To Gel or Not to Gel - That Is the Question

[Fishman_Tx]

Originally Posted by Solitude

Hi Fish

The links I sent have some good info from the Gougeon Brothers West system.
They are one of the leaders in the area. I went to epoxy on my blisters because I was told (as Nick said it bonds well )and is stronger. I belive that you can’t use polyester over epoxy after. It’s a one way street.

That patch sounds nasty. How is the bulkhead. Is it glassed in to the hull?

As for tools... I used a DA sander 60 grit on the blisters. Sanded the epoxy with 80. All my fixing was below the waterline and I was less concerned about beauty and more about never doing it again.

If you do decide to go epoxy. Play with it first. Mix small pots as it generates a lot of heat. Make sure that when you fill the blisters it is thick enough not to sag.

Yes send pictures. I’m sure we will all learn things along the way.

Take your time

All the blisters are large enough to require cloth to be added and these went deep. Thru the chop and cloth, between the first layer of cloth and the roving, but no significant delam. We used a grinder with a standard 4" grinding wheel to "dish" them out cuz the DA with 60g was taking forever. It requires a 30-45 deg angle with a continuous sweeping motion. Also, a high RPM is required or the disk will "hop" and give you a ripple surface rather than a very smooth bevel! Each was ground past the cloth until the stippling of the roving was starting to show. We'll let them dry til spring, which is when we'll finish the exterior.

I read that using a grinder is not a preferred method as even professionals don't do it right a lot of the time, but this is what I used for the process.

For reading, David Pascoe:
Boat Hull Blisters : Failed Blister Repairs by David Pascoe, Marine Surveyor
Boat Hull Blisters: Blister Repair Failure Part 2 - by David Pascoe, Marine Surveyor

For method, Don Casey:
Blister Repair by Don Casey

The pix are just the ones we found that were obvious, so we ground them in place and let them dry out while we removed the paint and gel.

[James S]

So you did remove all the paint and gelcoat?

[Fishman_Tx]

Yessir, one side so far, except the rudder and skeg. The rudders gotta come off, we got water down in the skeg and gotta attach a vac a suck in some resin. We know it's coming from a little sump spot under the stuffing box.
We've only removed the gel below the waterline, but are considering the necessity of removing the gel above it. Stress cracks, gouges, spider cracks, etc. We plan to paint with Interlux in the end. Trying to get some opinions in that area. This whole area above the line is rife with stress cracks. Probably due to the hit she took that warranted the patch. (see the arrow) These are old pix. I'll get some better ones this weekend.

[Solitude]

One more thing. Dont forget to check for blisters under the stand pads.

Are the blisters in the pics weeping or is it just that you have cleaned them out?

[Fishman_Tx]

Originally Posted by Solitude

One more thing. Dont forget to check for blisters under the stand pads.

We'll move those as soon as the other side is done.

Are the blisters in the pics weeping or is it just that you have cleaned them out?

Both! They wept, then I "rubbed 'em out" They weep no more!

[James S]

Big job Fish....all the best with it.
I don’t know if its necessary to remove the gel coat above the water line...if the cause of the stress cracks has been eliminated , my gut feeling is you could repair/fill them as with the gouges.....then paint.

[Solitude]

Fish read a little about tip and roll method when your ready. And of course filled everything.

My brother did this (two people 1 roll 1 tip) and it turned out perfect! One side on 25 ft took 20 min to complete. It was light blue and he had read that lighter colors are easier as they don't show mistakes as much.

I am more partial to dark hulls...

Its hard to see how much cracking and gouges you have but my first choice would be to fill it...and paint. Removing the gelcoat above the waterline may be overkill. I'm not sure what you would gain by doing it.

[Fishman_Tx]

We have a guy at the yard who is really good with the spray rig. We're going to do the epoxy spray and barrier coating ourselves as my pop-in-law is a painter by trade and used to do epoxy paints regularly. But let the other guy do the paint above the waterline if Pop don't want to play. I figure 6 coats of epoxy (2 of them barrier) after the fill and fair. Might throw in some tint in the last coat before the bottom paint. I like the Bristol blue but what-the-heck. KISS.

[Fishman_Tx]

Should the epoxy and barrier coats extend above the waterline if we plan on painting over the gel?

[Solitude]

You don't need to barrier coat above the waterline. You can use epoxy for filling gouges.

