Gelcoat blister questions

[Fistful]

After looking through some of the previous topics regarding gelcoats and blisters, I thought I would ask for a little feedback/advice.

I am currently looking at a 20 ft 1991 Grady White. The owner kept it in a marina for a few years about 4 years back it hasn't been used since (dry stored inside since then). The bottom has never been painted and is showing some blistering in the gelcoat. I would be primarly trailering it. Now my questions:

1. Is this hull compromised or in need of repair or is it sufficent to sand and simply bottom coat with a good marine grade epoxy? Being the quality of a Grady is this less of an issue?

2. What is the typical cost to have this professionally cleaned and painted / coated on a boat this size?

3. Any other thoughts?

I just want to take into account an additional costs this will bring about before moving any further forward.

Thanks in advance.

 

[BWT]

Re: Gelcoat blister questions

my recommendation would be to sand the bottom with 40-60 grit to remove most of the gel and open up the blisters. Then go over with a barrier coat (inter-protect 2000 for ex) and then bottom paint. It's a bit of an investment with time if you do it yourself, but you won't have to look at it again for MANY years. As a guess to have a yard do the work with materials probably in the neighborhood of $2300 give or take.. To do it yourself, probably under $300 and a solid week of work. There isn't any immediate concern for extended damage if left alone for a season, but the longer it's left the deeper the blisters will get.

Hope this helps!

~BWT

 

[ondarvr]

Re: Gelcoat blister questions

Blister repair can be very involved if you want to do it correctly, so first you should post some pics so we can see the type and number of blisters we're talking about.


Although people call them gel coat blisters, they typically form in the laminate, so not only does the gel coat need to be removed, but so does the affected laminate. sanding all the gel coat off plus a layer or so of the laminate is a great deal of work. Then you need to dry the hull (this can take months), add back the removed laminate with epoxy, plus fair the surface, then paint.

If you plan to keep the boat on the trailer there is no need to rush into anything, and possibly nothing needs to be done at all.

 

[Yacht Dr.]

Re: Gelcoat blister questions

Whoh whoh horse !!

Sanding or Stripping off All the GEL ?? Adding a Layer of Glass ??

Hold the horses guys ! Im sure your are Freaking him out now .. not needed at this point.

Fistful .. First off is get some pics up ( overall and then some close-ups ) Ok ..

There are products and methods to take care of anything related to Blisters on the market today .. you have to know what you have and how to repair ( or even when to repair ).

Relax Right now .. dont go taking Strippers or Busters to your hull atm .. just some pics .. Relax

Posters should know better then that to jump on some Bottom Doom here on Ibaots !! IMO ..

"Can BE" or " Could be" or anything other than Direct Subjection on the project at hand is only a Guess at best m8 ..

Get Pics ..

YD.

YD.

 

[BWT]

Re: Gelcoat blister questions

you're right; quick post on my part between layups and may have jumped to conclusions Let's see what we're dealing with first.

 

[Fistful]

Re: Gelcoat blister questions

Thanks YD, ondarvr, and BWT. Don't worry about me rushing into it, I appreciate the various perspectives and worst case senarios to consider. Once I get an opportunity to get some pics I will share them on here (it might be a couple weeks - boat is 4 hrs away).

I am just trying to hear from those that have more knowledge on this subject than I.

 

[ondarvr]

Re: Gelcoat blister questions

Intersting response YD.

The first and last sentance of my post says "lets see some pics before doing anything" and then to end it
"possibly nothing needs to be done at all"

And yes, for proper blister repair the gel coat needs to be removed and so does any affected laminate, if you have other proven methods or short cuts please inform the rest of the FRP industry as to what they are.

 

[Yacht Dr.]

Re: Gelcoat blister questions

Thanks YD, ondarvr, and BWT. Don't worry about me rushing into it, I appreciate the various perspectives and worst case senarios to consider. Once I get an opportunity to get some pics I will share them on here (it might be a couple weeks - boat is 4 hrs away).

I am just trying to hear from those that have more knowledge on this subject than I.

Over all and close-ups will be real helpful here .

Intersting response YD.

The first and last sentance of my post says "lets see some pics before doing anything" and then to end it
"possibly nothing needs to be done at all"

And yes, for proper blister repair the gel coat needs to be removed and so does any affected laminate, if you have other proven methods or short cuts please inform the rest of the FRP industry as to what they are.

