I have an 8 year old QCC 500 with an Arctic White hull and lots of “experience” scratches on the bottom. Most of them are between the front and rear hatches and under the cockpit.
When I run my hand over them, I can feel most of them. They are all stained from paddling in water with a high algae level and look worse than they feel.
The boat doesn’t leak and in my opinion none of the scratches are deep enough to worry about a leak in the future.
A friend has suggested that I have the bottom re-gel-coated.
Is that expensive?
What is the process?
Can a person do it at home?
At what point is that really necessary?
How thick is a gel coating?
You guys are always such a wealth of info. Thanks for your replies. Ray
cosmetic
Sounds like just cosmetic damage to me; not that damage is even the right word. Experience is a good one. 
I personally wouldn’t worry about it unless you can see fiberglass in the scratches (it’ll be a darker layer). I have seen a re-gelcoated hull and didn’t think it looked as good as a factory job, but I don’t know who did it or how it was done. QCC’s are very lightweight boats so I’d guess the gel is pretty thin on them, but regardless if you’d be adding weight.
If the sratches are not too deep,
just wet sand the hull and polish it. Start with 400-600 wet in the heavy/deep sratch area, then up to 800/1000, then 1200, and finsh with 1500. All sanding is wet, and I like to use a rubber block (has some flex but is still firm).Radiused portions of the hull should be sanded with minicell block or other flexable yet solid feeling material. Wheel it with 3m heavy duty rubbing compound, and finsh with 3m finesse it. The 3m products are expensive, but they work, especially the Finesse it. Good luck. Bill
Exposed cloth in a scratch is not an
immediate concern. In fact, exposed cloth can be left indefinitely unless cloth layers are cut, indicating possible local structural weakness. I’ve had kayaks with cuts into glass, Kevlar, polyester, and Nylon where I’ve left the cuts alone for years with no consequences whatsoever, in spite of hard use in whitewater.
Resin prevents water from wicking through the fabrics in the layup. Boats don’t gain weight, layers don’t delaminate. The only concern might be if cheap polyester was used in a layup, rather than vinylester or epoxy. Polyester resin can undergo hydrolysis, which will weaken the laminate, though this problem is less common in boats that spend a lot of time out of the water (kayaks, canoes) than in motorboats or sailboats which sit and soak for long periods.
Hull Scratches
Are typically not a problem to worry about unless the fabric is exposed as I was advised. I had some Spider veining on my QCC and Steve from QCC told not to worry about it unless the boat was leaking which it was not. I only repair the gelcoat if it’s a deep/large area that is affected. I personally would not re coat a whole boat. Others may have different thoughts.
regelcoating a larger area is …
– Last Updated: Jul-20-10 10:38 AM EST –
...... really not an option unless you are going to spray the gelcoat . (well , you can brush on layers and sand them out to fair , but that is a ton of sanding work , but it can be done and achieve a semi OK result in the end , depends on what you are looking for in the result)
Spraying gelcoat is similar to spraying paint but requires special spray gun , tips , air pressures and technique , because of the thicker viscosity of the gelcoat and it is a two part catalyzed resin . The gelcoat is thinned for spraying also .
Types of thinners for gelcoat are debatable depending on what you are trying to achieve .
You can work small areas at a time with disposable (compressed air) units like a Preval spray gun or similar , but these are minimal at best , and you need many compressed air cartridges to just do a decent job on a small area .
You can use products containing containing Oxalic acid (read product handling and spill precautions) on fiberglass gelcoats to remove tough water stains from algae , rust (trace metal elements found in water that have oxidized on boat) etc. ... one such product is called "On and Off" (West Marine is one place that sells it) , it is a hull and bottom cleaner - has Hydrogen Chloride , Phosphoric acid , Oxalic acid ... "before you do anything (even sand) you would want to sterilize the intended area of work on fiberglass if it is stained by algae , rust etc. .
For something like multiple (many) rather deep scrapes and gouges over a larger area in gelcoat , after sterilizing sand lightly with 150-180 , sterilize with acetone after sanding , fill gouges with filler like 3M Marine Premium filler (a vinyl ester paste (consistency of toothpaste) with micro ballons , uses blue creme hardner , sets fast so golf ball size "or less" each mix up (mix on smooth board) , sands and fairs very well) .
Repeat filler application and sanding as many times as desired until fair as you wish . What you should see after filling , sanding and fairing out gouges and scratches , is the original gelcoat with the gouges all filled in with the filler ... sand that much excess filler away until you reach the highest gelcoat again , the lower areas will show the filler , and feel with hand for fair smoothness .
Begin ghost coating with gelcoat sprayed layers (finish gelcoat - cures open to air) , build up as required (probably 15 mils for a kayak) , sand built up gelcoat to fair (if waiting till gelcoat has cured before building up more , sand w/150 between build layers , sterilize w/acetone) , bring out glossy finish by sanding - 400 work to 600 papers , compound to higher gloss (course then fine compunds) .
From beginning to end , it's a progressive step process , always getting better while you watch the deep scrapes and gouges disapear .
My suggestion is if you want to try this type repair , do a small 1' x 1' spot for starters , learn how the materials react and work as you go ... and then see if you want to continue on doing more .
To do a whole hull , each step in the process for prep is the same but magnified , plus a primer coat is used between filler and gelcoat ... then comes the whole hull spraying of the gelcoat which takes the special equiptment and only the final 2 out of 4 coats is with finish gelcoat (different spray tips also) , and the ratios of thinner are different for each layer .
another and much easier option than …
… regelcoating large areas (whole hull) , is to do the prep work as previously described with sanding and 3M Marine Premium filler , or a slower setting marine filler … and when faired to your liking , paint the hull .
Many very acceptable marine application hull paints out there that are very durable , can be sprayed or hand applied . Spraying of two part urethanes and epoxy paints is not recommended (dangerous) unless you use “extreme caution” with the highest level of breathing protective face mask , but the same can be hand applied very safely .