Little help with Replacing Tabbing (first time doing this..)

ShawnL · May 8, 2026

It doesn't need to be smooth, etc. You just want to remove the paint and any dirt so you have a good surface to bond to. From what you've shown in the photos, you're ready to go.

Project_Mayhem · May 9, 2026

Tabbing is usually quick and a bit sloppy from the factory. I've sailed two catalinas with broken tabbing in the hull around the companionway. No noticeable difference or additional damage. You should ensure that the hull is not being significantly pushed in by your trailer's supports. If it is, do this job in the water. This is one of the easier and more forgiving fiberglass jobs.

colemj · May 9, 2026

It is hard to see what is catching your eye wrt flat vs non flat areas. From the pictures, it looks like you are almost there, in that you just need to grind off the gelcoat and expose a roughed surface of glass underneath. Looks like you have pretty much done most of this.

If you are concerned about the indentations caused by the weave of the glass, then that isn't too much of a concern, but a grinder should even that out pretty quickly. If your concern is the pinholes and little gaps in one of the pics, then those are no concern at all.

You have the right materials, and congratulations on getting 6" biax tape instead of trying to cut strips yourself. That tape role with edge binding is going to make your job much easier, and even more strong.

Instead of using 4" and 6" wide tapes (you didn't mention having 4"), I'd just use two layers of 6". Put the first layer on with 4" on one side of the joint and 2" on the other, and the second layer the opposite of that. This way you end up with 4" and 8" staggered tabbing

Before glassing on the tape, brush or spread on the area you are going to install tabbing a layer of epoxy thickened with colloidal silica to a thin gruel consistency. This will prep the surface and fill any small gaps or dips. Then wet out the tape you need and stick it on. Use a brush or roller or spreader to remove any bubbles and smooth down the tape. My favorite way is to use a cheap 2" chip brush and quickly and repeatedly poke at the tabbing with the bristles (stippling). This pushes out bubbles and doesn't cause the tabbing to move around like a spreader or roller. Also makes it easy to get the tape to sit down into the joint.

Mark

colemj · May 9, 2026

Sorry if this is obvious and you knew it, but the side of the biax containing the chopped strand goes down against what you are glassing to.

Mark

colemj · May 9, 2026

Carl Wonderful said:
Yeah the 6" was nice....although its really thick and was hard to get saturated...but I think it went okay. Looked clear by the time I was done. What would be the next step down (little thinner) than the 6" 1708?

17oz biax is pretty much the most common standard for tape. The next step down I'd guess would be 12oz, but that would be a specialty item for a tape. Common for cloth though. For tabbing, where tape is very useful, 17oz is almost always the right choice.

Carl Wonderful said:
I was using the chip brush and doing the dabbing/tapping. I'm an artist/ painter so I feel really good with a brush...I actually use those same chip brushes to make landscapes and other fine art paintings, lol. I did find it hard to do the tapping at the bend? I sort of just scooped/tapped the brush at the bend cause you really cant get "behind" the fiberglass there to push air out. Any tips or tricks on that?

Not sure I understand what the "bend" is? If you mean the 90* angle from the bulkhead to the deck/hull, then that should be relatively easy. Either bend the tape in half lengthwise and stick it in the angle and work both sides to their position, or start from putting half of it on the bulkhead and work it up to the deck/hull through the angle. The point of stippling with the chip brush is to either push the air through the tape, or to move any air bubbles toward the edge of the tape to release. Pushing air through the tape is more difficult with epoxy than polyester or vinylester resin, depending on which epoxy you use.

If I'm using epoxy for this type of work, I'd choose a thin laminating epoxy. West System is a general epoxy that covers a lot of ground but really doesn't do anything specific very well. It is my least favorite epoxy to work with, but it has the advantage of its characteristics being reproducible - so if you don't work with it a lot, but you have projects every once in a while, you always know what to expect. Good for many, but working with it annoys me.

Carl Wonderful said:
I liked your suggestion to do a 4", 2" then 2",4". That makes sense. But I needed to get this done tonight and just wasn't able to grind any more area to make that happen. So I used a 6" strip and also cut another 6" strip down to a 4" strip. I can see why you don't want to cut it up. Got little messy. Any way to not get thousands of tiny glass pieces all over the place and on myself?

Yes, that is why I said you were smart to get the tape! There is no way around making a mess when cutting tape strips from cloth, and it is much worse trying to cut down an existing strip. You want a real mess, try cutting strips from 1800, which is 17oz cloth at 90/90 orientation rather than 1708's 45/45.

Carl Wonderful said:
So do you wet out the tape on... like a separate surface? I used a piece of thick plastic to wet it out..both sides...then took a plastic scraper thing and lightly took excess epoxy out..then moved it to the tabbing area and used the brush to tap tap tap. Is that weird or wrong or what?

