Lowest Temperature for Bottom Paint Application

[thomm225]

So I'm seeing the guys at the boatyard applying bottom paint in temperatures down to 45 degrees and lower

Is there a limit?

[captain465]

Look at the label on the can!!!!!

[Kenomac]

Call the manufacturer or read the can.

[Tylermartinsail]

I have a sailing school in Portland Maine, so working around the weather is just part of it. It’s not optimal to apply bottom paint in temps below 55. However, if the temp is going to be above 55 in the next 24 hours, and it’s not going to rain or heavy dew before it dries, then it should be ok. It just won’t dry for awhile, and it may be difficult to apply.

[thomm225]

Originally Posted by captain465

Look at the label on the can!!!!!

Yeah, it gives the standard 50 degrees to 80 degrees which we pretty much all know about, but the experts, the guys at the boatyard, go much lower.......maybe even down to 42 degrees and even when it's drizzling.

And the boats look great when they are through. (and of course they do an outstanding job sanding the bottoms first. There usually isn't a blemish left)

I have applied it at 48 degrees with no problem but at 42 degrees, I would have a larger weather window to get my painting completed.

[Bill O]

+1 for reading/following the manufacturer's notes for application temps.

Also in the colder temps keep the boat out of the water (don't launch) for the max. cure time to allow the solvents to blow off and the paint to properly cure. The curing will happen much slower in cold temps.

Bill O.

[thomm225]

Originally Posted by Bill O

+1 for reading/following the manufacturer's notes for application temps.

Also in the colder temps keep the boat out of the water (don't launch) for the max. cure time to allow the solvents to blow off and the paint to properly cure. The curing will happen much slower in cold temps.

Bill O.

Yeah, it's pretty obvious you should follow the instructions but since the experts at painting boats don't, I thought I'd see if others are doing the same. And I did spot painting in the upper 40's last time in 2015 after the stands were moved and then again after the boat was on the lift for a few hours before launch

Cure time isn't a problem as this boatyard has a Winter low rate that covers the months of November - February.

Btw, I was told that this doesn't apply to topside paints, only the more hearty bottom paints.

Usually the temp just affects the spreading of the paint and the drying time anyway......is my experience

[thinwater]

It's not because they are experts. It's because they need to generate revenue year-round. I frequently see contractors applying epoxy, fillers, and sealants right at the edge or below, in the full knowledge that it will be WELL below as soon as the sun goes down.

If you contract off-season work this is something to be aware of; it will often be done at or below the accepted temperature because the men need work and because they can't get it all done in the spring rush. It's just reality.


And it is NOT just slower. With many products, slow curing allows time for water absorption and side reactions that would not otherwise occur. Varnish in the winter can be cloudy and lumpy. 2-part products will be lower strength. Polyurethanes may not cure for months.

[Bill O]

Originally Posted by thomm225

Yeah, it's pretty obvious you should follow the instructions but since the experts at painting boats don't, I thought I'd see if others are doing the same.

Not sure which experts you are talking about when it comes to bottom paint.

We just did our bottom in late summer this year and asked around to see if reasonable to have a yard do it. The typical job was a power wash, followed by sanding w/80 grit then 1 coat of paint. (that's fine if you pull your boat every year). Most of the time the bottom was prepared/painted by the very lowest yard help (sometimes just summer labor) and the work we saw was just ok. Surely no experts here and doubt they ever read the application instructions. A 2nd coat was an add on item and if you wanted a 3rd coat (seemed like it was almost unheard of) at the waterline was an hourly rate to do the work. In the yard we hauled out at, moving the stands (once) was included so at least it allowed for a proper cure time of the bottom paint before launch.

It does bug me that one pays so much to haul a boat, pays for expensive bottom paint, then have the yard hustle you in the water just after you've painted the under the keel or where the stands were (if you don't pay extra for them to be moved). Even in the summer heat (90F), my paint manufacturer's recommendations are for a min. of 8 hrs before launch and at least 24 hrs at their min. application temp. of 40F.

We did the bottom paint ourselves just to make sure it was done properly and I wasn't wasting $$$. With the bottom paint done properly one should get multi seasons out of it.


Bill O.

[thomm225]

Originally Posted by thinwater

It's not because they are experts. It's because they need to generate revenue year-round. I frequently see contractors applying epoxy, fillers, and sealants right at the edge or below, in the full knowledge that it will be WELL below as soon as the sun goes down.

If you contract off-season work this is something to be aware of; it will often be done at or below the accepted temperature because the men need work and because they can't get it all done in the spring rush. It's just reality.


And it is NOT just slower. With many products, slow curing allows time for water absorption and side reactions that would not otherwise occur. Varnish in the winter can be cloudy and lumpy. 2-part products will be lower strength. Polyurethanes may not cure for months.

I'm thinking they wouldn't do it if they thought the job wouldn't stand up. They do so many sometimes with the owners observing

Also, as I mentioned, with paint it's usually that it won't spread well below 50 degrees except for bottom paint and the label instructions mostly just say what is best not the absolute limits.

[thomm225]

Originally Posted by Bill O

Not sure which experts you are talking about when it comes to bottom paint.

We just did our bottom in late summer this year and asked around to see if reasonable to have a yard do it. The typical job was a power wash, followed by sanding w/80 grit then 1 coat of paint. (that's fine if you pull your boat every year). Most of the time the bottom was prepared/painted by the very lowest yard help (sometimes just summer labor) and the work we saw was just ok. Surely no experts here and doubt they ever read the application instructions. A 2nd coat was an add on item and if you wanted a 3rd coat (seemed like it was almost unheard of) at the waterline was an hourly rate to do the work. In the yard we hauled out at, moving the stands (once) was included so at least it allowed for a proper cure time of the bottom paint before launch.

It does bug me that one pays so much to haul a boat, pays for expensive bottom paint, then have the yard hustle you in the water just after you've painted the under the keel or where the stands were (if you don't pay extra for them to be moved). Even in the summer heat (90F), my paint manufacturer's recommendations are for a min. of 8 hrs before launch and at least 24 hrs at their min. application temp. of 40F.

We did the bottom paint ourselves just to make sure it was done properly and I wasn't wasting $$$. With the bottom paint done properly one should get multi seasons out of it.


Bill O.

Yeah, the haulout etc is a bit expensive which is why I do mine once every 3-4 years. It's been 4 years this time. I apply about two coats with 1 gallon and 1 quart of bottom paint.Micron CSC.

Good thing here though is that Winter Storage is $8.00/ft/month for the four months of Nov-Feb

[Shrew]

The long-term performance and results are not really their concern. They have a list of work orders that they need to turn into invoices.

[thomm225]

Originally Posted by Shrew

The long-term performance and results are not really their concern. They have a list of work orders that they need to turn into invoices.

Yeah, I can see that at some boatyards but not all especially the ones that have lots of business and have been family owned for years on end .......say from the 1950's

I usually wait for a day above 50 degrees but have done the regular touch up, stand spots and keel spots, in other than optimal temps/humidity

My boat is ready for the paint right now except I need to wash the bottom and then apply some 202 solvent to the bare spots then I can paint. That's just the bottom, we are also going to redo the topside paint and the interior

[Shrew]

Originally Posted by thomm225

Yeah, I can see that at some boatyards but not all especially the ones that have lots of business and have been family owned for years on end .......say from the 1950's

Which boatyards are you seeing the behavior in? Technically it can't be BOTH. They can't be both conscientious and applying paint well outside of the manufacturers' recommendations. (e.g. damp hulls and/or outside recommended temperature ranges).

[ferrailleur]

love this thread..... Timing is everything!.. thanks to all contributors.