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You guys are going to laugh when you realize I missed this one.
First off thanks for all the help on the barrier or not after soda blasting discussion. Unfortunately I think I may have jumped the gun. The back story is that this is my dad's boat. I clean it, maintain it, wax it, move it, etc. In the fall Dad had the boat soda blasted and looked over by a fiberglass repair person. They said all looked good and there was no work to be done. I saw the boat once over the winter and just took a quick look and noticed that the rudder had been faired at one point and needed to be faired again but not much else.
I ended up purchasing all the bottom paint and supplies to get the job done and visited the boat for the first time since last summer to drop them off. This is what I found:
The entire port side of the keel looks like this for the most part, lots of tiny holes down to the fiberglass mat. They are less than 1/4" in diameter. The starboard side is completely clean with nothing of the sort. Any ideas on this one? It looks like the boat might be sitting out this season to get this sorted.
I am with Mitch on this one. Not sure what I am seeing. Maybe better pictures would help.
Usually blisters are weepy bumps. When pierced they ooze a vinegary purple liquid. What you may be looking at are old "popped open" blisters that were not repaired previously. The soda blasting may have taken off the tops of blisters leaving the craters behind. Blisters are usually most apparent when the boat is first hauled. They tend to dry up and disappear as the boat sets out of the water.
I suggest sanding the area uniformly and investigate further as they look like something that needs repair.
Being on one side only suggests they may be painted over old barnicle/hard growth scars. If a boat sets at a dock the growth tends to be bad on one side and not the other.
It's been three years since I had similar symptoms, so this account might seem a bit garbled:
After one season of sailing (and after a barrier coat), my boat developed tiny blister-like bubbles in the bottom paint. They were so small that I didn't spot them, but the yard did. They were afraid it was their fault, so they brought somebody in from Interlux (maker of the barrier coat), and eventually soda-blasted my hull at their expense.
Portions of the boat had tiny pinholes, like the ones in your picture.
Nobody was really sure what caused the bubbles in the fiberglass--if that's what they were. One theory: That work stopped on the boat (perhaps because of lack of funds) before the hull was completely laid onto the mold--and that work was resumed sometime later.
Whatever the reason, I had the hull boat resurfaced, made fair and then had a vinyl barrier coat applied.
Things have been fine since then.
Hope this helps.
--Joe
Former Commodore, CDSOA
Former Captain, Northeast Fleet
S/V Crème Brûlée, CD 25D, Hull # 80
"What a greate matter it is to saile a shyppe or goe to sea."
--Capt. John Smith, 1627
Joe that sounds like the same symptoms as ours. If the fix is that easy and something I could do myself I feel a little relieved.
To clarify for everyone else, the boat has been soda blasted. What you see around the holes is scuffed up gel coat. We are having the yard that does the mechanical work on the boat take a look at it this week or next week. I agree that they are more holes than bubbles. I believe the soda blasting may have broken them open or opened them up.
Previously the boat had many many layers of caked on bottom paint. There were no apparent signs and I only saw the boat once over the winter and today. I was not present when it was hauled.
Has anyone else had a similar experience? Thanks for the help so far.
Joe Myerson wrote:Greg,
It's been three years since I had similar symptoms, so this account might seem a bit garbled:
After one season of sailing (and after a barrier coat), my boat developed tiny blister-like bubbles in the bottom paint. They were so small that I didn't spot them, but the yard did. They were afraid it was their fault, so they brought somebody in from Interlux (maker of the barrier coat), and eventually soda-blasted my hull at their expense.
Portions of the boat had tiny pinholes, like the ones in your picture.
Nobody was really sure what caused the bubbles in the fiberglass--if that's what they were. One theory: That work stopped on the boat (perhaps because of lack of funds) before the hull was completely laid onto the mold--and that work was resumed sometime later.
Whatever the reason, I had the hull boat resurfaced, made fair and then had a vinyl barrier coat applied.
It’s interesting you report no other blisters were found on the other side of the hull. This leads me to believe that these are not blisters. Usually like others have commented hull blisters weep fluid and have a distinct odor of styrene. On my CD27 there were some blisters, they are very distinct looking and look nothing like your image.
