CONTINUOUSWAVE

Q1: what color gel coat was used on a 1992 13-foot hull for the interior? I need to know so I can buy a Spectrum Gel Coat Patch Kit.



The area of the cockpit gel coat seen in Figure 1 was wet sanded with 2000-grit, buffed with a heavy-duty compound, and finished with 3M Marine Finesse-it. I believe it to be very close to the original color.

ASIDE: I believe the interior gel coat to be the same color as the hull gel coat.

[Moderator's note: I have removed an image showing the boat illuminated indoors in a garage by unknown light source. All color imagery depends on the light source. The only useful light source for color matching is daylight.]

The cockpit gel coat color is Desert Tan, a custom color by Boston Whaler that does not exist on a Pantone Matching System (PMS) color chart or on paint manufacturers' color charts.

Q2: What repairs are you planning that will require a gel coat color match?

I just need to [use] some gel coat resin [to cover a] few screw fastener holes that have already been filled. I do not want to spend money to custom mix a quart of gel coat resin.

The challenge with repair patch kits is the color variation.

Back in the day, gelcoat was hand mixed at the factory and there was color variation. Aging also has added to that.

The Spectrum and other "color-matched" gelcoat and repair kits are close but rarely a perfect match. Not inexpensive.

I have used and recommend Locktite Marine Epoxy in white for gelcoat nicks, green line separation and screw holes. While it is not a perfect match for desert tan, it is very close and very affordable.

Try it out. At ~ $8 a tube, worth a try.
https://www.homedepot.com/p/Loctite-0-85-fl-oz-Marine-Epoxy-1919324/205361752

Phil T wrote:Back in the day, gelcoat was hand mixed at the factory and there was color variation

I believe that the blue interior gel coat color used on the early 13-foot hulls was perhaps mixed on the factory floor, and thus likely to vary slightly, but I don't think that in 1992 there was a particularly wide variation in the standard gel coat colors used by Boston Whaler.

Off-white shades are particularly hard to assess for color matching, and generally that task requires very acute color vision to accomplish.

Using epoxy resin that has been tinted to match Desert Tan may not be a good long term solution; epoxy resins tend to yellow with age and exposure to ultraviolet light (sunlight). Gel coat resin will be more color stable.

Generally gel coat resin begins as titanium white color. You can approach a good match for Desert Tan by adding a small amount of "brown" pigment (using acrylic paint Raw Siena pigment) to a larger amount of white resin. Then use a small amount of this slightly-reddish-brownish tinted resin to mix into a larger amount of white resin, adding the tinted resin in small increments until the proper hue is obtained. This can produce a nice match for Desert Tan if mixed carefully.

Note that gel coat resin will not cure to a hard surface if exposed to air. For this reason a gel coat repair is often top-coated with polyvinyl alcohol, to create a barrier layer to air. You can also buy a special gel coat resin that includes a wax component; the wax comes to the surface and makes a barrier layer to the air. This is what you are getting when you buy a "patch kit" of gel resin; the resin is already mixed with wax.

Gel coat resin is already slowing curing in the can. When gel coat resin is applied, a reagent is added to the gel coat to speed up the curing process. The reagent is usually methyl ethyl ketone peroxide, which is a severe skin irritant and can cause blindness--be careful using it.

Cf.: https://en.wikipedia.org/wiki/Methyl_et ... e_peroxide

A good close paint match to Boston Whaler Desert Tan is Krylon 1506 Almond Gloss. Especially for small screw hole repairs. Try drilling out hole to clean it, filling with Marine Tex or similar epoxy, let cure, mask using hole punch in masking tape, then paint with artists brush and 1506 Krylon sprayed on plastic lid.

This Krylon 1506 Almond Gloss paint sounds like a great inexpensive way to take care of these screw holes after they are filled with MarineTex. Thanks for the tip.

A layer of paint won't be very thick. The gel coat layer in the laminate of a Boston Whaler boat is generally sufficiently thick that small defects in the surface can be removed by very gentle abrasion. Blending a repaired area covered with paint into the main gel coat area surrounding the repair may be difficult to accomplish due to the thinness of the paint layer. Any abrasion of the paint may remove too much paint and reveal the underlying different color.

The simplest remedy for a old fastener hole that is no longer needed but happens to be in a high visibility area is to just install a screw fastener with a dress washer. Of course, this is only practical if the number of old, empty, unused screw fastener holes in high-visibility areas is not very large. But to fill a stray empty screw hole here or there, just fill it with a nice, new, stainless steel oval-head screw and a dress washer. I have a couple of those type screws threaded into old holes that are just there for appearance sake on my boat. Again, this remedy demands that you don't have very many of these old and no longer used holes.