[LtBrett]

My bet is whatever cracking is in the gel coat will reappear in the paint sooner or later. I may have mentioned that I re-glassed my transom instead of dealing with the myriad of spider cracks/checking. My transom was originally black fiberglass. The sun weathered it much faster than the white fibreglass parts of the boat. The p.o. sanded and painted the transom with imron. I bought the boat about three years later and every little crack was showing through the imron. So I glassed it. As I was working on my boat, I met a gentleman with an 80' yacht stored near mine. His boat was dark green fiberglass that the sun had also cracked. You could see where he painted over the cracks to try to cover them up, but the cracks came right through. I drew two lessons: first, get rid of the cracks prior to paint. Second, dark hulls wear worse than white. Not to mention that dark hulls show every imperfection. Painting an old boat a dark color leads either to disappointment or to substantially more prep time.

To answer your question about extending the barrier coat above the water line. You now have two different levels of thickness on your hull. If you remove gel coat right to your water line, you've got an easy way to hide the seam you created--painted waterline. Carry barrier coat above your water line, you've created a blending problem.

Brett

[s/v Jedi]

Fish: I think I made a mess of my previous post. What I meant is that you roughly fair using colloidal silica filler after the first or second coat of epoxy. After that, let it cure for at least 24 hours, sand and continue with coats of epoxy (you'll never be able to do all 6 coats wet on wet anyway).
You can't do final fairing before all but one coat is on. If you do the rough fairing nicely, and considering it's below water line anyway, you may be able to skip final fairing completely.

About the blisters drying out. You must wash and wash and wash again for at least the coming week. Don't worry that you make it wet every time, it's much more important to wash it out.

Now "the plug": man I can't believe that. Well, grind it completely out and bevel it. The more round it is the better. You will end up with a hole and the bulkhead across it. A little more work but a stronger result so no worry.

This is how to build it up:

Start on the inside.Cut pieces of formica (or thin plywood) to close the hole on the inside. Overlap the hole 2 inches where possible. Just put them there so you can get them when you need them.

Next, the outside. You will need a piece of plastic foil and a somewhat smaller piece of formica. Both must fit over the hole incl. the beveled edge. You also need a work surface big enough or a couple of A-frames. Put the formica on it (nice side up) and drop the plastic over it so that it overlaps everywhere.
This is where the fun starts. Cut a piece of cloth so that it fits the hole and overlaps the complete beveled edge. Put it on the plastic foil on the table. Next, cut woven roving to fit but an inch smaller then the cloth. Put it on top of the cloth on the table, making sure that they are aligned top-to-top if you understand what I mean. Finish with another layer of cloth, again, an inch less overlap. Put it on the stack again.

Sit back, have a smoke and do some yoga. When ready, take the stack of three layers from the plastic and put them with the same orientation on a second clean surface. Take the first layer from that (the smallest) and put it back on the plastic. Mix a batch of epoxy and hardener (start with 3 "pumps" ; slow hardener if warm climate) and just pour it in the center of the cloth. Use a plastic spreader to work it outwards so that it completely wets out and air bubbles are worked out. The cloth must go transparent. Add more epoxy if needed, guess how many extra pumps you need. Move excess to the center. Now, drop the woven roving on top, center it so that it overlaps the first layer everywhere and smooth it out. Do the pouring and spreading again and repeat for last layer of cloth. On that last layer, you must remove excess epoxy that would sag otherwise.

Now you need more hands. Take a deep breath and put the whole thing, incl. plastic and formica onto the hole. Don't press too much in the middle. This is easier than it sounds although it is often done while cursing ;-) The helper must be experienced with electric drill and screwdriver. He/she must drill holes through the formica into the hull very close to it's edge (1/4") all around every 2 inches and put small screws in. test for right size drillbit and screws into the hull laminate beforehand.

If that is secure you can breathe again but not for too long because there's more work on the inside. Start with looking and the spreader to estimate how many layers you need to add before you are flush with the inside of the hull. Use woven roving for all but the last layer. Work on each side of the bulkhead, don't try to get a layer behind it. Also, keep the fibers inside the hole, don't let them come onto the inside of the hull or the bulkhead. I would advise to do each layer apart here. Instead of pouring epoxy, you use a roller and/or brush. If the epoxy runs a lot, add a little colloidal silica filler but keep it as thin as possible or it won't wet out good enough. You can still use the spreader to smooth it out and work the air away to the edges.
When you are flush, cover it with plastic foil and screw the formica on.

