| Re: Bottom of Hull Repair
[Re: HMurphey]
#142316 05/06/08 06:08 PM 05/06/08 06:08 PM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
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Carpal Tunnel
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Posts: 6,049 Sebring, Florida. | Would Kevlar tape be any better than glass tape, ie. last longer, or would that get ground down just as quickly? I've got to do the same repair on a Prindle. I was thinking of using Kevlar but will it work with the same epoxy (West) or do I need something special, or am I wasting money on Kevlar?
Blade F16 #777
| | | Re: Bottom of Hull Repair
[Re: PTP]
#142318 05/06/08 06:52 PM 05/06/08 06:52 PM |
Joined: Nov 2003 Posts: 749 Santa Cruz, CA SurfCityRacing
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Posts: 749 Santa Cruz, CA | An outstanding, easy, and less expensive option is to properly repair the boat with what it was built with: Polyester resin, glass, with a layer of gelcoat. The problem with using epoxy is twofold: 1) Gelcoat will not properly cure over some epoxies. 2) It's more than double the cost of polyester. You don't need the bonding ability of epoxy for this type of repair, just fix it properly and gel coat. For a good primer on f-glass repair go Here. Scroll to page 14. or Here.Scroll to page 16. | | | Re: Bottom of Hull Repair
[Re: SurfCityRacing]
#142321 05/06/08 08:40 PM 05/06/08 08:40 PM |
Joined: Jan 2005 Posts: 6,049 Sebring, Florida. Timbo
Carpal Tunnel
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Posts: 6,049 Sebring, Florida. | I too was thinking Epoxy for hardness, I am not going to try to gel-coat it afterwards, I am more interested in strong vs. pretty, it's not a race boat, just a beater.
Blade F16 #777
| | | Re: Bottom of Hull Repair
[Re: Timbo]
#142322 05/06/08 08:58 PM 05/06/08 08:58 PM |
Joined: Sep 2007 Posts: 757 japan erice
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Posts: 757 japan | in my experience polyester is harder
you can usually just dig a finger nail into sun warmed epoxy but you never can into polyester
epoxy is the best for wood, it's easier to mix, the chemicals aren't as dangerous and the fumes nowhere near as bad
but for repairs to polyester boats polyester bonds better, is harder and cheaper
keep in mind the polyester reaction requires a "Kick" from a small toxic catalyst and that the surface chemical left over from the epoxy reaction inhibit this kick
so if someone does a small epoxy repair to a normal polyester boat but later wants to spray new gelcoat over it the gelcoat over the epoxy won't cure correctly if at all
eric e 1982 nacra 5.2 - 2158 2009 weta tri - 294
| | | Re: Bottom of Hull Repair
[Re: WillNicholson]
#142325 05/06/08 11:12 PM 05/06/08 11:12 PM |
Joined: May 2006 Posts: 1,383 Kingston SE South Australia JeffS
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Posts: 1,383 Kingston SE South Australia | On my old A class this season I applied fibreglass tape and wessystem along the entire bottom of the hull which I didn't paint. It works fine but its not as tough as paint and abrades away with movement on sand leaving light scratches which would be slow for racing. regards
Jeff Southall Current boats Nacra 5.8 1703 Animal Scanning Services Nacra 5.8 1667 Ram Raider Nacra 18 Square Arrow 1576
| | | Re: Bottom of Hull Repair
[Re: HMurphey]
#142326 05/07/08 01:43 AM 05/07/08 01:43 AM |
Joined: Nov 2003 Posts: 749 Santa Cruz, CA SurfCityRacing
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Posts: 749 Santa Cruz, CA | Apply epoxy let it tack up ... apply a layer of cloth,and smooth out ... apply a coating of epoxy ... let tack up ... apply next layer of cloth ... etc etc.
