What tool to sand the bottom?

[maine50]

I share with a fellow boater a Porter Cable 9 in motorized drywall sander with vacuum attachment built in. They go about $450 new but frequently they can be had used for 200 to 250 on Craigs list. Reduces the sanding effort by 75 to 90%. It has about a 5' pole attached.

[DMBOS]

Porter Cable 6”
“random orbital sander” with dust collection hood and interface pad. I would do the first pass with 36 grit and end up with 80 grit that Epoxy Primer recommends for paint. You invest a little patience and time and you will end up with a perfect ( no digs ) bottom. Use ear muffs ! And a bag vacuum. I never focus on one spot - keep moving and let the paper do the work - changing discs when they stop cutting

[warrior 90]

Looking at the Festo website I see this tool....
https://www.festool.com/products/san...180-e#Overview
It´s recommended for high material removal rates even so they don´t talk about paint removal in specific..... but bottom paint is soft.
It also comes with a depth control. So You just have to dial it in to max allowed depth.
What I like is ... there is no sand paper or disk, etc to change. With centrifugal force it should be self cleaning. Also comes with dust removal system.
IMO if this tool works ??? it will work very fast and very well on large surfaces with out the chance of damage the surface
I would talk to the Festo application guys and see what they have to say. Usually they are very knowledgeable and real experts on speciality applications.
Another approach...this tool looks basically like an angle grinder with the attached box for depth control rollers and dust removal connection. You could just buy a set of the the rotor brush disks and give it a shoot with a drill and test performance before taking a chance of wasting Your money on the machine.

[Bill whitmore]

look into a chemical paint remover

[keyway]

I just bought a new 6inch Bosch sander with the vac attachment to replace the old porter cable sander. Bought some extra vac hoses and put an old cyclone chamber from a broken household vac in-line then to the shop vac. It all works great. Anything to make the job easier. I cut the old micron 66off with 60grit. I have used 40 grit if there is years of paint build up. You will see the layers of paint as you cut though them. The barrier coat is probably dark grey. Once it starts showing I move on. I never totally remove 100%of the old paint. I try not to cut into the barrier coat. I prefer to use lots of soap and water and scrub the surface until it’s really clean then use solvents lightly before I paint I agree it’s not a piano but with the value of my labor and the high cost of materials it’s worth doing a good job.
Happy sanding

[roland stockham]

With the epoxy coat underneath that you dont want to damage I would be tempted to use a heat gun and scraper. No dust and no risk of gouging the epoxy

[malbert73]

Originally Posted by slug

Use a pole sander..60-80 grit wet and dry sandpaper, plenty of water



Keep the sandpaer fresh..sharp



Antifoul is soft ..comes off fast



You can do you bottom in one day

This! Drywall sanding pad and pole, mesh wet/dry drywall sandpaper. And you won’t be inhaling paint

[Steve Perkins]

I have found a new approach on my 44ft Adams down here in Aus. This will change your life!! If I had had a boot full of these I could have cleaned up in the yard last haul out.

https://tinyurl.com/yx3eznde (Ebay example.)

I use 60-80 grit discs on a plasterboard sander with a shopvac barrel vacuum attached. Near zero dust, and sanded both sides of my Carinya 44 (so 88 linear feet for 2 sides) including the stub keel in about 90 minutes. It was Micron Extra so pretty soft but does an amazing job. I only thought of it as I had a heap of sanding disc's left after a home plasterboard reno and thought I'd get rid of them.

Good luck with the job and don't forget to use a separate epoxy primer if you have blister repairs under the Micron Extra.

[billknny]

Originally Posted by Cap Bill Des

I have to sand off 6 years of Micron 66 (what's left of it) from the bottom of my 33-ft sailboat. We have returned from 6 years in the Caribbean to the fresh water of Lake Ontario. Interlux tells me I must sand off the Micron 66 before I can put on a paint suitable for fresh water ( or cold northerly salt water) like Micron Extra.

What tool to use? One person said rotary sander. Another said angle grinder with sanding disc. The boat is outdoors so I don't need to tent the boat and the boatyard said they don't care (!?) about sanding dust. Underneath the the bottom paint is several coats of epoxy barrier coat, which I think is in fine shape and I do not want to disturb or have to redo.

