What tool to sand the bottom?

[jdecris]

Originally Posted by scarlet

Why would you use a 5" or 6" sander on a boat rather than a 10" sander?! The larger orbital sander would cut 50% off your time...

Many boat bottoms are not usually so flat. A 10" sander would not sit well on a curved boat bottom. On a concave section of the bottom, only a portion of the sander would touch the bottom, and on a convex section of the bottom, the outside portion of the sander would touch the bottom, and have a tendency to gouge.The result would be uneven wearing of the sanding pad and paper, and uneven sanding.

It would also be heavier to hold, and more challenging to control. More tiring more quickly. No time saved really, and certainly not as good a result.

[gulfislandfred]

There are paint strippers that will take the bottom paint off in sheets. You need to do a bit of research to find the right one.
If you must sand, use an air powered random orbit sander WET. Lay a tarp under the boat, use just enough water to keep the dust down. The paint will settle on the tarp, especially if you lift the corners. You can suck it up with a wet and dry vacuum, put it in a barrel, and let it settle, or put it where the yard puts the water when they pressure wash boat bottoms.
If it looks like there is no provision to get rid of the bottom paint dust, roll up the tarp, with the wet dust in it and ask the yard guys where to put it.

[chalupo]

Recommend calling Interlux technical support line at 1-800-468-7589 and asking them. I'd take their advice over most found in this forum.

[TonyDove]

I fully endorse the use of a pole sander … and use plasterer's pads instead of sandpaper … these are a grid of wet & dry abrasive with nice gaps that mean you can easily wash the build-up of dead paint off. Wash them out regularly and they last longer and don't get clogged.

Doing it wet means no dust … and laying down tarps will collect all the crap.

The pole sander has an articulated head … so it adjusts to your sanding angle and doesn't gouge. It also means that you can reach the underside and keel without having to crouch under the boat … your lack of aching backitis will thank you. The good sander heads usually have a rubbery padded surface under the sand paper … so it works a treat on curves and leaves a really nice faired finish.

I've used a pole sander for a dozen or so years and wouldn't go back. Okay … I do use a random orbital sander for any repairs. I found it the best way to deal with fairing a repair although I know some folks swear by a long belt sander. The trouble with a belt sander is that they are designed for flat floors and not many boats have truely flat bottoms … so if you do end up using one … keep it moving and rock it to ensure your finish is curved.

Happy sanding and sailing

[robertmfranklin]

Thank you to those who focused on the environmental issues instead of an answer to the somewhat selfishly framed question. Sorry OP.

I plan to check out the expensive dust collecting system several people described. I now regret the times I have been careless, not only about my own health, but the health of those around me.

My club's well intended decision a few years ago to prohibit power washing has led to people relying on divers to clean their bottoms in the water. The serious racers do this every couple weeks the non racers once a month.

I imagine there has become an epidemic of bottom cleaning in the water, everywhere. Unless you've been in the water watching what happens, you can't imagine how much material is released. The toxic cloud is sickening.

Does anyone know how the container ships 1,000 feet long handle the anti fouling problem? It must be a huge impact on the speed and efficiency of these behemoths. How often are they cleaned? Is it done with divers? Are they dry docked every few months. It must be a remarkable process and if it is done in an environmentally responsible way, how is that accomplished.

[MistyCat]

Have you considered using a chemical stripper like Interlux Interstrip? No dust or airborne contaminants. Using a disposable drop sheet catches all the hoop you scrape off the hull. I took down about 15 years of AF paint on a 26’ hull in a marina yard here a few years ago with 2-3 applications. There are a few techniques including covering the coated area with tin foil to enhance the ‘curing’ while it softens up the paint for easy scraping. Physically much easier than sanding over your head.

