As many of you undoubtedly recall, I picked up a new-to-me bass boat at the tail end of last season.

Along with it came a nice gouge in the keel, just forward of the pad. Of course, it was at a slight angle (maybe 15 degrees) ACROSS the keel, not straight in line with it.

I did my best with some tiger hair/bondo glass and an epoxy rattle can.

However, the time has come to complete this repair in the proper fashion (I didn't remove all the old cracked gelcoat from around the edges of the damage, just sanded everything "flat enough" to stuff the bondo hair into).

I've ordered some 1.5oz CSM, laminating polyester resin, P-14 filler, laminating gelcoat, PVA, and assorted sandpapers and polishing compound.

The plan is to grind out all the old filler that I stuck in there hastily last fall, as well as all the damaged gelcoat, until I get down to perfectly smooth, solid fiberglass.

Once that's done, I'll bevel that into the surrounding several inches, and then clean the whole thing with acetone.

Resin will be catalyzed at 10-12 drops of MEKP per oz of resin, and the CSM will be laid in to build the area back up again.

Once complete, it'll be sealed with PVA so it kicks, then finished with P-14 to even it off before gelcoat (which will be hand-painted on, then sealed with PVA prior to sanding).

After sanding and polishing, the area should be a professional-grade repair.

The most difficult part that I anticipate will be getting the contour correct. This is at the far back end of the keel, perhaps 4-5 feet in front of the transom (it's a 20' bass boat). So, it's not a SHARP keel like the front, but it's not quite "flat" like the pad would be.


A couple questions:

Anything I'm missing here?

Any suggestions on how to make sure I get the contour correct other than take my time and look at it from many angles?

I'll be using a 5" palm sander, and a hand block sander, doing this on my back in the driveway (not optimal, I know, but I works with what I have to works with). I MIGHT try backing the boat to straddle the ditch in front of my house (if it's dry) to give me a bit more room to work with.

For the polishing duties, I'll be using Meguiar's #67 on a wool bonnet on that same 5" palm sander (a Porter Cable).

I think I remember posting back to you about this. Have you inspected the stringers?

It is WAY more important to be sure the stringers are solid and the other interior supports are good, before working on the outer hull etc.

That is rather difficult to do without cutting holes in the deck and/or removing the cap.

I did have the seat deck off, which covers the fuel tank, and found no rot under there at all.

The previous damage did not go completely through the hull, and was solid after I sanded it, so I have no reason to think that there would be any stringer damage.

In addition, at high speed (>60mph) the boat handled just fine, so there are no hooks or other soft spots in the pad anywhere.

Lastly, Stratos switched to 100% composite construction in 1997, my boat is a 1998, so I have no reason to think there's any rot in the stringers.

Use a 24" straight edge from bow to stern over the repair and that should get you pretty straight/even.

It sounds like you have a pretty good plan. I have been repairing fiberglass sailboats for 30 years and have a few tips.

Working under a boat on a trailer sucks. Drive the trailer up on ramps or jack it up. Ideal if you can get it high enough to use a creeper.

Grinding fiberglass overhead also sucks. A $20 box fan will take a lot of misery (and itch) out of the job.

Laying up fiberglass overhead is the worst kind of suck. Do the layup on a clean piece of wood. Wet out the hull and transfer the layup with plastic gloves. Make sure to get all the air out of the layup. The plastic bondo spreaders work well.

I'd skip the PVA over the fiberglass. I only use PVA over gelcoat.

Matching contours is the toughest part. I use a fiberglass batten but an aluminum yardstick works well. On edge it is a straight edge, slight angle will work for curves. Blacken the edge with a sharpie and it will transfer to the repair area and show high spots.

Gelcoat doesn't brush well. For small repairs I use a Preval sprayer. 7-$8 at most hardware stores and disposable. You have to really thin the gelcoat to go thru a Preval so that means extra coats.

Good luck,
Fred

quote:

Originally posted by F_L:
It sounds like you have a pretty good plan. I have been repairing fiberglass sailboats for 30 years and have a few tips.

