Help with my restoration. Nida stringers/deck

If you have to make saw dust, you better leave it, and use cabosil or even your leftover from grinding the roving out.

Do not overthink this filler issue, almost all the **** mentioned will work well for this purpose.

Have fun with your beloved ones!

Regards
Richard

 

Steve is quite correct, FGCI is in St. Pete and is open on Saturday (www.FGCI.com), just over the bridge around 22 St., if memory serves me, right off the interstate. I also use milled fibers in these types of repairs, as it has excellent strength and abrasion resistance and seems to make the best glue on old polyester hulls. I still don't use phenolic balloons or spheres against a structural member, even though the fabric is bearing the most of the load, these materials have little adhesive value, marginal compressive and elongation properties, which don't lend well to their task as a fillet on a structural element.

Incorrect, wood flour (much preferred) or saw dust is an excellent structural filler material. Balloons and spheres are not. Think of it this way, the materials that make good structural fillers are rough and irregularly shaped, while the fairing and smoothing materials are physically smooth, round and have much less physical surface area for the resin to grip (hence it's weakness).

Testing shows that the more you add of anything, the more the physical properties of the resin drop. Much of this has to do with the introduction of bubbles, but the filler material plays a role too, particularly if you mix in too much.

Again, nope, they're just little tiny balloons and easily crush, crack, break, etc., this is why they sand so easily. If a material adds strength to the matrix, it also makes it a ***** to sand.

Yes,, but it needs to be really fine, much more so then what comes off a disk grinder, belt sander, etc. The same is true of table saw or other machine saw dust. It works, but it's so coarse that making it smooth is imposable. Under tabbing it doesn't matter, but it's also harder to apply, having a tendency of breaking up the fillet or tearing it as you attempt to smooth it out.

 

Myself, a stringer or a bulkhead is a planned event, there is a 10 or a 12" fiberglass tape placed and I always use core fillets or a double beveled pad under the stringer to reduce the open span.

 

OK....ready to start tabbing!

I think we all agree that wood flour would be stronger, however "Fiberglass service" ( one mile from me) doesn't sell it. They do have the micro balloons. According to Ivan this would make a low density fillet, which would be acceptable for a boat my size.

- I know I have asked this before, but can someone give me a general recipe or a place to start as far as what ratio of epoxy, cabosil, micor ballons. I understand it's a "feel" thing, but it would be nice to have a place to start.

-Also how clean does the surface need to be. The entire boat hull has been sanded with 36 grit and is free of dirt, oil , etc. The only thing that might be left is fiberglass dust the wet/dry vac did not pick up. Do I need to wipe the surface with Acetone before I start this?

 

Vac cleaned does it.

There is no ratio I can recall, (though there will be one at my yards probably), it is as you say a "feeling", and can be quite different in different mixes. You cannot go wrong, just try.

 

I went with the pine wood floor. I made the fillet as suggested and then tabbed them into place with my 6 inch tape (1708 or 1208 not sure). It worked very nicely on a verticle surface. I had some 50 inch material (12 oz cloth I think) that I cut to size to make a wider section to go over the 6 inch tape. The cloth was a PITA!. The resin kept running off into the hull of the boat. I kept soaking it up with a brush from the hull and reapplying. Eventually the brush starting catching some loose strands on the cloth. What a mess. Is there a reason the 6 inch tape worked so much better?


How many layers do I need to tabbed in the stringers?

 

As Richard said, vacuum cleaning does it. But keep in mind that when using epoxies amine blush can ruin the bond between a cured layer and the next layer(s). Water (the universal solvent) is what will solve and remove this oily feeling blush. Acetone will NOT help, it will only smear it around. In fact, acetone is not much good for anything epoxy. Denatured alcohol is the first choice.

 

Most likely the glass tape is treated for Polyester resin. This "sizing" or "finish" (most common silane) is not suitable for Epoxy layups. You need a raw glass or epoxy sizing.

The number of tabs depends on the quality of material and loads of course. Have no figures at hand here on board, and don´t dare to comment without...

 

Multiaxials keep resin in much more easy than a course cloth. That is what you have witnessed. Peelply over the laminate can sometimes be a solution to keep the resin in. also adding a bit of cabosil into the resin can help.

 

Bonding?? I would use 3 Layers of 1708 to the hull ,you will be amazed how strong that is in epoxy,this is not a place for 0-90s.

 

I did some research from the girl I bought the Fiberglass Tape and 50" biax from. She purchased the material from Bateau for a boat kit she was planning on buying. The material she sold me was designed for epoxy. The tape is 1208 (six inches wide biax +45/-45). The 50 inch material is 12 oz 0-90 degree biax ( no mat).

I think what I experienced is what you have Herman and others have just said. The mat in the 1208 (although not necessary for epoxy) held the resin better against gravity which resulted in a better job and less wasted resin in the middle of the hull. I am not going to use the 12 oz 50" material anymore. I like the 6 inch tape and will continue to use that for the bulkhead and stringers.

I only have one PIC for now, but will post more tomorrow. This was before I started the fiber glassing.

 

Raka has an epoxy that does not create an amine blush and just requires a light rough up with sandpaper to create a good bond.

 

I am trying to follow the advice given and minimize the need for sanding. I am tackling the boat in sections. The bildge section is the most aft. Followed by the fuel tank section. Then the ski locker and finally the bow.

- In both the Bildge section and the fuel cell section I have at least two layers. The first being the 1208 and the second being a layer of 12oz biax (no mat) cut from the 50" wide roll. The hand cut pieces are wider then the 6" tape and overlap the seam on the stringer and the hull.

-I know the preferred method is to start out with a smaller piece of glass and then overlap with a larger piece. Is this absolutley necessary, or can I use one of the methods I have in my diagram below.

- I have already used over 2 gallons of epoxy to tab in a little more then half the boat. Does this seam about right?


-I don't want to use the 12 oz biax 0-90 degree for reason already stated by me and backed up by you guys. The problem is that I only have 6 inch tape (nothing wider). I can order wider tape if necessary.

-Please take a look at my diagram and let me know if either one of these methods is acceptable.

 

A couple of other tips that i dont think were mentioned,(maybe i just missed them) You will save a lot of time and effort if you plan things so you can lay your biax into the wet fillet.What i often do is tack the bulkhead (or whatever) in place with a minimum of short fillets of polyester filler,this sets up quickly and locks the item in place so it wont move when you apply your epoxy fillet, run your fillet with your tool of choice and scrape up the excess with a narrow putty knife and then apply your biax into the wet fillet and finish with a strip of peel ply and of course compact it with a metal roller.When the epoxy has cured, peel off the peel ply and your done. This avoids virtually all sanding of either the fillet and finished tabbing, gives a perfect chemical bond and is very neat. The other thing is you dont need (or want) DB1708, use DB1700 instead, the 08 has the csm bonded to the DB1700 which is there for use with polyester resin, with epoxy you should skip the mat. Also when tabbing in with multiple layers of biax be sure to stagger the layers so you get a taper onto the hull and b/head or whatever.
Steve.

 

OK,you were posting while i was writing. Yeah,you dont want to use the 0-90,use the double bias and stagger it by 2" per layer for 3 layers. Wherever practical i do my layup on a piece of melemine faced mdf (my son is a cabinetmaker and has lots of scraps) and then offer it in place and compact it, i find it easier than doing it layer at a time in place.
Steve.