2007 320 Sundancer How Do I Put the Props On?

[Scuma]

The props had to be taken off when I had the new boat shipped down to me so now I need to get them back on. I asked Marine Max how much it would be and they wanted $150...not a chance!

It's a double nut so I'm not sure if they just need to be tightened and will tighten on eachother or need to be torqued. Anyone?

Also there looks like there is a hole for a cotter pin but I seem to be missing that so not sure if it ever had one. Is that something that should be there on the 320 and is it necessary?

Also, not positive on the prop orientation so if anyone knows about that, would be a big help so I'm not spinning in circles :smt101

Thanks guys

 

[MasterFab]

Before you condemn the $150 charge from Marine Max, consider how much work is involved with installing the props properly.

First, the shafts and props should be examined for proper machining, to verify that the keyways are properly radiused, and no burs are present. Next, the keys themselves should be cleaned and dressed, and carefully fitted to the keyways, so they do not bind as the props are installed. A poorly fitted key will not allow the prop to fully seat on the shaft taper, resulting in vibration, or possibly even a broken shaft due to the imbalance and eventual fatigue failure.

Then, before the props are installed, the contact pattern should be checked. Normally, blue dye is applied to the prop shaft, and the prop is fitted, and rotated on the shaft while applying light pressure (keys not installed). When the props are removed, the contact pattern is visible in the dye, and can be evaluated. You will want to see a minimum of 70% contact between the shaft and prop taper. Any less, and the prop may "wobble" on the shaft, again resulting in vibration. Ideally, 80% and more contact is even better. If the pattern is not acceptable, the props have to be lapped to the shaft, and while this is also not difficult, it can take a bit of time to do properly.

Once the pattern is corrected, everything has to be cleaned, and then the props are installed for the last time. When all this is taken into account, $150 isn't bad. There is a lot more info about prop installation on my blog, so you can refer to that as well. This is not a job to skimp on, and it needs to be done properly....

Dale

 

[Scuma]

Before you condemn the $150 charge from Marine Max, consider how much work is involved with installing the props properly.

First, the shafts and props should be examined for proper machining, to verify that the keyways are properly radiused, and no burs are present. Next, the keys themselves should be cleaned and dressed, and carefully fitted to the keyways, so they do not bind as the props are installed. A poorly fitted key will not allow the prop to fully seat on the shaft taper, resulting in vibration, or possibly even a broken shaft due to the imbalance and eventual fatigue failure.

Then, before the props are installed, the contact pattern should be checked. Normally, blue dye is applied to the prop shaft, and the prop is fitted, and rotated on the shaft while applying light pressure (keys not installed). When the props are removed, the contact pattern is visible in the dye, and can be evaluated. You will want to see a minimum of 70% contact between the shaft and prop taper. Any less, and the prop may "wobble" on the shaft, again resulting in vibration. Ideally, 80% and more contact is even better. If the pattern is not acceptable, the props have to be lapped to the shaft, and while this is also not difficult, it can take a bit of time to do properly.

Once the pattern is corrected, everything has to be cleaned, and then the props are installed for the last time. When all this is taken into account, $150 isn't bad. There is a lot more info about prop installation on my blog, so you can refer to that as well. This is not a job to skimp on, and it needs to be done properly....

Dale

Ok well if they actually were going to do all that, then 150 isn't bad. However from previous experiences with them, especially around this time of year, I know that all they're gonna do is put them on and that's it. They love to cut corners.

Someone i was with last night told me not to put grease on at all. Is that true?

Thanks for the info

 

[MasterFab]

Yes, it is true. Grease is extremely viscous, and will form a thin hydraulic wedge between the prop and shaft . Over time, as the grease migrates from between the prop and shaft, and the prop may actually come loose. I use a very light oil on the shaft taper and prop hub, and tighten the first nut to 80% of torque specification - then go have lunch or watch a movie. While you are away, the oil flows out from between the interface, allowing for a nice tight fit. When you return, tighten the nut to 100% recommended torque, tighten the 2nd nut, and finally add your retention device - cotter pin, lock wire, etc.

Dale