Tips on fiberglass maintenance and repair

Gelcoat care and maintenance:


After and Before

After and before finish of severely weather damaged metal flake gelcoat.
Wet sanded then buffed with rubbing compound... not waxed, yet.

   Gelcoat is the finish surface that most fiberglass boats are built with. Maintained properly, Gel coat will last for many years and will hold up better in a marine environment than paint.

Gelcoat is the first material applied to a prepared mold, it contains the color, and other products that give it UV protection, gloss, resistance to discoloration, and ease of maintenance and rejuvenation.

Now that I said that, let’s start with basics. It’s always best to keep it clean, a good soap and water wash does a boat good. The preference here is a soft bristle brush and a sponge or soft rags for the smooth areas of the boat. A biodegradable, marine safe, detergent, recommended here, it doesn’t have to be strong soap, because it’s not the soap that cleans anyway, it’s you. If it’s kept clean and waxed, washing is not that bad. Some non-skid cleaner and a stiff brush works wonders on the textured surfaces. Do not use abrasive products like soft scrub, kitchen cleansers etc. for general cleaning because may damage the gloss finish and shorten the life of your boats finish.

Once the boat is clean, it’s time for that coat of wax. Several times a year is a good idea, an easy to apply and remove cleaner wax will due, try a brand that lasts, because it will give the best protection. But, what if your boat’s not new, and maybe it’s not got that new boat look anymore? we will have to start with more than just wax. Gelcoat is an easy to restore finish, providing the finish is not already dried out and / or porous.

Before we go any further, let’s talk about ability and tools. If you have never done any type of work like this before, odds are that you lack the tools too! First of all, safety is always first, use safety equipment (eye, face, and respiratory protection and since your probably going to be near water a g.f.c.i.), always use the proper tool for the job, the wrong tool can make a job harder or can damage more than it will fix. If you have never operated any of the tools needed, and are willing to rent or purchase them for your task at hand, have someone demonstrate the proper use and the safety precautions before you start.

Machine compounding and polishing is the best way to make an old boat look new, (short of painting). A heavy duty high-speed buffer works best for me, coupled to a 3m super buff compound or polishing pad. I’ve seen it done with an electric drill and a pad, but I’ve never seen a professional finish gotten that way. A heavy duty, high speed buffer will probably pay for itself the first time you use it. For heavy oxidation (the dull, dry look), a product like 3m super-duty compound works best, from a squeeze bottle, apply to the surface enough material to wet approximately. A 3x2 foot area with the buffer pad without creating lots of spatter when the machine is running. Work the pad up and down, back and forth slowly, with the pad at about a 15 degree angle off the surface until the compound is dry and a gloss is present. Work in small areas, do not allow the compound to dry on the surface, and do not work in direct sunlight. Wipe the compound residue off before it sets. Take extra care when working near corners and sharp edges. The abrasive action of the compound and machine can cause damage to the finish, also watch out for decals, emblems, rags and the buffers cord, especially on deck.

If your boat is not in that bad of condition, only light oxidation and light discoloration then you may not need a compound as strong as the super-duty, then try something like 3m finesse paste and a clean compound pad. Apply the paste with a chip brush, in a 2x3 foot area working the compound like above. This product also works well to remove the swirl marks left from the super-duty, and increase the gloss. Clean off any residual compound before it dries.

Once the compounding is finished, it’s time to protect that shine with some wax. Put the polishing pad on and apply a coat of liquid cleaner wax by machine, this removes any missed swirl marks, polishes, and adds a layer of wax. There is no substitute for a good hand waxing, so follow up with a coat of wax applied and removed by hand. Use a wax that is easy to put on and remove, and has UV protection. Wax it often and keep it clean to protect all the hard work you’ve put in to it. The 3m products are available at most body shop supply stores or your marine retailer. The 3m brand does not support me but, I have used these products in the past and have had good, predictable results with them when used as directed, but you should use whatever product you find to your satisfaction.

So, the boat is compounded, polished, and waxed, looks great ? All except for that spot......

Now that the boat has been detailed 90 times over, every little thing has caught your eye. You find that chip that’s been bothering you, or the scratch your brother put in the boat, or that dull area where the bumper sits. Let’s take the easy stuff first, how about that dull area?

Gelcoat has remarkable repair properties, fine scratches, and some larger (if not to deep) can be sanded and polished out. Here’s how, first let’s clean it, wash to remove any loose dirt, with the water handy lets sand in a circular motion with 600 grit wet or dry sand paper, then with 1000 grit over the entire dull area. In areas with heavy wear or see-thru spots ( dark areas in white finish) sanding will probably make it worse and re-gel-coating may be in order. Clean up any sanding residue before it dries (rinse off of bottom paint). Compound area with 3m super-duty, then polish with finesse, and apply wax.

Those chips and scratches ( minor ones ) can be easily patched by obtaining a gelcoat repair kit from your boats manufacture. If the boat is relatively new the dealer should have access to these kits. This kit usually contains a gelcoat paste and hardener, sometimes a mixing stick and instructions. It’s not as hard as it sounds, just a few simple steps and if you are patient and have a good color match it will look better than the chips. Do not use this repair method if the damage extends deeper than the gelcoat ( any fiberglass damage must be repaired with fiberglass to maintain the strength of the area). So, if it’s just a chip or scratch in the gelcoat let’s start by cleaning it out with acetone with a clean white rag (not the rag used for waxing). Next, score or sand the damaged area, be careful not to sand the area around the repair then re-clean with acetone. Mask around the chip so, that when applying the paste it only goes in the damaged area, we don’t want to make any more work than needed. Mix the gel paste in the container, then put enough to fill the repair on a mixing board (non-porous like Plexiglas ) and add the hardener, use 2% hardener to gelcoat ratio or follow the directions on the kit. Once completely mixed, apply the gel-paste to the damage and fair level with the masking. Some kits come with a plastic sheet to place over the gelcoat paste while drying, be careful not to trap air between the plastic and gel. If this sheet is supplied, try and use it, the sheet also keeps air away from the gel because it will not fully dry exposed to air unless additives are supplied. Be patient, give it time to fully cure, the harder the gelcoat becomes the better it is to polish. Here’s the tricky part, the tape is still on, if at all possible it’s best to pull the tape when the gel is still wet, that’s not always possible so here is the alternative; carefully remove the tape and the stuff that’s left behind can be scraped level with a razor blade. Once the tape is removed use a sanding block and a sheet of 400 grit wet or dry sandpaper and lots of water ( note you may want to protect the adjacent areas with tape to prevent damage from the sandpaper ) sand in a circular motion until almost level, at that point switch to 600 grit and finish leveling it. Remember to always sand to remove scratches from the coarser paper, then switch to a finer grit. Sand with 1000 grit, wipe clean and polish as needed.

A little about the author:

One of the top fiberglass sculptures, I've ever met, Bob Schnieder can turn cloth and resin into masterpieces. He specializes in accident repair to boats in the 30 to 50 foot bracket, but has been known to play with experimental fiberglass projects as well. You can't teach what this artist knows, but we hope his tips will make your day go faster...



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