It all depends on the extent of the blisters ..

If there Into the lam then yes.. Your quote of ..

"Although people call them gel coat blisters, they typically form in the laminate, so not only does the gel coat need to be removed, but so does the affected laminate. sanding all the gel coat off plus a layer or so of the laminate is a great deal of work. Then you need to dry the hull (this can take months), add back the removed laminate with epoxy, plus fair the surface, then paint."

Is quite extensive and expensive ..

All Im saying is we dont have enough Info to start any type of resto info where we have very little Information..

We Should learn to look before we start the Doom and Gloom aspects of the repair ..

It can be as simple as a 2 hr grindout and some filler..followed by some IP2000 or a few hot layers of epoxy then coat ..

But we just dont know yet..wait for it ..

YD.

 

[ondarvr]

Re: Gelcoat blister questions

So isn't that exactly what I suggested in my post prior to you chastising me for the doom and gloom.
I briefly explained the correct way to fix laminate blisters, grinding out a few obvious blisters and using something you call a "hot coat of epoxy" is not a good fix for blisters. It's a fly by night, short term, feel good band aid.

 

[Outback Jack]

Re: Gelcoat blister questions

Blister repair can be very involved if you want to do it correctly, so first you should post some pics so we can see the type and number of blisters we're talking about.


Although people call them gel coat blisters, they typically form in the laminate, so not only does the gel coat need to be removed, but so does the affected laminate. sanding all the gel coat off plus a layer or so of the laminate is a great deal of work. Then you need to dry the hull (this can take months), add back the removed laminate with epoxy, plus fair the surface, then paint.

If you plan to keep the boat on the trailer there is no need to rush into anything, and possibly nothing needs to be done at all.

This is how I will be doing my blister repairs, all epoxy, then going with the IP 2000. With my experience with fiberglass and working around condensation problems in houses, behind a sealed barrier . The blisters I have seen on my boat look to be caused from voids or a dry lay up. They are dry blisters. I feel as gelcoater and chop gun operator-fiberglasser for 4 years (25 years ago )that a boat sits in the water and if there are any dry spots or voids between the gelcoat and first layer of fiberglass a condensation will gradually build up in these voids and when the boat comes out of the water these voids blister as the heat dries the condensation out of these voids. With the variance in temps of inside the boat on a hot day to the cool water sitting against a hull, it has to happen in these voids. They only get bigger over the years. Now if there was a good chemical bond from the start and none of these products are suppose to be affected by water if fully cured and layed properly from the start, I can't see how water can cause a seperation between the products. There has to be a void form the start between the gelcoat and first layer of fiberglass. I always laid a layer of chopped glass on the gelcoat before going any farther on any product I built.Now I don't know if this is how boatbuilders did it before they added their laminate layer,but I know that is how we did it. We were mainly bathrom products but we built and few boats and had a few car molds. Now I never did much repair work in my day as I built the products we put out. Now a wet blister I have not seen to make an opinion on. This is just an opinion of mine from working around the products years ago and my thinking could be a whole lot of overthinking That is why I have come here to read the forums because there is alot of experience here at repair work( that is a whole different field then building)..Take some pics the guru's will definately swing you in the right direction.....thanks guys

 

[Yacht Dr.]

Re: Gelcoat blister questions

So isn't that exactly what I suggested in my post prior to you chastising me for the doom and gloom.
I briefly explained the correct way to fix laminate blisters, grinding out a few obvious blisters and using something you call a "hot coat of epoxy" is not a good fix for blisters. It's a fly by night, short term, feel good band aid.

Just saying there have been a few times that an hour or two with a die grinder and some epoxy filler can take care of " Visible Blisters ".

The " Hot coating " of epoxy is reference to "window coating" or meeting a window of over coats of resin. NOT to suggest you Kick it HOT .. LOL .. HOT coat is Recoat .. Not Hot Kick Coat ..

IE. IP2000 has a hot coat window of 3 hrs each .. after which you need to cool coat ( requires sanding ) .. HOT mix coat would be for non structural parts that you need to cure FAST.

Sorry for the misunderstanding .. MY bad ..