I believe the holes are voids in the hull that were created when the hull was made. As you know the gelcoat color is the first layer of material applied (usually sprayed) when the hull is constructed. This is followed up by resin and layers of matting and or chopped fiberglass. When the resin is applied and wetted out on the matting bubbles can work there way into the material. As you can imagine hand working a hull is a tedious task. Not to mention time is your enemy when the resin is setting. The air bubbles are now embedded in between the gelcoat layer and initial layer(s) of matting. There are probably thousands if not millions of voids in every hull manufactured. If you follow the manufacturing industry, modern techniques for hull layup include vacuum bagging to help eliminate these inherent voids.
In my own work on the cabin trunk I have found numerous rather large voids when repairing some gelcoat cracks. I found mine with a dremel tool. Soda blasting under pressure as well as removing some gelcoat exposed these defects on your hull. Do not be overly concerned this is not a major repair nor should it be costly. You can definitely do the work yourself. A day or two is all you need.
As I mentioned earlier I found large voids in the forward bottom edge of the trunk where most owners report cracking gelcoat. Mine looked rather severe so I had it on my short list to repair. As I removed the gelcoat I ran into major voids on the bottom edge (no I didn't sand through the trunk, in case you were wondering). These voids probably weakened the structure enough that compression/tension stress caused the cracks. I epoxied some fiberglass cloth and layered on a mix of colloidal silica/epoxy leaving enough room to apply new gelcoat. Lucky for you yours is below the waterline. I would just sand the area paying attention the larger holes where the edges should be beveled a bit. Then wipe clean using acetone sparingly. Mix up a batch of epoxy along with some colloidal silica until thick; carefully work material into holes with small spatula trying to keep the material as level as possible. Let the epoxy cure apply a second coat if necessary. Hopefully if you applied the epoxy carefully you may not even have to sand it down. Apply a fairing coat if you do need to sand. I cannot gauge the area that needs to be repaired but it does not look too big. This repair is real easy to do. Follow directions on the epoxy and look with satisfaction when you complete the job. West System makes a premixed packet repair kit that if this were a small area would work great.
I'm still working diligently hoping to launch 2nd or 3rd week of June after a 2-year break working on the refit.
How old is the boat? I have had the misfortune of blasting a few boats and have seen a lot of them after being blasted. Based on my experience what you are seeing is not uncommon in older boats. A number of factors can cause it. A few being:
1. The gel coat has degraded due to osmosis even though you may not have seen a raised area. (Without getting scientific blisters develop over time not immediately).
2. Voids behind the gel coat due to improper lay up.
In either event, the pressure of the blasting destroys the brittle or degraded gel coat.
Okay now that what and possible why is over, the here and now is that the areas need to be sealed and faired not just painted over. If you just paint the areas you are asking for trouble. However, it should be as dry as possible before you fill and fair.
Based on the photo alone, here are my observations. The gel coat in the area shown appears to be shot. If you look closely, you will see a circular area near the center of the picture which appears to be covering a void. This could have been a void in the lay up or a depressurized blister (more likely). Also, at the bottom of the picture there is a black zig zag streak that appears to be the staining associated with a weeping blister.
I would suggest that the gel coat be judically removed and the hull be checked with a moisture meter. In lieu of a meter, take some saran wrap and cover the area and seal the wrap with tape. Extend the wrap beyond the bad looking areas a few inches and make sure that you seal the perimeter well. Leave it overnight and then check it for condensation. If you find condensation, the hull is wet and the repair procedure will have to be adjusted.
Thanks for the advice everyone. I feel like everything that has been said so far is correct. They are some sort of voids that most probably aren't blisters which need to be filled and faired. I feel confident in doing the work myself knowing that this is likely an easier fix than I first imagined.
Furthermore, the boat was blasted in Sept/Oct and has been drying out since then. The yard that works on the boat was supposed to go over with a moisture meter. Hopefully the results are good. I should know in a few days. Thanks for all the help, you guys and gals are great!
Looks like a chunk of something, slightly left of center.
The soda blasting will remove anything loose. Along with the old paint, bad repairs can be removed, along with blisters, if the top of the blister is thin enough. Even sniffing may not be enough, as the blasting has cleaned out the crater.
INVESTIGATE!!
