When to Strip the Bottom

[sailpassport]

Last year I was recommended by a boat yard to have the bottom soda blasted before painting but did not have it done because their machine broke. I now need to have the bottom repainted and wonder if it is worth the extra expense and time to strip the bottom, apply a new barrier coat and new anti-fouling. The boat is a 1987. The current bottom paint is ablative but I have no idea what kind. I plan to repaint with SeaHawk 44. The current paint does not appear to have chipped off in too many places during the past year in the water. It is "lumpy" where over the years paint has chipped off and been painted over.

[boatman61]

If you've no idea what the antifoul is and its 'lumpy' take it off and start fresh.. many makes are not compatible and apart from that you'll have a nice smooth bottom for next year.. and for a few years after..

[Fortytwo]

I agree with boatman.

[Wand]

Er, someone's gotta do it...I disagree. Given that it seems to have all held on pretty well and you know it's an ablative, no need at all to get it off. The lumps you mention don't matter in the slightest - at worst it'll cost you 1/100 of a knot. Which is important of course if you're racing but zip for cruisers.

Unless you want a perfect bottom for the sake of it, just sand and go over the top with the new stuff. You'll save mega on work and cost and time.

[Jon Hacking]

We've always used ablative paints (whatever we could get, mostly in the third world) & always just slapped the new paint on top of the old (after power-washing & a light sanding) with no problems. Been doing it for 9 years now...

[O.C.Diver]

My boat is 34 years old and is getting sandblasted this winter. The bottom paint (copper) is so thick on the hull that it is now flaking off in large pieces. I would guess the coating is over 1/8" in spots that are cracking and flaking. Don't know after how many years you should do it, but I clearly waited to long.

Ted

[Minggat]

Mine was severly "lumpy" when I bought the boat. I had the yard take it down and there were blisters exposed. So they got taken care of. Then the yard did a barrier coat for me with the promise that I "would never have blisters again". Wish I had gotten that in writing. 5 yrs later, same yard, a few blisters. I repeated what the yard owner said, to which he replied, "I would never have said that".

[matauwhi]

G'day, mate. I was starting to experience some flaking of the ablative bottom paint layers. An opportunity presented itself two years ago and I "bit the bullet". Scrapped off the entire bottom down to gelcoat, installed 6 coats of new barrier coating and new ablative bottom paint. I fully expect NEVER to have to do again (at least on this boat anyway). All the best in the New Year. Cheers.

[boatman61]

Seriously... strip it down to gelcoat asap and leave it bare till 2 or 3 weeks before the time you want to launch... that'll give the hull time to dry out a bit... you'll know what it looks like under the paint and then when you apply the barrier and antifoul you'll feel much better in your mind for a few years to come....
If you've a few blisters, grind em out to the glass about an inch past the rims and power wash with clean fresh water... then leave it to leech moisture out of the hull.. before you barrier coat, sand the area's, fill and fair...
Skip the lazy way... thats fine if your sloppy with your property..
Personally I like to know my boats... intimately

[Wand]

Originally Posted by boatman61

Skip the lazy way... thats fine if your sloppy with your property. Personally I like to know my boats... intimately

Was some one unkind to you today boatman? Or maybe too much of that eggnog again?

Whatever, when fellow CF members offer advice different to yours, calling them names like "lazy" and "sloppy" is no way to win friends and influence people.

But then again, what else could I expect from a silly old pom.

[Benz]

My can of Islands 44 says it will go over most paints but soft ablatives. It seems it would be a shame to pay so much for paint (unless you got a killer deal on Islands 44 you paid out the nose) and not make sure of a good adhesion. I sanded my previous paint (Pettit horizon) really far to ensure a good stick, but if it had been ablative I would have surely tried to get it all off.

[Fortytwo]

I agree with boatman, it's really not necessary for everyone to affirm that for this thread. But, I do appreciate the help.

[Wand]

Originally Posted by Fortytwo

I agree with boatman, it's really not necessary for everyone to affirm that for this thread. But, I do appreciate the help.

We know...you said so already in #3 above. A case of "vote early and vote often"?

[Sandero]

My experience.

Shiva was 25 last spring and there was a fella at the yard where she was stored on the hard that had started a soda blasting biz. I had 25 yrs of bottom paint and figured it alone weighed hundreds of pounds and it would... if nothing else lighten the boat.

The blaster was new at the game and honestly no too careful. He oversprayed the boot stripe - and so I had to re do that as well as the bottom. He was also a little to aggressive and dimpled the bottom which required an awful lot of time fairing with expensive epoxy.

The keel of course was in good shape and did not need to be blasted and blistering wasn't even an issue. He took that down as well and that too required lots of fairing since he blasted out some of the fairing.

Once he was done... I had to take over and the fairing was a huge task taking many days... expensive epoxy fairing and lots of sand paper.

Once that was done it was multi coats of Interlux epoxy barrier coat. Again, an expensive product.

Finally - remasking and applying the bottom paint and then... remasking top and bottom this time and applying the boot stripe after more sanding and fairing. This was another multicoat operation with Interlux Brightside.

I went through 100 rubber gloves many roller sleeves, tons of sand paper, solvent, protection suits, rags, masking tape.

I then decided to tackle a repair of the rub rail. Wax and then launched on June 30... latest I've ever gone in the water in 25 yrs.

They blaster said he removed over 500# of paint which was mixed in with the soda.

The boat was so fast and slippery when we sailed her the first time. WOW. But this is a once in boat's life operation. We had no blisters, but I wanted to remove the 25 layers of paint and get the bottom smooth and fair.

Way expensive, lots of hard work... worth it? Probably not if you don't have blisters and are not racing. I'm glad it's behind me

[nv5l]

I redid my bottom a couple of years ago when I bought the boat. The deck was a little mushy and the bottom didn't look too good, especially a bumpy patch on leading edge of the swept forefoot right where it met the keel. I wanted to know what was under there.

I also pulled the rudder and shaft, replaced the cutlass bearing, both stuffing boxes, and all the through hulls. Once I got the bottom paint off, I discovered other poorly done patches and ground everything smooth and patched the flaky gel coat before applying 5 coats of barrier coat.

It took a while and was a lot of work, but I did it all myself and am glad I did. Bottom paint can cover a lot of sins. I now feel very confident about everything below the water line.

I also replaced about 14 square feet of cork core on the deck, but that's another story.

just my 2 cents...