what type of sander?

[Wotname]

Originally Posted by turkish6

what kind of attactment would i buy to remove bottom paint.

Be cautious with the bottom paint, some types can be sanded off fairly easily, some types only with difficulty, some can't be sanded at all - to soft and "rubberly". ALL are toxic and require great care in that regard.

I am sure there are others on this site who can give much more detail on the methods and techniques for different types of bottom paint / antifoulings.
Cheers.

[saint]

I just gort a real big job here ,should I use a sender or paint striper ?

[pjbsailing]

I've used a big powerful disc, with a soft pad. Start the sander while against the hull, and keep it moving and you'll be fine. The small orbital will take forever if you've got a really thick coat of bottom paint. I cut it down with the disc, then used the orbital to finish up.
PJ

[saint]

Don't you think that the barrier coat will clog the sender quikly ,I have to remove all to the glass.

[Rick]

Some of the pros in this area use the 5" disc Festool Rotex for bottom work. I bought one with one of their vacuums. The vacuum is amazing because it has HEPA filter so you don't get any dust "puff" out of the unit when you turn it on. The bags close so that it is super easy to change them, again, without getting any dust out into the air.

I got a long hose so for a 40 ft boat you don't have to move the vacuum and when you turn on the tool the vacuum comes on automatically.

Because of the vacuum passing through the disc I only used 3 discs for the whole bottom and that was from removing two bags of bottom paint!!!! After sanding I passed a rag over the bottom and got almost no dust on the rag!!

Europe has a different grade system for grits so don't expect to ask for 50 grit, for example.

[Wotname]

Originally Posted by saint

should I use a sender or paint striper ?

Depends (and this is in part an answer to both Saint and Turish6) on the type, age, thickness, condition etc of the old paint. Often it is just a trial and error approach until you know what works for different paints. Be cautious (am I sounding like a broken record ) as some strippers destory the gelcoat / glass and others will destroy plywood (but not necessary wood (as in planks). Last time I removed bottom paint even a 9 inch variable speed angle grinder with super coarse disks (#16) would just clog up. Boat had accumlated 30 years of bottom paint. Finally got it off with a local concoction of caustic soda, palm oil, talc etc. Took three weeks (part time) for a 31 ft boat
Caustic is OK on glass and wood (but not on all plywoods) I am told but some common household types with Methyl - something - (can't remember full name and don't have a can close by) are bad for glass. IMHO.

[Alan Wheeler]

OK, some technical views of all this. The real trick is seen in the specs. When choosing a sander, you need to look at two things. The number of strokes/minute and the size of the stroke/orbit. I have not heard of Rupes, but I see in there specs the orbit is really large at 5mm. That is what will make it quick at sanding. Air tools also usually have very long strokes/orbits. It is why they also make good tools for sanding. However, they take a lot of air and most "home depot" type compressors will not keep up. Most air tools will be requiring a free air delivery of 12-16CFM. That's a machine of 3Hp minimum.
Depending on what you are sanding, will determin what sander is best. I use a 4" wide belt sander for large flat area's. They are the fastest at ripping away. An angle grinder is not controllable enough and you will get into trouble very quickly, however, there are circular sanders that have special pads and quides and can also be a very quick method of sanding. Random orbitals are next and the 1/4-1/3-1/2 sheet orbitals are excellent for finish sanding.
I use a Delonghi bagless centrifical vacum. There are many cheaper versions of this around now and is far the best with no bag to block up.

However, Turkish, you mentioned bottom paint. Are you talking Antifould paint? you do NOT and anti-foul. It MUST be wet sanded and I highly recomend it wet sandblasted off with a Soda blast or similar soft blast. Do not do this dry, the dust is extremely toxic even just on your skin.
Bottom paint does not have to always be removed, so only do it if you really need to.

[drewke07]

30 years of boat construction, repair, and operation leads me to one fact. The festool rotex sanders and vacuum setup is by far the best investment I have ever made. Yes they are expensive, but the job they do in so many different applications in truly unbelieveable. The Rotex sanders are both a random orbit, and a disk / rotary sander at the flick of a switch. The amount of material they cleanly remove is second to none.

