Going The Distance

[TitanTn]

A fillet is just a rounded corner. You can make bedding and fillet material by mixing a filler (micro balloons, talc, chopped strand, wood dust, etc) with resin to form a goopy putty like substance.

You want to use a bedding material between the stringers and hull so that there is uniform contact between the two surfaces which avoids air pockets and local stress points that can lead to cracks. It takes a little practice to get the consistency just right - too dry & it won't squish well, too wet & it won't hold shape. Be fairly liberal with laying down the bedding material and use what squishes out when you set the stringer in to form a radius (fillet) between the hull and stringer before it sets up (I like to use the rounded end of a 1" wide wooden tongue depressor). You'll probably have to go back after it sets to build up and dress up the fillets before glassing. Again, a fillet is just a radiused filler to help the glass lay down in the corner.

1-1/2" seems pretty big for biaxial cloth. I'm no glassman, but I can lay heavy 17 oz biaxial with a 1/2 to 1" fillet. Also, rather than sanding the fillets perfectly smooth prior to glassing - you can rough sand (80 grit) them relatively smooth & then lay down another pass of fillet filler material and then lay the glass while the filler is still wet. This way you can really work the glass into the fillet without bubbles. Preparation is key (cloth pre-cut, all supplies handy, etc.) & have to pre-wet the cloth, work quickly, & watch your resin kick times.

Thanks for this explanation. I've heard it described before and had a decent understanding, but this was very clear and easy to follow. Thanks for taking the time to type it all out.

[rlhahn]

Thanks for this explanation. I've heard it described before and had a decent understanding, but this was very clear and easy to follow. Thanks for taking the time to type it all out.

Yes, thank you for the clear explanation. One more question. I've cut my stringers to fit very tight to the hull. I would say they are making about 85 to 90% contact. Is this a good thing, or a bad thing? Now that I've read your paragraph on bedding material I'm not sure if I should do the fiberglass over the stringers yet.

[sybrmike]

Great job getting that much contact - the more the better. The bedding material itself is not inherently strong, so the tighter the stringer fit, the less bedding material needed, and the stronger the structure.

Lay a bead of bedding material down down the entire length of the center of where the stringer will go. The thickness will depend on just how tight the stringer/hull joint is. You want just enough bedding material so that it squishes out both sides of the stringer and fills all the gaps, but not too much so that you can't get the stringer pushed down all the way. Again, re-work the bedding material that squishes out to form the base pass of your fillets.

[rlhahn]

Great job getting that much contact - the more the better. The bedding material itself is not inherently strong, so the tighter the stringer fit, the less bedding material needed, and the stronger the structure.

Lay a bead of bedding material down down the entire length of the center of where the stringer will go. The thickness will depend on just how tight the stringer/hull joint is. You want just enough bedding material so that it squishes out both sides of the stringer and fills all the gaps, but not too much so that you can't get the stringer pushed down all the way. Again, re-work the bedding material that squishes out to form the base pass of your fillets.

Awsome. Thanks!

[Okie Boarder]

Another way to bed the stringers is to set them in place so the tops are where you want and there is a gap at the bottom. Shim them up to get that gap. Then you can brace them in place so they are level and plumb. Then fill the gap with the bedding mix...using a ziplock bag with the corner cut out works well. This gives a lot more time to work with it then the method already mentioned. Either one would work well and be effective, it would just be a matter of personal preference and how much time pressure you want to be under while getting it set in place.

[sybrmike]

Okie makes a good point. 1000 ways to skin a cat, just find the way the works best for you.

[rludtke]

Just a curious question fo ryou rlhahn? I've heard talk on other boat forums about replacing stringers...Now in more than a handful of other pages I've seen people say NOT to let the new stringers touch the Hull of the boat...They say You will set up local stress points that will crack the hull. Many people suggest a 1/4" gap between the stringer and the hull....Has anyone heard this before???

It is common practice to maintain a gap between the backside of the decorative composite surface (such as a mold or layup tool), and the supporting wood or other structure, to prevent the backing structure from "printing" through to the finished surface. The backing strucure is laminated in place on both sides, but a gap is maintained by tacking it in place with dobs of body filler, so that the wood (or other) material does not touch the surface laminants. Print through will not likely be a problem on the thick boat hull, and if it occurred, nobody could see it.

Instead of body filler and gaps, I would shape your stringers and frames to match the contour of the hull, and bed them in place with a bead of body filler spread down the lenght of the structure. Set the structure in place, and form the squeeze out on either side into a fillet (radiuses) with a popsicle stick or tounge depressor (larger radius) which helps the fabric transition across the sharp inside corner. Dabs of hot glue can be used to temporarily hold the structure in place and to each other until the body filler sets up.Then the parts and fillets are ready to be sanded and laminated in place.

[rlhahn]

So I've been a little preoccupied and haven't been making the progress that I thought I would. Got her cleaned out and ready for floor. Lots of grinding, sanding and DUST. The factory "glass job" had a few air bubbles, and when I'd set the grinder to them, they would be full of water...?? How the hell does that happen?

[mapleleaf]

So I've been a little preoccupied and haven't been making the progress that I thought I would. Got her cleaned out and ready for floor. Lots of grinding, sanding and DUST. The factory "glass job" had a few air bubbles, and when I'd set the grinder to them, they would be full of water...?? How the hell does that happen?

Foam....keeps the water where you don't want it....
Great work so far, ur helper looks very pleased...

[jet]

How do you set the floor up at this point to lay the stringers (i have seen string used)?? And..the stringers are different heighths at diff points??