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obiec 01-14-2003 05:06 PM

lots little tiny blisters???
 
I have delt with blister before. My outer boat developed a couple dozen large blisters. I just ground them out and filled them with epoxy and painted. But this boat I am looking at is covered with little tiny blisters about the size of a pincel eraser or smaller and just under the gel coat. What to do. I haven''t a clue. I was thinking maybe I could belt sand the entire bottom this will not remove them but would probably open up most of them. Then I would role a layer of west system epoxy over the hole hull and paint. How dose this sound.

Jeff_H 01-15-2003 03:05 AM

lots little tiny blisters???
 
When you talk about lots of very small closely spaced blisters, that is usually a gelcoat adhesion problem. Often you can just peel off the gelcoat with a sharp chisel without getting into the laminate because there is often such poor adhesion in these area. Once the gelcoat has been removed,you will need to sand the surface, fair it, wash it down to remove any contaminants and then build up enough layers of a barrier coat (either epoxy or vinylester) to protect the hull from further blistering.

WEST system epoxy has a good monograph on blister repair. I''d take a look at that if I were you.

There is no way that I would use a belt sander as they tend to create a series of flattened spots and belts are very expensive compared to disks. This will project eat up alot of sandpaper. You can probably buy a high quality disk grinder for the savings in sandpaper costs.

Good luck
Jeff


thefantasea 01-21-2003 03:17 PM

lots little tiny blisters???
 
I''ve never encountered blisters but I have wondered -- considering the effort and expense of removing them, what''s the downside of doing nothing?

Jeff_H 01-21-2003 04:16 PM

lots little tiny blisters???
 
Moisture works its way into the laminate causing deeper seated blistering and greatly weakening the hull in that area.

Jeff

amps 01-23-2003 02:14 AM

lots little tiny blisters???
 
I have encountered the same problem om my Hunter 34 only I have about 100 to 150 small blisters, most of them already split open. It was recomended to me that I grind out each blister, let every thing dry out then fill each cavity with thickened epoxy resin after filling each repair coat each area with unthickened epoxy resin to seal the repair. After the repairs are made I am going to apply a Barrier Coat over the entire bottom. Hopefully after all of this work I will not have any problems for many years. The recommondations were made by the folks at Tidewater Marina, Havre De Grace, MD. Hope this is helpful.

Dave

amps 01-23-2003 02:15 AM

lots little tiny blisters???
 
I have encountered the same problem om my Hunter 34 only I have about 100 to 150 small blisters, most of them already split open. It was recomended to me that I grind out each blister, let every thing dry out then fill each cavity with thickened epoxy resin after filling each repair coat each area with unthickened epoxy resin to seal the repair. After the repairs are made I am going to apply a Barrier Coat over the entire bottom. Hopefully after all of this work I will not have any problems for many years. The recommendations were made by the folks at Tidewater Marina, Havre De Grace, MD. Hope this is helpful.

Dave

VIEXILE 01-23-2003 04:28 AM

lots little tiny blisters???
 
I''ve done several boats, larger whalers and sail, with nastified hulls that, where repaired, seem to be holding up. Buy yourself a dremel tool and figure out what bits will best serve your purpose. You have gelcoat blisters, as discussed, which may or may not turn into laminate blisters. I believe saltwater blistering is more common, per unit floating, than freshwater. Osmotic migration of molecules is the reason, but osmosis requires a molecular level differential - which saltwater provides, hence, migration. Studies have shown that freshwater standing inside a hull in saltwater MAY, depending on hull quality, more readily cause blistering than any freshwater situation. Use the dremel tool to carefully grind out each and every gelcoat blister. I then take a small grinder and feather the GELCOAT back somewhat. It takes a touch. DON''T flush with acetone, contrary to some beliefs. Blow it clean with high pressure air. Acetone only piles up the waste and causes contamination problems. Once you wipe it with acetone, it''s tough to actually "clean" the surface. Let everything dry. Figure out which West System filler is best for your purposes. There are also considerably less expensive, yet just as good, epoxy alternatives. Think advertising. Make a peanut butter paste with no more than two squirts of West and hardener and filler, and, using plastic applicators, fill the depressions. When I mix it, if it doesn''t "drip" off the applicator when I hold it up, it''s close to what I want. Don''t mix up too much west, ''cause it''ll kick fast. The smoother the mix the better. Larger amounts of west filler is best spread out on a pallette (plywood or whatever) because it heats up when in thick masses and kicks faster. It will actually combust under certain conditions in a container. Putting it on a pallette will make it last longer and save on waste. Don''t use bondo-level west for the first fill, since you want to basically recreate the hull and gelcoat you''ve removed. Use the softer stuff for final coats. Fill the holes, sand it off, fill again with softer stuff, sand it off and then final fairing and sanding. Between layers of West be SURE to scrub with a scotch bright pad and warm water to "de-blush" the West and let dry before the next application. Also do this before painting. The blush, limiting oxygen to the surface, causes the West to kick off. Better yet, read a west manual before you start. Put a barrier coat on the bottom to mfg specs. and bottom paint, float. It''s actually pretty easy. You can do a better job than a yard can. Just watch who''s doing it for a living. I''d go easy with the chisel idea. At that point, you might as well pay for a planer to de-gelcoat the bottom. Skip re-gelcoating and apply a barrier coat. Gelcoat is porous no matter what, and won''t provide the protection some of the new barrier coatings.

obiec 01-23-2003 05:36 AM

lots little tiny blisters???
 
Thanks for all the info. One yard I talkted to said that it would have to dry out for 6 months after it is opend up or planed. dose that sound right.

obiec 01-23-2003 05:38 AM

lots little tiny blisters???
 
also anouther yard told me to paint over it and dont worry it is a verry thick hull. Thay said I would loose around 6 seconts a mile. But she is a cruser not a racer any way.

VIEXILE 01-26-2003 08:07 AM

lots little tiny blisters???
 
some say not to bother with minor blister repairs at all, and to just repaint. Thing is with gelcoat blisters, they could pretty much spread the gelcoat off the hull below the waterline. Ya. It''s gotta dry out, and six months seems to be the rule of thumb.


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