Paint Stripper: Bottom Paint removal, osmosis barrier prep

[Popeye.Tom]

Hi,

I'm getting ready to haul Typsy Gypsy.  I have a large list of tasks for a couple of weeks of hard labor.  The boat hasn't been out of the water in years, I think.  I just became the latest caretaker at the end of this June.

I'm expecting to find some blisters.  Hopefully nothing more than the gelcoat pimples that I've seen in photos from others doing the bottom on their 365.  Praying for nothing or only a little more! 

I have a lot of experience from back in the day working on the boats from the mid → late 80s that were made with the fire resistant resins that were so prone to osmosis damage.  I worked at SeaView Marine in Ballard, Washington.  I've got many hours under boats doing structural repairs, filling, fairing, sealing.  We used the full Interlux system then.

I'm planning to use Sea Hawk products, Tuff Stuff as the barrier coat (similar to Interlux 2000e but thicker.)  I have just had a great call with Tony B, technical sales for Sea Hawk in Seattle.  The plan is to apply 3 layers of Tuff Stuff to get a 12 mil or maybe thicker barrier coat.  (0.012"/0.30mm)

I'm interested in anyone has experience using paint stripper to prepare an old bottom.
 > How much stripper did you need?  1 gallon? 2 gallons? 5 gallons?
 > What brand stripper did you use?  Did you like it?

The paint stripper from Sea Hawk is MORE $$ than the bottom paint and about as much as the Tuff Stuff epoxy barrier coat! 

Can anyone recommend how much stripper I will need?

I am planning on the stripper (step 3) because like refinishing the topsides or painting a car, you have to ensure all wax and any silicone from polish is removed.  You want to remove this before sanding so you don't grind these contaminants into the existing finish.  Talking with Tony B, I want to use the stripper to the same end to ensure my barrier coat adheres properly.

The paint stripper from Sea Hawk costs as much at the Tuff Stuff epoxy and more than their bottom paint per gallon!  I want to have enough, but not buy more than needed.

My plan is:
1. Have the underbody pressure washed while in the slings
2. Manually scrape the entire bottom.  I have few new 2-1/2" Sandvic scrapers with carbide blade.  (my arms and back hurt already just thinking about this!)
3. Apply paint stripper and remove wash per instructions
4. Sand underbody with DA900/DAQ/long board with 60 or 80 grit
5. Any required structural repair with polyester resin, mat, roving, cloth as needed
6. Fair as needed with epoxy putty.  Probably make my own with epoxy & silica powder & maybe some micro-balloons (maybe no micro-balloons since they are to make sanding easier and hopefully sanding will be minimal 'cause my application is spot on!  )
7. Acetone wipe
8. 3 coats of Tuff Stuff

9. Sea Hawk Sharkskin or Tropicoat or maybe CopperCoat for bottom paint.

Thanks,
Tom

[Dale Tanski]

Tom,
Sounds like a plan.  I am an Interlux guy day in and day out.  Thicker may be better but that thickness will probably add to the roller stubble and orange peal during application unless you spray.  I just redid the bottom on my 1976 and there we a dozen small raised "blasters" all by the waterline.  At least 75% of the boat had existing barrier coat except where it hung by the slings and all the pad areas and under the keel. 
I went the 2000E route alternating colors.  It is more difficult than one would think to apply full coats without the alternating color thing.  I doubt there will be any remnants of silicone or mold release on the bottom requiring stripper but it can't hurt.  I scraped what I could and sanded down to gelcoat (or existing barrier coat with 36 grit.  Did a final sand with #80 after all the barrier coat was cured. 
For repair I use epoxy.  Epoxy is more of an adhesive than anything else.  As you know, post bond with polyester has always been iffy and all of the gelcoat has got to go.  With epoxy one never worries.  Cost more but piece of mind and all the prep time makes it worth it. For fairing I stick with West Systems #410.  Goes on like butter and easy to sand.  For bigger fairing jobs I like Awlgrips Awl-Fair.  You can spread it with an 18" drywall knife and it does not sag.  Fantastic product. 
I recently finished a bottom job on a TP52 with Durpox.  Sprayed 3 coats of the "primer" and then overcoated with 2 coats of their clear.  Nice shiny bottom.  No bottom paint as the boat is dry sailed. 
Good luck, you already know what you are getting into but it is once and done.  I always recommend to my customers that it is a 20 minute job.  I tell them stop on the way home from work, scrape/sand for 20 minutes and head home.  Don't do the marathon 6 hours on the Sunday because by Tuesday you will be in a wheel chair.  20 minutes at a time over and over breaks it up and makes it more manageable.  Anybody can do 20 minutes.
Nothing beats a nice bottom.  Being in fresh water I went with Interlux VC17.  Slippery and smooth.  So slippery in fact we often tie the travel lift straps together as they tend to slide towards the ends when you pick the boat up.  The pucker factor is a 10 when that happens.  Being up north and having the hard water season, we pull every year.  VC17 is so ablative that it is basically gone at the end of the season.  ZERO build up year to year and being acetone based it self dissolves anyway. We use to shoot it with those cheap Wagner airless guns.  Never even cleaned them just poured in new product in the spring and good to go. 
Dale