Working under a boat on a trailer sucks. Drive the trailer up on ramps or jack it up. Ideal if you can get it high enough to use a creeper.

Grinding fiberglass overhead also sucks. A $20 box fan will take a lot of misery (and itch) out of the job.

Laying up fiberglass overhead is the worst kind of suck. Do the layup on a clean piece of wood. Wet out the hull and transfer the layup with plastic gloves. Make sure to get all the air out of the layup. The plastic bondo spreaders work well.

I'd skip the PVA over the fiberglass. I only use PVA over gelcoat.

Matching contours is the toughest part. I use a fiberglass batten but an aluminum yardstick works well. On edge it is a straight edge, slight angle will work for curves. Blacken the edge with a sharpie and it will transfer to the repair area and show high spots.

Gelcoat doesn't brush well. For small repairs I use a Preval sprayer. 7-$8 at most hardware stores and disposable. You have to really thin the gelcoat to go thru a Preval so that means extra coats.

Good luck,
Fred

Yes, working overhead sucks. I laid in the bondo hair last fall this way, I have a decent idea what I'm in for. I'll try to find some ramps, if they'll fit under the trailer.

Good tip about the box fan, I do have one. I also ordered a proper 3M respirator.

To get air bubbles out, I ordered one of the aluminum rollers with the grooves in it for $13.

If you wouldn't use PVA over the glass, what would you use? I'll be using laminating poly resin, so it has to be sealed up somehow in order for it to cure before I can sand it.. ?

Good tip about the sharpie, thank you!

Gelcoat typically doesn't brush well, I agree. However, I have been watching a series of videos by (come to find out) a local guy (BoatWorksToday on YouTube), and he has a method of brushing gelcoat on that actually does work pretty well. I'm going to give it a try. If not, I have 2 of the prevail sprayers coming (planning to use them for the PVA applications).

Good luck. Most have it covered here. Depending on depth of gouge I have mixed up an epoxy colloidal silica slurry to shallow out the gouge after first roughing up...basically rough it, single layer fine glass mat (if you can without having voids) and then a bit of colloidal slurry, then the final layup. That way no air voids, actually fairly strong and with layup very strong and sandable. If you need to shape, I use small amount of the colloidal expoxy like bondo on a body - dry and sand. Then gelcoat.

I've been working on boats since a kid - but after rebuilding a 76 seacraft 18 (floor, transom, stringers) I won't do that again. Grinding glass even in a bunny suit sucks.

quote:

Originally posted by FlyingScot:
Good luck. Most have it covered here. Depending on depth of gouge I have mixed up an epoxy colloidal silica slurry to shallow out the gouge after first roughing up...basically rough it, single layer fine glass mat (if you can without having voids) and then a bit of colloidal slurry, then the final layup. That way no air voids, actually fairly strong and with layup very strong and sandable. If you need to shape, I use small amount of the colloidal expoxy like bondo on a body - dry and sand. Then gelcoat.

I've been working on boats since a kid - but after rebuilding a 76 seacraft 18 (floor, transom, stringers) I won't do that again. Grinding glass even in a bunny suit sucks.

I've seen that method as well.

Thing is, 95% of the research I've done (as well as the advice of the local guy who I'm going to trailer it to to "bail me out" if I screw it up) all says not to use epoxy resin on repairs that will be finished with gelcoat.

Yes, I've seen the recent(ish?) research that indicates that it is possible to get a solid polyester (gelcoat) bond onto epoxy if the surface is prepped JUST RIGHT - but being that this is my first repair, and I'll be doing it upside-down, I figure my changes for success are higher if I stick to poly everywhere.

Plus, while epoxy is "harder", it doesn't flex as much/as well as poly. Give the location of this repair, and the impact of waves at high speed, I'd rather not have the potential for any cracking of the repair in the future (even if that concern is only in my head - being that this is my first repair, confidence in that repair will have a big impact on how I drive the boat in the future!).

This message has been edited. Last edited by: exx1976,

quote:

Originally posted by exx1976:

quote:

Originally posted by F_L:
It sounds like you have a pretty good plan. I have been repairing fiberglass sailboats for 30 years and have a few tips.