Looking for advice on what tool to use for the sanding. Thanks.
( I'm planning on doing the sanding now in the cold weather so that the whole bunny suit and respirator outfit is not uncomfortably hot...)

Wow... so much bad advice. First, NOT an angle grinder! Holy crap, that will make a mess of your boat. You can not sand the bottom of a boat fair with an angle grinder. Just ignore ANY advice from that person.

Use a 6 inch random orbital vacuum sander. 40 or 60 grit paper. Fesstool makes good ones, but they are pricey. Do NOT do this without some type of dust collection. Life is short, change paper often.

Different yards have different local rules. No yard you should let you just spray the dust all over the other boats in the yard, even in the absence of other rules! If they don't care about that, you need a different yard--seriously. That is a dump. Your boat will be filthy, from your own sanding, and anybody else's.

Micron 66's incompatibility with freshwater has always been one of the reasons I refuse to use it. We move between fresh and salt water way too much to worry about how it affects our bottom paint!

[Paul Howard]

Perhaps the yard does not care if the sanding dust gets blown around and dissipates, but I bet the neighbouring boat owners do.
Especially if black or blue or red or any other dark colour will show up as specks on any boat decks and cling to gelcoat sort of like charged with static electricity.
Tent around your boat as a courtesy to others.

[LouK]

Bottom paint such as micron creates horrribly fine dust which can make a mess of a the good quality random orbital sanders that I use for my woodworking. It’s difficult to get the sanders really clean after a bottom job even if you use compressed air to blow them out afterwards. This year I was surprised to find that a lowly Craftsman random orbital (w/80 grit) has good dust extraction & a great vacuum attachment and when hooked up to a shop vac with the proper filters, did a great job. Cheap too. I found it every bit effective as my DeWalt & Bosch sanders which were double the cost.

If you’ve got a CI keel you might consider a grinder but I found a couple of passes with the orbital and then a follow up w/ a rotary wire brush mounted on a drill or grinder works best for me.

Remind yourself to get a silencer for your vac or you’ll go deaf rather quickly. Also recommend a proper mask and a cheap plastic face visor as well. You might want to consider a white Tyvek suit as well as your clothes will never completely clean up.

[mikedefieslife]

Originally Posted by billknny

Different yards have different local rules. No yard you should let you just spray the dust all over the other boats in the yard, even in the absence of other rules! If they don't care about that, you need a different yard--seriously. That is a dump. Your boat will be filthy, from your own sanding, and anybody else's.

Never go to Europe then. Pretty much every Med yard i've been to or seen the yard workers themselves will sand with a Bosch GEX150 Turbo without any dust collection. The yard dogs end up blue and green.

I use a GEX 125-150 on boat with either the built in or a shop vac. Still gets dust everywhere.

[Cadence]

Originally Posted by roland stockham

With the epoxy coat underneath that you dont want to damage I would be tempted to use a heat gun and scraper. No dust and no risk of gouging the epoxy

Sounds like a good idea if heat is used judiciously.

[jharding]

when I did my 52 everybody in the yard was using 7 inch disc sanders, these take to long and dig in quite easily. I had a disc sander and made a lexan backing plate and got 17 inch floor sanding discs, these worked much faster and didn't dig in. I also read an article in west epoxy works about making and using a 9 X 11 lexan plate and using spray glue to hold on cheap sheet sand paper, rectangle plate on a round sander sounds stupid but works real well and the odd shape won't dig in like a 7 inch round disc will. I used a respirator with integral face mask, this doesn't fog up and seals your whole face off, and is good protection when sander catches and gets away from you and hits you in the face. Yard I was in didn't care about collecting dust. wear tyvex suit and face mask and get it done. chances are you will have to redo barrier coat, no big deal.

[chowdan]

The point of soda blasting is to remove the paint - not the gel coat. You can have someone remove the paint and not miss anything other than the hell spent sanding the paint

Originally Posted by thomm225

So if you have someone soda blast it you will miss lots of stuff you would otherwise not know.

Sand it off yourself and you will see …...