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1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Sun Feb 05, 2017 7:28 pm
by Tailwind
I've done a fair amount of reading here and am not sure whether to paint or fix the gel coat.

I recently bought a 1989 15' and the poor thing has been trailer-gouged and sun-baked. There are also many careless holes drilled all over the inner liner.

I'm going to have to drill-out and re-seal a bunch of mounting holes and simply seal a bunch of others. But beyond that, there are lots of cracks along the stern and there is even some separation in the upper lip of the transom. No love at all to this poor baby. The only blessing is that it has no bottom paint and seems like it was never kept in the water.

Aside from simply not buying boats in such condition, what have people done with fiberglass defects such as these? And what kind of luck have they had?

Got most of the engine and trailer [problems] resolved and moving on to the fiberglass and gel coat.

Thanks a bunch!

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Sun Feb 05, 2017 9:59 pm
by jimh
With no prior experience working with fiberglass, I was able to accomplish very successful repairs of small abrasions and fill many, many empty mounting holes no longer needed. I used WEST System epoxy for the repairs. I used generic gel coat resin and some tints to make my own custom-color gel coat. In almost all the repairs I made, the damaged area was on the hull bottom or on the transom below the water line, and, as such, these repairs were not particularly visible unless the boat was on its trailer and a close visual inspection was made. I described my procedure and the outcome in an article, available at

The Epoxy Cure

In the REFERENCE section you can find the original factory instructions for making repairs, reproduced in HTML, with original illustrations. See


You can also see a very well done repair that follows the factory instructions in an illustrated article at

Repairing Hull Damage the Whaler Way

I have no real data on how often a Boston Whaler boat has been repaired by following the advice provided in those three articles, nor do I know the outcomes, but I would estimate that hundreds and hundreds of boats have likely been repaired using those methods and I would bet in many cases the outcome was quite acceptable.

As for whether restoring gel coat or making an entirely new top coat using a new top coat material is preferred, I would advise that restoration of gel coat is preferred as long as the original gel coat is in a state that can be restored. If the original gel coat is deeply crazed and spider cracked over large areas of the hull or cockpit, repair may be more work than adding a new top coat.

Regarding what material to use for a new top coat, I don't have any experience in applying gel coat resin with a spray gun, applying two-part modern paints with a spray gun, or even just applying single-part old-fashioned marine paint with a spray gun. I suspect that the outcome of such applications would depend to a great degree on the skill of the applier, the quality of the top coat materials, the skill used in preparation of the surface area to be covered, the humidity and temperature of the environment when applied and curing, the spray guns used, and some luck.

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Mon Feb 06, 2017 9:41 am
by Tailwind
Hi Jim. I have read those, very informative posts---and probably will many more times as I gather the courage to get started on the cosmetic part of the work. I will say that there are definitely parts of the gel coat that simply look too far gone.

Re: 1989 15-footer Rough Gel Coat

Posted: Mon Feb 13, 2017 8:54 am
by borrowedtime
Tailwind--I just did those repairs [i.e, the repairs Tailwind will need to do: to drill-out and re-seal a bunch of mounting holes, seal a bunch of other holes, repair lots of cracks along the stern, and repair a separation in the upper lip of the transom--jimh] to an 1981 STRIPER I purchased a couple of months ago.

The hull repair mix from Spectrum works great and is a great product.

I tried to match the sun baked color of my boat by mixing the Desert Tan and the newer Marine White. Surprisingly, it worked better than expected for the hull, but on the interior it did not. I could not find a way to mimic the non-slip tread.

I used spray foam to fill-in holes that were bigger and a fiberglass repair kit I got from the local O'Reilly's.

Doing gel goat work is just like doing any other type of body work--most of your work is going to be in the preparation.

I did detail the entire surface inside and out with a buffing disk and medium cut compound, which worked wonders.

It took me quite some time to build up the courage, jump in, and work. But if you haven't broken through the fiberglass, and you are only repairing gel coat I would not worry about anything. This type of work is very forgiving; however, if you mess up it also very labor intensive.

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Mon Feb 13, 2017 12:31 pm
by jimh
I believe that Spectrum Color just sells pre-tinted gel coat resin that they have mixed in colors in small batches to match Boston Whaler hull and deck gel coat colors to make small area repairs. If they are now selling complete hull repair kits, it would be good to mention more details about what is supplied in the hull repair kits besides a small jar of gel coat resin and some hardener.

