Straightening prop

[pandos]

My new to me boat has a feathering prop. It has a few bits of damage where I presume stones or rocks were encountered..

There are places where the edge is curled over. I think this must create an imbalance which won't do any good.

I want to straighten these in place between tides. Should I heat the prop first, if so will a heat gun be enough or do I need to use gas.

I am sure I can get them straightish just by hammering against a block of steel, but I don't want to risk tearing the metal...

In time I know i can take the prop off but I want to sail this boat next week and it will take me a week to get it home so the quickest improvement I can do the better.

 

[Tranona]

What make of prop is it? Most have fairly thick flat blades and some are stainless rather than yellow metal. I think you might struggle to hold the blade in a solid enough position to apply enough force to straighten the metal, but without seeing what the bent bits look like difficult to say. Heat will certainly make yellow metal more malleable. I would be concerned about damage to the gear mechanism inside the hub, having had a feathering prop damaged by force being used (big hammer!) to drive the prop off the shaft. They look all big and beefy but the gears and shafts are rather delicate.

 

[vyv_cox]

With most copper alloys the most likely consequence of deformation by contact with fixed objects is work hardening. A single contact may not have done too much, so reversing the damage cold might be enough.
If you need to reverse any work hardening the metal would need to be heated to cherry red, needing oxy-acetylene or oxy-propane. A heat gun would be nowhere near enough.

 

[pandos]

Thanks for those replies. I had not really considered the effect on the grease and innards of applying heat.


It's a yellow metal 3 bladed feathering Variprop. (AFAIK)

I think I can get enough force with the hammers so I'll just go at it cold with them..

And hope for the best.

Thanks..

 

[B27]

Is it possible to acquire or borrow a fixed prop that's 'near enough', to get you home, while you get the expensive prop sorted?

I'd be scared of breaking or bending something, whether it's the innards of the prop, the shaft, the gearbox bearings....

I have a strong dislike of fixed props on sailing boats, but being confident about getting home without breakdown might trump that.

The experts who repair props can work wonders, worth having it done properly IMHO.

Other than ebay, where should you look for a good used prop?

 

[Neeves]

Using sufficient force with a hammer on a prop retained by its shaft without completely solid hard point opposing the hammer looks like a recipe for disaster. Taking a prop off is really not difficult.

Could you borrow and lash up an outboard to get you home.

If this is a boat you have just bought why do you assume the damaged prop will cause an imbalance. Logically you are correct but was there an imbalance when the engine was tested and put into gear?

Jonathan

 

[rogerthebodger]

I made a fixed blade propeller from stainless steel by laser cutting each blade to the required shape welding them on to the boss and twisting each blade to get the required pitch using a little heat

I would try heating the damaged blade and hammering it back into shape using a support block on the oversite side to the hammering

I you can take the prop off and take it to a workshop with a hydraulic press you can straighten the blade in a press cold I have a 20 ton garage press that I use for bending stainless steel or straightening and bent stainless steel back to shape

 

[pandos]

Thanks for the suggestions...I'll give it a go with the two Hammers and if it is too difficult or likely to damage the yoke, then I will stop.

It's 250 miles home most of it a lee shore facing the Atlantic so I won't be using an outboard...