This is how I will be doing my blister repairs, all epoxy, then going with the IP 2000. With my experience with fiberglass and working around condensation problems in houses, behind a sealed barrier . The blisters I have seen on my boat look to be caused from voids or a dry lay up. They are dry blisters. I feel as gelcoater and chop gun operator-fiberglasser for 4 years (25 years ago )that a boat sits in the water and if there are any dry spots or voids between the gelcoat and first layer of fiberglass a condensation will gradually build up in these voids and when the boat comes out of the water these voids blister as the heat dries the condensation out of these voids. With the variance in temps of inside the boat on a hot day to the cool water sitting against a hull, it has to happen in these voids. They only get bigger over the years. Now if there was a good chemical bond from the start and none of these products are suppose to be affected by water if fully cured and layed properly from the start, I can't see how water can cause a seperation between the products. There has to be a void form the start between the gelcoat and first layer of fiberglass. I always laid a layer of chopped glass on the gelcoat before going any farther on any product I built.Now I don't know if this is how boatbuilders did it before they added their laminate layer,but I know that is how we did it. We were mainly bathrom products but we built and few boats and had a few car molds. Now I never did much repair work in my day as I built the products we put out. Now a wet blister I have not seen to make an opinion on. This is just an opinion of mine from working around the products years ago and my thinking could be a whole lot of overthinking That is why I have come here to read the forums because there is alot of experience here at repair work( that is a whole different field then building)..Take some pics the guru's will definately swing you in the right direction.....thanks guys

Good post here ..

YD.

 

[ondarvr]

Re: Gelcoat blister questions

Just saying there have been a few times that an hour or two with a die grinder and some epoxy filler can take care of " Visible Blisters ".

YD.

This is exactly right "visible blisters" . The problem is there may be far more blisters in the process of forming that aren't visible, which means as they continue to develop they frequently become visible at some time in the future. This means whatever time and money spent doing the quick and dirty fix and then epoxy coating the hull was wasted.

 

[oops!]

Re: Gelcoat blister questions

munch munch (sitting back eating popcorn)

 

[Yacht Dr.]

Re: Gelcoat blister questions

munch munch (sitting back eating popcorn)

Do you have room on your couch .. My wife likes M&M's in hers ( Non nut ).

YD.

PS. * awaits the pics *

 

[Fistful]

Re: Gelcoat blister questions

Hi guys,
I had a relative snap a pic of the blisters on the bottom of the hull. Unfortunately only one turned out due to camera issues. Needless to say they seemed to be pretty prevalent along the bottom although fairly small in size (pencil eraser or smaller) and none that were ruptured. I would really appreciate your thoughts on this. My current plan was to have a shallow sanding then coat with a barrier and then some sort of good wearing paint (recall this will be primarily trailered. Thanks for any input.

 

[ondarvr]

Re: Gelcoat blister questions

Those don't look good, but they aren't horrible either. Does the rest of the hull look about the same?

You have two options, grind all of the blistered laminate off and re-do it, or since you plan to keep it on a trailer, just convince yourself they don't matter and ignore them. Those don't look to be structural.

 

[Yacht Dr.]

Re: Gelcoat blister questions

I agree..does the rest of the hull look like that ? or are these in the bunk location of a previous trailer ?

I dont think it will take that much to sand with some 80 Grit until there gone and continue on with your BC coatings.

Please update if you can .

YD.

 

[cp2009]

Re: Gelcoat blister questions

Wouldn't it be a good idea to pop some of the blisters and check if there is fluid inside that smell/taste like vinegar, to check if it's osmosis?
In which case it would need to be sandblasted and washed with clear water for a period of time and dried out, then ceiled with epoxy primer?
-Just a thought, maybe off topic here, what do the pro's say? (Ondavr, Yacht Dr. etc)

 

[Fistful]

Re: Gelcoat blister questions

These blisters are randomly distributed throughout the hull below the water line, some areas more than others...not necessarily under trailer bunk locations.

cp2009,
This boat has been in dry storage for 4 years without use. I would assume any mositure in the hull would have evaporated by now.

 

[oops!]

Re: Gelcoat blister questions

not good my friend........here is your answer

You have two options, grind all of the blistered laminate off and re-do it, or since you plan to keep it on a trailer, just convince yourself they don't matter and ignore them. Those don't look to be structural.