Ballast Tank & Blisters?

[jg9546]

Once in a while a topic of bottom painting comes to the discussion on our board with many opinions. Many people have decided to bottom paint their boats. I still have not painted my boat due to the consideration of making a large initial expense (I was quoted $2,000). However, if someone decided to protect his/her boat by bottom painting what about a water ballast exposure to the same water where the boat is sitting. I keep my boat in my slip for about 4 months (rather cold lake in the mountains in Utah) and even if I protect the bottom of the boat I may face the same problems with blistering from inside of the water tank.

Your thoughts would be greatelly appreciated.

Jacek

[DLT]

"Blisters" are between the fiberglass and the gel coat.

There is no gel coat in the ballast tank.

Do Blisters actually propegate through the fiberglass itself?

[Sloop John B]

Who cares about blisters where the sun don't shine. They won't slow the boat down.

[Richard O'Brien]

blisters usually occur when the matte , was not wetted thoroughly enough, and also often with chop gun work. Macgregor doesn't use chop guns, and they are really pretty good at rolling down the resin,... at least on my boat. I haven't heard of any blister problems on this board yet!

[Bobby T.-26X #4767]

I haven't heard of any blister problems on this board yet!

here's one!

I gambled on placing 2006 M in Arkansas wet slip for the summer with wax only bottom. Craped out. Boat is covered with Blisters after 14 weeks. I'm exploring fixes but haven't heard of a cheap or easy one yet.
Better luck to those who try the same.

Gelcoat Blisters

[Night Sailor]

After one year in the water with only three heavy coats of wax on the bottom, my 26X blistered. Hundreds of shallow blisters the size of a this capital O. Most of them were in a narrow line, directly underneath the fore and aft tubes connecting front and rear ballast tanks. I had kept the boat with ballast full at all times for stability at the dock, and sailing. There were no blisters in areas not covered on the inside by a ballast tank. I conclude that water inside the ballast tanks may help blisters form on the outside if the boat is in warm, fresh water. Until it's time to pull the boat for the next bottom retouch, I intend to keep the boat ballast empty at the dock, to see if the blisters reappear in the same pattern.

[Dimitri-2000X-Tampa]

Haha Richard, when I first read your post, my mind accidentally left out one of the T's in matte.....and I was thinking...what the...

Sea growth needs light so its not likely you would have hard fouling inside your ballast tank (plus, the animals couldn't get in anyway). But I never leave my ballast full for more than a day or two at a time. I like the nice dryness of the Mac. After owning a keelboat for 7 years which stayed in the water and had a prop shaft drip which kept the bilge with water in it all the time (and a lot of vigilance to the bilge pump and float valve).

The keelboat did in fact have some blisters and a boatyard guy once told me to try to completely dry out the hull every once in a while because it was good for the hull. Since blisters are caused by osmosis, this does kind of make some sense. I have left my Mac in the water for months at a time, one time for about 9 months I think and it never got any blisters, even when the bottom paint wore off in places. Seems like there are more reports of fresh water blistering (maybe the only advantage of salt water?). Growth was always heaviest on the south side of the boat btw.

[Bruce M16]

I think an epoxy barrier coat and paint is a must for anyone who leaves thier boat in the water for months at a time. Yards will quote you $2,000 but it is actually very easy and cheap. My wife and I did our 97x as well as our 03M. As I recall our material was about $ 350.00 total. ( 200 for interlux epoxy, 100 bottom paint and maby 50 for brushes rollers, etc, etc). Three or four afternoons and it was done. We have never had a problem with either boat.

[jg9546]

Thank you guys for your thoughts.

Do you have any recomendations for easy to follow books or vidoes on bottom painting?

Jacek

[Frank C]

Click the "Featured Articles" button, upper left of this page.
One owner wrote up his experience w/ bottom painting.

[DavidG]

In all the posts I have read on this topic, one question has never been answered in small enough words for me to understand. I understand that the first layer of a bottom paint job is the epoxy which protects from blistering, and the second layer is an ablative coat which inhibits critter growth. I think I understand that the ablative coat functions by 'wearing off', thereby taking said critters with it. Right, so far? And I am pretty sure that bottom paint has to be reapplied every year or two, maybe three if you are lucky. So do both layers have to be reapplied, or just the ablative coat? And if it is just the ablative coat that has to be reapplied, I am thinking that should not be nearly as expensive. If I am right in my thinking here, what is a typical price for getting just the ablative coat done professionally?

[normo]

A few years ago I became an "expert" on blisters. I bought a derelict Catalina 22 and was redoing it for racing. To my amazement I found 54 blisters. I distinctly remember each one. Two of them were so deep I ground completely through the hull. Quite a surprise to find yourself wondering what that structure (inside liner) was when viewed through dust covered goggles.

This is what I recall. Blisters are a chemical reaction between the resin and water which creates an acid. Given time, the acid solution will work its way through the gelcoat, internal resin, matt, roving and cloth. It doesn't need light. Water on the inside of the hull can cause blisters however I have never heard of this. Repair should not begin until the moisture content meets the mfg. criteria. This often involves keeping the boat on the hard for several months. Repairing blisters must rank as one of the worst jobs of all time.

Applying the barrier coating is not hard to do. You can save a lot by doing it yourself. Several coats are needed to build up the required thickness. Interlux has excellent tech notes on blisters. I called their tech reps a couple of times for advice.

[kmclemore]

At the risk of repeating myself....