Hi

Sorry for the long post, but I have decided to try and be brave and do a few more of the maintenance issues on my boat- a solid fibreglass 27ft (cut away) integral full keel with barn door rudder from the early 1970s - rather than getting a pro to do it, but being practically challenged, was hoping for some guidance.

Next week she is on the hard in Brisbane for some (minor - I hope) osmosis treatment and an anti-foul. I have not done either before, but I have made a couple of ply dinghies/boats so have had a little to do with epoxy. Mixed success though.

She will only be on the hard for a week - time and money constraints don't allow anything more. I know that might not be long enough to treat the osmosis. I have been trawling the interweb, and some "how to fix old boat books" at home, but thought that you can't beat local knowledge, so here I am..

I was thinking that I will:
- Have her pressure washed down when she is lifted.
- Look for the blisters - it seems that they are more easily identified when the hull is still wet, looking along the length of the hull ?
- Sand the blisters and remove the rubbish with an angle grinder (maybe a dremel), faired to allow an epoxy filler after allowing to dry
- Tape the line of the anti-foul with the top sides so that I don't accidentally run the sander onto the glass - bound to happen..
- While the blisters are drying out, sand the rest of the hull, doing one section at a time. Last time I looked it seemed to be a little bumpy all over, like it hasn't been sanded before applying anti-foul before, at least not for many years.
- I was thinking of going at it with an Ozito orbital sander, 60 grit. Long sleeves, and dust mask on.
- After letting dry for as long as possible, epoxy fill the blister holes. Maybe speed things up with the wife's hair dryer. Not sure what sort of filler with which I should thicken the epoxy ? Does it matter ?
- Sand the epoxy blister fills for a fair finish once ground and filled, but do I need to apply something like a barrier coat (whatever that is ?) or a primer as the base layer before anti- foul ? Any recommendations ?
- Apply 2 coats of anti-foul. It is currently an ablative and I was going to apply the same - I don't know the current brand. Any recommendations ?? She won't venture out of Moreton Bay in the near future.
- I was going to anti-foul with a roller and brush as necessary. Not sure what sort of nap for the roller ? No spraying though (I don't trust myself).
- Any ideas about what sort of coverage can I expect from the anti-foul - how many litres will I need ?? I'm not a very conservative painter.. - Back in the water and sail away !

Does that sound like a reasonable plan ???

Appreciate any thoughts !

KK

I was thinking that I will:
- Have her pressure washed down when she is lifted.
- Look for the blisters - it seems that they are more easily identified when the hull is still wet, looking along the length of the hull ?
- Sand the blisters and remove the rubbish with an angle grinder (maybe a dremel), faired to allow an epoxy filler after allowing to dry
- Tape the line of the anti-foul with the top sides so that I don't accidentally run the sander onto the glass - bound to happen..
- While the blisters are drying out, sand the rest of the hull, doing one section at a time. Last time I looked it seemed to be a little bumpy all over, like it hasn't been sanded before applying anti-foul before, at least not for many years.
- I was thinking of going at it with an Ozito orbital sander, 60 grit. Long sleeves, and dust mask on.

If its thick as hell like it was on mine, use a good scrapper before sanding. Paint stripper highly recommended (don't leave it too long, can be nasty for the gelcoat). wear good protections and goggles. This step took me three days on a 24 ft...

- After letting dry for as long as possible, epoxy fill the blister holes. Maybe speed things up with the wife's hair dryer. Not sure what sort of filler with which I should thicken the epoxy ? Does it matter ?

for gelcoat blisters (no damage on the laminate) epoxy resin mixed with filler (I used HT120 epiglass)
If it goes deeper (damaged laminate looks white) you need to properly repair with epoxy and cloth and finish with thickened epoxy to make it smooth..

- Sand the epoxy blister fills for a fair finish once ground and filled, but do I need to apply something like a barrier coat (whatever that is ?) or a primer as the base layer before anti- foul ? Any recommendations ?

Apply primer on any reparation or bare gelcoat (like primocon)

- Apply 2 coats of anti-foul. It is currently an ablative and I was going to apply the same - I don't know the current brand. Any recommendations ?? She won't venture out of Moreton Bay in the near future.
- I was going to anti-foul with a roller and brush as necessary. Not sure what sort of nap for the roller ? No spraying though (I don't trust myself).
For the bottom paint it does not really matter, just use a cheap roller, no need to brush

- Any ideas about what sort of coverage can I expect from the anti-foul - how many litres will I need ?? I'm not a very conservative painter.. - Back in the water and sail away !

