Hard growth on drivetrain and other complicated areas

[gaucho]

I just hauled out and I need to get all this hard growth off my prop, drivetrain, shaft, rope cutter, external strainers, ground bar, etc. I have many questions on what tools, grit, and how to go about the whole thing of removing hard growth on uneven, strange, contorted surfaces. For example in between the rope cutter, on surfaces like the blades of the prop, or the ground bar which is uneven with bolts coming out. Also, how should I try to pry the external strainer free? I (evidently!!) had some overheating issues. So I want to do this right. Remove the external strainer and clean it and paint inside, clean the thruhull, etc. How do I go about removing hard growth INSIDE a thruhull?

So I need to unerstand:

- how to remove an external strainer, should I pry it? Is it glued besides screwed in? How do I bed it once all my painting is done and I paint the strainer? 4200? 5200 around the screws?

- how do I clean inside trhuhulls that have growth?

- how do I go about working with uneven/strange surfaces, example the rope cutter, the ground bar, etc?

Please help me understand the tools and expendables I should use. This is my first time, so try to be specific like telling me what disc or grit of sandpaper to use. Thanks in advance!

[gaucho]

Here are some pictures.

[Jim Cate]

Oh my! You have a lot of work ahead of you, that's for sure!

The primary tool(s) you will need are scrapers, AKA putty knives. I'd suggest at least a one inch one and a 3 or 4 inch one. These will do for the flatter areas and some of the curved ones. For detailed work like the rope cutter, a flat blade screwdriver will get into crevices.

It's not until you have scraped the shell off, down to paint or bare metal areas, that use of abrasives will enter the picture. The exact nature of abrasive that you will need depends on the substrate and it's condition. Get the hard stuff off take more pix and we'll try to help in more detail... but there is a lot of hard work ahead before that becomes an issue.

In case this isn't obvious, bottoms like this are why regular slipping and antifouling are so important in boat maintenance.

good luck

Jim

[Spindrift NH]

When we bought our current boat it was almost as bad as yours. It took me about 60 hours with a painters 5 in 1 putty knife. They’re a stiffer than a normal putty knife and have a pointed side that’s great for getting in tight areas.
Once you’ve dealt with a bottom that bad you’ll never let it get that way again!

[jmschmidt]

Remove prop, shaft, etc. and soak in chemicals that are available that will soften the scale but not harm the material the parts are made of. Maybe different stuff for bronze or stainless. I've used it, it works but I don't remember the name or the chemical content. Check around and test something cheap before wrecking something expensive.

[JPA Cate]

Just plain household vinegar works for soaking and eating off the calcium carbonate on something small, like that poor strainer. But I agree with Jim that it's scritching with putty knives, and the biggest flat blade screw driver that will do it. The screw driver will actually do a pretty good job on the inside of the through hull fittings.

If you are somewhere you can hire someone to work with you on it, it would be a great temptation. Jim once scraped 16 years' worth of bottom paint off our previous boat. It took about 5 days, 10 hr. ones. And there was almost no hard growth on the hull.

So, good luck with it, mate, clean off the hard stuff, and then show us more pictures.

Ann

[grahamb]

….I use a tool I know as a 'Bolster'...…. or 'brick bolster' …….. used by bricklayers to cut bricks...….about a 4 inch/100mm blade....and weighing about 1 pound/500gram......but the heavier the better.....and ideal for underwater work......have net floats tied on to give positive buoyancy.....barnacles give little argument.....

[Mike Banks]

Give the parts a really good blast while on the boat with high pressure water using a Spitwater or something similar at about 1500 psi--that will get rid of most of the organic matter, then if you can get the parts off--soak them in vinegar solution--that will dissolve the lime and the rest of the adhesive and residue should come off with a bit of a scrub using stainless steel scrubbing pads.

Then coat all parts with Prop Speed. Once all moving parts are coated it will make it easier to remove any future growth using a scrubbing brush and a mask and snorkel, if one does not allow any growth to accumulate. It does not stick to Prop Speed very well.

[Quadrille in JB]

Caution!
Once propspeed has been applied properly it does a great job of preventing growth but...it is soft and very fragile ( and expensive only use a soft glove or rag to clean it.
But everything has to be clean and sanded with 80 grit paper before applying. Be sure to follow instructions exactly or you will be wasting your money.

[Uncle Bob]

Have to agree with Jim, scrapers etc are the go. The only thing I will add is the suggestion to radius the corners of the scrapers to avoid the probability of them scratching/digging in to the hull. A good set of scrapers and the effort to use them will remove the offending growth that is left after a pressure wash quite quickly.

[Secondshift]

Originally Posted by Spindrift NH

When we bought our current boat it was almost as bad as yours. It took me about 60 hours with a painters 5 in 1 putty knife. They’re a stiffer than a normal putty knife and have a pointed side that’s great for getting in tight areas.
Once you’ve dealt with a bottom that bad you’ll never let it get that way again!

Plus one on the painters 5 in 1 scraper. It has several shapes including a rounded cut out that I find helpful on the shaft and that sharpish corner. You'll need an assortment of putty knives as well.

Best Luck

[Jim Cate]

Note: From the pix, I believe that the pressure washing has already been done, for there isn't significant soft growth visible to me. And typical water blasters won't touch the hard stuff shown.

The tip about radiusing the corners of the scrapers is a good one... do it!

Jim

[gaucho]

I ended up using scrappers, muriatic acid and pressure water. Please understand the whole bottom wasn’t badly fouled. It was just the drivetrain and the scuppers (or external strainers). I had a very bad bottom cleaner where I left my boat behind in the Caribbean for three plus months. Not all of us live on or near our boats, and sometimes this stuff Happens.

Thanks for the help



In having the guys at the yard (RAM in Rio Dulce) finish the job by sanding and painting the bottom. Because my raw water intake was fouled and I wanted to regrese the prop, I decided to do the clean up myself so I make sure it’s properly done. Its not easy doing bigger maintenance or the proper way when you can’t be here for everything that needs to
Be done. So I rather get the “important” stuff out of the way