[Thermal]

Originally Posted by Wotname

Caustic is OK on glass and wood (but not on all plywoods) I am told but some common household types with Methyl - something - (can't remember full name and don't have a can close by) are bad for glass. IMHO.

The stuff in most paint strippers is methylene chloride - a very powerful solvent and pretty nasty stuff as your body can easily absorb it right through the skin.

[Alan Wheeler]

Yes I have heard a lot of positive comments about the Festool brand. I looked at the sander too, but the Trade price tag of NZ$1100.00 was just too steep. The vacum system was on top of that again.
I have used/owned DeWalt, Makita, Bosch and Hitachi. I have to say I am slowly being won back over by Makita.

[Wotname]

Originally Posted by Alan Wheeler

However, Turkish, you mentioned bottom paint. Are you talking Antifould paint? you do NOT and anti-foul. It MUST be wet sanded and I highly recomend it wet sandblasted off with a Soda blast or similar soft blast. Do not do this dry, the dust is extremely toxic even just on your skin.
Bottom paint does not have to always be removed, so only do it if you really need to.

I have always thought Americans used "bottom paint" to do the same job the Brits and Aussies do with "antifouling" (what is it called in NZ?). I agree with Alan Wheeler that it should not be sanded (especially dry) but haven't we all sanded it sometime - perhaps before we knew better! I liked to think my skin never fouled up after a days sanding . I also remember seeing people BURN it off - criminal to say the least.

While this thread maybe getting off the topic a bit - what is the best method of getting old built up layers of unsound "botttom paint" of FRG, WEST and plywood hulls etc. The caustic (90% NaOH) compound I used is deadly on the skin and especially aluminum and titamium.

BTW, how long is it before I can refer to Mr Alan Wheeler as "wheels".

[Sandero]

Anti fouling paints may be toxic, but don't the mfgs recommend some sort of sanding over old paint as prep for new paint?

I am facing removing lots of build up and am leaning toward soda blasting or scraping. The yard tells me that you end up finish sanding no matter what method is used for the heavy removal.

Is there any reason non to use wet sanding?

[Alan Wheeler]

Hard anti-foul paints can be sanded. Wet sanding is the prefferd method and certainly the safer for both the sanding person and anybody in the nearby vacinity.
Ablative/Eroding antifouls do exactly that. They wear way. However, over time hard patches of paint can biuld up and eventually the entire surface has to be removed and this is best done by a yard with a wet blast.
Wotname, anytime mate.

[Rick]

Here in the Pacific NorthWest the Environmental Protective Agency, Soundkeepers Alliance and many "eyes-wide" open observers about are quite dilligent about violators who may be "polluting" the environment. As a result one has to tent the boat and collect any and all particulates that come off of the bottom.

Wet sanding requires that the water be collected and shipped to a hazardous waste facitlity. Trucking the water carries a huge risk and liability should it drip out along some long path one could get hit with unbelievable cost in cleaning up the roadway. They can be quite paranoid about this here.

This is why I chose to buy the Festool setup to amortize off the cost against paying off boatyards to do the work. Because the dust released beyond the sander and vacuum is minimal wearing the usual good dual filter masks, gloves headcover and gown sold for the purpose does not expose one to the hazard. Clean-up is minimal as well.

At least here Festool distributors sell any three tools as a package deal shown in a matrix in their catalog. I got the sander, discs, vacuum, hose and a brushless dc high-torque motor drill for close to a grand.

The job goes fast and by comparison I can't see wet sanding with all of the mess. Two vacuum bags are much easier to legally dispose of here (free for individuals here at our county hazardous waste facility).

[Sandero]

Rick,

Aside from the $1,000 for the equipment, how big was the boat, how thick was the paint and how long did it take? Any other costs?

A soda blast is about 2-3K for a 36' boat I think.