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Author Topic:   greenline repair
njboland posted 05-06-2002 09:20 PM ET (US)   Profile for njboland   Send Email to njboland  
Greetings all! Great site with great advice. I am going to attempt to repair a green line split on my "new" '86 Montauk. My question is which type of epoxy to use. West or something else? Boatyard resin? I have heard some conflicting advice (not here, via friends) on not mixing oil and water so I thought I would ask. Thanks, Nick.
Soho posted 05-07-2002 07:24 AM ET (US)     Profile for Soho  Send Email to Soho     

West system is generally pretty good for all manner of repairs, especially the more major ones. It does require some experience or investigation into what sort of technique to use for the repair in question. What is a "green line split" ? ( pardon my ignorance, this is a new one to me ) Knowing this will help on advising the medium to use for repair. Marine Tex is also used for some repairs, but people seem to use it more for minor nicks and gouges as well as bedding screws.



jameso posted 05-07-2002 08:41 AM ET (US)     Profile for jameso  Send Email to jameso     
Use what ya got, any good two part will work. I pried open the 'seam' with a couple of small screw drivers then poured the split full of resin, let it sit for about half hour then 'C' clamped it all together. Good idea to scrape off the excess before it dries, I also coated the transom green line with gel coat.
jimh posted 05-07-2002 09:06 AM ET (US)     Profile for jimh  Send Email to jimh     
"A greenline split" I assume must mean a split in the outer laminate of the hull that goes sufficiently deep so as to expose the inner layers of the laminate which are greenish in tint as opposed to a simple cosmetic crack in the white or tan gelcoat outer layer.

WEST System epoxy is being used to lay-up multi-million-dollar mega-yachts, so I am sure that it will work well for repair of your Boston Whaler. In the small quantities you will need there does not seem a compelling reason to try to scrimp on the cost of the epoxy.

The only cautions in using epoxy are:

--be careful of excessive contact with your skin;

--be careful to remove all traces of amine blush before attempting to topcoat epoxy with gelcoat resins. Soap and water is effective at removing amine blush; acetone does not remove amine blush.

Independent of whatever resin you use for repair, if the fracture is wide enough you should add some glass-fabric material to strengthen the repair.

njboland posted 05-07-2002 08:57 PM ET (US)     Profile for njboland  Send Email to njboland     
Thanks for the advice. I will try to reply in kind. The green line is a name for the seam between the hull and the topsides at the transom. I actually learned the term by searching this site. The fiberglass has a greenish hue to it and at the line, there is on gel coat. The crack occurs where the line is and what happens is the finished seaward side of the transom pulls away from the wood of the transome and from the top of the inside of the hull. Seems that water dripping and freezing in winter contributes to the split. It is not a big deal, just a few inches or so, so the cost of the resin is not an issue with me. I posted the question because an acquaintance of mine whow actually builds glass over plywood boats mentioned something about incompatibility issues. Anyway, thanks for all of the great advice. I will go with the West System epoxy because it seems to make sense. Thanks for educating me on the difference between epoxy and polyester resin. I am off to check out that site mentioned. Regards, Nick
browning20ga posted 05-07-2002 09:30 PM ET (US)     Profile for browning20ga  Send Email to browning20ga     
The nice thing about the West System product is you can get a little repair kit that has several packets of resign and hardener, like little musterd packets, no measuring. The larger kits include about 6 packets of each, a couple little tubs of a thickening medium, gloves, brush and a syringe for injecting the epoxy into tight spots, stir sticks & mixing cups ($25,00). If you have the West Marine 2002 catalog, check out page 447. $10 - $25 for repair packs.
Good Luck, Darrell
jimh posted 05-07-2002 11:53 PM ET (US)     Profile for jimh  Send Email to jimh     
Well, thanks for the explanation of "green line." I don't think I recall that expression being used before, but it sounds good to me.

Any delamination of the transom is pretty serious. Be certain you make a strong repair.

By the way, I went through a couple of those $20 mustard-tube kits of WEST epoxy before jumping in for the cans with pumps. You have to invest about $50-60 for those.

They are very handy. I can mix up any amount of resin in a few seconds. For example, last weekend my wife wanted me to rebuild a computer desk we used to have at her office. Being made from that wood-particle-board instead of real wood, many of the fasteners were loose. (They are metal threaded receivers that are set into the particle board.) I mixed one "pump" worth of epoxy and set the metal threads back into the particle board. In an hour or so they were rock solid.

When mixing epoxy it is very important to maintain the ratio between resin and hardener as close to the specified ratio as possible. The chemical reaction that occurs causes the two components of the mixture to change into a new molecule, so if they are not mixed in proper proportions (as the stoichiometry of the reaction requires) there will be left over portions of one of the reagents that do not form epoxy. This will dilute the remaining epoxy slightly and reduce its strength.

This is unlike polyester resins where the resin is catalyzed and all of the resin (eventually) converts to the new molecule. In that case the proportion of the mixture does not demand as much accuracy. Too much or too little catalyst will affect the reaction rate, of course, but given time it will cure.

For forming secondary bonds, that is bonding to previously totally cured resins, epoxy is stronger than polyester resin. They would build more boats with epoxy if it was not so expensive.

andygere posted 05-10-2002 11:00 PM ET (US)     Profile for andygere  Send Email to andygere     
I prefer MAS brand epoxy over West. It does not leave any amine blush when used with the normal hardener, so there is never a problem with paint, varnish or gel coat adhering to it. I built a stitch and glue touring kayak using MAS and never had a single fish eye or blem.
jimh posted 08-05-2004 09:00 AM ET (US)     Profile for jimh  Send Email to jimh     
[Thread closed.]

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