[warrior 90]

Well, I tried, YEAH vvvvv

Hello,

Thank you for contacting Festool. The BMS 180 E is not available for purchase in the North American Market. Festool is a German company with world-wide distribution, not all tools and accessories are available in every market. The BMS 180 E is not available in this market and there are no future plans to bring this tool to market. Festool North America only has hand held sanders that will have a random orbital or rotary capability without the ability to set the depth of removal.

Now I got really curious and checked on YT

https://www.youtube.com/watch?v=k8f1z_N7tbc

They say ...works on hardwood.I asume the steel wires must be a real hungry dragon on bottom paint. The grey drum is kind of nylon with abrasive 80 grid on the tips and the white drum is kind of a fiber supposed for final surface prep > paint or oil....
Yeah some 1100 € for the whole pack

I guess the next YT speaks books...there are just some things that You can do with a rotating brush that You will never be able to do with an orbital or a rotating sanding disk. The drum brush only removes in one direction and is capable to adapt to a curved surface.
Should also be good for stripping varnish and great for restoring teak decks.

https://www.youtube.com/watch?v=eKfqf5plvas

Here You will find the specs and useful info for application. Great page for DIY inspirations & creative hacks. They say.... also good for stripping paint.
I am sure those brushes last a lot more then sand paper.

https://www.sitbrush.com/Brushes-for-Wood/
https://www.sitbrush.com/Industrial-...al-Brushes.php

SIT is starting to develop abrasive linear ragged brushes using filaments in tampico, that are currently used in sanding of raw and painted surfaces.

Next is a YT from the Glorious Sanding Champion channel with two very interesting tools.

https://www.youtube.com/watch?v=b_qR1d9Cu5g

At closer look You will be able to observe the advantage of adjustable depth control and how accurate it is posible to adapt the machine for the required app.
Of course those machines work with blades and they will cut very fast. But this is only with sharp blades. The steel brush might not cut that fast but it will adapt much better to irregular shapes with the advantage that it will not get dull and just wear off. The wire will always stay sharp and clean and due to many different types of wire material it is very flexible for a wide range of situations. In the case of bottom paint I also think a cutting blade might be too agressive and cut too deep some chips of the barrior code or even the gel code. Bottom paint is usually applied by roller that does not warrant a certain paint thickness. Main object is removing bottom paint fast and clean "without risk of possible damage and the required fairing compound job as a consequence. Taking all the pros and cons under consideration I think the brush is much better for removel of bottom paint then sand paper. Furthermore I am sure that talking to SIT they will also come up with a brush type that will cut right through the gel code and down to the bare fiberglas.
Well, maybe now in some cases this Festool is not so expensive anymore. You never know what You gonna find once the bottom paint is removed
https://www.festool.de/produkte/schl...%C3%9Cbersicht

GelPlane Gelcoat Peeler Osmosis Treatment, Gelcoat, Gel Plane, Gel-Plane, strips, peels gelcoat, stripper[

https://paintshaver.com/

https://www.youtube.com/watch?time_c...ture=emb_title

[warrior 90]

Part missing

Paintshaver has also two types of machines and one is similar then the one from Gelplane with the cutters mounted on the drum.
https://paintshaver.com/
https://www.youtube.com/watch?time_c...ture=emb_title

[Warren149]

Why would influx not be able to find a paint that can be painted over the 66?
If it's in good condition put some more on and don't worry , almost no growth in freshwater. Get a dri-driver to clean hull in water of slim.
Cheers Warren

[C. Addict]

OK so here's my 2 cents worth. To overcome the anti-foul build up problem I adapted some bits together and made a water flush sander that works very well. I used a plastering sanding float (they're a plastic sanding paddle with a handle approx. 10"x4" base with a thin neoprene rubber layer) I fed a 10mm light weight hose line from a standard hose fitting into a small plastic stop cock on the base and through the bottom. I then fitted a 3M 150 grit mesh onto the base; standard plaster sanding equipment but conveniently very water proof. This gives you a light weight water wash sanding board with adjustable water flow. 20 years later I am still using it and have made and sold about 30 of them to other yachties. Feel free to make your own.