[Popeye.Tom]

Hi Dale,

"As you know, post bond with polyester has always been iffy and all of the gelcoat has got to go." 

Yeah, I may just use epoxy for any repairs that actually call for adding glass reinforcement.  Fortunately all modern glass materials have sizing that is epoxy, polyester, vinylester compatible.  I have both medium and some low viscosity resin.  The low viscosity epoxy (RAKA) will probably wet out and work as easily as polyester.

Update on barrier coat...  I do realize the 2000E will likely lay down much nicer than a thicker barrier coat, but I'm not too worried about that, we're not looking at a course burning race boat.  I am still leaning towards the SeaHawk TuffStuff, but I talked with the Sherwin-Williams industrial coating engineer today, we're going to connect again tomorrow.  I might consider the Sherwin-Williams "5000 HS".

Couple of questions for things I need to get before hauling out.

1. Both port and stb raw water (cooling) seacocks seem frozen.  In your experience, do you think this will disassemble and clean up or should I plan to replace them?  If I should have new seacocks on hand, what size are the seacocks and hoses?  The boat is 2-1/2 hours away and I won't be heading there until I go to haul it.

2. I am really considering a Kiwi Prop.  17" 3-blade.  I just wanted to confirm the 1-1/8" shaft size.  There seems to be a discrepancy in the old scanned owner manual parts list.  The shaft p/n 11453 is described "PROP SHART, 1" X 90".  The propeller itself is p/n 13228 with the description, "PROPELLER, 3-BLAD, 17 X 10 X 1-1/8 BORE"

Is the prop 1-1/8 bore?  I know there are some that really have liked the Kiwi and some that hate it, just as some have had good success with CoperCoat anti-fouling and others that curse it.  I know that my mileage may vary, but I think it would be nice to have a feathering or folding prop and this is the best time for me to do that.

cheers!

[Dale Tanski]

Tom,
You should only have one raw water cooling thru hull. If they are factory originals, they are Willcox Crittenden.  I still think nothing is better because of their tapered rotating plug core design.  You simply loosen the core keeper nut and the taper fit gets looser.  If they leak, snug them up.  You probably just need to loosen them up, take them apart and clean them out.  You can't do that with ball valve designs.  If you need the size let me know.

The prop shaft is indeed 1-1/8" diameter as from the factory with a standard taper.  As far as props go, they are like anchors.  If it works for you... you will love it. If you go the KIWI I would get a spare blade right off of the bat being plastic and all.

Dale

[Popeye.Tom]

The seacocks are the original Willcox Crittenden.  I planned to approach them first by rebuilding first.  Hopefully they will be fine once the boat is on the hard and I can pull them apart.  Unfortunately, there is not a chancellery in Brookings where the boat is moored and I plan to haul.  I'm trying to figure out the contingencies I can foresee and have parts on hand before I haul.

I just committed to 3 x 2 gallon kits of the Sherwin-Williams 5000 HS epoxy!  I'm setting up a commercial account and will get 2 gray and 1 white so I can alternate and hopefully achieve better coverage - no holidays!  6 gallons of material should ensure I get a good thick barrier coat.

My next concern is that I'm pushing this so late in the season, I may loose my weather window.  Worst case scenario is I haul, go zincs, prop, through hulls and leave the barrier coat for next season.

Now to go spend some more money on parts and supplies!

Cheers

[Popeye.Tom]

Update:

Last week I spent a long few days scraping.  The boat was actually surprisingly clean for not being out for a few years.  It cleaned up really pretty darned good with the pressure wash in the slings.