4L of awlcraft (ablative international) gave me two coats on a 24ft fin keel

Hi KK in my limited experience , one week is not enough time to do the jobs you speak of . But you may just do it ,if all goes perfectly , like say you work 12 hrs a day for 6 days , solid work not normal boat yard work !

A couple of things to consider .
some places wont let you dry sand all your old anti off with a cheap sander with little or no dust extraction , nor would you want to for your healths sake !
better to scrape it off somehow , dry or using paint stripper ,or pressure blast using beads of some sort.

Ive never done any osmosis repairs , but it sounds like your on the right track for that, from what ive read elsewhere .

yes you will need to epoxy the whole under water section before applying the anti tie coat and anti .... for this part of the project follow anti manufactures procedures .

go for it !! but be prepared for a time blow out !

Also if you sand antifooling, a cheap dust mask is not enough, you should use a respirator, like the 3M thing.

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SandS said..
Hi KK in my limited experience , one week is not enough time to do the jobs you speak of . But you may just do it ,if all goes perfectly , like say you work 12 hrs a day for 6 days , solid work not normal boat yard work !

A couple of things to consider .
some places wont let you dry sand all your old anti off with a cheap sander with little or no dust extraction , nor would you want to for your healths sake !
better to scrape it off somehow , dry or using paint stripper ,or pressure blast using beads of some sort.

Ive never done any osmosis repairs , but it sounds like your on the right track for that, from what ive read elsewhere .

yes you will need to epoxy the whole under water section before applying the anti tie coat and anti .... for this part of the project follow anti manufactures procedures .

go for it !! but be prepared for a time blow out !

Sorry but I will disagree with SandS, epoxy the whole under water is not a good idea after only one week. The hull needs to be completely dry to do that. In one week, you just repair the obvious blisters, prime and bottom paint then back in the water.

Better for your health to wet sand [with a hose] it wont take too long then allow to dry as you deal with grinding out your osmosis.

While your osmosis is drying out you can apply most of the primer.

When you do your antifoul read the directions which usually call for 3 coats if applied with a roller. If you some left over apply that as another coat. Depending on how foul your anchor place is, 2 coats will give a year, 3 coats about 2 years and 4 will give you 3 years. During that time you save on slippings and a tin or 2 of paint!

As others have said this is a dawn to dusk task Oh that's each day!

A little Ozito orbital sander will be slightly quicker than sanding by hand but not much. You really n something better, especially with a thick buildup. You'll save a couple days of the worst job imaginable.
Getting someone to sandblast it would be the best option if you are going the whole hog and epoxying your hull, but drying may take longer.

I'd just scrape/sand, epoxy the worst blisters, prime and antifoul. 2 litres of primer and 4 of antifoam should be plenty.
If you are going to dry sand, buy or rent a 200mm orbital sander with a good dust extractor. Talk to the people who are going to slip your boat. They may have requirements or suggestions. I haven't tried the chemical antifoul softeners/removers but I've heard mixed results.

I do not like your chances of using a cheap sander. For one they will not like the hard work of getting a 40 or 60 grit abrasive through sticky paint, they are probably not allowed in many boatyards and you will go through paper super quickly. Wet sand with 40 grit or 60 grit wet and dry - make some muscles and consider getting some help.

When it comes to removing blisters, I do not like to use paper abrasives. I used a 7 inch sander polisher as it is one of my favourite tools. But every time I would puncture a blister the nasty gooey mess inside would instantly clog up the 40 grit paper and I would have to change it. Consider using a really tough wire brush set up on a 4 inch angle grinder. The goo inside a blister is very sticky and will clog paper.

Epoxy is nothing special. Mix it like it says on the directions and use temperature to control pot life. In summer, store it out of the sun and keep it cool to get more pot life - DO NOT ALTER RATIOS.

As others have said, I would split the job if it was mine. Sand off antifoul, grind out blisters and leave the boat for at least a few days to dry out the blisters. You may find more blisters appear as the gelcoat dries out on the hard. Go back to work, have a few days doing something else and then epoxy fill, glass and epoxy clear over the underside. Then prime and antifoul. In some yards in the US they will suck the water out of the voids with vacuum bags. You can't rush a good job.

cheers

Phil

I agree with Kankama. Wet sand the paint smooth with a good sanding block. Don't bother removing all the paint just get it smooth and remove the build up. Grind out any blisters and dry the best you can. Use a digital kitchen scale to measure exactly the ratios by weight of the epoxy. Micro spheres is fine as a filler. Paint over any bare spots and blister repairs with special purpose grey primer of your choice, brands are all compatible so use Primicon or Jotun and for antifouling Altex or Jotun in ablative paint. Cheap 8mm nap rollers and toss them after use. If you get a smooth surface then 4 litres will get you two coats. Airless guns will give the best result.
The hard part is going to be the wet sanding and this is where you will benefit from having friends. Years ago you could slip some cash to some youths to do this part but they have disappeared. Watched a 73 year old do all this plus repaint the topsides on a Northshore 33 in just over a week in extremely hot weather. He had to redo a cast iron keel too!

