TOPIC: wood stringer replacement

I am new to the site and was hoping for a little help with a question i have. I picked up a 1964 Corvair fiberglass runabout that needed the floor replaced. The original and previous owner had hacked out half of it some time ago and the it looks to have been sitting for quite a while. Yesterday i finished cutting out the floor and glass that held in the wood stringers. Some parts of them are solid but they seem pretty well past their useful life and in need of replacement. My question is this, can i fill the voids where the stringers were with a 2 part closed cell foam and glass over that? Would that be strong enough? Any input is greatly appreciated. Thank you....love the site. Noel

I would stay with a wood stringer? The grain in wood makes it much stronger than foam. Use cardboard to make a pattern that fits to the bottom perfectly, then cut the same shape out of wood. Be sure to completely encapsulate the new stringer in fiberglass or water will seep in and rot the wood. (again)

Do you think it matters what species i use? The old ones look to be mahogany but without cutting into them i can't be sure. Also, the old stringers popped right out the channels that they were set into (i am presuming because they were water-logged) and didn't appear to be bonded to the hull underneath. When setting the new ones into the existing channels in the hull, do you recommend bedding them into any kind of resin or epoxy before glassing over the top of them?

Kiln dried Spruce or Douglas Fir works well and is very economical. Dont use "green" wood(most of the stuff you find at Home Depot or Lowes)...it has a ton of moisture in it and will cause problems later down the road. You pay a little more for kiln dried but its dry, generally straighter and ready to work with.

Make sure you take the time to properly prep the hull before attaching the stringers into place. I went over mine with a coarse wire wheel on a grinder to rough everything up really good, then wiped everything down in Acetone to remove and dirt, grease, oil, etc. The more coarse(within reason) of whatever you use to prep the floor the better as it will give the resin a better surface to grab on to. The wire wheel was about the equivalent of 40-60 grit sand paper.

When i did the stringers on my Performer, i bedded them directly to the properly prepped hull in a mixture of poly resin and chopped glass mat(like a thin peanut butter consistency). I then came in with heavy mat and resin and tied them into the floor along all the edges that i possibly could. Go heavy with your resin and completely saturate every square inch of the wood to keep moisture from getting to them.

Ive had it out in some REALLY bad chop since doing the floor\stringers and its worked out perfectly.

Thank you so much guys for the good advice and the quick responses. I am looking forward to putting some time into the boat this long weekend. Thanks again! Noel

Surely bedding them in would be best. Just a thought here for the "collective"....Gorilla Glue or the equivalent. This kind of glue never existed when the boats were made, but I would think it would be the cat's meow for this project. It fills gaps, and holds tight. Thoughts? Pros, cons?

I just tried my Dremel Multi-max vibratory saw. Oh yes! that is the way to slice fiberglass. It cuts quickly and easily. To top it off it does not stir up clouds of dust. I am very pleased with this discovery. I removed the thin fiberglass coating over a rotted rib in just a few minutes. Buy one, rent one, but by all means, if you need to replace reinforcement ribs/stringers on the floor, this IS the tool to use.

jepstr67 wrote:

I just tried my Dremel Multi-max vibratory saw. Oh yes! that is the way to slice fiberglass. It cuts quickly and easily. To top it off it does not stir up clouds of dust. I am very pleased with this discovery. I removed the thin fiberglass coating over a rotted rib in just a few minutes. Buy one, rent one, but by all means, if you need to replace reinforcement ribs/stringers on the floor, this IS the tool to use.

Sure are handy arent they?? I used one of the Harbor Freight equivalents when building my Performer earlier this year and was thrilled with how much easier it made the work! I wont tackle another boat project without one!

Are the forms of fiberglass that were around the wood still there?
If so, you don't need to put the wood back. If you removed that fiberglass, then you have some carprentry to do.
Do you have a picture?

Jepstr, and Jerrfy, can you post a pic of your (new) tool over in the NEW PRODUCT REVIEW section? (Just got the heads up about it's creation, seems like a good first post for that!) Seems I be be diving into a stringer, transom, floor project soon, would like to get some input on the best tools to use.

MarkS wrote:

Jepstr, and Jerrfy, can you post a pic of your (new) tool over in the NEW PRODUCT REVIEW section? (Just got the heads up about it's creation, seems like a good first post for that!) Seems I be be diving into a stringer, transom, floor project soon, would like to get some input on the best tools to use.

Sure thing!! Im gonna be picking up one of the pneumatic variants since im not overly confident in Harbor Frieghts electronic tools(though, im sure they are fine...they are getting RAVE reviews!) and ill do a quick write up on it!

The fiberglass on the top side of the stringers was mostly intact but paper thin and very comprimised. Over the long weekend i cut out the rotted stringers, blended down the high spots with a flap wheel and grinder and just to get a feel for it, bedded in one of the new stringers i fabricated in the polyester resin. this seemed to work well and i am looking forward to finishing the job sometime this week when time allows. I took a bunch of pictures and plan to post them if anyone is interested.
Also, being a remodeling contractor by trade i have used polyurethane glues before (Gorilla Glue) and although they have slightly less strength than a convential wood glue they do seem as thought they would be a good fit for this particular type of repair. Has anyone used this glue for a stringer or floor replacement before?

I took a bunch of pictures and plan to post them if anyone is interested.

Of course we're interested, please post your pics Noel! (Pics of the boat, the project, anything and everything boat related, we're picture junkies around here. LOL )

In the future simply leave out the wood, then put another layer of woven cloth over the forms of the old stringers. Keep it tight so you are not raising the floor up more than it was. No need to put the wood back. The wood will rot again even though it may be 40 years from now.


That is what I did to this floor, but since the framing was everywhere there was a lot of support for the new floor. I realize you don't have side to side frames on that boat.