(Editor's note: I don't remember where I found this article, so if someone knows the source, let me know - I want to give credit where it is due.)


From Awlgrip.....

"Unfortunately, we do not have a product for the bottom of trailered boats. If the boat is regularly left in the water, such as all weekend, every weekend during the boating season or for 2-4 weeks on an extended vacation, there will be a tendency of the coating to blister and eventually peel. Also trailers with carpeted pads are sometimes a problem as the carpet is soaked in water and traps water against the finish, resulting in blisters where the boat sits on the carpet. This is not always a problem, it depends on the climate and how fast the carpet dries. If the trailer has rollers, sometimes the Awlgrip cracks as the coating is not designed to bear the weight of the boat.

Regardless of how the boat is used there would be no warranty of any kind for topside finishes used below waterline.

Basically paint which works well in water does poorly in the air and vice versa. The below the waterline product we carry is an ablative anti-fouling, which is intended to wear away as the boat is in the water. When you pull the boat on the trailer, you essentially will be causing the coating to rub off on the trailer pads leaving less anti-fouling on the boat.

The process for cleaning, dewaxing-degreasing, preparation of the substrate, and priming for topcoat is below":

Gelcoat/fiberglass surfaces are found in four basic forms:

1.) New gelcoat and aged gelcoat which is sound; basically free of any crazing, damage, or delamination.
2.) Aged gelcoat with minor crazing and oxidation but no major cracking, crazing, damage, or delamination.
3.) Heavily crazed, cracked, broken and delaminated surfaces.
4.) Raw fiberglass, laminating resin with no gelcoat.

Most projects involving molded fiberglass/gelcoat usually fall into categories
1.) or 2.) and require very little filling or fairing. Refinishing these surfaces can be accomplished with relatively simple systems of:

Cleaning and de-waxing the surface.
Sanding the surface.
Applying 545 Primer or AWL-QUIK® Primer.
Topcoat application.
Surface conditions described in catagories 3.) or 4.) require more extensive attention to abrading the surface and the use of fairing and surfacing products.

Heavily crazed and damaged surfaces require thorough inspection and removal of all damaged or deteriorated materials. Cracking and crazing caused by excessive flexing of the surface may require structural reinforcement to reduce the flexing. Deep crazing and cracking must be ground out before filling to change the dynamics of the working surfaces. Just filling and painting over cracking and crazing usually results in the defect quickly "printing through" in the new finish.

Raw laminating resin is very hard and slick compared to pigmented gelcoats and fairing compounds.

Both polyester or epoxy resins must be washed with household cleanser and water before sanding or grinding. Washing removes mold release materials, un-reacted styrene on polyester surfaces and amine residue on epoxy resins.

Raw fiberglass resin must be ground with 36-60 grit sand paper until 100% of the surface is dull, with a 36-60 grit surface profile. Allowing even small spots of un-sanded resin in the weave of the fiber strands can lead to adhesion failures.

Fiberglass repairs often have an extra layer of laminating resin applied to give the repair a smoother finish. This allows easy sanding without exposing the fiberglass itself.

Even though these areas may appear fair and true it is important to give them the full 36-60 grit grind to ensure good adhesion of the coating system.

Refinishing heavily crazed, broken, delaminated surfaces, or raw laminating resin requires more steps involving more products:
Cleaning and de-waxing the surface.
Sanding/grinding the surface.
Applying primer to the surface.
Fairing with AWL-FAIR® L.W.
Applying HIGH BUILD or ULTRA-BUILD® Surfacers.
Sealing with 545 Primer.
Topcoat application.

This section provides detailed instructions for surface preparation and priming of gelcoat and fiberglass.

This first system covers new and sound, aged surfaces. The second is for heavily crazed/damaged surfaces and raw laminating resins.

GELCOAT/FIBERGLASS
System I.
New and Sound Aged Surfaces Preparation and Priming

Removal of all surface contamination (waxes, mold release products, dirt, grease, oil, and mildew) is imperative to insure adhesion of the new U.S. Paint Coatings Systems.

Sanding the surface with sandpaper does not remove wax or other contamination. Sanding spreads the contamination from one area to another. The heat generated by the sanding melts wax and other contamination into pores in the surface.

1. The surface must be clean and free of any waxes or mold release compounds before beginning any other work.

De-wax with AWL-PREP® PLUS T0115 using the Two Cloth Method.

Thoroughly scrub with commercial detergent or powdered household cleanser. Then rinse with fresh water until a break-free rinse is obtained. Allow to dry. Some surfaces may need a second application of T0115 and additional scrubbing. Be sure to rinse thoroughly.

2. Inspect the surface for pinholes and small scratches. Mark the imperfections with a pencil. Do not use a felt tip marker.

3. Sand out and feather any scratches or dings with 80 grit paper. Sand any raw resin until completely dull.

4. Brush prime these areas with 545 Primer or AWL-QUIK® Primer.

5. Scratch sand primed spots with 150 grit.

6. Fill scratches, gouges, and dings with AWL-FAIR® L.W. Allow to cure 12+ hours.

Caution: If polyester putties are used, they should be kept to an absolute minimum. Only use polyester putties for pinholes and very slight scratches or dings. Polyester putties shrink and distort rapidly. Epoxy fillers are much more stable.

7. Block sand the filled areas leaving a smooth, level surface.

8. Smooth sand the entire surface with 100-150 grit to remove all gloss from the previous finish. Feather any dents, dings, or scratches. Sanding must be thorough enough to remove all gloss from the gelcoat, all oxidized gelcoat, and any light crazing in the surface. However, do not over-sand. This needlessly exposes porosity in the gelcoat which will require extra materials and labor to fill.

9. Prime the entire surface with 545 Primer (spray) or AWL-QUIK® Epoxy Primers (brush & roll). Allow to cure 12+ hours.

Tip: Use care when applying this primer. If smoothly applied and all surfaces are adequately covered, it may be used as the final prime step.

Surface is now ready for final priming and topcoating.

System II.
Surfaces with heavily crazed, cracked, broken, delaminated gelcoat, and raw laminating resin.

1. Thoroughly scrub with commercial detergent or powdered household cleanser. Then rinse with fresh water until a break-free rinse is obtained. Allow to dry.

2. Inspect heavily crazed areas or damaged areas for excessive flexing or structural damage. Make structural reinforcements and fiberglass repairs as needed.

3. Remove heavily crazed, broken and delaminated gelcoat or fiberglass laminate.

4. Thoroughly grind out damaged areas with a 36-60 grit disk. Heavy crazing must be completely removed. Grind raw resin areas with 36-60 grit sand paper.

5. Prime these repair areas with 545 Primer. Two or three coats may be needed. Allow to dry 12+ hours.

OR:

For heavily damaged areas and all areas where 36 grit paper was used, prime with HIGH BUILD Epoxy Primer. Reduce the first coat of HIGH BUILD Epoxy 25% by volume with T0006 Reducer. Two to three coats may be required.

6. Sand primed areas with 80 grit paper.

7. Blow off the surface with clean, dry compressed air while dry wiped with clean rags to remove sanding dust and residue.

Note: The repair areas are ready for fairing and surfacing. This will include application of some or all of the following products:

HIGH BUILD Epoxy Primer
ULTRA BUILD® Epoxy Primer
Sprayable Fairing Compound
AWL-FAIR® L.W. Trowelable Fairing Compound
AWL-QUIK® Sanding Surfacer.

After the fairing and surfacing is completed all areas of sound surface must be cleaned, sanded, and primed and prepped before applying a topcoat. See preparation of sound gelcoat/fiberglass and final prime and topcoat.