Don't run aground.Any helpful tips?
I wouldn't use micro balloons underwater. They are after all tiny balloons. I'd use silica instead.I could be wrong, but I think the deep keel on the 35s5 actually was made of lead, and I'm pretty sure it wasn't encapsulated. Probably the damage you see is to fairing material, which is easily repaired with epoxy thickened with microballoons. As dlochner says, you should carefully check out the hull and interior structure supporting the keel.
Silica makes the epoxy extremely hard which makes for difficult sanding and fairing. A thin final coat or two of epoxy thickened with micro-balloons works, except they are prone to pinholes. If an expoxy barrier coat is going over the top, this isn't an issue.I wouldn't use micro balloons underwater. They are after all tiny balloons. I'd use silica instead.