What tool to sand the bottom?

[Pete the Cat]

Originally Posted by wingless

My Festool RO150FEQ ROTEX sander with my Festool dust extraction tools have been a workhorse for well over a decade.

These tools are perfect for bottom sanding.

There is almost zero dust plus the abrasives last a looong time, with very few sheets to do my 38' boat.

I would agree with this, but I am too cheap to invest in this equipment. If you have the money, Festool system is the professional choice. If you have a more meager budget you can just get a 5” Dual action disc sander by Bosch or DeWalt (I have used my DeWalt for a decade of sandings) with a box of 80 grit sanding discs with the 5 holes—or 8 depending on the model (I love Merkel sanding discs) and attach it to a shop vac with the hoses and connectors provided. I think you can put this togther for about $100. Use the dust bags for drywall and you will get the results of the Festool (no dust, and the sandpaper will work much better and longer with the vacuum going). The shop vacs are the weak link. Mine seem to last only about 5 years before the bearings give out—but, heck, they are $40. I do the bottom of my 37 foot boat in a few hours. Wear a good mask anyway. And yes, every year fewer and fewer yards let DIY folks do their own work. I have always been able to convince the yard to make an exception for me when I explain. And I clean up every day behind my work. OSHA can have some hefty fines for folks who do not follow their rules.
Ray Durkee
T37 #373

[DeValency]

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...)

Been through it over the years as a DIY but never again on a heavy built. The last project was to remove 11 coats of primer, paints, barnacles and more paint all the way to the original gel coat... so only sandblasting could handle it.
In your case, I think, 6” orbital sander with 40 grit discs should be good enough. If you realize it is too aggressive you can step up to 60. It isn’t fun but doable.

[clockwork orange]

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

Epoxy softens with heat but there are hundreds of different formulations so you would want to check with the manufacturer of the specific barrier coat before using heat.

[mghorton]

Having done it the hard way, I would never do it again.

Last time I paid $900 for soda blasting and a light sanding to be done by the yard and they did a great job. You should still lightly sand afterwards to remove any soda contamination. Simply connect a small $30.00 shop vac to the sander and do the environment and your lungs a favor.

[clockwork orange]

Originally Posted by billknny

Well, there are lots and lots of yards in the world I would never put my boat in. And clouds of sanding dust from toxic bottom paint is one damn good flag to a place anybody who values their boat needs to avoid. I don’t want that stuff all over my boat, inside and out! A good boat yard is a clean, neat place. Like any good workshop.

If you are sanding next to my boat and I end up with your sanding dust all over MY deck, you‘ ARE.going to clean it. It has happened to me twice in thirty years. In both cases the yards charged the offender for cleanup. And for one repeat offender they picked his boat up within the hour and put it in the water and sent him packing—half sanded and unpainted. As they should.

I don’t care what gear you use, but it has to work. There are sanding systems that leak almost nothing if used properly and maintained well.

A few years ago some moron boatowner sanded the bottom(not approved) without dust collection inside a large heated indoor storage building at a marina in Bayfield with about 40 large boats in it, the forced air heating system did a great job of distributing the pain dust throughout and it became a huge insurance claim for cleaning.

[David Mathis]

Your comment that "the yard doesn't care" is not a positive comment for you. I retired as a police investigator for a state environmental crimes unit. If the ground is tested and the investigation leads to you as being the source of the contamination, even though you state that the yard didn't care, you may find yourself paying many more times for remediation than you would pay to have a professional strip the bottom. it's not that uncommon for the operator, manager, owner, etc. of an environmentally dirty business to leave the country or take other action that makes the person hard to attach to civil liability. The state or sometimes the EPA keeps looking to find someone with responsibility for the contamination. Non-fouling paints are effective because they contain substances that are toxic. And you want to put the sanding dust on the ground because the marina doesn't care? If the marina owner decides to sell next year and the buyer has an environmental survey done (usually required for financing of any business of this type) that shows contamination, it will be reported to the state environmental agency. So, in a year or two someone from the state Office of the Attorney General starts a process to collect $280,000 or maybe much more from you for remediation. You protest and retain an attorney skilled in environmental work. Due to the nature of the contaminant and its proximity to water, the state does the remediation now rather than wait, and bills you. A year later the bill, has increased to $430,000. The legal bills are mounting and liens are placed on your property to prevent a sale while the case is pending. Now, how does the money you saved by stripping the bottom yourself sound? Not so good? Hire a professional or at least cover the ground with plastic and use a tool that prevents the contaminated dust from blowing onto uncovered areas, and document everything with photos to protect yourself from the tort. Hiring a professional sounds much better, right?