Working under a boat on a trailer sucks. Drive the trailer up on ramps or jack it up. Ideal if you can get it high enough to use a creeper.

Grinding fiberglass overhead also sucks. A $20 box fan will take a lot of misery (and itch) out of the job.

Laying up fiberglass overhead is the worst kind of suck. Do the layup on a clean piece of wood. Wet out the hull and transfer the layup with plastic gloves. Make sure to get all the air out of the layup. The plastic bondo spreaders work well.

I'd skip the PVA over the fiberglass. I only use PVA over gelcoat.

Matching contours is the toughest part. I use a fiberglass batten but an aluminum yardstick works well. On edge it is a straight edge, slight angle will work for curves. Blacken the edge with a sharpie and it will transfer to the repair area and show high spots.

Gelcoat doesn't brush well. For small repairs I use a Preval sprayer. 7-$8 at most hardware stores and disposable. You have to really thin the gelcoat to go thru a Preval so that means extra coats.

Good luck,
Fred

Yes, working overhead sucks. I laid in the bondo hair last fall this way, I have a decent idea what I'm in for. I'll try to find some ramps, if they'll fit under the trailer.

Good tip about the box fan, I do have one. I also ordered a proper 3M respirator.

To get air bubbles out, I ordered one of the aluminum rollers with the grooves in it for $13.

If you wouldn't use PVA over the glass, what would you use? I'll be using laminating poly resin, so it has to be sealed up somehow in order for it to cure before I can sand it.. ?

Good tip about the sharpie, thank you!

Gelcoat typically doesn't brush well, I agree. However, I have been watching a series of videos by (come to find out) a local guy (BoatWorksToday on YouTube), and he has a method of brushing gelcoat on that actually does work pretty well. I'm going to give it a try. If not, I have 2 of the prevail sprayers coming (planning to use them for the PVA applications).

Just the surface of the laminating resin stays tacky. I have never had any trouble grinding through it. I use 36-40 grit for all glass grinding. Finer grits might clog up. PVA certainly won't hurt.
Keep us updated and gets some pics.
Fred

Sounds like you have good advise so far.

The one safety factor about working with MEKP is,
when you have cleaned you implements in acetone, be aware that the pink residue (mekp) in the bottom of the contain is a potential hazard.
If the crystals have dried out and laying on a table or other surface, DO NOT drag anything across it. It could spark and catch fire.

If you are using a small amount of materials you most likely won't have a problem. Just thought I would mention that.

Have fun on the water.

quote:

Originally posted by F_L:

quote:

Originally posted by exx1976:

quote:

Originally posted by F_L:
It sounds like you have a pretty good plan. I have been repairing fiberglass sailboats for 30 years and have a few tips.

Working under a boat on a trailer sucks. Drive the trailer up on ramps or jack it up. Ideal if you can get it high enough to use a creeper.

Grinding fiberglass overhead also sucks. A $20 box fan will take a lot of misery (and itch) out of the job.

Laying up fiberglass overhead is the worst kind of suck. Do the layup on a clean piece of wood. Wet out the hull and transfer the layup with plastic gloves. Make sure to get all the air out of the layup. The plastic bondo spreaders work well.

I'd skip the PVA over the fiberglass. I only use PVA over gelcoat.

Matching contours is the toughest part. I use a fiberglass batten but an aluminum yardstick works well. On edge it is a straight edge, slight angle will work for curves. Blacken the edge with a sharpie and it will transfer to the repair area and show high spots.

Gelcoat doesn't brush well. For small repairs I use a Preval sprayer. 7-$8 at most hardware stores and disposable. You have to really thin the gelcoat to go thru a Preval so that means extra coats.

Good luck,
Fred

Yes, working overhead sucks. I laid in the bondo hair last fall this way, I have a decent idea what I'm in for. I'll try to find some ramps, if they'll fit under the trailer.

Good tip about the box fan, I do have one. I also ordered a proper 3M respirator.

