Stringer/ Floor Replacement Lessons Learned

I thought it would be a good Idea to start a thread where everyone could post up lessons they have learned when they did their stringer or floor jobs. That way newbies can read through this and learn before they made the same mistakes and have it all in one place.

This is not meant to be a how to do a string or floor job but a helpful tips for when you are doing a project.

What I was thinking was as you posted up your tips I will copy that into this first post and give you credit so everything is up at the top and easy to get to.

Feel free to join in on what you have learned and give your best tips. If there is another section to be added just let me know what Category.

Here is my list to get things going.



Tools
The 2 tools I used the most in my project were
1. my orbital sander – I used this in every step of my project from cleaning up the hull after grinding out the stringers, to shaping the stringers, to finishing the bilge, to prepping for the carpet
2. my Shop vac – This is a must for ease of keeping things clean and helping to be able to see what you are doing

Get a prefilter for your shop vac filter. This will help to keep your filter from clogging up so much when vacuuming fiberglass dust.

Use a bag on your shop vac. This combined with a prefilter will help keep the exhaust of your shop vac blowing somewhat clean air.

vondy wrote: I got one of these for my dust vac Oneida best money I spent. Probably saved me 2 dozen filters and countless time. I barely had to touch the filter in my vac this worked so well.

ultrarunner wrote: One thing for folks to consider for dust-control is to remote locate the shop vac, in addition to the pre filter. This will naturally require a longer hose, and possibly additionally capacity as well as a remote on/off, but not having that damn thing inside blowing all the dust around is sure nice....

7” Grinder – Great for knocking down glass fast after removing the old stringers. Just watch it so you do not remove too much

inline sander - If you are going for a straight and smooth bilge this will help you get there.

crobi2 wrote: When I was doing my second old floor/stringer ripout, I really enjoyed using a pneumatic cutoff saw to cut the fiberglass. On the first job used an electric one and was in fear of loosing fingers.

Metallman56 wrote: add to the tool list a power plainer. doing it by hand with a file sucks, and is very time consuming. i picked one up tonight for about $35 from H.F, the cheapest one if could find. i got done about 3 days of work in less then an hour. a must have for shaping the bottom of the stringers!!

pmt2234 wrote: Buy the best shop vac setup you can get, and buy yourself a new sander/angle grinder. I used a 4" for all the tight spots. I have a 3x24 belt sander I used where I had room for such a big tool.

Grinding/ Sanding
Harbor Freight sand paper is cheap and there is a reason for that, it sucks!!

Go ahead and stock up on 4” flap disks (Coarse as you can find), orbital sand paper (From coarse to about 220), and sanding belts. You will go through them!!

Wipe down with baby powder before grinding on the fiberglass. This will help to keep from itching so much.

Wear long clothing in multiple layers to keep the glass dust off of your skin to begin with to keep the itch down.



General Tips
Kind of common sense but, If you are working in the heat and wearing multiple layers, Keep hydrated and take breaks to cool down.

A fan in the boat to help move the air around works wonders to keep you cool on the heat.

Go ahead and invest in a good 3m respirator (like This) , it will work 10X better than the normal dust mask.

crobi2 wrote: Thumbs up on the expensive respirator-type mask- used one both times.

Do not buy the mixing sticks from US Composites. I did and they are tiny sticks that break easy, just run by your local hardware store and grab you some paint mixing sticks. They will work much better for you.

Before you start your project cover the top of the sides and back of the boat with plastic, cling wrap, floor covering or something to keep the inadvertent fiberglass/ foam off. After washing my boat today I learned that I am going to have a good bit of clean up to do to get this kind of mess cleaned up!!

If I had it to over again I would cover the entire top of my boat and the tops of my trailer fenders with this stuff. Carpet Protector Film

vondy wrote: Allow ample time, it will take forever. Be prepared for countless problems when putting everything back together, nothing never fits right. Expect to spend about 3 times as much, when your putting things back together you realize you need to buy this $50 part to make something work, etc. Never ends. Buy several boxes of chip brushes (harbor freight) and as many gloves as you can get your hands on. I probably blew through 300 pairs of vinyl/latex gloves. Respirator and Tyvek suits. Amazon has the Tyvek for about $5 each if I remember. Again, I would stress finding time and patience before starting. It will save you money, your sanity and probably your marriage

Use the thicker 9mil nitrile gloves. They do not rip no where near as easy making them last longer.

Also use the Cotton gloves with the palm and fingers dipped in vinyl when sanding or cutting out the old materials. It will protect your hands and you can still get a grip on things.

crobi2 wrote: Do lots of research. I didn't think to search the internet back in 2000 and probably reinvented a lot of stuff that I didn't need to. Internet barely existed in '91. Probably the most important advice is to keep dreaming about how you are going to use the boat when the job is done.

pmt2234 wrote: When the engine and trans were out of the boat, I just made a frame out of 2x12 boards atop a 2'x4' piece of plywood. It worked great, just don't buy little casters if you want to be able to move it around much.

