Prop blade preparation pre launch.

[Gybe Ho]

In the world of marine leisure boating propellors get a lot of attention before launch. There are two schools of thought:

 

1 - Polish the blade surfaces to a mirror finish that marine growth will struggle to attach to.

2 - Paint the blades with a hard antifouling paint.

 

There is a third idea which is to melt a lanolin wax onto the blades.

 

All these preparation succumb to weed growth within 18 months, in reality marine boat owners are just postponing the inevitable.

 

Do canal boat owners do anything similar before launch?

[Jen-in-Wellies]

No.

[Gybe Ho]

2 minutes ago, Jen-in-Wellies said:

No.

 

Not even a buff with Basso?

[magpie patrick]

No, and TBH I think you may be overthinking this. Unless there is a blimmin great chunk missing from the prop just put the boat in the water and go

[Tony Brooks]

May be use a hammer and dolly to straighten any minor bends and possibly angle grind rough nicks, otherwise nothing unless it is singing. In that case, one would grind anti-singing edges

[Russ T]

Being in the envious position of owning at least two boats, one on a drying mooring on the coast, and a narrowboat with a weedhatch. I can say, with some certainty, that UN-antifouled coastal boat succumbs to barnacle growth within 3 weeks of scraping in the warmer months (including the prop). The narrow boat, does not, thankfully. If it did, then a quick dive down the weedhatch  before lunch (definitely after breakfast) would have it sorted.

 

You could try a thin layer of weedkiller, or linseed oil on it.

 

Didn't even need Alistair for this one.

 

Next question.................

Edited July 3 by Russ T
scraping not scrapping

[Gybe Ho]

12 minutes ago, Tony Brooks said:

May be use a hammer and dolly to straighten any minor bends and possibly angle grind rough nicks, otherwise nothing unless it is singing. In that case, one would grind anti-singing edges

 

The prop is in perfect condition, not even a minor nick. Went down to double check while writing this. It is a large 22" diameter prop that will be slow revving, I hope it won't sing.

 

While having a close look at the blades I noticed some lumps of epoxy paint overspray, these were over a mm think. I will knock those off with a soft edge (plastic or a wooden spatula) to eliminate the risk the lumps will promote cavitation and associated strange noises underway.

 

The prop blades also have beveled edge on the trailing side of the blades, not noticed that until today.

[Russ T]

1 hour ago, Gybe Ho said:

 

Not even a buff with Basso?

What is Basso? Isn't that for musical instruments?

[IanD]

13 minutes ago, Russ T said:

What is Basso? Isn't that for musical instruments?

Or fish?

[Alan de Enfield]

13 minutes ago, Russ T said:

What is Basso? Isn't that for musical instruments?

 

[DShK]

10 minutes ago, Alan de Enfield said:

 

 

Let's not turn this forum into facebook....

[Mike Coombes]

What a coincidence. I have just had our 12.5 long keel motorsailer hauled and propped. The stern gear, a 21x16 RH Bronze prop and the S/S shaft, Ambasador Marine rope cutter and the S/S retaining nuts were all given the 'brick cleaner' treatment. Barnacles and other stuff left from the high pressure jet wash just melt away. Even the worm like barnacle larvae disappear easily. A wash with a rough sided small sponge bought it up like new. Brick Cleaner is a mild dilute Hydrocloric Acid. It does not affect metal at this dilution, but is the most effective cleaner. No need to disassemble the rope cutter and reset the clearances when refitting.

 

I have every expectation it would be just as effective on a freshwater prop, should it be required.

[matty40s]

I would normally stick a plastic bag over a  boat prop going back into the water.

Not only will this keep it clean, it will also allow you to practice your weed hatch moves for when you finally cruise your boat to its brokerage for sale.

[Kingdom Isambard Brunel]

In the navy, the definition of wasting time and effort is "polishing the propeller"

[Slim]

9 minutes ago, Kingdom Isambard Brunel said:

In the navy, the definition of wasting time and effort is "polishing the propeller"

I think that says it all.

[IanD]

16 minutes ago, Kingdom Isambard Brunel said:

In the navy, the definition of wasting time and effort is "polishing the propeller"

You're sure it's not a euphemism for something more personal? 😉 

[PeterF]

The first time your prop sucks up a load of grit in the shallows it will clean off 99% of known weed.

[matty40s]

16 minutes ago, PeterF said:

The first time your prop sucks up a load of grit in the shallows it will clean off 99% of known weed.

Pour some Domestos down the weed hatch straight afterward,  that's the other known 1% gone too.

(NOTE..(for GybeHo), do not attempt to do this whilst moving.)

[TheBiscuits]

3 minutes ago, matty40s said:

(NOTE..(for GybeHo), do not attempt to do this whilst moving.)

 

Or at least film it for us ...

[NB Saturn]

Just now, TheBiscuits said:

 

Or at least film it for us ...

 

And to help the MAIB 😀

[TheBiscuits]

Just now, NB Saturn said:

 

And to help the MAIB 😀

 

It wouldn't be classed as an accident though.

 

"There's been a terrible deliberate!"

[Bod]

On a more useful note.

Carefully check the prop for any numbers, then clean and photograph them, for future reference, when this one falls off, you know what to order, without getting wet!

Bod.

[Mike Coombes]

1 hour ago, Bod said:

On a more useful note.

Carefully check the prop for any numbers, then clean and photograph them, for future reference, when this one falls off, you know what to order, without getting wet!

Bod.

 

Sensible suggestion. However, not all props/shafts have the same taper.

 

Our American made Motorsailer has a shaft with a long, shallow taper as opposed to a steeper, shorter taper on European vessels.

[cuthound]

On 03/07/2025 at 12:52, matty40s said:

I would normally stick a plastic bag over a  boat prop going back into the water.

Not only will this keep it clean, it will also allow you to practice your weed hatch moves for when you finally cruise your boat to its brokerage for sale.

 

I once got a fertiliser bag stuck over the prop on our first shareboat.

 

Took ages to cut the ba*tard off... 🤣😅

[MtB]

On 03/07/2025 at 22:37, Mike Coombes said:

Sensible suggestion. However, not all props/shafts have the same taper.

 

True.

 

There are 1:10 tapers and there are 1:12 tapers. 

 

I generally see 1:10 tapers on narrowboat shafts. In fact I don't think I've ever seen a 1:12. 

 

Or is is 10:1 and 12:1 ?