Questions about hull defects.

[Ward H]

Closely inspected the exterior hull and bottom of my O'day today. The bottom paint was very thick and rough. As it dried in the cradle it begaing flaking off in big chunks. Yard recomended sand blasting the hull and letting it dry over the winter. I agreed.
First surprise was the patch on the keel shown in photo 1. This is port side, forward of center, slightly lower than mid height.
I sounded the keel all the way around. All areas at mid patch level and above sounded hollow. Bottom edge of patch to bottom of keel area sounded very solid and was the same all around the keel.
Disappointing part was that the patch edge was put over old paint and not feathered properly. It looks sturdy, just 25% of the edges are not attached to the fiberglass due the old paint not being taken off properly.
I think I can feather, lay on fiberglass cloth and epoxy to extend the patch, then feather again.
Also found a lot of chipped gel coat over the patched area. Photo 2. Not as bad around the rest of the keel. I am guessing a coat of epoxy and sanding will correct these.
Good news is the centerboard has no bulges. They pulled that for me because it had been sticking. I think it was just due to thick paint.

I also was closely examing the topsides for scratches and dings since I plan on following MainSail's how to on shinning up the hull.
I thought the boot stripe and top stripe color would be in the gel coat but light scratches and a poor edge now leads me to believe the stripe was painted. Photos 3 & 4. What do you think?

Appreciate your thoughts.

 

[NC-C320]

Ward,

I'm sure that there are many others more qualified than me to address this issue. But here are my thoughts. Having had thick patches of paint that was flaking off, suggests to me that whatever made the patch necessary occurred many years ago. The accumulated paint flaking off is not particularily concerning and you have taken care of that by sandblasting. My guess is that there was some damage to the patched area in striking an underwater object, or possibly a localized defect/failure in the fiberglass in the distant past, and obviously, the patch was not done very professionally. But the patch seems sound except at edges over the paint, and you have a plan to handle that which seems appropriate. Fiberglass is strong, and my guess is that you won't have any structual issues from the patch.....otherwise, giving the apparent length of time that the patch has been there, trouble, if it was going to occur, would have happened long ago. As to the center and top portion sounding hollow, that may be exactly what it is and is ok if this is an internal ballast boat wherein the lead or ballast material is placed in a keel cavity and this is the point where the ballast stops...i.e. ballast is recessed down into the cavity. Typically, they would place resin mixture over the ballast to fill the cavity and there may be a void there, and if so, could have contributed to the initial problem. If it were my boat, I would do what you have said and then continue to use the boat. If on the other hand, you really want to do it right, you could grind out the old patch to see exactly what is going on and then completely repair it properly, but that is going to be time consuming and expensive, and as I said, if it were my boat, I would take a calculated risk that the original repair was sufficient and just feather the edges in as you have mentioned, then paint the bottom.

 

[Shoaldrafter]

hull issues

Ward,

You present an interesting question on the patch. I would grind by hand around the patch to find where it makes good contact with underlying FRP.

If it was patched over paint, I would grind it out and make surface contact with new patch direct to old FRP. As to hollow sound, that may be due to thickness of patch as being made thicker than original hull. On O 25 you should be able to see inside of hull except for keel area.

If there is question of what is going on in keel where you cannot see, just drill hole to see if any water or intrusion. If o.k. then just fill hole and fair.

There are many yards who use sandblasting as expedient way to clean hull.

The issue with sandblasting is damaging the glass reinforcement in the resins. In plain English, it ruins the FRP's strength.

While I do not like sandblasting, in your case it might be fastest way to clean hull. However, do not be affraid to sand off the paint layers by hand. Just wear hazmat suit and have lots of sandpaper. Also, have bigger orbital sander.

Welcome to older boat rebuilding.

Ed K

 

[Ward H]

Thanks guys. You both bring up good points which helped to ease my mind. I agree it probably is an old repair and since it remained hidden until all paint was removed, it is probably in good shape.
I new that once I had it sandblasted I might have to put on an epoxy coat. Just got a little more work to do.

