Wod preserver?

[fisherman]

So I'm refurbing an old workboat. I cut dovetails in the thwart ends and glassed them to the hull, this has worked well in the past, saves all the knees and stuff. The end grain needs protecting, so I can drill small holes in the GRP over the ends, and dribble something in. What might work, and not spread a stain?

 

[RunAgroundHard]

I have used Smiths Clear Penetrating Epoxy Sealer from Make Wood Good store with great effect on bathroom wood sink tops, shiplap walled shower booths, cockpit locker lids, window cills and sealing exposed edge on ply boards for various jobs. Very satisfied with the protective qualities. As another brand states, it does exactly what it says on the tin. I would recommend it. No association with Smiths or Make Wood Good except as a customer.

Make Wood Good | Wood Hardener & Sealer, Clear Penetrating Epoxy Sealer

 

[thinwater]

Borax. I've used borax and borax/glycol product many times, as well as done long term side-by-side testing. It is is sealed in, it stops rot even if the wood gets wet. Epoxy seals always fail.

Preserving the USS Constellation
Preserving buildings, NZ
Preserving totem poles

It is also used in the US for electric poles (they drill holes and insert borate rods).

 

[Hacker]

G4 would be your other option. Thin enough to be injected via a syringe (without the needle)