That "Nef" is very nice and is tempting me into getting one of those skiffs...( not ANOTHER project!!).
I've already got the same model for the landship which has been sat on my shelf for more time than I can remember. Excellent idea with the front cannons.
With reference to a harpoon, have you thought of using one form the old "GORKAMORKA" range.
I haven't got the spare rack of harpoons but it's yours if you want.
PM me if you want it.
Regards
PM