Damaged Propeller: Repair or Replace?

At some point or another it happens to every one of us, even the most cautious of guides – the prop gets dinged. Some of the time it’s somewhat more than a ding, yet the greater part of the sharp edges are still there, pretty much.

Your pontoon merchant, nearby repairman, and the neighborhood boatyard will all reveal to you a similar thing – supplant the prop! (They can’t settle it and need to offer you another screw.) But you ponder: “Can’t a decent prop shop rescue this with some innovative metal working and make it nearly in the same class as new?” If you’ve confronted that issue, you are not the only one.

As a matter of first importance, was your prop making a decent showing with regards to before it was harmed? That implies—

1. Was your prop keeping your engine in the best possible rpm run? Inability to do this outcomes in poor efficiency, poor execution, and most costly of all—conceivably cataclysmic harm to your engine.

2. Did your watercraft quicken and corner well?

3. Did you encounter discernible vibration from the prop? No good thing originates from vibration!

In the event that there are issues with these things, it may be a great opportunity to counsel with a prop maker or your propeller merchant and supplant your prop. All things considered, a prop that is impeccably repaired, however isn’t appropriately suited for your application—is splendidly uncalled for.

 

Damaged Propeller
Can this prop be repaired? Should it be?

Aluminum Props

On the off chance that the fundamental execution factors were alright, next you have to assess the plausibility of repairing the prop. In the event that you have an aluminum prop, you ought to investigate for over the top metal misfortune (over 10% of the sharp edge region), expanded splits, edges that are too thin, or cavitation consumes. In the event that your prop has any of these issues, do what needs to be done.

An extra thought is whether your prop may require the internal center point that secures your drive prepare supplanted. This can add another $40-60 to the repair cost, so it should be inspected too. Aluminum propellers are genuinely cheap to buy new, so you would prefer not to put excessively cash into them, except if they are in great general condition.

 

Propeller Before Propeller After
The left image shows the results of collision with a heavy chain. As you can see the bronze blades are badly bent and damaged. The right hand image shows the finished result. (Pictures courtesy of French Marine Motors, UK.)

Bronze Wheels

Imagine a scenario where you have a V-drive or inboard skiboat/cruiser with bronze wheels. The basic issue here is cutting edge thickness. Regardless of whether you made a “pretzel” out of your prop, gifted prop shops can work ponders. Be that as it may, if the sharp edges are too much thin, you might sink cash into an acts of futility. When you fix, you have to regrind to smooth the surface and expel imprints and scratches. Each time this is done, basic metal thickness is lost. Keep in mind that a 20% decrease in thickness may lessen the quality by up to half.

Propeller Cavitation
Cavitation has worked its magic on this stainless steel prop.

Stainless Steel Screws

Stainless props need to be evaluated on similar criteria as bronze ones. First of all, is the remaining thickness okay? Any signs of cracks? How extensive is the damage? How much metal is missing?

Generally speaking, stainless props are made from two general types of metals. High carbon stainless is very strong and damage resistant. It welds well and can generally be repaired unless it is bent excessively. Given its high strength, it does not like being bent into a pretzel and straightened. Typically this metal is used by Mercury, Yamaha, Turbo-Stiletto (now a Yamaha company), Michigan Wheel, and PowerTech.

High-Strength or Low-Strength?

Another characteristic of high-strength stainless is the fact that it shows more corrosion than low-strength stainless. This is a natural consequence of the higher carbon steel content used in the alloy. Low-strength stainless uses more nickel in the alloying combination. This provides a significant increase in corrosion resistance, but also drops the tensile strength, typically by 50% compared to the high-strength material.

The material used in low-strength stainless props is more similar to that used for deck hardware. Since the strength of the material is more like bronze than a high strength stainless, it will “pretzel” pretty easily. The good news is that it can normally be straightened out again.

In either case, the issue will be to examine for enough blade thickness to allow the repair to be completed and still have sufficient “meat” left for durability.

Propeller Repair
Proper repair takes time and the right equipment.

 

Repairing Props is an Art

If the decision is to repair the prop, look for a well-recommended repair shop. The proper repair of propellers is an art. It takes a true skilled technician to do the job you want.

In Riviera Boat we are able to repair most of the propeller in house.

Book your yearly maintenance in our shipyard and we will inspect your propeller  for free.

 

 

 

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