Some dimples along the waterline where muscles may have attached earlier and popped gelcoat when scraped, but amazingly, I found NO blisters!

The first layer of black bottom paint scraped and chipped off well.  Messy, but it came off.  The next layer was a red that almost seemed to polish when I scraped.  I used nice carbide blade Bahco (Sandvig) and flipped the blade to the new edge when scraping got slower.

After the black there was a dark red layer.  I found that it just kind of polished and was not easily scraped with a sharp edge.  I then tried three different strippers, none were great.  I didn't order any of the strippers tested by Practical Sailor.  I had Bare-Z-All and bought a can of Sunnyside 2-Minute from the hardware store.

The Bare-Z-All is a nice thick almost custard consistency.  It is low odor, non-flammable and water rinse-able.  I tried both covered with plastic and uncovered.  I didn't give any of the strippers hours and hours, but pretty reasonable working time.  This worked as well as the solvent and highly stinky and flammable 2-Minute.

The 2 minute is the general gel consistency.  Mostly petroleum products and highly flammable.  You would not want to use this indoors.  Uncovered or covered, it really did little better than the Bare-Z-All.  I would not recommend this, if only for the hazardous flammable nature and the hazardous stench!

I'd be curious to see how the Soy Strip or other recommended strippers tested by Practical Sailor performed.  BUT, I simply realized I'd not the time nor the inclination to order strippers and spend more days upon days...

I hired the local (Brookings, Oregon) "Dustless Blasting," Ashton and Tony.  They have a mobile rig with a diesel compressor and use a wet blast system.  The water injection with the abrasive media does go a long way towards reducing the fine dust cloud.  It does still spread dirt around.  They setup tarp screens around the boat that further reduce the spread and are planning to fully enclose their own area at the boatyard in Brookings.

Ash went through 4 pots of abrasive, but the boat is pretty much ready to epoxy seal coat now.  The blasting found what are probably some small voids just under the original gelcoat and some ~iffy~ or just OK blister repairs.  I will clean these up and will refill with epoxy putty.  Not sure if I'll do it between the first and second barrier coats but more likely will do it before the first barrier coat.

I need to find a cloud place to stash some pics and I'll add those to the thread.

Dale - I didn't check my notes and had brain fade on the big Wilcox Crittenden seacocks.  These were the bloody cockpit drains.  I was able to get them apart and they now turn properly! 

I'm in pause because of a large storm coming through.  High winds and cooler temperatures.  Long term weather shows this passing and I should be able to work again in the second week of October.  I will likely only be able to do one layer a day, according to the drying/recoat time vs temperature graphs for products on the NST Center NAVSEA reviews.  This will mean I need 5 days or maybe 6 go get through 3 full epoxy barrier coats and 2 coats of bottom paint.  I'm considering a visqueen skirt and a propane or kerosene space heater to reduce the recoat times.

Cheers!
Tom

[Popeye.Tom]

Let's see if I can make this work!

Here's Gypsy just after being set down by the TravelLift:


And here it is, 4 days later.  Dustless Blasting is just starting the first section.

[Popeye.Tom]

Well, that didn't work.  Here are links:

Sitting on stands:  https://flic.kr/p/2p5mbKQ

Getting blasted:  https://flic.kr/p/2p5kHAZ

[Dale Tanski]

If you weren't so ambitious you wouldn't have all these problems!  Looks great and the end is near. Don't cut any corners, see yourself it through. 
I have been sanding a Melges 24 hull for a repaint. Somebody put awlgrip below the waterline over barrier coat that was over two separate layers of bottom paints.   Yup, it was losing adhesion and chunking off.  Currently over 12 hours of sanding starting with #36 up to #150.  I even air filed trying to smooth out what looks like a aggressive sanding disk hack on a drill motor.  But... the new primer is now on.
Good luck
Dale

[Popeye.Tom]

Congrats on the primer on the Melges!

Dale, can you confirm stern tube is 2-1/4" OD?  All my research says it is. 

Do you have any strong aversion for the dripless shaft seals or a good experience of one versus another? I was going to go ahead and put a dripless shaft seal.  I know a lot of people use the traditional and I could repack, but was thinking of just replacing with a dripless.  Not cheap, but also not too dear $. 

I just got a call 10 minutes ago from the Sherwin-Williams store in Coos Bay.  My 5000HS epoxy is in.  Waiting still on the ablative paint.  Now I just have to hope for a weather window and time off work!