Gel coat damage. Caused by?

Funny, I didn't see your point made, just some inferior repair techniques touted.
Did I miss the video tutorial, or the pics somewhere?

Perhaps you should write up something for the Hotline? I've got a few titles you could use. How about:

Boat Repair: How to Spend 3 Times the Money for an Inferior Outcome

or maybe...

Gel Coat: Curing and the Effects of Amine Blush

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Oh, leave him alone, Jeremy. He's having a tough week, been busted three times now for poor/incorrect advice.

You're right, Mr Nixon. My apologies for calling you out, fast.

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Opinions are just that and you are entitled to yours. I do not see the big cost difference you mentioned, but then I have not run a cost analysis. My repairs combined cost ~ $35.00, I’ll bet you charge a might more. For small repairs I do not see a functional difference – my opinion. Same goes for others, Dick, for seeing alternatives (or misunderstandings) as incorrectness. Oh if we lived in a perfect world, I'm sure you would rule.

One thing you can bet on, my posts have got you logging on this the Forum.

Neither I nor Jeremy require your assistance in boosting our post count.

I value your knowledge Matt & Jeremy and kudos for your post count.
Matt, hope to see you at Austin Lake this year. I'll try to remember the jib this year

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Sure, everyone can have opinions, and I respect that. You can fix your boat with bubblegum for all I care. The problem comes when you suggest to someone that's new and who is asking for repair advice, that your 'opinion' is correct.

When I suggest that polyester is a better choice for this repair, it's not opinion, it's fact. There is a slew of reasons why, cost and amine are two biggies against epoxy. Its safe to say that there are no professional glass guys that would reach for a can of epoxy to work this repair.

Let's do this:

In your opinion, why is epoxy beter suited for this repair?

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SCC Since you asked so nicely

Epoxy resins have performance advantages over polyester and vinyl
esters in five major areas:
1 Better adhesive properties (the ability to bond to the
reinforcement or core)
2 Superior mechanical properties (particularly strength and
stiffness)
3 Improved resistance to fatigue and micro cracking
4 Reduced degradation from water ingress (diminution of
properties due to water penetration)
5 Increased resistance to osmosis (surface degradation due to
water permeability)

Yes - I did get this off the web from a marine specialist company, so I guess it is not just My opinion.

Another opinion
Epoxy resin is known in the marine industry for its incredible toughness and bonding strength. Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters. In areas that must be able to flex and strain WITH the fibers without micro-fracturing, epoxy resins offer much greater capability. Cured epoxy tends to be very resistant to moisture absorption. Epoxy resin will bond dissimilar or already-cured materials which makes repair work that is very reliable and strong. Epoxy actually bonds to all sorts of fibers very well and also offers excellent results in repair-ability when it is used to bond two different materials together. Initally, epoxy resin is much more difficult to work with and requires additional skill by the technicians who handle it.

Vinylester resins are stronger than polyester resins and cheaper than epoxy resins. Vinylester resins utilize a polyester resin type of cross-linking molecules in the bonding process. Vinylester is a hybrid form of polyester resin which has been toughened with epoxy molecules within the main moleculer structure. Vinyester resins offer better resistance to moisture absorption than polyester resins but it's downside is in the use of liquid styrene to thin it out (not good to breath that stuff) and its sensitivity to atmospheric moisture and temperature. Sometimes it won't cure if the atmospheric conditions are not right. It also has difficulty in bonding dissimilar and already-cured materials. It is not unusual for repair patches on vinylester resin canoes to delaminate or peel off. As vinylester resin ages, it becomes a different resin (due to it's continual curing as it ages) so new vinylester resin sometimes resists bonding to your older canoe, or will bond and then later peel off at a bad time. It is also known that vinylester resins bond very well to fiberglass, but offer a poor bond to kevlar and carbon fibers due to the nature of those two more exotic fibers. Due to the touchy nature of vinylester resin, careful surface preparation is necessary if reasonable adhesion is desired for any repair work.

Polyester resin is the cheapest resin available in the marine industry and offers the poorest adhesion, has the highest water absorption, highest shrinkage, and high VOC's. Polyester resin is only compatible with fiberglass fibers and is best suited to building things that are not weight sensitive. It is also not tough and fractures easily. Polyesters tend to end up with micro-cracks and are tough to re-bond and suffer from osmotic blistering when untreated by an epoxy resin barrier to water. This is really cheap stuff.

Once again from the web.

And another

Polyester Resin Vs. Epoxy in Boat Building

Though 75 percent of the resins consumers use are unsaturated polyester resins (uses for saturated polyester resins are limited to coatings), epoxy resins stand out as superior for reliability and multiple uses. Though both resins do well above and below water, epoxy completely resists moisture where polyester does not. Knowing the properties, advantages and limitations of these two bonding agents can assist you in choosing which fits the project best.

Advantages
The principal advantage of polyester resin is the mechanical, chemical and electrical stability of its properties. The primary advantage of epoxy resin is its superior mechanical properties in making high-functioning composites of different materials. Epoxy wins over polyester resins in its resistance to acidic liquids and locations. With its better electrical properties, outstanding performance at higher temperatures and ability to bond with multiple types of surfaces, epoxy resin again outdoes polyester.
Strength
Fracturing easily and lacking durability, polyester is best suited to building lighter weight objects. In tension and flexibility strength, epoxy resin is the better of the two and is especially useful for high-strength bonding.
Uses
Compatible with only fiberglass materials, polyester resins have limited use for laminating, seaming and repairing. Both the epoxy and polyester resins are popular in the marine industry, but epoxy strength and durability make it the first choice. Epoxy resins reinforce such materials as glass, carbon and aerospace materials.
Adhesion
Epoxy resins have an extraordinary ability to bond dissimilar and already cured material. Polyester resins have the poorest adhesion power. Superior epoxy resins have a 2,000 p.s.i. (pounds per square inch) adhesion strength over polyester resin at 100 p.s.i.
Other Factors
The shelf life for polyester is 18 to 24 months and a minimum of two years for epoxy. Epoxy has a longer cure time, with five to seven days, versus six to eight hours for polyester. Epoxy costs more than polyester resin. Polyester allows 20 to 30 minutes working time. Depending on the catalyst used with the epoxy resin, the working time ranges from 30 minutes to 6 hours.

Hopefully these articles help me make my point.

Every single 'superior' property of epoxy that you cut and pasted above is moot. THE REST OF THE BOAT IS POLYESTER!

Electrical properties? Does that matter?

Resistance to osmosis? Didn't realize that wan an issue here.

Able to withstand higher pressure? Again, the rest of the boat is polyester. Why does that property matter?

Does higher resistance to acid matter? No!

Adhesion? There's not even any problem with adhesion right now.

Does superior bonding matter? No! The boat got a ding, it's not delam.

I'll ask again, as you're having a difficult time grasping the concept. No cut and paste this time.

Why would you suggest epoxy for this repair?

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Duct tape? It will keep the water out. Its easy to work with. I could copy and paste some physical properties...but

Oh yea you can buy white duct tape so people won't notice you used the wrong material to fix it.

When all you have is a hammer, every problem starts lookin' like a nail.

The most astonishing part of this thread...Look at Brogger and Wessels!

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Karl lives in Minnesota, so that's easy. Nothing else to do in the winter.

Wessels is in Clear Lake, IA, where the last big thing that happened was "the day the music died" - 52 years ago.