What kind of sander would you use?

[adieu]

I have an older fiberglass boat (30') which has seen its share of paint topsides.

Now, the thick layer of old paint, right down to the gelcoat, in places is starting to bubble and crack. Looks like a blistered boat. Not sure why this is suddenly happening, but the paint must come off.

I have a couple finishing sanders that are not up to the job.

Can anyone suggest a good sander that will take the paint off reasonably quick. I need quick, because dry days for sanding are few in the winter here on the BC coast. I'd like to have all the prep work done before painting, I hope in March.

Belt sanders are too damn heavy and imprecise, and random orbital sanders that I have picked up are too lightweight. Not much else available in the small town where I live.

I have found a Makita GV5010 disc sander online. Looks like what I might need, but you can't tell from pictures.

New here. Hope someone can help. Any suggestions welcome.

[TeddyDiver]

Better to use paint remover IMHO

[delmarrey]

Originally Posted by TeddyDiver

Better to use paint remover IMHO

With that may layers, I'd agree. But you'll still need to sand. I've had one of these 5" for hours and hours and hours, and even had to replace the hook pad twice and the collection bag once, but the sander keeps going strong using the 40 grit pads. It'll collect about 90% of the dust as well. Tip: Take the spring out of the collection bag, it'll last longer.

[resilientg]

If it was me, id use a 7 inch flat pad sander polisher for all the big areas, then a 4 - 5 inch random orbital for getting closer to stuff and lastly good old hand sanding for all edges and corners etc.

with out looking at your boat i dont know if i would use paint remover or water blast, either way will remove most of the paint, but after that you still need the sanders.

Start with an aggressive grit like a 40 to get close to the surface (gelcoat), then 80 grit, 120 etc, then undercoat, 240 grit after the undercoat for a nice surface for the finish coat.

Matthew

[ssanzone]

if you want REALLY fast a grinder with a 40 grit flap disk.

be warned... it will chew thru everything so dont be too heavy handed.

[delmarrey]

BTW for those hard to get areas like corners, you can use a heat gun and scraper, but be gentle the heat can burn the FG if too hot.

[Cheechako]

Yeah, a random orbit. I've found some of the cheaper ones are too light, much harder on the hands and wrists as the vibration transfers to you..... definitely not a belt or big disc.....

[Wotname]

You need an arsenal of weaponry here. Heavy duty random orbital, the most industrial model you can afford and 36 or 40 grit discs, 5" angle grinder with 16 (yes, 16) grit discs, very hot airgun and scrapper, specialised paint strippers - be cautious as some attack fiberglass resins - but some are safe.

And some filler for when you overdo it

[Artif]

The best sander in the world will be useless without good quality abrasives.
Buy the best you can get, not the cheap no name brand stuff.

If your struggling to remove the coating then go for a coarser abrasive, then work your way up the grades.

Let the tool do the work, people think pushing harder when their abrasive is too fine or worn out will help, it doesn't it only makes them work harder.

We currently use Suhner abrasives on a particularly difficult clean and polishing job I work on, they are far and away better than anything we've tried so far ( 7 years), but I'm not sure they are available on your side of the pond.

[Gerry Connolly]

A festool rotex 125 combined with a cleantex 26 vacume system is expensive, but if you want the best, can't be beat. Can get the unit and the sanding disks from Lee Valley. Very aggressive but precise and super clean.
Used one to finish stripping 25 years of bottom paint (after soya strip and scraping)

[Blue Crab]

Originally Posted by Gerry Connolly

A festool rotex 125 combined with a cleantex 26 vacume system is expensive, but if you want the best, can't be beat. Can get the unit and the sanding disks from Lee Valley. Very aggressive but precise and super clean.
Used one to finish stripping 25 years of bottom paint (after soya strip and scraping)

Oh hell yeah. why use an eighty dollar tool when you can spend $450 on the Festool? Hurry, only 4 left at Amazon: Amazon.com: Festool RO 125 FEQ Rotex Sander: Home Improvement

[aclmck]

The Fein is the best but a good and less expensive option is the Metabo 450 turbo, just throw away the bag and adapt a vacum cleaner to it.

All of the top end sanders will work but make sure you use the hook and loop system and have a large assortment of various discs available, purchase them by the box of 50 or so is normally the cheapest option start off wth the heavy grit (40) and work up to acheive your finish a disc will vary on area that it will sand but to start off allow 1.5 discs per square yard or Metre and go out to 1 for the finer dics. They will either clog or stop cutting efficently after a certain area, you can keep them for reuse on other surfaces.

just let the sander do the work if you find your putting too much pressure on it change dics. Seems like a lot of wasted discs but that is how the professionels do it for the best finishes (and most of them don't like to waste anything) they certianly dont use burnished discs ever

[aclmck]

forgot to say that the discs come punched to suit the vacum ports for most sanders normally, or if not using the vacum system they come plain but are all usually all the same cost.

a sander should be a random orbital type for more pricise control, the makita is really a paint stripper that could be used for the inital stripping but after that the higher revs of the orbital sanders are easier to use for the better detail and finish, when using them sand one way then vary you stroke by 45 - 90 degrees to avoid sanding grooves in your boat

[Tia Bu]

I had a boat once that exactly met your description. A Bosch 6" random orbital sander with 50 or 80 grit discs (I can't remember now) made quick work of the whole job in a few hours. Don't over analyze. Knock it out. Not a big deal.

Also, the first time you paint it doesn't have to be perfect. Get it looking 1000 percent better on the first pass. Then use the boat and have fun. The second time you paint it, you can take the time to obsess over removing all the flaws from the first time.

And primer is a magic bullet. Don't miss the opportunity to allow it to cover up flaws.

[David M]

I purchased a Rigid 6 inch random orbital sander to finish my deck. At 4 amps it is not wimpy at all and the price is right, about $160 new and $65 factory reconditioned on Amazon.

I would not use a belt sander, they remove too much material too fast. They are just too out of control to get a smooth flat finish.