Internal patch.

raymillard · 17 November 2011, 14:14

I'd like to do an internal patch on my boat. I can't see how I could do it with 2 part adhesive as it's so "sudden death". I'm sure I'd finish up with a wrinkly patch in the wrong place. Does anyone know how you do it?

Courageous · 17 November 2011, 15:05

Yes Ray, tear a hole next to the existing hole big enough to get an iron through and then you can iron out any wrinkles

sinner · 17 November 2011, 17:49

Be vawy vawy cafful!!!

sinner · 17 November 2011, 18:06

Seriously though, it can be done: This was taken off the iboats.com forum

"......First off, let down the tube, then we make the hole / rip bigger and also make it an "L" shape, then trim all the edges to get rid of the fluffy stuff, fold back the triangle bit and hold it with some gaffer tape, reach inside and rough the surface with sand paper, clean with MEK or Acetone, mix the two part glue and give it a thin coating, also the square patch you have cut which is about 2 inches bigger than the L shape, let them dry for 30 mins, then a second coat, wait 10 minutes then carefully place it inside, REMEMBER that hypalon glue is a contact adhesive so when it touches it sticks, then rub the patch all over with a screwdriver handle to get it dead flat, now glue the triangle bit you held out of the way with tape and again rub all over working from the middle out, time then to cut another patch 2 inches bigger than the rip, prepare the surfaces, and glue again as for the inner patch, 2 coats and rub it on well, LEAVE for 24 hrs to cure, then inflate the tube to just under working pressure of 1.5psi, check for leaks with lots of soapy water and you should be good to go for years to come.

Dont forget to Round off the corners of the patches as they do not catch as easy and lift, especially the outer patch."

Hope this helps!

biffer · 17 November 2011, 18:17

don't make the hole bigger, you just have a bigger hole to repair, you have to sand inside and prep as they say, you can either put the patch in wet and move it about till it's right and then apply even pressure untill dry, fold the patch in half and fit it to one side of the hole first then unfold it or cover the patch with polythene until its in the right place then carefully peel it back.
it's no denying it's fiddley but it can be done. you will still need the outside patch

raymillard · 17 November 2011, 18:50

Thank you very much, folks. I feel a lot more confident now. Won't be doing it for a while as I'll wait till Spring for better temperatures/ lower humidity, but I'll then put in a post to let you know how I get on.

sinner · 17 November 2011, 21:16

Quote:

Originally Posted by biffer

don't make the hole bigger, you just have a bigger hole to repair, you have to sand inside and prep as they say, you can either put the patch in wet and move it about till it's right and then apply even pressure untill dry, fold the patch in half and fit it to one side of the hole first then unfold it or cover the patch with polythene until its in the right place then carefully peel it back.
it's no denying it's fiddley but it can be done. you will still need the outside patch

In this case, making a bigger hole may be the only good way to do an "internal" patch. You can't adequately stuff a wet patch into a small hole and get a good patch job. The op doesn't mention the size of the needed repair, but if it's not large enough to get adequate access to the inside it will need to be enlarged for an internal patch. I also agree that an outside patch will still be required.

It's not stated in the op why an internal patch is desired or required.

Don't take any shortcuts concerning the gluing process or you will have a poor repair. Make sure you follow the glue manufacturers instructions fully.
Also, some pvc (you didn't mention pvc or hypalon) can chemically melt the material if it is put together wet.

If an internal patch is going to be done, it's worth doing it right.

biffer · 17 November 2011, 22:39

If its a large hole the repair is sometimes easier. On bad tears we sometimes split the original seams. do the repair then close the seam back up

sent from a remote device

biffer · 17 November 2011, 22:46

I don't know what glue you use in the states but the PVC glue won't melt the tube anymore if it's put in wet or left to dry. It's still the same layers of glue and the volume of air inside a now sealed tube will only slow the glue down a little

sent from a remote device

kelson · 17 November 2011, 23:30

One thing to remember, an inside patch is usually used in conjunction with an outer patch. The inner patch is primarily structural reinforcement. Your repair can be successful without having the inner patch sealed perfectly. I have patched small holes where I threaded the material with some sail thread, stuffed it through the hole after solvent washes, coated with glue (along with the prepped inside boat layer), pulled the thread up got a light bond and pressed against the other side of the tube ( but has to be pulled away so it won't bond there too). Pull the thread and the hole gets sealed when you patch over the outside.

I usually run with just an outer patch on anything not too big or irregular.

Pics?

S4Simon · 20 November 2011, 11:42

If it's a PVC craft, then the inner patch is a pretty easy repair. You just need a heat activated glue. A hypalon based inflatable will be a lot harder but can be done with just as good results. Here's a link I made a few years back repairing a large hole in a Zodiac using an inner and outer repair.

Inflatable Boat Hole repairs

Henkies · 11 May 2020, 12:24

Quote:

Originally Posted by S4Simon

If it's a PVC craft, then the inner patch is a pretty easy repair. You just need a heat activated glue. A hypalon based inflatable will be a lot harder but can be done with just as good results. Here's a link I made a few years back repairing a large hole in a Zodiac using an inner and outer repair.

Inflatable Boat Hole repairs

Does anyone know of this link still can be viewed?
It seems dead, but I'm interested in the heat activated method....

John Kennett · 11 May 2020, 13:44

Here you go:

https://web.archive.org/web/20111228...ir%20large.htm

Henkies · 11 May 2020, 15:15

Great! How do I know the glue can be activated by heat? I have Adegrip PVC glue that instructs to activate the last layer by heat or solvent. But I never understood the heating method. It's a PU 2k glue...