Help with new stringer installation

When I repaired my small stringer, I used 3 layers of gla$$, starting with epoxy mat, then 6 oz cloth, and another layer of mat. This built up to about 1/16" of gla$$, with the mat contributing to most of the thickness. Each layer was successively wider, the first being ~2" up the stringer/2" down the hull, and the last layer going to the top of the stringer and 3-6" down the hull. It seemed very strong, though I might consider putting on another 2 layers if it were a main stringer.



Lots of people were helpful (especially DavidF) in this thread: stringer repair

Im certainly no expert, so I dont know if that will be strong enough. I do know that the epoxy mat I used a)gave the gla$$ strength along the directions the cloth was weak, and b)soaked up a significant amount of resin and added a lot of thickness.

I was very satisfied with my results- but your approach may be sufficient without the mat. Hopefully someone with more fibergla$$ experience than me will chime in.

Waterdog,

I am interested. Several years ago I bought a manual specifically for replacing stringers. However, it was geared toward outboards. There was no specific information on the strength required to handle the forces of an engine mounted to the stringers.

When I started I had what I believed to be a solid plan. The plan is only a 90% solution at best. The devil is in the details.

I noticed as the resin cured that on the outbound side of the stringer (where the stringer stands between gravity and the bilge of the boat) I have as much as 3/8" of resin that pooled. On the bilge side the extra resin just slowly ran downward. Based on your post, I am going to have to grind out some of that built up resin on the outbound side. Am I correct?

I tried working with chopped gla$$ in my resin. It is a mess and produces excess air bubbles. Is talc a good additive?

Thanks for your input.

Ski Bum-

An easy way to fill the epoxy and to keep the resin where you want it is to use West Systems fillers. They are pre-made and settle right into the resin.

Use 403 Micro Fibers for the thick fill jobs and when you don't want resin to run. Add fill untill you have a peanut butter consistancy.

Use 407 Low Density Fairing Filler for the final fill in to make the surface smooth and easier to sand. Add fill untill you have a peanut butter consistancy.

These two make the job alot easier and they are not that expensive if you order them through US Composites.

I applied both with a 1" china bristle brush. Then I let the warm heat from my heated garage settle out the epoxy. It comes out pretty smooth but final sanding is necessary before you paint it.

Later-
NM

Bill,

If you have access to a power planer that will be a lot faster than a belt sander. Use it just like you're planing down a door to size. personally I don't think I would glue more strips to the top and sand them down, I would probably shim the stringer to the right height and set the stringer in a bed of thickened resin once the final fit is acheived to fill the gap at the bottom. If you start with a nice straight 2x then I would remove material off the bottom to fit it rather than the top.

Someone here made a cardboard template of both sides of the stringer, laid it out on the new stringer, mark and cut. Seemed to work pretty good for them.

The dial caliper might be a little overkill.

Using the straight edge and dial calipers I was able to accurately mark the proper height for the new stringer. The hand plane made smooth, thin slices until I got the height just right. Lesson for next time is too leave a little extra material...it is easier to slim it down than to laminate additional material then slim it down.

Alan,

If you have a comealong, you can throw it over the rafter of the garage, lift the engine, and then move the boat out from under it. BKH

Sorry I don't know the weight. My dad did it a couple of times with our old inboard. The cherry pickers we had just wouldn't lift the engine high enough to clear the boat. It's been a lot of years, but I think he used two comealongs. BKH

SkiBum wrote: I can't imagine using a rafter in the garage.

Though he was a professional mechanic, let's just say my dad had a fair amount of good ole' boy in him. What's that thread someone started? - Rednecks have all the answers.

Seriously, we used the rafters several times that I can remember, no issues. I don't think I'd leave the block hanging from the rafters, but for lift, slide the boat out, set the engine on a stand, it was no big deal. BKH

No doubt Doc, but Dad was the real McCoy. Clayton, OK, 1939. BKH

I finished fine tuning the observer side stringer. Rounded the edges for better lamination with the final applications of gla$$. Also, shaped the cut out areas to better facilitate the flow of water from the engine compartment into the bilge.

Cut out the driver side stringer. This time, I marked a line about an inch above the hull. I cut along this line so it will be easier to reconstruct the stringer for use as a template once I remove the last inch of the stringer that is bedded into the hull.