Stringer bedding advice

[snibbornairb]

I am doing some stringer/floor repair and am curious about seating the new stringer. Do I need to keep separation between the stringer and the hull? recommendations on how to achieve this? It seemed there was a green (in some spots, brown in others) material under the original stringer.
Also, what oz. cloth should I use around the stringer.
I really enjoy this forum. Thanks to those out there sharing their experience.

[Salty87]

hello snibbornairb

lots of rebuilds this winter. there are a few threads going, more if you search ;)

yes, you don't want wood to contact the hull. the hull and wood have different flexing properties. this goes for cross-supports and the plywood for the floor itself. you'll fill in the gaps with thickened resin. that's probably why you saw different colors. depending on what you use to thicken the resin, the color can change. there are various things you can use to thicken the resin, kinda depends on the next question...

are you using poly resin or epoxy? that and your budget will dictate the cloth you'll use.

[snibbornairb]

i had noticed all of the rebuilds going on, read most of them, I think. It has been a wealth of knowledge and experience. I am doing my best to keep the cost as low as possible, so I will probably go w/ poly. My damage seems to be all on the drivers side, mostly up by the captains seat. Just like all the other pics that have been posted, the unprotected cross supports rot out and contaminated the secondary stringer. I am trying to do just the one side, as i have made some exploratory holes on the passenger side at it seems pretty good ( a little water at the bottom of the foam but the majority is dry). The main stringers seem strong and the motor mounts are still tight; knock on (wet) wood.
I have the drivers side floor torn up, foam removed, and mushy portion of the stringer cut out. I am goin to try to tie into the existing floor along the edge and up under the cockpit, with a few extra cross members for good measure.
I just need to work out the fine details, like wich glass, resin, wood, ect. to get for the project. I have been checking out US Composites because that seems to be the popular site around here.
Any advice on what i may have left out would be much appreciated.
I have read on some other forums about putting 1/4" of foam between stringer and hull... ?? or wedges?? or just a bead of resin with cabisol (sp?)
Thanks for the response

[Okie Boarder]

Sounds like you are coming along. I'm concerned that you found water in the foam. That is what essentially seems to cause the rot. As long as you feel confident that you found solid wood, then the patch seems reasonable. I'd make sure you don't allow water to get trapped again.

You should post some pictures for us to see the areas you're talking about and working on.

[snibbornairb]

my idea is to cut out a "core" in the very back of the compartment were the exhaust goes through the cross support (poor explanation, i know). I'll put some sort of pvc waterproof cap on top so that i can regularly monitor (and suck out) ant water that makes it in. I think i like this a little better than draining into the bildge because if for some reason my bildge fills w/ water it will not back flow into the other compartments. I'll post some pics soon to hopefully better explain.

[snibbornairb]

the major rot is under the drivers seat and helm, the exploratory hole is on the passenger side and the top of the stringer was dry and hard.

[Okie Boarder]

the major rot is under the drivers seat and helm, the exploratory hole is on the passenger side and the top of the stringer was dry and hard.


How far does the rot appear to go under the helm and into the bow area?

Is the foam wet where the exploratory hole was made?

That rotted stringer picture looks a lot like what most of my stringer sections look like. It's pretty much rotted wood all inside a fiberglass skin.

[snibbornairb]

The bottom 1/2" or so of the foam was wet in the exploratory hole.
The rot does entend pretty far forward. Unfortunately, I don't have the time or money to split the cap, so I intend to do the best I can to control the damage until I can do the whole enchalada like you are tackling. (or until i can get a v-drive) Doing major repairs on a tight budget sucks <<shrug>>

[Okie Boarder]

I would do as much as you can do to remove any foam that is wet and look to see if you can't try to prevent more water from getting close to the stringers. Remove as much rotted stringer section as you can and tie back in some new wood and glass. As long as the stringers are still solid where the engine is, you should be able to buy yourself some time this way. Trying to get water away from the stringers will probably help the most in buying yourself some time. Keep a close eye on things too...especially the motor mount lag screws and ski pole lag screws. Those tow give you an indication of the main stringer integrity. As long as they are still snug, you are in decent shape.

[87SunSportMikeyD]

I thought snibbs' stringer looked pretty good from the pic anyways... snibb have you drilled a small pilot hole with drill bit into the stringer and looked at the wood that comes out???

[Okie Boarder]

I agree, the non-rotted one in the picture looks good. Of course, most of mine "looked" good too. ;-)

[snibbornairb]

on the passenger side i cut a piece of the glass off the top of the stringer (you can see it in the pic if you look close) it it was hard and dry.
I did the same on the driverside main stringer and it too was in good shape. The motor mounts are tight, so I am happy about that. Where i removed the cross members there is some localized rot at that joint. I am going to to dry it out, remove the loose stuff, and fill it in w/ resin/cabosil or something like that, then glass in new cross supports.
I also saw a post about setting stringers in 3m 5200. I am thinking of doing this to avoid hard spot.

[Salty87]

snib

5200 is overkill and expensive. some chopped strands of glass and cabosil will thicken resin if you've got a wide gap to fill. if the gap is smaller, this is what alot of people use...
http://www.stickwithpl.com/Products.aspx?ID=fef65cc9-47bf-4802-aaa9-a343f2ef9458

i think it fills up to 3/8" and is compatible with poly resin. comes in really big tubes too.

for raising the stringer off the hull. foam underneath works, setting up some sort of rig to hold the stringer also works...you need to keep the stringer vertical too while the resin sets. i found some fiberglass shims in my hull, i used those to raise the stringers.

[snibbornairb]

I was looking at the 435 resin @uscompoites. Is that adequate or is there a better (poly) resin to use?
Also 6 oz. for the sole? and not sure for the stringer?. I have seen someone else say 1708 on the stringer.

[Salty87]

i used 435 resin and bought some locally, pretty much the same stuff. i used woven roving on my stringers, can't remember how many oz it was. i also think i used 8oz on the new deck. you can always put multiple layers to build it up. lay em right on top of each other when they're wet so they cure as 1 piece.

i've never used 1708. from what i understand it's a combination of glass and chopped strand mat. i would think it's easier to use than separate layers of mat and glass. if you decide to use a different type of cloth, you have to lay mat down first or the glass won't stick very well.

[Okie Boarder]

I'm planning to use 1708 for the stringers. 1708 is a biaxial fabric. From the sounds of the descriptions it yields good strength kind of like woven roving, but it is a little easier to work with. Of course, to get the same strength, I'd assume you need multiple layers where you might only need one with the roving.

[snibbornairb]

easier to work with sounds promising

[snibbornairb]

http://www.fiberglasssite.com/servlet/the-68/Fiberglass-Information%2C-and-How/Detail
I found this site that gives alot of info on how much resin is needed as well as general glass info.