Teria's foredeck and cabin top had serious foam sandwich core issues. The foam core had disintergrated and the deck fibreglass, without internal support, was very springy.
Finally decided on repairs using a method used by Peter on the Investigator 563 forum. Epoxy injection technique, which turns out to be a very strong and probably a permanent repair. It was like "keyhole surgery" rather than "open heart surgery" (of the sheet foam core replacement methods.) This minimized damage to the outer deck layer, and it could be restored to near original.
Epoxy is an extemely strong substance and it sticks to everything with diabolical tenacity. It added a bit of weight to the decks, but it's a cruising boat with a lead keel (and water bottle ballast in keel sumps etc).
Firstly the deck needs to be taped over with painters masking tape, then the holes are drilled through it. An aircompressor is needed to blow the cavity dry (and eject some foam bits), the cavity must be absolutely dry for epoxy to adhere well.
I used about 8 litres of WEST system epoxy, it's not cheap but "do it once and do it right" was the motto.
The stainless deck fittings and bolts were removed, and all holes underneath were taped over with strong CLOTH tape (painters tape won't hold..). All interior items in under work area were removed and painters drop sheets deployed, for those last uncovered deckhead holes. Had acetone, papertowels and rags handy for any spillage. I stuck some plastic straws through bolt holes in cavity areas, to act as formwork for epoxy and allow the hole alignments to not be lost (alternatively just re-drill with drill jig etc). Fittings with wooden blocks premoulded into core didnt need straws.
Used container pumps to measure the mix ratio and vetinary syringes from the rural shop, to inject epoxy through 5mm holes on deck (within the rough non-skid tread surface areas) spaced about 6" apart. Started at the lowest holes, then as each was filled it was plugged with a wooden dowel (taped to fit by putting the dowel in a drill and spinning on a sanding block). Dowels are removed when the epoxy congeals and stops flowing, but before hardening (otherwise they become one with the epoxy core).
Once the epoxy cured the foredecks and cabin top were rock-solid structures again. Both areas have heavy crew foot traffic and the mast step area has the heaviest rigging loads. The epoxy fill area extended just aft of mast step/ mast archway and the chainplates for shroud rigging. This should make Teria very strong for heavy weather bashing to windward and also anchoring loads etc.
In the tropics, epoxy is not very viscous, so it flows by gravity into the smallest cavities. If any foam is inside it would flow around and into it, bonding against solid fibreglass and any wood patches etc. I used epoxy with optional slower rate hardener, which gives more time to work. Also i did this job in the "dry season" and early arfternoon when daily humidity is lowest. (never try this during a "wet season" with >90% relative humidity plus heat = even more water vapor) strong epoxy needs low humidity conditions.
Wet epoxy is a dangerous substance which can cause lifelong allergies etc. So good skin protection is needed. A pack of black nitrile surgical gloves and long sleeved clothes, glasses etc is required. Good ventilation as well, Teria was outside in the breeze. If indoors suggest good fans and respirators. Fiberglassing disposable overalls would be good, it ruined my work shirt. Hardened epoxy is unremovable from clothing. It was the first time i've ever used this stuff, alot of learn the hard way involved, even after allot of reading/utube study, practical tutoring would be the best way to learn good epoxy techniques.
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