Using pre-tinted gel coat resin can be useful if the color of the hull gel coat is still in its original hue, but often one sees in older boats the gel coat color has changed with age due to exposure to sunlight and the lack of care in maintaining the surface.

TAILWIND says his boat has been sun-baked, so I would expect the gel coat color has probably faded and there is oxidation. It may be possible to get the old hull back to being close to the original color if the oxidation is removed and the gel coat layer is polished and buffed to a suitable lustre. When trying to match colors you should have samples of similar finish and lustre, otherwise judgement of the hue and saturation of the color can be difficult. Also the influence of lighting source is significant. Don't try to match colors in any type of light other than sunlight and sunlight that is somewhat diffused--not direct Noon overhead sun. And color matching requires some visual skill for color; not everyone has this skill.

Re: 1989 15-footer: Repairing hole, cracks, and transom separation

Posted: Wed Jan 31, 2018 9:27 pm
by Tailwind
I originally wrote to ask for help with a trailer-gouged and sun-crazed 15 Classic. After a great summer using the boat, I have now stripped it to the bare hull and talked to a number of fiberglass guys. Honestly, no one seems very interested, but that's the nature of service people in South Florida, I suppose.

In a nutshell, the hull is pretty good and just needs reasonable repairs of the many trailer gouges, none of which appear to breach the fiberglass into the foam. I wet-sanded the hull sides and they came out pretty good, so I think I just need to repair the gouges. Should I use the West System to repair the gouges? Or, do I need the Spectrum repair kit?

Secondly, the deck or liner has a bunch of stress cracks, plus tiny cracks all over the non-skid and more than 120 holes. Amazingly, the boat seems solid, despite a lack of care that I cannot rightly understand. It seems like this area needs to be heavily sanded, cracks filled, prepped and Awl-Gripped. Does this sound like the correct solution?[

Also, if anyone could recommend a competent Boston Whaler glass guy in South Florida (seems reasonable), I would appreciate it.

Thank you!

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Thu Feb 01, 2018 10:19 am
by jimh
Tailwind wrote:... Should I use the West System to repair the gouges? Or, do I need the Spectrum repair kit?

A Boston Whaler hull has a typical laminate layer structure like this:

    --the outside surface exposed to air
    --a beautiful layer of wax applied all over with sufficient thickness, then buffed to a nice luster--may be missing on some boats
    --gel coat resin layer with thickness of about 0.020-inch (or slightly more in some areas), with uniform color throughout the layer
    --mixed resin-fiber layer with polyester resin and chopped fibers, thickness varying with location, perhaps 0.125-inch or more, generally bluish or greenish in color with some variations in color in the layer
    --wood or other reinforcement in some locations
    --closed-cell foam, thickness very great, extends throughout interior of the double-bottom hull
If a "gouge" is only to a depth that the gel coat resin layer or just the bare surface of the mixed resin-fiber layer is exposed, you can fill the gouge with just gel coat resin. If the gouge still has the hull color, repair it with must gel coat resin. If the gouge reveals blue or green, it may be too deep for just gel coat alone. See the earlier mentioned advice from Boston Whaler.

The SPECTRUM company has well-matched color gel coat resin kits with additives to help the resin cure in open air.

If a "gouge" or other penetration of the hull is deep enough to go deep into or even thought the mixed resin-fiber layer and expose the foam layer, you should probably not try to fill that depth with just gel coat resin, but instead use a repair resin, possibly mixed with cloth or fibers or fillers.

Gel coat resins are not designed to be adhesives, and they aren't designed to be applied in great thickness. They will adhere themselves to a properly prepared surface, but you can use them to glue together parts of the boat that have become separated.

For repair resins you can choose from polyester resin or epoxy resin. Epoxy is a better adhesive for repairs and is very waterproof. It is easy to mix and will cure reliably. Polyester resins are not as strong as adhesives, they are not completely waterproof, and the mixing of the resin and catalyst is generally imprecise in small batches; they won't cure if exposed to air unless specially mixed with additives (waxes) that will form skins and prevent air contact. There are two groups of users: those that use epoxy and those that don't. It is somewhat akin to religions.

