Best way to remove old bottom paint

[Boatyarddog]

Originally Posted by jordanbigel

So, I have 2 bow thruster props, 4 blade, 8" diameter, bronze (not sure which kind).

They were "accidentally" painted over with bottom paint about 5 or 6 years ago (an ablative paint, possibly Micron CSC) by an over-zealous yard guy who thought I wanted them painted.

I've tried some paint remover (Max Strip). I actually was able to remove about 2/3rds of it after soaking it overnight and then using a hand held wire brush. But still, only about 2/3rds.

Now what?

Do I go buy another bottle of paint stripper and keep going?

Or, can I get it sand blasted? There's a local place here which does stuff like this at very reasonable prices.

Or, should I put it in a vice and use a wire brush on a drill or angle-grinder?

Or.... is there some other way I am unaware of?

I don't think they need to be mirror polished or anything, but I would like to get them "clean" again.

Thanks in advance.

https://www.amazon.com/Black-Hawk-Su...14866796&psc=1
Try these, but I wouldn't use a dremmel, I'd use an electric drill or faster, air tools.
Boatyarddog

[jordanbigel]

Originally Posted by Scorpius

Why bother?

Great question. I am under the impression that old, uneven, cracking paint and rough surfaces in general make a prop inefficient and can cause cavitation. Am I mistaken?

In this case, I'm dealing with 2 bow thruster props and the thruster is underpowered to begin with, so I want to try and get the most efficiency out of the system, so, I thought it would be better to have smooth, unpainted props, or at least start with them smooth and unpainted before deciding what coating to put on them, if any - there were a lot of good suggestions in this thread for prop coatings and I am considering trying some of them (maybe one for the port prop and one for the stbd prop and compare next haul out).

[jordanbigel]

Originally Posted by Boatyarddog

https://www.amazon.com/Black-Hawk-Su...14866796&psc=1
Try these, but I wouldn't use a dremmel, I'd use an electric drill or faster, air tools.
Boatyarddog

These look interesting. Thanks.

[Scorpius]

Originally Posted by jordanbigel

Great question. I am under the impression that old, uneven, cracking paint and rough surfaces in general make a prop inefficient and can cause cavitation. Am I mistaken?

In this case, I'm dealing with 2 bow thruster props and the thruster is underpowered to begin with, so I want to try and get the most efficiency out of the system, so, I thought it would be better to have smooth, unpainted props, or at least start with them smooth and unpainted before deciding what coating to put on them, if any - there were a lot of good suggestions in this thread for prop coatings and I am considering trying some of them (maybe one for the port prop and one for the stbd prop and compare next haul out).

By all means, sand them smooth - but that should be enough. IMHO paint on them is not going to significantly adversely affect their performance.

[tomtriad]

Try soaking with Xylene (Goof Off). Why abrade when solvent might work?

Peel Away works well too and is non toxic and water soluable. I used it to remove 10 layers of bottom paint in one go.

[tfay412]

I would use a wire brush on a drill. It will get the job done much faster and alleviate the frustration. Or you can also use a fine grit sand paper so you don’t damage the propeller.

[sailorman14]

I use a soda blaster to strip old varnish off
Wood. It allows me to take the varnish off without damaging the wood.
Harbor freight sells one for less than $100.
But you will need air to run it.

[jordanbigel]

Originally Posted by sailorman14

I use a soda blaster to strip old varnish off
Wood. It allows me to take the varnish off without damaging the wood.
Harbor freight sells one for less than $100.
But you will need air to run it.

I've seen them, but I don't have an air compressor, and since I live aboard, I try to avoid buying large pieces of equipment which are not really essential. But I am lusting after one in my heart!

[NevilleCat]

Originally Posted by jordanbigel

I've seen them, but I don't have an air compressor, and since I live aboard, I try to avoid buying large pieces of equipment which are not really essential. But I am lusting after one in my heart!

After watching Sailing Nanji where he drills a split pin hole through the propshaft in the water (without having to slip the boat) using a compressor driven drill, has opened my eyes to possibilities. Sure, you're probably never going to need to do that but it just justified whatever it cost.
At least another point to spin to the financial controller anyhow.

[jordanbigel]

Originally Posted by NevilleCat

After watching Sailing Nanji where he drills a split pin hole through the propshaft in the water (without having to slip the boat) using a compressor driven drill, has opened my eyes to possibilities. Sure, you're probably never going to need to do that but it just justified whatever it cost.
At least another point to spin to the financial controller anyhow.

That is impressive. I have a friend who replaced his cutlass bearing with his boat in the water. He was a professional hard hat diver on oil rigs, in his youth, so he knew how to get **** done underwater. I am not so accomplished in that area. A man has got to know his limitations.