One thing when applying antifouling with a roller. Buy a good quality double handed handle[extension]. You will thank me later!

The 1st time we slipped our boat we used a variety of electric sanding methods ie sanding pad on grinder, 9" sander polisher, belt sander, never again, all machines died either during the job or within the next few months due to the powdery nature of the sanded antifoul, it stained our skin and traces of it could be found for the next year.
Its been wet sanded ever since and as Ramona said an extension handle for the roller

yeah, you don't wanna be creating clouds of that toxic mess!

Hi

1st of all, thank you so much for taking the time to share your wisdom & experience. It is very much appreciated !

Going OK'ish so far - have done all the sanding I am going to do - maybe ever ! I do wish that I could turn back time and buy the best breathing mask as suggested above - crumbs, I may never recover ! I do have a much better appreciation for the work done by the yard, and I don't think that i will be so quick to judge a boat tradie based on the size of a bill anymore ! (Just to top things off its been cranking hot on the hard stand this week in brisbane....)

3 types of osmosis discovered so far:

a - kinda like acne - a whole bunch of pimples in isolated groups (not many). I hit it with the sanding block and it looks ok. I don't intend to try and grind them all out. Thinking that i will epoxy over and antifoul.

b - bigger, kinda like a weeper. i have ground them out with the ryobi, removing all the wet soggy stuff. Didn't appear to go through to the fibreglass. Scarfed them ready for an epoxy filler.

c - a couple of bigger ones - heaps of liquid inside It looks to me like the gelcoat has delaminated from the fibreglass (i may not be using the right terms here - my apologies...). See photo for details.

My thinking is to remove the wet soggy stuff and the delaminated material until i reach a decent bonded patch. then scarf and fill. The removed patch is getting a bit big though - about 5 to 8cm and counting. Not sure how I am going to fill it at this stage. I was thinking that i will

- paint an un-thickened epoxy into the hole
- put in a few layers of cloth fibreglass
- fill over with thickened epoxy
- sand to shape
- coat with epoxy paint
- coat with barrier coat
- coat with antifoul
- go sail

As always, any thoughts would be appreciated !

cheers

kk

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keelkicker said..
Hi

1st of all, thank you so much for taking the time to share your wisdom & experience. It is very much appreciated !

Going OK'ish so far - have done all the sanding I am going to do - maybe ever ! I do wish that I could turn back time and buy the best breathing mask as suggested above - crumbs, I may never recover ! I do have a much better appreciation for the work done by the yard, and I don't think that i will be so quick to judge a boat tradie based on the size of a bill anymore ! (Just to top things off its been cranking hot on the hard stand this week in brisbane....)

3 types of osmosis discovered so far:

a - kinda like acne - a whole bunch of pimples in isolated groups (not many). I hit it with the sanding block and it looks ok. I don't intend to try and grind them all out. Thinking that i will epoxy over and antifoul.

b - bigger, kinda like a weeper. i have ground them out with the ryobi, removing all the wet soggy stuff. Didn't appear to go through to the fibreglass. Scarfed them ready for an epoxy filler.

c - a couple of bigger ones - heaps of liquid inside It looks to me like the gelcoat has delaminated from the fibreglass (i may not be using the right terms here - my apologies...). See photo for details.

My thinking is to remove the wet soggy stuff and the delaminated material until i reach a decent bonded patch. then scarf and fill. The removed patch is getting a bit big though - about 5 to 8cm and counting. Not sure how I am going to fill it at this stage. I was thinking that i will

- paint an un-thickened epoxy into the hole
- put in a few layers of cloth fibreglass
- fill over with thickened epoxy
- sand to shape
- coat with epoxy paint
- coat with barrier coat
- coat with antifoul
- go sail

As always, any thoughts would be appreciated !

cheers

kk

That's a big hole in the picture.
Carefully grind away till you find a solid connection between the 2 layers.
It will definitely need multiple layers of cloth.
look here for inspiration -
Good luck with it all. I did the same thing last year. only small blisters though. more than 50 of them. Did the whole project in 5 days including some repairs inside the boat.

Sounds good
after fairing the repair i would put a one pack primer then antifooling paint.