Miscellaneous Maintenance

I wanted to mention that the hole is about a foot or two behind the tang, on the outside of the hull.

Matt

The curing agent you are referring to is most likely a mold release agent. You can spray this over the gel repair so that it cures tack-free. Gel coat that cures in the open air will remain tacky - great if you are going to apply more layers, not so great for the finish.

Is there are brand or application method you would suggest?

Some guy on the beaccats web site did the same thing to his 6.0 hulls and apparently he used pledge spray to block air from getting to the curing gel-coat.
http://thebeachcats.com/modules.php... mp;file=index&include=view_album.php

Maybe I will try pledge on a small section.

I was also thinking about using wax paper, but it seems like it might be hard to get it smooth. You can mold it a little that way.

Matt

Matt,

Just about anything will work for that pencil sized hole. Marine Tex would be a good quick and easy solution - I don't know that you even need the piece of wood on the inside...but it wouldn't hurt. It's probably not very structural so having glass fibers in the repair isn't critical.

I don't recall what kind of boat you sail, but if your bottoms are worn extensively, you probably need a layer of fiberglass in there to rebuild the bottoms before a top coat. Some put Kevlar fabric on the bottoms instead of fiberglass because it has considerably better wear characteristics. Also note that if you intend to gelcoat on top of your repair - do NOT use epoxy. Use polyester resin instead because gelcoat does not adhere as well to epoxy resin.

With regard to gelcoat...I'm learning a bit too there (www.teamseacats.com). I've yet to try and cover a large area with it but there are multiple options and methods for coating an open 'wound' with gelcoat. If you are spraying it, you will need to thin it somehow. Some recommend using acetone to thin the gelcoat, others claim that's the worst possible thing and recommend using styrene (a rather harmfull chemical). You can purchase gelcoat that already has a wax additive in it so that when you spray it the wax floats to the surface and seals the gel so it will fully cure. Other "mold" system gelcoats are intended to be sprayed in the bottom of a mold before glass is laid on top sealing it off. the "mold system" gelcoats require either the wax additive or a top coat of a PVA (poly vinyl alchohol) to seal out the air so it will fully harden. I'm going to be experimenting soon and will keep the website updated.

In my experience I don't like the wax additive. The gelcoat will cure fine with the wax. But the finish is not as nice as if you spray it and then use PVA. So wax in my experience causes you to have to sand quite a bit. I'm sure pledge is basically the same thing as PVA. Anything that keeps the air out will work. I've heard wax paper, hair spray, PVA, Pledge, ... I would just use PVA. It's cheap and it washes off.

Mike Hill
www.stlouiscats.com

Ive mixed small amounts of gelcoat inside a waxed paper cup as theoretically the wax dissolves and is used as the curing agent. I also used pledge afterwards just in case...

Jake,

I have been looking at the pictures on you site every couple days. Thanks for the tips; I will use your suggestions.

Matt

I was just at the store and all the pledge products they had make a big deal about not containing any wax. I don’t know if they changed the formula, has anyone used pledge recently?

Matt

"Styrene- a rather harmful chemical"- Hold the phone: the whole boat is made from styrene catalyzed with methyl ethyl ketone + benzoyl peroxide as catalyst= polystyrene.

Styrene can be used to thin the gelcoat for spraying.

I think I'm going to try Mike's advice and go with the PVA...results to be posted soon.

I use the wax additive and find it works well. Don't over catalyze the gelcoat and make sure it's at least 70 degrees. Mix it well. The only time I have trouble is when Gel is sprayed over epoxy. Styrene to thin.

If you do a search you'll find a lot of info on this.

Yeah, me too. I have already wasted more than 10$ worth of time thinking about it.

Matt

ok, i ve watched this kind of stuff here for years now. it is chemistry. plain and simple. pledge may 'work' but it is not right. pva will 'work' but it is not right. use the wax additive and be done with it. this is why these things are made. it is what the professionals use. dont screw with the chemistry.

