79SN Rebuild

if you have partial rot one place...there is worst rot some where else. im rebuilding my 79 sn right now and all the wood around the battery box was pure rot! i did not realize wood can turn to dirt!!


Nick

Dave,
Yes, the recommended cure is stringer replacement. You may be able to put it off for 1 or 2 seasons depending how bad it is. If you haven't checked the alignment, I suggest doing that and then checking it again every month of boating.

Welcome to CCfan.

BTW,
Being around wood boats and wood all my life, I feel I do know my rot! There is no such thing as "dry" rot. It was wet at one time and now dried out!

Use Photobucket (search for intructional thread on here) or the full "Post Reply" button and there is a gree tree looking button above the text box to search your hard drive.

Here is a picture of the area in question.
http://www.correctcraftfan.com/forum/uploads/10882/IMG_1134.JPG

Just reading through the forum posted by 79SNbrady it appears that, pardon the expresion, "I am in the same boat". Looks like stringer replacement is inevitable.

Dave,
The real trick is to see how much of the wood is not there around the battery box. About right in that area where your wood is gone, my wood was a tad bit better. But once i went forward from that point there was nothing solid!

All ive got to say is pick the engine and start cutting out the floor!

Nick

Rebuilding these old boats is a huge undertaking just because of the time thats required to get it all done. I believe someone else added up how many hours its taken for them to finish there boat was like 200hrs. so far i believe i have 24hrs invested with plenty more to go. But best of luck to you!

Just depends on how much spare time and energy you have. I spent the better part of 2 1/2 days a week starting in August and did a floorless water test at the end of November! Then I took my time for 4 months doing the last 40 or so hours in my garage.

4.5" Angle grinder with a diamond wheel will take care of most of your cuts. DO yourself a favor first though and gut the boat. Take everything you can out of it but the gauges unless they are not working. You cant cut the whole floor up until the engine is out. My cables were all pretty new so I coiled the controller cables and electric cable up, zip tied them together and hung them from the shifter. I completely pulled the steering system though. The floor cut pics start here in my thread to get an idea what its like.

'Peanut butter' is epoxy resin thickened with a solid like cabosil or milled fiberglass. It is just a filler to create a radius.

Dbat 79SN wrote: Thanks. Couple more questions: Has anyone used LVL lumber instead of douglas fir for the stringers? The secondary stringer was made of 3/4", can 1 1/2" be used there just like the main stringer?

Dave,
Yes, LVL is an alternate and in fact we have a member who has done it. There's a complete thread with pictures on it. I recommended it and he tried it. It came out great. Don't worry about the secondaries and having to use doug Fir. They are not the main structure so you can use some decent 3/4 pine of any species. Just make sure you CPES all the wood.

Try the advanced search feature. (over 6 months old) If you can't find it, I'll see if I can. Sometimes the key words can be tricky.

FYI for you guy's that are doing stringer jobs and don't know:

Cab o Sil - fumed silica, used for altering the properties of resin to change thixotropy, add viscosity or increase bond strength. Use to prevent draining from glue joints or on vertical surfaces. Use in combination with other fillers to improve working properties and minimize draining with polyester and epoxy resins. Use with resin or gel coat to make a patching paste or putty.

Milled Fibers - fine powdered glass fiber used as a reinforcement to increase mechanical strengths of resins. Add to fillets for increased strength. Use when laminating to fill tight radius.

Microspheres/ Microballons - use to extend resin, to reduce weight, shrinkage and sanding effort. Use to fill laminate weave, as a fairing compound and for making fillets.

We use all three at the 'Big D' with Microballons probably what we use the most of. We use a resin mixed with 22% ratio of Microballons for a rubstrip on an air oil seal that is attached to the main rotor shaft on a CFM -56 motor. Needless to say it's pretty tuff stuff.

** post edit** Resin and Microballoon mixtures are also used to pot replacement honeycomb core into a damaged portion of aircraft panels, fairings, cowlings etc. It's a normal Boeing repair so if we're using it to fix panels that go over 400 mph I'd say its pretty safe to use to bond stringers to a boat.

BuffaloBFN wrote: Nice break-down Tim; almost sounds like it came from someone who's worked with it before? What's your tech 411 on talc?

Yeah, just a little bit. 10+ years of composite experience for DAL. Guess if they go belly up I can get a job in Orlando building boats. Built up an air/oil seal just yesterday.

Guess I need to start taking pics of all this stuff. I'll have to post pictures of a acoustic liner that I repaired but first had to pull parts of 'Tweety' out of.

Here's the scoop on:

Talc - an inexpensive filler used to extend resin and reduce shrinkage. Talc is a component in many fillers and faring compounds imparting excellent sanding properties where weight is not an issue.

I do have a confession though...I'm not that techno savy when it comes to definitions. I do know the uses of each and why you use one or the other but cheated when it comes to short descriptions. Here's the link where I got the info:

Resin Fillers and their descriptions of use.

Tim - Careful posting shop pictures on the web -- I know that would get me fired from my job.

well, coverage depends on what soaks in. I think its maybe a little under a gallon for stringers? Are you doing a wood floor? because mine was like 2 gallons for everything.