Tapping the shaft with the puller tensioned is a great idea.
 
#12 · (Edited)
OK, here is a blow-by-blow description of how to pull your prop from someone who does it for a living. It is very unlikely that you will be able to remove the prop without a prop puller. I wouldn't even bother trying to do it without one.

Tools you will need:
Prop puller (a gear puller will be difficult to use by yourself underwater)
Pipe wrench
Pliers
Flathead screwdriver
3' or 4' length of lumber (preferably 2"X2")
Small sledge hammer (optional)

Procedure:
1.- Pry up the ends of the cotter pin with the screwdriver. Use the pliers to pull the pin from the shaft.
2.- Place the 2X2 between the strut and rudder. This will immobilize the prop as you use the pipe wrench to remove the prop nut(s) from the shaft. Leave one nut on the the shaft near the end of the threads as this will keep the prop from falling off the shaft when it pops free.
3.- Place the puller on the shaft. Remember that you want the pulling force to be as nearly aligned with the shaft as possible. Any angle in the pull will tend to cause the prop to bind as it comes off. Snug the puller up against the end of the shaft and the forward end of the prop hub. It just needs to be snug, this is not where the pulling force comes from.
4.- Begin tightening the puller. Do not over-tighten as it is possible to break the puller. If the prop does not come off immediately, bang on the aft end of the puller with the pipe wrench or hammer. If this does not free the prop, remove the puller and rotate the prop a bit and reset the puller in a new spot. Repeat instructions 3 and 4 until the prop comes loose. Pressure, vibration and persistance are key here. Keep the pressure on and bang the hell out of the puller. All props will come off, but some just take more effort.
5.- The prop will likely pop loose quite forcibly. Once it does, rotate it so that the shaft key is on top of the shaft. Remove the prop nut and slide the prop off the shaft. Be sure to see if the key has remained in the keyway in the shaft. It may want to stick inside the prop. Either way, be aware of it as you will need to use it with the new prop.
6.- Put the key back into the keyway on the shaft (if it came out during removal.)
7.- Slide the new prop onto the shaft. Force it up hard enough that it does not slide back down.
8.- Re-install the larger of the two prop nuts. Hand tight is fine.
9.- Place the 2X2 between the strut and rudder.
10.- Using the pipe wrench, tighten the main nut as tight as you can get it. Repeat this process with the jam nut (if you have a 2-nut system.)
11.- Put a new cotter pin in the shaft and bend the ends over with the pliers. You're done!

I generally line all my tools up on the edge of the dock for easy and safe access. The puller I attach to the prop shaft with a short lanyard as it will fall away from the shaft when the prop comes loose. You can do the same with the wrench or hammer to give your arm a rest in case you're doing a lot of pounding. If the distance between your strut and rudder are too great for your 2X2 to span, you can wedge the 2X2 up against the shaft forward of the strut on the opposite side of the strut where the wood will be lodged.

Good luck!
 
#14 ·
Dont forget that to swing a hammer underwater require a fair amount of effort, much of which is wasted. This isnt an easy task, just doing up nuts is a apian as when we are on dry land our body weight assists us, down there itb just goes around instead of the nut. Best of luck and have fun!

Keep it black side down

Mick
 
#16 ·
OK, guys, I've managed to change my prop. What an effort but its done. The 2x4 block of wood sures help in getting the nuts off the shaft. The extractor did take some getting used to as it keeps dropping off (boat is surging with tide).
 
#17 ·
Congratulations... let us know in a while how you feel about the Campbell prop!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top