Looking for some input on this one. Just picked up an older 18' cat and other than some beach rub on the bottom of the hulls she is in great shape. She is not even rigged right now so I will be able to turn her upside down fairly easily and get the boat on some foam or cushions to sit for a while. What has everyone had the most success with for the rub lines. We are talking about 2'-3' sections of the bottom of the hull being worn down to bare fiberglass. I was thinking of using 4"-6" wide tape fiberglass cloth or even springing for the kevlar cloth for a little upgraded rub resistance. Any thoughts from you guys and ladies out there who have done this already?

Sounds like a good plan. Fibreglass tape and gelcoat. Do not use Kevlar on it. Kevlar is terrible to repair and sand.

I appreciate the reply. Did not know if putting a little Kevlar cloth in there would make it last a little longer between times of fixing it. I take it you speak from experience <img src="http://www.catsailor.com/forums/images/graemlins/tongue.gif" alt="" />

Tape really is not needed unless it has worn right through.
The resin is enough and needs to be as hard as possible for longer wear.
Tape each side of repair so no clean up is needed and lie hull in sun. Heat will help the resin to go off quickly so it can be worked.
Glue pwder makes a thicker and very hard compound but must be respected.
Cut any excess off with knife when half set and repeat next day until desired thickness is formed. Sand clean with lessening grades of wet and dry.

warbird I mainly am used to using West Systems for all my epoxy resin needs. Usually to strengthen the resin I add some of the structural fillers that they have. Is this along the lines of what you are talking about? I have had quite a successful amount of repairs done with this mixture and have been happy so far. I am just looking to put something on there that will last for a while. Of course I know that it will last longest by not dragging it on the sand <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Use polyester gelcoat (if thats whats originally on the boat)of the same color.
If all it is the color (gelcoat) don't make it more of a problem than it is by adding cloth if it is not necessary. The last thing you want to use is Kevlar...when you try to sand (or the resin is ground away by beach sand) it makes little fur balls. It doesn't sand like fiberglass, you can't feather it. Don't use epoxy unless your going to use paint over it.

Regards,
Bob

What I do is have a filler/glue mixture which I mix to bring it to a viscous state so it can be shaped and create a strong, thick but workable product. It is a lot harder than filler but sandable. After fairing I paint two layers of pure West System ofer the top, sand and paint. If the hulls are inverted in the sun you can often get three layers in one day.
I have had great, quick and tidy results with this. Just be sure to mask properly and there should be no probs.

Thanks for the help. I really like the idea of the repair using the thickened epoxy. This is not a structural repair really just a build up for the bottom. What is everyones feeling about gel coating this? I do not keep it in the moored or docked. She comes out everytime when I am done with the days sailing fun. I could mix in some of the pigment into the epoxy, they have a white pigment but I would almost like to leave it be for full strength. Any opinions?
Thanks!

the white pigment added to the west system epoxy does a good job of making it white but it is still not UV stabilized though so it will yellow with exposure to the sun theoretically.
If you are doing this to build up the hull so you don't have to worry so much draggin it up and down the beach I wouldn't go through the trouble of gelcoating it

Epoxy is not going to have the UV resistance of Gelcoat...if you put cabosil in the resin it will be hard to sand but hold up better...if you put glass bubbles in the resin it will be easy to sand but ware away fast...there is no free lunch...unless the bottom is all gouged up there is no reason to use a filler. Again if the color coat (gelcoat) is all that is worn away then just lightly sand the surface with 80 grit, wipe it down good with acetone and re-gelcoat the area...its not paint...you can build it up 1/8" of an inch if you want (or more) and sand it down to suit your fancy. Don't make a mountain out of a mole hill. Use the gelcoat...it will be less steps, match the original better, be more resistant to ware than other methods and we be considerably cheaper. Clean/Sand/wipe/gelcoat/sand/polish or Clean/Sand/wipe/Epoxy/sand/prime/sand/wipe/paint/sand/polish the choice is yours.

Regards,
Bob

But ain't it a pain to match the color of the gelcoat (even white) ? I do a decent amount of glass work- but by no means a professional- and although my next step is learning how to apply gelcoat I am SO not looking forward to learning it. Everything I have read about it makes me think it is a serious pain in the butt. IF it weren't the bottom of the boat I would say cheap white spray paint.

I Ditto Seekers comments!

My next question is then, what type of gel-coat do you guys recommend? And being a gel-coat newbie what is the best way to apply it?
Thanks again guys, I really appreciate this help <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Standard West Marine Gelcoat. Get some Acetone too. You might need some styrene to thin it a little to spray it. Practice on a piece of wood. Here's a list:

1. Spray bottle
2. Mold Release
3. Gelcoat
4. 3 mil plastic sheeting
5. Tape.
6. Color agent for gelcoat if needed.
7. Preval sprayer (available at West Marine)
8. Acetone to clean the sprayer.

Turn it upside down
Sand it to get a smooth finish 100-220 grit.
Tape it off with the plastic and tape that you don't want sprayed. Overlap a little.
Spray it with possibly a little styrene to thin it.
Spray 3 coats about 20 minutes apart.
After the last coat sits for about 15 minutes spray the whole thing with Mold release.
Let it sit for 24 hours.
Wash off the mold release and start sanding. Start with 220 and work your way to 600 or so wet with a long board.
You can finish with a 3M product. I forget the name.

Mike Hill

I have been talking about an older boat with keel wear that can be fixed easily and quickly at home.
I have had no trouble matching white for this using a LITTLE yellow added. This two inch wide strip on keel is almost impossible to see and will wear out again anyway unless you are a serious racer only. What the thickening gives you is peace of mind at the beach in future as you know you have some sacrificial thickness there.
But if you want show room finish miine is a little rough.

Adding to Mike Hill post:

Wetsand to 1000 - 1200 grit (Optional for some)
3m Heavy Duty Rubbing Compound (05955 - Gallon part number; it does come in quarts but I could not find it quickly) or
3M Perfect-it III (05936) and
3M Finesse-it (09048) and
3M Ultra Performance Paste Wax (09030)

I don't know where spraying PVA over wax free gelcoat started, but working with fiberglass extensively since 1968 and a decade in Professional Custom boat building I have never worked in a Professional boat yard that used PVA over gelcoat in place of wax additive in the gelcoat...never worked with any reputable professional boat builder who used PVA over gelcoat in place of wax additive in the gelcoat, never heard a factory rep for any major fiberglass supplier ever recommend anything but putting wax "in" the gelcoat before it is applied. I can't understand why this method keeps coming up every time there is discussion on fiberglass repair or refinishing as it is not the industry standard and the proper products are readily available to ensure the consistent quality results the Fiber Reinforced Plastics Industry has spent over a half a century perfecting.

Regards,
Bob