Let’s get down to business

I need some opinions. I’m going to be doing a fair amount of fiberglass work on my boat. I’m doing this myself. I have read conflicting information about the best temperature in which to do this. I plan on doing it the third week in January. What is the lowest temp I should apply in?

I would wait for 60 degrees or better. The nice thing about North Fl, if you "tent" the area,the sun will heat it up enough to kick. You didn't say if it was interior or exterior work so I'm assuming exterior.
Whats the project?

I’m going to re fiberglass just above the gunnels. Also the corners of the stairs collect water. I want to do this before it becomes a massive project. Yes it is exterior.

Poly work or Epoxy?

Either one, the manufacturers are pretty good at hitting the temps they will work in.

A common mistake is substrate or work surface temps versus air temps.

Tenting and warming do work as long as the warming is regulated and uniform enough till most pf the chem reaction has occurred. Often overnight for even faster setting epoxies if working near the limits of their temp ranges.

Polyester is more forgiving unless huge layups....as you can increase the hardener appropriately.

There is no good or bad temperature except the extreme, everything depends on what type of hardener you will use and to do what. Just keep in mind that warmer it is faster it is drying. Sometimes it is good to get things dry very quickly, sometimes not.

L

No, it’s fiberglass. I have worked with it before just not on a boat and the temp was around 70. It needs some prep work but I do not want to leave it exposed for a prolonged period of time. Florida is tough. It is either too humid or hot for comfort and in the winter the weather can go sour on you very quick. Manufacture says 50 but it can easily drop below that at night. It does not say how many hours it needs to stay above 50. Ideally for me working above 60 would be best. After the glass i will paint the topside. The hull was painted in the Bahamas last may when I had her out for bottom paint. Just didn’t want to spend another 5 Grand on the topside when I knew I could do it myself.

Email boatbuildercentral.com and they will tell you. They are in the same area and have 25 years experience with repairs. Free advice too.
On one of their tech. support web page, at bateau2.com, there is a table about curing temp. for epoxy.

Just like painting the key is to be totally set up before starting.

50F is no problem with polly , if it kicks too slowly another 1/2 % of hardener can be used.

The important concept for repairs is the surface you are sticking to must be 85% ground down to bare OK glass.

Brushing resin in place is done by some folks , but we have found a 9 inch roller with deep nap , cut into 3 or 4 sections is much faster and easier to get good coverage.

Just stick the cut section on a 7 or 9 inch roller frame , and when all the resin is used , tap it off .

Have your steel rollers ready ,standing in a 1 Quart can of Acetone 1/4 filled is easiest to keep functioning all day.

Have fun.

Excellent! So everyone is in agreement that 50 is fine! I’ll bundle then! Thank you!

What I have done in the past is use a heat gun/small electric heater at a distance to warm up the area I glassed so it cures.
I actually prefer to do fiberglass work when it's cool because you get more working time.

Keep in mind that your boat acts as a heat sink. If it was 40 degrees all night but warms to 60 degrees in early morning, the boat will still be at 40 degrees for some time.

Keep your resin warm before start 70 to 80

The resin, cloth, and surface you're repairing all needs to be above 50°. Store the resin and hardener somewhere warm like a heated room. Several days in advance if in gallon or bigger cans. After wetting out, as the day cools, the resin needs to be most of the way to cure before the temps reach 50°. Too cold and it may not cure fully. Heat the underside so the repair area is always above 50° until semi cured. If it doesn't fully cure, the resin may appear cloudy, the surface remains tacky, and paint or gelcoat may not stick well.

When adding heat , remember that GRP burns about 5x better than wood , and is very hard to stop once burning.

A heat lamp, not a torch is best.

Donna, "fiberglass" refers to the substrate. It says nothing about the resin used to impregnate the substrate. While your hull may well be laid up with polyester resin, epoxy resin performs better as an "adhesive" for adhering new laminate to existing fiberglass laminate.

Epoxy has a strong bond, but it is overused and often misused by amateurs, depending on the project.

Epoxy is fantastic for repairs , BUT it must be painted as sunlight destroys it , slowly.

Thank you all so much! Looks like this coming week is a no go. The are even talking about snow flurries on Wednesday. I’m working the following week, so as of right now I am 3 weeks out from this project. Sigh....