You can make repairs in many ways. In my experience, I have had very good results using WEST System Repair Kits, using their instructions, and making repairs to many small defects in the hull. My experience trying to use polyester resins has been bad; they didn't cure properly, either due to poor mix ratio of resin and catalyst, or to exposure to air. I found them much harder to use than WEST System epoxy.

If the repairs are on the hull bottom and won't be in sight or represent a giant breech of your aesthetic sensibilities when crawling under the trailer and closely inspecting the hull, I would not be overly concerned that the repair resin provide an exact and perfect and undetectable match to the original hull color. If you were to crawl under my boat trailer and look at a few spots on the keel center line, you might see a few color changes where I have made a repair with epoxy resin that the color match is not perfect. Does that cause me to lose sleep? No.

If you make a repair in a very visible area and want to obscure the repair and blend it into a smooth and unobtrusive repair, apply color-matched gel coat resin as the final top coat layer, then buff and polish to restore lustre and reflectivity. It is quite possible for amateur repairers to make very good color matches and hide their repair work to the point of being practically undetectable.

I recommend you pick a method and try it on some not-too-visible area. See how the method works and what results you get. If you don't like the outcome, try another method or improve your technique. Take on the most visible areas last, when you have become more proficient at making these repairs.

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Thu Feb 01, 2018 10:43 am
by jimh
Tailwind wrote:...the deck or liner has a bunch of stress cracks, plus tiny cracks all over the non-skid and more than 120 holes...
It seems like this area needs to be heavily sanded, cracks filled, prepped, and Awl-Gripped. Does this sound like the correct solution?

Repair of areas with a lot of spider cracks or crazing by individual repair of each crack is probably going to be very tedious. Your propose method sounds better.

With regard to the appearance of stress cracks, the cause is usually from the gel coat layer having been applied too thickly or from some flexing or movement of the underlying laminate. If there were flexing and movement, cracks may reappear. Cracks in surface gel coat resin in some locations seem unavoidable. Crazing occurs if the gel coat was allowed to fall into poor condition, not waxed and buffed, not treated with restoring poslishes. Those cracks should not come back. But make sure you have stabilized the area to be resurfaces and removed any old top layers that are unstable and weak.

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Thu Feb 01, 2018 3:59 pm
by dg22
I agree, it sounds like your best option is to paint. I painted my 1967 13-footer and I'm happy with it.

For the fiberglass repairs, I removed all the gel coat in the surrounding area to get a good bond with the new fiberglass to the original underlying fiberglass. Just a heads up. I discovered that I needed to remove the gel coat in the areas where there was a lot of spider cracks. Originally, I didn't do this and I just filled the spider cracks with marine filler, sanded and then painted. I noticed the spider cracks returned after a few months of use. A few years later, I decided to re-fix properly. I used an orbital sander and removed the gel coat in those bad areas and then painted and all is good. Best of luck.

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Thu Feb 01, 2018 9:09 pm
by Tailwind
Thanks for the notes, guys.

Jim, I think I must have used polyester resin in the past, because I always had problems with curing and adhering. I'm going to try the West System and start under the keel. This is one of those times when it really would be great to have a neighbor that had the skills so I could, at least, have one chance to watch before diving in.

I'll see if I can post some pix.

Thanks again.

Re: 1989 15-footer: Repairing hole, cracks, and transom separations

Posted: Fri Feb 02, 2018 9:59 am
by jimh
Re using WEST System repair kits: you will be very surprised how much resin will be produced when you use just one foil-package of resin and hardener and mix in a bit of filler. You can fill many small fastener holes with one batch. I caution you to prepare many sites to receive the resin-filler mix, because you will get a lot of it from one foil package mix.

If you do not plan to later apply a color gel coat resin to top coat the repair area, you can tint the WEST System epoxy with a bit of acrylic paint pigment. Also, use the low-density white filler instead of the high-density clay-color filler as this will give the resin a white hue. You can also add white paint pigment, but just add a small amount. Do not overdo the paint pigment as it will weaken the resin. If you want to get a match to DESERT TAN, use this method:

--take a dab TITANIUM white pigment and into it mix a very small amount of RAW SIENNA pigment. These are artist colors and you can buy them at an artist supply store just about anywhere in small tubes. One small tube will tint hundreds of batches.

