Sunfish-Laser Hull Flex - What's in the core?

[DaveSailer]

First post, first questions. I've gone through the really good content around hull flexing, trailer damager, re-coring ("The Core Project"), etc. I have a new-to-me 1992 Daysailer with about 1.5" of hull flex on the port side over the trailer bunk. Starboard seems much more rigid with no major deflection while sitting on the trailer. It looks like the previous owner smeared 5200 on longitudinal cracks or scrapes above the port bunk on the outside of the hull and in the cockpit sole above the damage on the outside. To me, this seems like they were trying to address some trailering damage or otherwise heavy load being placed on the port side while the boat was on the trailer. The is a large semi-circular craze with a similar repair on the port side seat. I'd like to address the hull flexing and carry-out a proper repair for the cracks I anticipate finding under the 5200 repairs.

To that end, does anyone have knowledge of: What's between the cockpit sole and outer hull of the Sunfish-Laser Daysailers? Balsa laminating into the hull?
Is there a void between the hull and the sole? Are there reinforcing stringers present? Floatation foam?

My initial path forward was going to be removal of the cockpit sole, removal of anticipated rot, adding stringers with a few layers of fiberglass to the inner hull, and installation of a new fiberglass floor if the old floor could not be salvaged. Then I thought I could just install inspection ports similar to the ones on the DS-2 to get a visual of what's under the sole. I thought I could possibly inject polyurethane pour foam through holes drilled in the cockpit sole. I know I am getting into a tremendous amount of work if I remove the sole, but without knowledge of what's inside I don't know if the pour foam approach will be enough to stabilize the hull.

Poke holes in this approach before I poke holes in the boat - that's why I'm putting it out there.

[GreenLake]

I'm slightly unsure from your word-picture, where precisely you have the damage, and how extensive it is.

If there's any "gunk" covering anything, that must come off before you can evaluate your options. In other words, is it just a soft spot, or is there perhaps an actual crack?

I think the idea of inspection ports beats simply removing cockpit sole.

Depending on the hull construction details you discover combined with type of damage, you may want to fix the boat from the outside, not the inside. If the gelcoat is in great shape and the hull is only soft, but otherwise still assumes a fair shape (or can easily be made to assume a fair shape) then reinforcing from the inside might be the preferred option - assuming that you can get good access.

If you have other types of damage, my inclination (without having seen your boat) would be that you might not "save" as much by retaining the damaged laminate as an outer layer. In that case you can just as well work from the outside, cutting out a section of damaged hull and rebuilding it. (If the hull is indeed cored, details would depend on the state of the inner skin as well.)

Now, you report that there's gunk spread inside and outside, that argues for more major damage and if it's 5200, I would be afraid that the damage includes perforation of the hull with attendant need to get hull and cockpit sole watertight again.

Let us know what you find when you remove the "gunk" - if there's an actual crack it may be simply to ascertain the hull construction.

[DaveSailer]

Thanks, GreenLake. I should be able to get some photos or videos this weekend. I'm waiting for some repair materials to arrive, so I may delay grinding out the gunk until I am ready to address the issue fully.