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.

i'm not sure why folks are hot to gelcoat the bottom of their boat. for me it's the part of the boat that gets run up on the sand/reef and is rarely seen. from my experience a nice carbon fibre stripe down the bottom wears alots better than glass or the super soft material known as gelcoat. also a graphite powder and aerosil epoxy bog makes a very slippery and hard surface.
my $.02

so jake, how is it going?

Jake is in Pcola right now for Alter Cup.

As for using gelcoat to repair what was lost, its only returning the boat to its previous, like new state. Its something that has to be done on all these beach race boats from time to time.

Smooth is fast, and I think the consensus is that gelcoat is the easiest to repair (making the hull smooth again). Other options may be more durable, but once they're scratched or gouged, it can be much more difficult to repair correctly.