To get air bubbles out, I ordered one of the aluminum rollers with the grooves in it for $13.

If you wouldn't use PVA over the glass, what would you use? I'll be using laminating poly resin, so it has to be sealed up somehow in order for it to cure before I can sand it.. ?

Good tip about the sharpie, thank you!

Gelcoat typically doesn't brush well, I agree. However, I have been watching a series of videos by (come to find out) a local guy (BoatWorksToday on YouTube), and he has a method of brushing gelcoat on that actually does work pretty well. I'm going to give it a try. If not, I have 2 of the prevail sprayers coming (planning to use them for the PVA applications).

Just the surface of the laminating resin stays tacky. I have never had any trouble grinding through it. I use 36-40 grit for all glass grinding. Finer grits might clog up. PVA certainly won't hurt.
Keep us updated and gets some pics.
Fred

Yep, the video series said that in order to avoid the top tacky surface, just PVA it so it cures then it's easier to sand.

I've got a bunch of 60 grit 5" discs to use on my palm sander to handle most of the heavy grinding/shaping duties.


The plan is to PVA it, let it fully cure, then wash off the PVA with soap/water and then get to the grinding/shaping. Then wash/acetone, then P-14, then sand that with some 180, then gelcoat, then PVA (repeat wash/rinse/acetone) and finish that with 180, 320, 600, 800, 1200, 1500, then polish.


I'll be sure to get some pics. The local guy wants to see how I do, so I'll be emailing him pics along the way as well.

Looks like this has turned into a next weekend project (forecast is 70s) since it's 40 here right now, and not supposed to be a whole lot warmer this weekend - and rain forecast for tomorrow.

quote:

Originally posted by USMCE4retired:
Sounds like you have good advise so far.

The one safety factor about working with MEKP is,
when you have cleaned you implements in acetone, be aware that the pink residue (mekp) in the bottom of the contain is a potential hazard.
If the crystals have dried out and laying on a table or other surface, DO NOT drag anything across it. It could spark and catch fire.

If you are using a small amount of materials you most likely won't have a problem. Just thought I would mention that.

Have fun on the water.

I did not know that. Thank you.

I'll be doing all my materials mixing in 1-quart disposable plastic containers that I ordered specifically for this purpose.

You are welcome.
I have, unfortunately, worked with fiberglass most of my life. I couldn't add anything more to the discussion that hadn't already been covered. Just didn't want you to have to go through all the work, then have the added expense of buying an urn to put the ashes of you boat in in the event of a fire

Have fun.
......................................
edited to add: A note on spraying Poly Vinyl Alcohol.
When spraying it on, don't try to cover it all in one coat. Spray lightly even if it looks like it is not covering well. Multiple coats(drying in between) is far better than having fish eyes or runs. Also, wet your floor so that dust isn't stirred up in the air.
If you do have a little mishap with the PVA you can always sand very lightly with very fine sand paper. If yo sand in tiny circles you won't have the tendancy to dig into the surface like you would sanding back and forth. Back and forth also tends to grab the PVA ( still somewhat sticky, even though it is dry), which would tear off a patch of PVA. When you are ready to spray on you gelcoat apply some good mold release on the pva.

Epoxy bonds with 6x the strength to old fiberglass than does polyester resin. Polyester on top of epoxy works fairly well if it is done "wet on wet". Usually I would do the entire repair in epoxy, than topcoat with polyurethane paint (LPU). LPU works satisfactory at an underwater location for a trailer boat, but will delaminate if the boat is in the water 24/7.

If there was a big concern with strength, I would use epoxy.

quote:

Originally posted by c1steve:
Epoxy bonds with 6x the strength to old fiberglass than does polyester resin. Polyester on top of epoxy works fairly well if it is done "wet on wet". Usually I would do the entire repair in epoxy, than topcoat with polyurethane paint (LPU). LPU works satisfactory at an underwater location for a trailer boat, but will delaminate if the boat is in the water 24/7.

If there was a big concern with strength, I would use epoxy.

No so much "strength" as much as longevity.