Gelcoat is resin mixed with a thickener and color added. The resin is usually not a finish resin (containing wax). If I have a small repair I can mix a bit of coloidal silica (not microballons) with finish resin and color. You have to add a bit more hardener to this mix (same as you would with gelcoat). This drys pretty nice. You just mix enough thinkening material to get to a gelcoat consistancy.

Most of the time gelcoat is sprayed or brushed on the inside of a mold then glass and resin is put over the top of that. This seals the gelcoat from the air and allows it to harden nicely. If you watch a repair shop add gelcoat to the outside for a repair, they will spray it with PVA. This is just a spray-on plastic material, usually green, that is water soluble when dry. A water wetted sponge will take it completely off.

Later,
Dan

dan, ive been building boats and doing repairs for the last 20 odd years. dont do it, just add the wax. that is what it is there for.

If there is one thing you can count on when dealing with Gelcoat...it's that everyone has a different opinion!

I've now done spot repairs in the field with gelcoat and a complete bottom job on a 6.0 in my basement. I used form release both times with good results. Note: When working in your basement, don't forget that pilot lights or ignitors should be turned off.

Listen to Basket.case…I have been using fiberglass for 39 years…use the wax additive. I don’t know where these off the wall fiberglass techniques come from…probably someone that didn’t have a clue what they were doing in the first place, screwed up the job by using tooling gel coat (no wax) and then tried all kinds of stuff to try and salvage the job.

Use the wax additive…if for some reason you can’t find it locally you can make the same thing by dissolving some paraffin wax shavings in a small amount of styrene…but use a wax additive.

Fiberglass is not a mystic art…get the right products…use them as intended …and you will get predicable…repeatable…quality results. Make up your own rules as you go and you may be dealing with a sanding nightmare. Ever sand wax free gel coat?…I have…it’s a royal pain in the butt. It can turn a half hour sanding job into a day long sanding job...

Seeker

well, this is what i did at work today. ive got a bit of an idea about boats.
use the wax.

Yo Basket,

I didn't mean to imply you didn't know what you were doing - you have to admit that there is a lot of confusing information out there about applying gelcoat.

I do have a question though - what should I look for and where can I find the wax additive? I hear that you can make it by disolving parafin wax in styrene but I really don't want to mess with all that. I have found a "Duratec high-gloss additive" that appears to do both thinning and adding an air dry additive - do you know of this stuff? Apparently it's widely used in mold making.

Secondly, I ran across some info about spraying gelcoat that I thought looked interesting. You spray three layers, each wider than the first. Pre-thin each batch/layer..mix the catalyst and spray the first covering about 75% of the repair area. Cear the spray gun with acetone (or styreene). Catalyze the second batch and spray it covering 100% of the repair area. Clear the gun again with a small amount of acetone. The third layer should already be thinned but have the wax additive (whereas the first two did not). Catalyze and spray the third layer feathering it out over the non-repair areas as you go. Thoughts? Comments?

jake, it was not taken that way.
you should be able to get 'air dry' at your local composites store. where ever you get the rest of your stuff should have it.
ive used duratec a fair bit, in all of its' forms. it is good stuff. still though, use the air dry. 5%. the high gloss makes the repair 'nicer'.
chances are you would spray the repair area wet on wet for the best results. if you have air dry in your gel wet on wet will be fine. the types of repairs we generally talk about here are no bigger then a softball and done outside so to do it any other way you risk contamination. dust, dirt and bugs.
find attached a bit of duratec work i did a while ago.

and this

and this one just to show i build cats also.

I'm talking about spraying the entire length of the bottoms of two 20' hulls. I had intended to spray three layers each one wet but use the airdry only in the final layer. You're saying put it in all the layers?

if you are talking waterline to waterline, id just paint the whole boat with a nice lp paint. you are going to be a long tome wetsanding it smooth. if it is just on the seam, sprey the thing in one shot your way, but go wet on wet.

jeez jake, after looking at your site and the photos, paint the boat with a lp. the amount of wet sanding you will have to do to get that much area smooth can be measured in weeks.
paint the whole thing and be careful on the beach with it.

There will be no talk of that....and like I've taken a short cut thus far.