How I wet and install glass depends on what I am doing. In your application, I would wet it out on a sheet of plastic and get it fully saturated, then squeegee out excess before installing - just like you did. Your instincts were 100% correct there. For large surface layups, where multiple layers are going on wet on wet, I would put dry glass down and wet from there if horizontal. If vertical, how I'd do it would be dependent on many variables.

Carl Wonderful said:
Lastly....Do you have a favorite tool or technique to grind down for prep that isn't super messy?

A grinder is my favorite fiberglass tool. I even use it through early stages of fairing. Once one learns the touch and control of a good grinder, and has reproducible quality discs, it is surprising how precise it can be.

But there is NO WAY to get around the mess. Yes, you can tent, bring in multiple shop vacs held at different angles by several people, but all that does is prolong the agony of the job. My motto is to get in, let the mess be whatever it is, and get out as fast as possible. Where I do most of my work in the tropics, fully suiting up and crawling into a tight space will kill you before you even start grinding. I've developed a relative lack of sensitivity to the itching and poking of glass fibers in my skin, so I've learned to live with it for the day it takes to go away.

Pic of a recent bulkhead addition project for your amusement.

Mark

Project_Mayhem · May 9, 2026

If you must be in an enclosed space with a grinder, get a full face mask. It's a big upgrade from a half face mask as far as breathing in and getting dust particles in your eyes

colemj · May 9, 2026

Project_Mayhem said:
If you must be in an enclosed space with a grinder, get a full face mask. It's a big upgrade from a half face mask as far as breathing in and getting dust particles in your eyes

I have one. Inside a 100F locker in 95% humidity, it fogs up instantly. Even with antifog on it, the sweat pouring into it renders visibility nill within a minute. If by some miracle I have enough visibility to see the work through a few narrow streaks, the grinding dust covers it as soon as I start grinding.

Sometimes the best option is make the punishment as short and quick as possible.

Mark

Project_Mayhem · May 10, 2026

colemj said:
I have one. Inside a 100F locker in 95% humidity, it fogs up instantly. Even with antifog on it, the sweat pouring into it renders visibility nill within a minute. If by some miracle I have enough visibility to see the work through a few narrow streaks, the grinding dust covers it as soon as I start grinding.

Sometimes the best option is make the punishment as short and quick as possible.

Mark

Till the day I die I will never forget being crammed into the bow of my boat with a bow eye in my back grinding away at the underside of the fore deck. It was 90-95F outside. I was in a boat, inside a second story warehouse. I have a Chinese full mask with 3M filters on it. Fogging hasn't been an issue. I've had some Chinese half masks that are better than 3M's and vice versa. Even with a full face mask, I still get some fiberglass dust inside

colemj · May 10, 2026

Carl Wonderful said:
About the bend...I was meaning whats a good technique to work the air bubbles out from the bend, the 90 degree.. .cause you cant really get the brush at a low enough angel to work outward (like you would on a all flat surface) cause the handle hits the fiberglass. But, I didn't realize you can work the bubbles out by just taping straight down (perpendicular)... which I think that's what you mentioned?

Yes, use the bristles perpendicular to the work. You can force bubbles through the glass, and in any direction across the glass toward an edge that you want. Just keep poking at them. I don't use brush strokes to move bubbles, just the stipple action of poking at them. I don't think brush strokes would work well for moving bubbles. If you need them to travel a long distance sideways, then a spreader is better for that. Or get a fiberglass roller, which is really the correct tool. I have them, and use them at times, but their cleanup is a pain. Also a bit cumbersome for tabbing.

Carl Wonderful said:
Yeah, I have West systems 105, 205 (&206). I got a good amount of it and using that. Just curious, Is there something in particular that you don't love about it? What's might be a better epoxy or even resin choice for something like this? I've heard of polyester and vinylester but never tried them.

West System is an all-around general epoxy. It doesn't do anything great, but it also does about everything good enough. My main dislike of it is it doesn't wet out or tool well, and the post cure blushing is terrible. Also the price. For laminating and tabbing, I prefer a thinner epoxy that doesn't blush. But for your project, you can't beat the availability and package convenience of West System.

But mostly, I don't like working with epoxy. Even though I've probably worked with epoxy more than polyester and vinylester. Epoxy is such a pain with cure times, not being able to adjust reaction rates to the project and environment needs, the critical need to be absolutely accurate with mixing volumes, having to deal with the blush and subsequent grinding to laminate over previous cure, and several other reasons. Not to mention it is very dangerous and a significant health hazard. In fact, I can't think of a single positive aspect of epoxy other than it is the correct resin for certain jobs.

Vinylester can take epoxy's place for most of these jobs, and is much better to work with in the above aspects, but it is a bit tricky if one doesn't have experience with it, and is a bit sensitive to environmental conditions.

In the picture where I was installing bulkheads in the bow of the boat, I was using polyester resin. Most will tell you this is inappropriate, but they are wrong. However, the prep is critical when using polyester for secondary bonding, and I have a lot of experience doing this.

