Hey guys, I remain adamant about my post. Ninety-nine times out of 100 it should make no difference. A properly executed repair will become a one-piece chemical bond.
However, that is not always the case.
Two Points: If there is to be a problem (other than a poor catalyst mix) it will most likely happen at the first (inner) patch and the hull. Poor practice in preparing the hull - removing contaminants - can result in just moving them around and if the 1st patch fails, it all fails.
Secondly, we all know that voids sometimes occur in the layup. I have had brand new boats delivered to me from the factory and noticed a break in the gelcoat at the top of the transom. Taking a mallet and tapping along the transom then opened up 20 to 30 voids. (Might as well fix them all and do it right if you're going to fix one.) The cause, of course, is trying to tuck glass mat into a tight radius. The glass mat wants to bridge the corner and leaves a void between it and the gelcoat. That's one reason boat designs in the last decade have avoided tight radii. It's also why we use a fillet when a tight radius cannot be avoided.
In the original case - the method in the link - the concave repair area presents a situation for the cloth/mat to bridge the recess rather than fill it and voids may occur. As a matter of fact, the very reason to dish out the repair area is so successively larger patches attach to the "V." - the scarf.
Truthfully, the use of epoxy, rather than polyester, minimizes the potential for this "bridging" because of its greater adhesive quality.
Again, properly executed either way probably makes little difference. I just think "best practice" is best practice in every situation.
BTW: as Tom J says, the blank plug is by far the easiest, smartest way to approach the specific problem in the original post.