--thoroughly mix the white and raw sienna pigments to get a nice tan color you think is about the base hue of desert tan but it will be much stronger

--now take a very small amount of the mixed tan color pigment and add it to a new dab of white pigment; mix these until you get a shade that resembles Desert Tan, adding more of the pre-mixed white-tan as necessary; don't add too much.

The ability of a human to match colors varies with many factors:

--the lighting and the color temperature of the light; best to use outdoor sunlight--but not glaringly bright direct sunlight
--the visual color perception and acuity of the human; generally humans are very good at perception of shades of red, but shades of tinted whites with some red or brown are often very subtle and require care and experience in matching

When working with WEST System epoxy, the cure time will be very dependent on two factors:

--the ambient temperature; don't try this on a day with 95-degree temperature in a blazing sun; the resin cure will be very fast; better to work in very moderate temperature, about 70-degrees; the cure time will be much longer

--the amount of resin in an area; as epoxy cures the chemical reaction is exothermic--it produces heat. If resin is applied in a big glob, as soon as it starts to cure it gives off heat; the heat causes the cure rate to increase; this produces more heat; it you pour a big volume of resin into a container and let it cure, it will get so hot it will melt the plastic container.

When working with epoxy, wear vinyl disposable gloves. Have some plain white vinegar handy and a lot of paper towels. You can use very inexpensive grocery store vinegar, not expensive and fancy cooking vinegar. Vinegar is a good solvent to remove epoxy from your skin and hands. Do not get the vinegar into the resin you want to cure in the repairs. You can wipe away uncured resin from spills in non-repair areas with water-vinegar and paper towels.

Be careful to avoid contact with uncured resin. Some people develop sensitivity to epoxy. A friend of mine who built a lot of model airplanes with epoxy became very sensitized to uncured epoxy resin and had to stop working with it completely.

For filling holes, get them ready long before you mix resin. Surround each hole with masking tape with fairly close margins to the hole; use a large drill bit to chamfer the edges of the hole to be repaired so the repair resin can have more surface area to bond with. If you sand off old gel coat, save the dust to use as filler and color tint.

Don't try to overfill every hole; it is better to make two passes with two batches than to overfill the hole on the first pass. If you leave a big dome of resin on a hole repair, you will have to sand it smooth. Well-cured epoxy will be much harder and resist abrasion much better than 40-year-old dry, oxidized gel coat. When sanding a repair watch that you don't sand away too much old gelcoat and leave the hard epoxy repair standing proud of the surface.

For holes where gravity will want to make the resin run out, push the resin into the hole and then immediate cover with masking tape. You get a plastic spatula in the repair kit that is very useful for manipulating resin before it cures.

Sometimes I start with pure resin to wet the repair area--working rapidly so as not to take too much time---then I quickly add filler and tint to the resin and apply the resin-filler mix to the wetted holes. You have to work fast because you only have about ten minutes before the epoxy will start to cure. Don't try to manipulate resin in a repair once it has begun to cure, as you can pull it away from the repair and you won't get the best bond.

There is one problem with epoxy that I have not mentioned: if exposed to UV from sunlight for long periods, cured epoxy will color shift with age, tending to become yellow. This effect seldom has any influence on repairs to the hull bottom, but it will affect repairs on the topsides that will get plenty of sun. There is no getting around this, other than to apply gel coat resin as a top coat to those repairs.

There are many old stories about gel coat resin not bonding to cured epoxy. They are true when the epoxy was not properly prepared for a top coat. Cured epoxy often exudes an amine blush to the surface. To be certain the epoxy resin is fully cured and will no longer produce any amine blush, after the epoxy has cured for 24-hours, the area repaired with epoxy should also be gently heated with a low-temperature heat gun or hair dryier to effect a post-cure of the resin.

Amine is not removed by the usual solvents used to clean fiberglass during repairs like acetone, but amine is removed by water with detergent and some scrubbing. Wash the area repaired with epoxy carefully with detergent and water and a good scrub before and after any sanding and fairing. There should not be a problem applying a top coat of gel coat resin to the area. It is just like any painting, a good outcome is a result of preparation of the underlying surface.