Aquarius Sail Owners

Hard to tell from the photo, but are you referring to the two vertical marks? If they are centered under the cross beam I doubt they are a dent. More likely they are due to shrinkage of the bulkheads during manufacturing.
Purely cosmetic and not necessary to do anything more then fill (glass not necessary) and refinish if you want to make them disappear. I should mention that changes in temperature might cause them to reappear.

Matt, thanks for the reply. It's hard to get a decent photo of this. It tends to white out. The dents are aft of where the forward crossbeam is. They are right where the side guide roller was. I got rid of the rollers and installed cradles as soon as I could after buying the boat. The temperature has no effect on the dents. If you don't think these dents have any structural effect I will consider just fairing them out. This will result in some thick spots, however. The worst example is about 2" wide, 2' high, and 1/16 deep. There is a crack in the gel coat at one of the dents. All relevant advice will be appreciated. Thanks, GH.

Vinylester resin has a glass transition temperature (GTT) you can gently heat the skin with your new variable temp heat gun. Drill a pinhole and use a small hook to pull the softened resin and fiberglass glass back out to shape. You will now have a void where the the foam core is crushed, inject resin into the pin hole until the void won't take anymore.

Yes, I have done this, yes it requires some extreme caution and a fair bit of skill. Overheating will be very bad news.
Attached is a picture of a compression ding that was completely repaired using this technique and additional cloth.

This is what two tons of ice on a tramp left all winter will do. Massively strong boats aren't they!!! Skip all the above fair it with putty and move on.

This is after pulling the dent with heat, fairing and adding tape to reinforce the seam. Tons of work, not necessary for your ding.

GH,
What you describe is different than what I thought I was looking at. I still think you can get away with just filling with a good quality fairing compound, however if the crack is into the glass than that needs to be repaired with a patch.
I cannot endorse the heat / Delamination / fill method described above.

Matt,

In the situation I illustrated I used a rather large hole and pulled the inner laminate, the core and the outer laminate all at the same time. Yes, I heated the entire area with a rather large amount of heat, applied uniformly and very slowly. It does not de-laminate in this case or rather it de-laminates and re-laminates. I soften the structure until it will return to the memory shape, ie that in which it was molded. It is tried and tested, however it will never be as strong as the original construct, thus you have to add material and more fresh epoxy.

If you pull only the outer skin, true, you are in fact de-laminating the structure, hence the injection of more epoxy. If the fresh epoxy is on the outside (a fill) or between the layers (an injection) I don't see much difference in ultimate strength.

disclaimer: don't try this at home, your results may vary

That's quite a pressure ding Andy. I don't think I need to get that med-evil on my cat. As long as I haven't lost any structural strength due to the compression of the foam core, fairing compound might be the way to go. Until it warms up here, this is a theoretical discussion. Matt, thanks for the advice. I'd like to hear from any member who has dealt with this issue. What worked, what didn't? I'll post pics as the situation develops. Thanks GH