filling cracks????

[lowride14]

Oh man its been awhile since iv been on here, misses you guys and gals.

So im redoing the exterior on my vessel and its all mahogany. Iv sanded all the old varnish off, brought it down past the sun damaged wood and have a couple of coats of clear varnish on, well at least parts of it.

Anyhow its an old boat and there are gaps between most of the different pieces of wood and the dowels are all rotted out. what sorta product should i use to fill these gaps and add a little more structural integrity to the walls?

The gaps are at most 1/8'' in width and the woods around 3/4'' - 1'' thick.