I'm thinking I should squegee on a thickened epoxy coat first to fill the small chips, then sand and do a regular coat of bottom epoxy sealer. Then my bottom paint. Plan to use the West 105 system. Any suggestions on this?

This boat was well maintained with topside and interior being in excellant condition and no soft spots. One owner for 31 yrs. Just needs a little freshening up so this is really a minor thing.

I did find some photos I took two weeks after it was pulled for Sandy and had started drying out. That was when the paint started flaking. There is no sign of the patch in these photos. Patched area is to the right. I think that is a good thing.

 

[Shoaldrafter]

bottom work

Thanks guys. You both bring up good points which helped to ease my mind. I agree it probably is an old repair and since it remained hidden until all paint was removed, it is probably in good shape.
I new that once I had it sandblasted I might have to put on an epoxy coat. Just got a little more work to do.

I'm thinking I should squegee on a thickened epoxy coat first to fill the small chips, then sand and do a regular coat of bottom epoxy sealer. Then my bottom paint. Plan to use the West 105 system. Any suggestions on this?

This boat was well maintained with topside and interior being in excellant condition and no soft spots. One owner for 31 yrs. Just needs a little freshening up so this is really a minor thing.

I did find some photos I took two weeks after it was pulled for Sandy and had started drying out. That was when the paint started flaking. There is no sign of the patch in these photos. Patched area is to the right. I think that is a good thing.

- - - - - // - - - - -

Coating the bottom with a layer of
epoxy before bottom seal is good idea.

I use penetrating epoxy as beginning
layer. It will seep into any cracks in gel
coat and help seal from water intrusion.

West makes a good quality product
and I occassionally use it. However,
for bigger projects such as you are
starting on I use thin epoxy from
Progressive Polymers -

http://www.epoxyproducts.com/

And I recommend on the base coat
adding pigment [color of your choice]
so that first you can see what you
miss and it makes seeing defects easier.
Then you can go back and fill and fair
defects.

Small containers of pigments can be
had from:

http://www.uscomposites.com/pigments.html

Also, progressive epoxy makes cold
weather epoxies so that you can work
when you have time now and do not
have to wait until sailing weather to
fix bottom.

If you use Progressive tell them you
want Paul's boat rebuilder discount.
Not that you will get a discount, but
get a smile on the other end.

Ed K

 

[Ward H]

Hi Ed,
I went through the epoxy products web site you linked. Here is what I found and thnk I would use. Just wanted to run it past you to see what you think.

1. Basic No Blush Epoxy with fiberglass mat/coth to "tighten" patch edges and to fair patch.
2. One coat of Low V thin and watery epoxy. Use as a pennetrating coat to seal gel coat and chips in gel coat.
3. Thickened Basic No Blush Epoxy to fill chipped areas.
4. Final coat of Basic No Blush Epoxy with color pigment.

Now, do I need to "paint" the bottom with another product before painting with an anit fouling bottom paint or is the anti fouling paint the next and final coat?

I will practice on the rudder and centerboard first, they are in the basement. Then will do the boat as the weather improves.

Appreciate all advice.

 

[emergpa1]

Hi Ed,
I went through the epoxy products web site you linked. Here is what I found and thnk I would use. Just wanted to run it past you to see what you think.

1. Basic No Blush Epoxy with fiberglass mat/coth to "tighten" patch edges and to fair patch.
2. One coat of Low V thin and watery epoxy. Use as a pennetrating coat to seal gel coat and chips in gel coat.
3. Thickened Basic No Blush Epoxy to fill chipped areas.
4. Final coat of Basic No Blush Epoxy with color pigment.

Now, do I need to "paint" the bottom with another product before painting with an anit fouling bottom paint or is the anti fouling paint the next and final coat?

I will practice on the rudder and centerboard first, they are in the basement. Then will do the boat as the weather improves.

Appreciate all advice.

Ward,
Regarding the anti fouling paint, I believe it depends on what paint you choose. Some may require a primer before the anti-foul goes on. I have called the manufacturers customer support line for the paints I have used in the past and found them helpful. I'm sure some of the guys on this forum will have some ideas.