Recoating Filets ?

[ccx2]

The West System user manual says to apply SEVERAL coats of resin/hardner over Filets before final finishing. Do any of you goo gurus think this is necessary if they are to be painted? Seems like alot of coats even if you werent painting, and for what reason? Thanks.

[JimConlin]

Depends on how smooth you got 'em in the first place and what finish will be on 'em.

If you applied peelply on glass to get 'em smooth and you're using an epoxy primer in your paint system, I would not add anymore epoxy. If the fillets are coarse wood flour and you're varnishing, several coats of epoxy are a good idea.

[Bob Triggs]

The fillets are usually thickened epoxy which can be porous with some thickeners. The top coats are for sealing out water intrusion. Its a very good idea.

[AstoriaDave]

Sand the piss out of them en route to making them blend well, prime, and paint. No need for multiple coats of resin unless there is adjacent glass with weave to fill ... even then three coats of resin, rolled and tipped on, should be enough.

[Cuyahoga Chuck]

Even if that was necessary I couldn't comply. I use the "wet on wet" system which means I'm laying out the glass strips as the fillets are hardening up and they will be applied before the whole mess kicks if I can work fast enough.
My entire procedure is three steps. Straight epoxy painted on the bare wood, the rest is mixed with thickener for filleting and the glass is overlayed with a second batch of epoxy. That's about as complicated as I'm willing to go. My boats are all rather small so building a hull as stiff as a bridge abutment isn't necessary.
And, one of my construction aims is to always use the least amount of epoxy possible to keep weight down which I have been modestly successful at.

[AstoriaDave]

Cuyahoga has me beat on filling weave. Best I have been able to do on 6 oz glass is two fill coats. I also try to do a wet-on-wet layup when fillets are involved, and definitely can recommend that technique. BTW, glass laid over a wet fillet will really help reduce sagging, making for more uniform fillets demanding very little sanding, done right.

Light is good, for sure.

[ccx2]

Thanks for all the good info. Actually these filets are on the bulkhead to inside of hull of a 16' garvey and i havent planed on glassing over them[the designer didnt say to in his building notes],and they are 2x the size the plans call for. I was going to sand them smooth and paint en with Brightsides. No?

[SScoville]

What did you use as a thickener? I've found that wood flour leaves a somewhat porous and course surface but that cabosil cures pretty smooth and without any noticeable pores. I always try to seal (with one coat) areas I've used thickened epoxy, whether fillets or faired spots. BUt my name is not Guegeon (or however it's spelled).

[ccx2]

What did you use as a thickener? I've found that wood flour leaves a somewhat porous and course surface but that cabosil cures pretty smooth and without any noticeable pores. I always try to seal (with one coat) areas I've used thickened epoxy, whether fillets or faired spots. BUt my name is not Guegeon (or however it's spelled).
406-colloidal silica

[Tom Robb]

You could call the Googe Bros and discuss it. Their reason may well be the sealing porous fillers thing Bob Trigs mentioned. My impression is that ordinarily glass tape is glued on over the fillet. I that case there's plenty of unthickened on the fillet.

[ccx2]

Actually the fillets are the seat bulkhead to hull fillets and i didnt think they were supposed to be glassed over as the chine fillets are so they have just been sanded for painting. Meanwhile someone told me they should be tabbed or taped over but the designer didnt say that in the plan notes so i assumed it wasnt necessary, still dont, and plus i made the fillets twice the size the plans called for. I have e-mailed the designer to ask him if they should be glassed and if not i will put a couple coats of resin over them for good measure. I hope he doesnt reply that they need glass if they dont so as just to CYA:) i dont want to do more than is needed at this point because i am about to paint. Thanks for the help guys. Feel free to post more.

[Cuyahoga Chuck]

Thanks for all the good info. Actually these filets are on the bulkhead to inside of hull of a 16' garvey and i havent planed on glassing over them[the designer didnt say to in his building notes],and they are 2x the size the plans call for. I was going to sand them smooth and paint en with Brightsides. No?

Care to name the design and the designer? Using glass tape over fillets is SOP in most S&G designs that I have perused. In fact the fillets used today are quite small and are used, in part, to lock the panels together so the ties can be removed and to present a gentle curve in all the intersections so the glass tape will not have to make a hard 90° bend. Glass tape has very good tensile strength and I don't think epoxy and woodflour can match it. Your fillets would have to be enormous to match the amount of glued surface you get with even 4" tape

[pipefitter]

There are many situations where fillets don't need glassing, such as, where fasteners/adhesives are used into a secure and redundant framework where the adhesive becomes overkill in short order. Just to be on the safe side it doesn't hurt to seal them with resin, especially if porosity is noted.

[AstoriaDave]

Tape is common for fillets, for structural reasons and to assist in shaping the fillet. For filler, I typically use milled glass fibers along with cabosil (aka fumed silica, etc.) on structural fillets, running about 1:4::glass:silica. Unless the joint will be exposed to extremely high stress, even a fillet with a half inch of cross sectional area should exceed the strength of adjacent plywood in 3/8ths or smaller.

[ccx2]

Chuck , The fillets are 1 3/4 radius with 406 additive ,2x heavier than suggested by the plans. Im new at this but i dont see where glassing would add much to the joint, I guess im wrong.
Pipefitter, ive sanded the fillets smooth , they feel and look smooth and it seems paint would not soak into them, but i value your advice as well as others and i will put a couple coats on them for good measure if i dont end up glassing them.
Dave, Yep, thats the way i see it as far as the strength of the oversize fillets ive applied goes, the bulkheads are a structural component of the boat though....i guess.:)

[Cuyahoga Chuck]

Chuck , The fillets are 1 3/4 radius with 406 additive ,2x heavier than suggested by the plans. Im new at this but i dont see where glassing would add much to the joint, I guess im wrong.
Pipefitter, ive sanded the fillets smooth , they feel and look smooth and it seems paint would not soak into them, but i value your advice as well as others and i will put a couple coats on them for good measure if i dont end up glassing them.
Dave, Yep, thats the way i see it as far as the strength of the oversize fillets ive applied goes, the bulkheads are a structural component of the boat though....i guess.:)

S&G boat construction is a kind of monocoque much like what you see in aircraft. Everything is glued to everything else and every component helps to soak up the stresses applied to it's neighbors. The interior structure isn't just going along for the ride. Each piece is supposed to buttress everything it touches.

[ccx2]

The designer has got back with me and said all interior components should be fastened to cleats and filleted, or filleted on both sides,as i have done it according to plans, no tape necessary. As i say i have made the fillets heavy 2x, so i will coat with resin and paint. Thanks again for all replies.