[Arsydian]

I have festool equipment with the hepa dust extractor, also have a 30' catalina that I would like to do the bottom work. Is a 5 inch sander submidting myself to a daunting task ?? The boat ( an 84 ) was purchased in the water and with out survey. Surprisingly upon haulout the bottom looked pretty good, none of the infamous Catalina smile.. Noticed some small pits.
Any advice is greatly appreciated.
Thanks.

[windcastle1]

I wet sand with an air orbital sander. The sand paper won’t clog and absolutely no dust. I also have used pumice/griddle blocks also with water. Also non clogging, no dust and as you use then they will take on the shape of the hull as they wear down. You buy them at restaurant supply houses. Cheaper than sand paper.

[sailorguydc]

I was faced with a very similar issue. I opted to use Marine Peel Away; a stripper made specifically for bottom paints. One version takes only the paint off and the other removes epoxy barrier coats as well. It’s simple and relatively fast. Apply it as a thick coat of mayonnaise, cover with the paper provided ( dry cleaning bags work too) and let it dwell for up to 36 hours. Longer will damage the gelcoat. Pull the paper and a wide scraper and the paint comes right off. Have to wash and perhaps neutralize; I don’t recall. Little mess. Dumont Chemical manufactures it.

[nofacey]

This is a great job for the yard. Go work on your rigging & motor.

[arcticmonkey]

I know it may sound strange, it did to me at first, but I knew an older boater
who used latex paint as a bottom coat on his 30 odd foot wooden hull he was a prof of chemistry at a university, and notoriously cheap... His theory was you gotta pull the boat out every year anyway why waste good money.... He would apply half a dozen coats(any color... whatever was available) donated by friends, neighbours, bottle depots let her dry then back in the water ...1 day
skeptical ? me too.... finally gave it a try... well it worked.. latex sloughed off just like expensive bottom paint... cleaning hull .... a good scrubbing...
I am sure there are sceptics out there who don't mind paying for expensive bottom paint and who will scoff at this suggestion but way back when we didn't have a lot of $.... worked well enough... ps did find some pretty deadly paint courtesy of our coast guard so toxic they couldn't use it... best bottom paint I ever used

[warrior 90]

Originally Posted by mghorton

Having done it the hard way, I would never do it again.

Last time I paid $900 for soda blasting and a light sanding to be done by the yard and they did a great job. You should still lightly sand afterwards to remove any soda contamination. Simply connect a small $30.00 shop vac to the sander and do the environment and your lungs a favor.

Yeah, 5 pages and no world changing ideas. Nobody reacted to my little commentary https://www.festool.com/products/san...180-e#Overview
so today I took myself the time and wrote a mail to the application Dpto. of Festo Tools.... Let´s see what happens

However I totally agree with You on the soda blasting
Some guys here recommend to buy expensive machines+dust collection+consumables....more days on the hard etc.

How much does that cost and on top of that WORKING LIKE A SLAVE

HELL NO... to save HOW MUCH ????

[Sidney777]

DRY WALL SANDER. @ 4ft pole with sander on end. It also has Vacuum attached to get dust. You can Rent at various places. Home depot or tool place. Important to get heavy grit.

[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...

[wingless]

Originally Posted by RossD

Sorry re the picture, not sure why it's sideways.

It is much easier to sand that way, than holding the sander over your head.