Question about 5200 sealer

Giorgio · #1 09-11-2019, 07:34 AM

My friend found a small leak in the motor well by the scupper and his question is, can 5200 be put on wet, while the boat is still in the water or does he have to take the boat out of the water, then let it sit for an hour or so? He asked me and I wasn't sure, I thought we would have to take the boat out and sit for a while. When I used 5200 on my boat, she was always out.

Destroyer · #2 09-11-2019, 07:43 PM

Not sure about the wet or dry angle, but since 5200's "cure" rate (even their fast cure stuff) is in days if not weeks I would think she has to be dry for it to cure at all.

Redloon · #3 09-11-2019, 08:13 PM

Take a look at J B Weld's Waterweld. I've used it before to seal a small hole in my hull, I believe it can cure under water.

Giorgio · #4 09-12-2019, 08:19 AM

Thanks guy's. I talked to a mechanic at Lockwood Boat Works in New Jersey, that's where I got stuff I needed for my boat. He said, let it sit for about an hour or so, then good to go. We shall see, if it doesn't work, time for another boat.
Thanks again.

cfelton · #5 09-12-2019, 09:47 PM

Check out Marine tex, they make it for fiberglass and metal. Its good stuff! I got some from NAPA. Its two part epoxy, sets up pretty fast.

Destroyer · #6 09-13-2019, 03:59 PM

All Epoxies will cure underwater. They use a chemical reaction rather than oxygen as the catalyst. However, they will also cure slower underwater because of the temperature difference AND they might wash out if used before they are fully cured.

As far as 5200 goes, it will cure underwater. It's designed to do so, and in fact it needs moisture to cure, just as well as air dry. As far as speeding the curing process up with water, you won't notice any difference. It will not stick underwater though. It needs a dry surface for a proper bond. Waiting 24hrs. is ok, but 48hrs. is best for 5200.

From someone with far more chemical experience than me:
It is my understanding that 5200 cure is isocyanate based - water reacts with isocyanate groups to form amines, which react with other isocyanates to form ureas linking the molecules together and increasing the the strength, water and solvent resistance each time a new bond forms.

In addition, the isocyanate groups are reacting with groups on the surfaces that the product is in contact with, chemically bonding it to the surface and covering polar groups that would let water wick between the sealer and surface it is being applied to. If there is too much water (as in immersed in water), a large portion of the isocyanates are converted to amines and do not have time to react thorooughly as described above - hence the reason for the delay before putting it in water. For maximum adhesion, strength, water and solvent resistance, you want slow cure from airborne moisture...

steplift20 · #7 09-16-2019, 07:49 PM

Sometimes a boat has to come out of the water to be worked or repaired on,and this my friend is that time.

Destroyer · #8 09-17-2019, 03:38 AM

Quote:

Originally Posted by steplift20

Sometimes a boat has to come out of the water to be worked or repaired on,and this my friend is that time.

Yep

Giorgio · #9 09-24-2019, 09:51 AM

Thanks!! The work has been done with JBWELD and 5200. I just got a call and was told their boat is still leaking, just a drop here and there. A drop here and there could mean later the the dam has gone down. To be continued in their off season which is this week or next week.
Thanks again!!