Seam Grip Sil or Seam Grip WP

[Marlin]

Best bet is to put like sides together. In this case put the two shiny sides together (PU sides) and use Seam Grip WP or, if it's the old stock, just plain Seam Grip.

That orientation might be better on the inside -- not sure -- but if it's an exterior (top side) patch, I definitely wouldn't put the coated PU side facing up where it gets exposed to the sun and weather if you want it to stay waterproof. The coating isn't durable enough for that.

[OneClick]

I did the PU side-to-PU side (inside) and the thing just basically blew right off. I give up, will just have to live with it.

[cougarmeat]

OneClick, I’m a little confused by the PU side issue. When I’ve used Tenacious (repair) tape, the key point wasn’t which side was PU, it was which side had the adhesive. You had cut the patch to the shape/size you wanted, then peel off the backing paper to expose the sticky side, and press it on. Maybe Tenacious tape has some that needs to “glue” on with sealer - like a waterproof version. T’were it me, I’d use the type with it’s own adhesion - and patch on both sides of the tarp - and if necessary, cover the small patch with SeamSeal. That way I’d know the patch will stay on and because it’s double (one on each side) and a small area, it might not need additional waterproofing. But if it did, it would be just like waterproofing the panel pull-outs - except you’d cover the whole (small) patch.

[OneClick]

I'll have to try something else like that. This wasn't an actual patch, but the same material as the tent. The storage sack was the same material, so I was able to steal a piece from that.