Timber for bowsprit

Douglas Fir and finish with Sikkens Cetol 7. Largest size Robbins do is 300*75 sawn so you may have to laminate anyway.
 
If it is laminated, you could just replace the affected parts or scarf in a new piece and save the rest if it's not too far gone.
Otherwise, as Tranona suggested, Douglas Fir is a perfectly legit timber for a spar.
 
The sprit is in poor condition because the coating has long since expired; whether it is solid or laminated is pretty irrelevant if the coating breaks down(unless you make it out of teak).
 
Personally at size I would laminate a new piece. A single piece of wood is likely to continue to move and the bow fitting won’t be in the same place. Laminated would also be stronger.
 
Top