Custom/Hybrid Hull prep for areas to be painted

[Mobile Chernobyl]

Well this will go with my turf question, and since this is a new forum - it would be good to have ALL info we can for composite work in one place right?

This question is mostly aimed at wet layups - where you don't have the ability to gelcoat in a mold.

I have a hull now that has been sanded to what appeared to be smooth - I only used body filler on the top side, my mentality is that if the bottom side has body filler and gets dragged up on shore, I don't want the paint to scratch through and expose body filler because it's a porous material and may absorb water and jeopardize the integrity of paint near by.

So after the first coat of primer on my hull, the top looks decent, but the bottom just looks extremely wavy as I was sanding wet laid up fiberglass and could not get it perfectly smooth. I have a load of pin holes that I will fill, but is it worth filling the bottom side or just live with the waveyness so that I can be confident in not having body filler on scratch prone surfaces?

I'm by no means an expert with body filler, and I could be completely mistaken about bondo being hyrdophilic, so let me know if my thinking has merit or if I'm just over thinking it!

Thanks

 

[tokarzl]

Use a longer surface for sanding like a 2x4 with sandpaper on it the wavyness can come from using smaller power sanding tools and filling small areas at a time

 

[Jp79]

Get yourself some micro balloons to mix with resin instead of using body filler. It takes longer to dry but well worth it in the end.
If you use a cardboard tube as a sanding block for the curves and look at the soft blocks that they sell at lowes or HD