Yeah...keep going...keep going...what do you do next if this were a repair on Will's Hobie 16? What do you topcoat it with to make it look nice and to keep the water out of any open fibers? | | | Re: Bottom of Hull Repair
[Re: SurfCityRacing]
#142327 05/07/08 07:27 AM 05/07/08 07:27 AM |
Joined: Oct 2002 Posts: 1,226 Atlanta bvining
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Posts: 1,226 Atlanta | Its always good to stay with what the boat was made out in terms of chemistry and construction. If you use Polyester, work outside, wear gloves. Long sleeves, long pants, and a mask are all good precautions. And dont smoke while doing the repair, its flammable. Here a blurb from US Composites on Polyester Resin. Polyester Material Info: Polyester resins are the most commonly used matrix in the marine and composite industry. These resins are styrene-based, flammable and catalyzed when combined with Methyl Ethyl Ketone Peroxide(MEKP). When working with these resins in large projects it is advised to use gloves and a chemical respirator to protect yourself from the fumes. These resins can be used with any type of fiberglass, carbon fiber or kevlar, as well as used over urethane foam and other sandwich core materials. These resins tend to be fairly rigid when cured and also more brittle than epoxy resins. http://www.shopmaninc.com/polyesters.htmlhttp://www.shopmaninc.com/pdf/MEKPDirections.pdfEpoxy Room cure type epoxy will soften in the sun, but the surface temp needs to be over 120 deg F for West and 140 for MAS, so the bottom of the boat isnt going to get that hot, unless you leave the hulls sitting on the black pavement and then stress them in some way you could be in trouble, not likely. If you use Epoxy, I recommend MAS, the slow hardener is no blush, and they make a no blush fast. Epoxy isnt as toxic, but you need to be more precise in mixing and measuring it. Wear gloves, dont get the hardener on your skin. MAS is low VOC so you dont need a mask. Work with epoxy in a dry, 70deg area, like a nice day in the shade, or a garage. Uncured epoxy doesnt like moisture, so evening dew, or fog could mess it up. I use peel ply on all my repairs, it goes on top off the last layer that you are leaving to cure, and it peels off after the area is cured, it helps keep everything held down nicely, and it lets you squeegee the fiberglass down and get the repair nice and smooth. Fiberglass gets realy slippery when its wet out with resin, and its hard to keep it straight, plus the fibers come off easily. Peel ply makes it less of a mess and make it easier to work the cloth and get it all smoothed out nicely. If you use Peelply, the amine blush forms on the outside of the repair, so when you peel the ply off, the blush comes off. No washing the blush, which is a pain in the ***. Bill | | | Re: Bottom of Hull Repair
[Re: WillNicholson]
#142328 05/07/08 07:49 AM 05/07/08 07:49 AM |
Joined: Oct 2002 Posts: 1,226 Atlanta bvining
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Posts: 1,226 Atlanta | Will I dont think Epoxy is materially harder or softer than other resins. Its just differient chemistry.
Most stuff made professionally out of epoxy, like Hall Masts, Forte beams, etc, uses an epoxy resin that requires heat to cure it. The Forte stuff is cured in an oven at 300deg F, and Hall uses an oven too. Since thats not feasible for the homebuilder, West, MAS and others sell epoxy that room temperature cures. The downside is that room cured epoxy gets soft at between 120 and 140 deg F. A black part left in the sun, in TX on a hot day will get to 160 deg F, and according to Tony Delima at MAS, you want a TG of 40-50 deg above the working temp of a part, so room cure epoxy wont work for black parts that have to work in the sun. Now, if you cool the part down in the water (like a rudder) and then stress it you should be fine, but its something to keep in mind. A white part can get to 130 deg, so painting your part keeps the temp down quite a bit.
Also the first time an epoxy part is first heated at an elevated temp, it goes through a secondary cure, so you get a higher TG if you leave an epoxy part in the sun, or in your car. I usually leave my parts in the sun to cure, or put them in my car to get a higher heat cure.
If you want to make a black part, and its going to need to be stressed in a structural way (like a beam) in the sun and you want to make it with epoxy, you need to use some of these higher heat cure hardeners like, Infucure HT, Anhydride, Dici, or Low tox. West's Proset line has higher heat property's but isnt clear, so you cant make a black carbon part with that stuff.
I havent gone the route making an oven, Im toying with getting an old oven and putting it in the garage for small parts.
Steve Clark build an oven out of plywood and electric baseboard heaters some thermocouples. Its not that far outside of the basement builder's reach.
Sorry for draining the pond on that answer, but I was just talking to Tony about this yesterday, so its still fresh.
Bill | | | Re: Bottom of Hull Repair
[Re: HMurphey]
#142330 05/07/08 10:03 AM 05/07/08 10:03 AM |
Joined: Oct 2007 Posts: 75 Florida soulcat01
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Joined: Oct 2007
Posts: 75 Florida | Hey Harry Is this what youre talking about. epoxy ![[Linked Image]](http://images.saleshound.com/broadreach/dyn_li/200.0.75.0/Retailers/pepboys/8978532_bondo_filler01.jpg) paint ![[Linked Image]](http://i81.photobucket.com/albums/j228/wnb85/krylon_spray_paint.jpg) | | |
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