We have a raider for my daughter, its one of the earlier actual fiberglass hulls. Someone at one point ran into rocks with it by the looks of the bottem, some of the gouges are all the way to the fiberglass. Thankfully its still good to go and not leaking, so I just want to fill in the gouges. Someone mentioned fiberglass resin and something to mix with it to make it thick, then just fill the holes and sand. Will that work on this hull, and what should I order to mix with the resin? Would this work on a superjet too in a pinch?
You need to know what resin the hull was made from, or use epoxy. Poly doesn’t stick to VE or epoxy, VE won’t stick to epoxy. It’s very unlikely that the hull was built using epoxy. I just use epoxy for all of my work and forget about it, but I have only worked on OEM hills and epoxy is the only option for sticking to SMC.
For a filler, you can use talc (or baby powder), microspheres, cab-o-sil, cotton flock, milled fibers and so forth. Cab-o-Sil is very hard to sand, which both makes it hard to work with but also more durable than other options. Microspheres sand very easy and are lighter because they are hollow, but leave pin holes after sanding. Talc is a good middle ground of sand ability, won’t leave pin holes but is not as durable as cab-o-sil. Cotton flock and milled fibers are extremely strong, but suck to sand, and they clump, so they are probably a poor choice.
A good option is to use cab-o-sil to fill the very deep gouges with an applicator leaving it slightly below level and clean off any excess. Then follow that with talc. Sand between each coat (although you can apply your talc layer over your cab-o-sil layer while it is still tacky which saves sanding). Seal with a plain coat of resin and sand with higher grits, and paint. The hardness of the cabosil will increase the durability of the deep repair while the talc will make the finish work easier to sand.
You can of course do the whole job with just talc or whatever else you choose.
You can sub the talc for microspheres, but your finish coat should be a little ticker than plain resin or even light sanding will leave pin holes.
You can also dye the resin which is cheap if you have a black bottom deck. Dyes are not UV stable but you should be just fine for the bottom deck. Even if you are going to paint or gel coat, dyes will help keep new scratches hidden. Probably not worth the expense for your raider. White will turn yellow after. Period in the sun.
But, if you are using poly or VE, you can actually dye the resin with the same gel coat you may plan to use at the end of the job. Just stick your clean stir stick into the gel coat before you stir the resin.