After 24 hours you get the shakes and take the formica off. It should come off and also the plastic should come off. If not, don't pull too hard, even if that means you have to grind the formica away (can only happen when the plastic had holes/cuts) or sand the plastic away. Admire it and move inside. Here, you need to sand until it is dull. Also sand the bulkhead around the area of the hole. You know how to do fillets? You must put a fillet on the patch-to-bulkhead joint. Use a 50/50 mix of high density and colloidal silica fillers and make it a thick peanut butter consistency. Use a round-ended stick of about 1/2" diameter to scoop it on and shape it. Scrape excess away with flat stick or putty knife (use that further on for the fillets). When the fillets are on, start cutting 3" wide strips of woven roving to go over the fillets, creating a strong bond with the bulkhead. The fillets are just to create a minimum radius for the fibers. When the fillets are gelled but still tacky (doesn't take too long with the filler added and the thick layer), put some plastic wrap on a work surface, put a strip roving on and wet it out. Add some colloidal silica to the rest of the epoxy and slap the roving onto the fillet. Spreader, brush, roller etc. Now you were smart and got some 4" wide fiberglass tape. Cut pieces to length so that they are 2" longer than the strips of roving. Wet out and put it over the roving.
Now the finishing touch: cut fiberglass cloth to cover and overlap the hole and the joint (from one piece if possible) including overlapping the fibers on the joint. Wet out the dry part of the patch AND the cloth and put it on. Make it look extra good now. Let fully cure.

The finishing is sanding and fairing and sanding. After that is done, add two coats of epoxy both outside and inside.

If you have good access to that hull-to-bulkhead joint, examine it before the job and decide if you want to reinforce the whole joint instead. If it's in view, you can get a much better looking result when you glass the whole joint.

This is something that every cruiser who can sand and paint can do. Don't hesitate, the worst that can happen is to put the grinder to it and start over ;-)

cheers,
Nick.

[Fishman_Tx]

Originally Posted by LtBrett

My bet is whatever cracking is in the gel coat will reappear in the paint sooner or later. I may have mentioned that I re-glassed my transom instead of dealing with the myriad of spider cracks/checking. My transom was originally black fiberglass. The sun weathered it much faster than the white fibreglass parts of the boat. The p.o. sanded and painted the transom with imron. I bought the boat about three years later and every little crack was showing through the imron. So I glassed it. As I was working on my boat, I met a gentleman with an 80' yacht stored near mine. His boat was dark green fiberglass that the sun had also cracked. You could see where he painted over the cracks to try to cover them up, but the cracks came right through. I drew two lessons: first, get rid of the cracks prior to paint. Second, dark hulls wear worse than white. Not to mention that dark hulls show every imperfection. Painting an old boat a dark color leads either to disappointment or to substantially more prep time.

To answer your question about extending the barrier coat above the water line. You now have two different levels of thickness on your hull. If you remove gel coat right to your water line, you've got an easy way to hide the seam you created--painted waterline. Carry barrier coat above your water line, you've created a blending problem.

Brett

Crap! That's what I was afraid of. The gel's got to go. Thx man! Saved me a lot o hassle later. I had heard it was possible for the cracks to transfer thru over time.

[Fishman_Tx]

What I meant is that you roughly fair using colloidal silica filler after the first or second coat of epoxy. After that, let it cure for at least 24 hours, sand and continue with coats of epoxy

I gotcha; put a coat or 2, rough fair-in, couple more coats, final fair if necessary, barrier coats (w/additive).

About the blisters drying out. You must wash and wash and wash again for at least the coming week. Don't worry that you make it wet every time, it's much more important to wash it out.

That's a given, we're wet sanding anyway since the last 3 weekends; you know, sand, wash down, sand, wash down, etc.. keeps the dust down too, gotta respect the neighbors.

As for the rest...
Holy Sh*t, sounds like you done this before!

Once again, Thx Guys for taking the time to school us newbies!

[s/v Jedi]

About the top-sides of the hull: removing all gel coat means hundreds of hours of fairing later. Think hard before you do that. If the gel coat isn't delaminating, I would at least try the following on a couple of cracks before making that decision:

Put a 1/4" drill bit in the machine and drill holes through the gelcoat at the ends of the crack. Make sure you have the very end of the crack not further than half-way the drill hole. Try not to drill too deep into the fiber; you can use a depth-stop when you decide to do all cracks later.
Countersink those holes so that they are at least 3/8" at the top but 1/2" is much better.

The rest is for a dremel or Fein Multimaster. Grind out the crack until you get to the fiber and bevel it 12:1. Check the fiber to see if the crack goes in there too but I have never seen that yet.

Vacuum it out (no cloths, hands, compressed air, solvents etc. use a vacuum!) and fill it with a stiff batch of epoxy and colloidal silica filler. I really really don't see that crack coming back. To prevent print through, sand it and the surrounding inch or so deeper than flush and fair it out with an epoxy and fairing-filler batch. Sand flush and coat with epoxy resin once or twice and sand flush again.

Even though this looks like a lot of work (it's much quicker than it sounds), it's nothing compared to fairing the complete hull!!!

cheers,
Nick.