West Systems on vertical hull repair Which Filler

[Fiftybucks]

I have an impact crack under the rub rail vertical surface that needs repair. Which West System filler to use? Perhaps 404? 3 inches by 4 inches.

[s/v Jedi]

Originally Posted by Fiftybucks

I have an impact crack under the rub rail vertical surface that needs repair. Which West System filler to use? Perhaps 404? 3 inches by 4 inches.

A crack? Filler? I think you need to grind out the crack and first use fiberglass to repair it, then a fairing compound (or fairing additive for West System) to get it smooth for finishing.

[Fiftybucks]

yes on grinding out. yes on glass fabric in several expanding layers. which stiffener for vertical surface?

[s/v Jedi]

Originally Posted by Fiftybucks

yes on grinding out. yes on glass fabric in several expanding layers. which stiffener for vertical surface?

A picture would help greatly. I do not know what you mean with “vertical surface” and “stiffener”.

[Benz]

Originally Posted by Fiftybucks

yes on grinding out. yes on glass fabric in several expanding layers. which stiffener for vertical surface?

I use Cab-O-Sil. Don't know which West number corresponds with that, but basically look for the one that's toughest. Others are for ease of fairing, and while OK for sag prevention, aren't as strong.
You can also use a pre-mix like Jamestown Distributor's "Thixo;" Pro Set (the best and most expesive), or another third option offered by 3M who's name I can't remember.

[deltaten]

Yes, Cab-o-sil, by any name.
On overhead surfaces, I very lightly coated with neat resin, then applied a skim of thicked resin (like peanut butter) using a notched trowel/applicator to "grade" the glue. Lightly pre-wet the back of your choice of glass and apply to patch area Apply resin gently with a mini roller till there's just enough to thoroughly soak the fabric. When glancing across the surface, it should almost appear dry... no noticeable pooling or wet spot sheen. Fin roller to iron out any bubbles or excess resin. Repeat as needed. Finish off with a sheet of film plastic and dry roll smooth...no bubbles or creases.
HTH

[Chotu]

Also known as colloidal silica

[Fiftybucks]

the silica will be my choice...
i will repost with pic and repair... looks to be west systems 406, peanut butter consistency. several layers.

thanks all for input...

[Secondshift]

Originally Posted by Chotu

Also known as colloidal silica

Aka fumed silica

[Chotu]

Originally Posted by Secondshift

Aka fumed silica

Silly number of names, really. Ha ha

[Secondshift]

… but also yeah., photos.
Might need grind and glass might not.
Sometimes gel coat will flex crack before the glass and can be repaired with gel coat paste or putty.

Best luck with it.