Carl Wonderful said:
When you said "If multiple layers are going on wet on wet, I would put dry glass down and wet from there if horizontal" Do you mean you would just immediately stick the totally dry 2nd biaxiel onto the 1st biaxiel, then just wet out the face side of it and go from there?

If going wet on wet with the west coast epoxy and biaxiel that I have, I can just immediatly put the subsequent layers on top of the last one...no need to wait right?

Yes, wet out one layer, lay down the dry glass for the second layer and wet it out, repeat for the number of layers planned. But for tabbing, this really isn't a good method. Better to wet out the glass, then apply it.

Carl Wonderful said:
Can you recommend a grinder (& favorite disks) for this kind of work?

The most important thing about the grinder is familiarity and experience with using the one you have. Otherwise, any decent brand is fine. I've even used Harbor Freight ones, but they aren't very reproducible as they get used until they fail. But I find discs are important. I like 3M discs, but there are other good ones too.

In the picture above, you can see my Milwaukee cordless grinder with a cheap 24 grit disc on it. This is about the least ideal combo, but I was just hogging out glass with it, not doing anything neat or precise. If I wasn't crammed into a tight space, I'd be using my corded Makita grinder, and if I was doing more precise work, it would have 3M discs.

Carl Wonderful said:
Yea, I was wondering about the mess of fiberglass fibers and cut bits particularity. I don't mind a mess and hard work, I've been getting proper messy cleaning/scrubbin every square inch of my boat all week, even full on crammin' myself down in the lockers and bilge areas cause I cant have any mold anywhere due to health issues. But since fiberglass is totally new to me, and when I started cutting down a few pieces from 6" to 4".. then looked down at my arm with my headlamp on... I was like whooa momma! Looked like millions of tiny little pieces of glowing glass parts all over me and everywhere!? Wasn't expecting to see that. I mean do they get into fabrics and cushions and stuff and haunt you. It seems like that'd be something you can never really get rid of I'd think? Or is it not a big deal...you just vacuum and shower and wash your clothes and its all fine?

Wondering the same about grinding fiberglass? I guess that's not really glass anymore...more just powder. But how do you clean your boat after that film covers everything?

You should absolutely tent off from the work area as much as possible. Fiberglass dust is almost impossible to get rid of, or get out of fabrics.

Those clothes I'm wearing in the picture above? The T-shirt and shorts together cost <$3. They just get thrown in the dumpster afterward. No way would I be allowed to put them in the washer.

Mark

Project_Mayhem · May 11, 2026

If you'd like to save some money on epoxy the next time around, try Totalboat. I can't tell the difference between it and West Systems. There's also some epoxies that advertise little to no blush

Davidasailor26 · May 11, 2026

Carl Wonderful said:
The blush thing sort of has me confused.

So the blush only happens sometimes?....
If it does, you can see it as a white-ish film?
Then if you see it you have to whip it off with just water (not solvent) or else any next layers will not stick.

Seems mysterious. Any tips?

Pretty much, yes. It’s a byproduct of the curing process. Some resins are more susceptible to blushing, and some curing conditions, especially high humidity, can make it worse. It can also feel like a wax on the surface. Warm water before sanding should take care of it.

colemj · May 11, 2026

Carl Wonderful said:
The blush thing sort of has me confused.

So the blush only happens sometimes?....
If it does, you can see it as a white-ish film?
Then if you see it you have to whip it off with just water (not solvent) or else any next layers will not stick.

Seems mysterious. Any tips?

The blush is caused by the amine-based hardener and not the resin. Some epoxies use different hardener chemistries that prevent or greatly attenuate blushing. The extent of blushing is related to cure rate, and I've found most 5:1 epoxies like West to blush, while 2:1, 3:1, and even 4:1 do not. Most epoxies advertised as non-blushing seem to be 3:1.

The blush will happen all of the time with epoxies that blush, and may or may not present as a visible film. It almost always can be felt, though. It will feel a little slippery, especially if slightly wet.

Yes, one just washes it off with water. If left on, the next layer will not stick well. You should also lightly tooth the cured layer after washing off the blush.

Mark

colemj · May 11, 2026

Carl Wonderful said:
So is it just best to assume that the blush will always be there and wipe with warm water after any epoxy work?

How long after applying to see the blush. I mean does it happen when its dry to the touch or does it not happen for days/weeks like when the epoxy it 100% fully cured?

The blush is present on epoxy as soon as it is initially cured (full cure actually takes days or even weeks for epoxy). If you can catch a layer while still very green (sticky and a little soft), but not initially cured, you can laminate on it before the blush sets. This is actually good practice for laminating, but epoxy's cure time to the green state often presents timing issues for doing so.

Mark

Little help with Replacing Tabbing (first time doing this..)

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