The area of damage is perhaps 8-10" long, and the damage is through the gelcoat and perhaps 1 or 2 layers of glass. It's still perfectly solid underneath, and once I lay up additional CSM, it should be as good as new.

If, OTOH, this were a hole, I might give epoxy a harder look.

Also, I would really prefer to finish it with gelcoat since the rest of the boat is finished as such. Yes, it is below the waterline, but my goal is to make this repair as seamless and invisible as possible, so that when the time comes to sell it and someone crawls under there, they are unable to determine that a repair has even been made - and to have that repair be done (structurally/methodically) as good as it looks. Also, with the future in mind, I don't know what the next owner will have in store, and I'd rather not have the repair delaminate on them. Plus, I don't know how long "in the water 24/7" means, and we do take trips with it where the boat is slipped for a week or so at a crack.

Yes, I did buy pigments to tint the gelcoat to match. I anticipate THAT being especially fun.

You might find this resource helpful too.

http://www.westsystem.com/ss/use-guides/

quote:

Originally posted by FlyingScot:
Grinding glass even in a bunny suit sucks.

Grinding fiberglass is the only thing I do that I absolutely HATE.I have the suits, full face forced air mask, etc, but it's still a nasty job. Now some manufacturers have pushed the suck factor even higher with carbon fiber. I have never suffered from fiberglass itch as bad as grinding carbon fiber. It's a great boat building material. Super strong and light but damn itchy to repair. Fortunately before carbon fiber becomes mainstream I will be long retired or dead.

The WEST system is probably one of the most popular and best methods of fiberglass repair and is epoxy based. There is no reason not to use epoxy based systems. You shouldn't need to get into using matting if the repair is 5/16" or less.... just prep the area really well and make a paste using cavasil/micro ballons and West system wipe it in there with a rubber/plastic flat spreader. OTOH if the bondo mixture you already did is holding, just leave it.

Are there any body shops that specialize in fixing corvettes in your area or people that do boat repairs? It would be just as cheap to pay a professional that does this for a living, because the quantities of the stuff you need and how much you need to buy will probably cost the same and a professional will have all of the stuff on hand.....it's a quick fix for a professional and should cost $300 to have a professional fix it, $500 at most.

No, there are no corvette repair shops nearby. I live in a small town of about 18k people.

I already ordered everything. It was about $500 in materials and equipment. But they way I'm looking at it is that it will allow me to repair some other, smaller areas in the boat that need it (gouges in the gel coat that do not go all the way through, random screw holes, etc). Plus, I will have material left for when I inevitably damage it again.

Plus, I think that as a boat owner, it's a pretty good skill to have.

Just for grins, though, prior to undertaking this, I did call a few boat repair places. I was quoted $500-1000 based on them seeing a picture, and the nearest place was 2.5 hours away. So, fuel, lost time trailering, more lost time while they have the boat, etc.

I like a challenge. And the bondo fix just annoys me. It looked like it was holding just fine when I put it up for the season, but.. The contours weren't right. I need to fix that at a minimum. So, may as well just do it "right".

The repair will end up being more than 5/16 by the time I grind back down to solid fiberglass. The gel coat on this boat is probably about 3/16" thick all by itself, it's quite stout.

The polyester vs epoxy argument been going on as long as they have been building glass boats. I keep both in stock as they both have their merits. Epoxy's main benefit is it's adhesive properties. Polyester's benefits are mostly economical as it's cheaper and cures faster. For cored hulls with thin laminates, I would choose epoxy. For thicker laminates or gouges that are slightly more than cosmetic, I would go with polyester. Fact is, there "professionals" that would repair your boat with nothing more than bondo and gelcoat and still charge you $500-$1000.

I think your plan is good and it is a good skill to develope for a boat owner. The most challenging part of any repair is color matching. Unless the boat is almost new and I have the original gelcoat, my only guaranty is it won't match. What color is your boat? Whites and off whites are not bad, darker colors are a PIA. You are fortunate that the repair is on the bottom and not very visible.

Good luck and keep us posted!
Fred