Glassing
Take your time and make sure to roll all the air bubbles out of your layups. Sure this will sometimes slow you down and can be aggravating but the end result will be much better.

I bought a roller to roll out the bubbles and I made one as well. I much preferred the one I made, it seemed to work better for me. It did cost more to make, but I could also take it apart to clean though.

Plan your layups, and have your glass laid out and ready to go.

If you want a smooth bilge as a finished product, pay attention to the bilge as you are glassing and try to keep that area as smooth as possible. This will help you when it comes time to use the Fairing compound and actually smooth things out.

Buy a set of sharp scissors dedicated to cutting glass. I went through a couple of pair of old ones, buying a new set would have saved me some time.

vondy wrote: The scissors are a good idea as well. I killed about 3.

pmt2234 wrote: I haven't had any problems with the quality of my work in the 6 years since I redid mine, but If I did it again, I'd use epoxy resin. Wouldn't cost that much more, and I know it's supposed to be way stronger. Also, I'd look into something like Plexus for joining the new stringers to the hull before they're glassed in. I used little bits of glass mat stuffed into any gaps and thoroughly worked over with a brush. It took forever.

Stringers
Use a diamond cutting wheel on your 4" grinder to cut out the stringers. It makes a mess but cuts fiberglass like butter.

Taking your time when shaping your stringers so that you get them shaped just right for your hull may be aggravating but it is worth it in the end.

Measure 50 times then cut once.

Round over the tops of your stringers (all wood that is getting glassed over for that matter) with a router and a 3/8 or ½ bit, this will make glassing over these parts much easier later.



Foam
Using a router to cut out the foam for your wood braces under the floor works wonders and is fast.

A Belt sander and orbital sander will make quick work of getting the foam down to the right level and smoothing it out. Just be careful not to sand off too much

pmt2234 wrote: I found the 2 part pour foam I got from Wicks Aircraft was way more flameproof than the old stuff I took out of the boat, and the new stuff I bought from a boat supply place. Price was about the same.

Fairing
Go ahead and get the Fairing compound. I tried to use glass bubbles to begin with and they worked, but the fairing compound works better and is much easier to sand!!

Use the plastic body filler spreaders to spread the fairing compound. They work great and it is much easier to spread the filler smooth.

crobi2 wrote: Excellent post! When I was doing my second old floor/stringer ripout, I really enjoyed using a pneumatic cutoff saw to cut the fiberglass. On the first job used an electric one and was in fear of loosing fingers. I didn't think to use a prefilter on my shopvac, but amazingly, the thing still works - bought new for a stringer job in '91, held up through a second job in 2000. Prefilter sounds like a great idea. Do lots of research. I didn't think to search the internet back in 2000 and probably reinvented a lot of stuff that I didn't need to. Internet barely existed in '91. Thumbs up on the expensive respirator-type mask- used one both times. Probably the most important advice is to keep dreaming about how you are going to use the boat when the job is done.

Thanks for your input!!

Yea the prefilter helped a lot. Both with having to stop and clean the filter to get suction back and with dust blowing out of the exhaust of the vac. The only thing worse than having to deal with fiberglass dust is having to deal with your shop vac blowing that fiberglass dust, literally, everywhere!!   

Kris, thanks for posting such a great write-up. One thing for folks to consider for dust-control is to remote locate the shop vac, in addition to the pre filter. This will naturally require a longer hose, and possibly additionally capacity as well as a remote on/off, but not having that damn thing inside blowing all the dust around is sure nice....

I haven't had any problems with the quality of my work in the 6 years since I redid mine, but If I did it again, I'd use epoxy resin. Wouldn't cost that much more, and I know it's supposed to be way stronger.

Also, I'd look into something like Plexus for joining the new stringers to the hull before they're glassed in. I used little bits of glass mat stuffed into any gaps and thoroughly worked over with a brush. It took forever.

I found the 2 part pour foam I got from Wicks Aircraft was way more flameproof than the old stuff I took out of the boat, and the new stuff I bought from a boat supply place. Price was about the same.

When the engine and trans were out of the boat, I just made a frame out of 2x12 boards atop a 2'x4' piece of plywood. It worked great, just don't buy little casters if you want to be able to move it around much.

Buy the best shop vac setup you can get, and buy yourself a new sander/angle grinder. I used a 4" for all the tight spots. I have a 3x24 belt sander I used where I had room for such a big tool.

I just learned something today. Before you start your project cover the top of the sides and back of the boat with plastic, cling wrap, floor covering or something to keep the inadvertent fiberglass/ foam off. After washing my boat today I learned that I am going to have a good bit of clean up to do to get this kind of mess cleaned up!!

Plexus is an adhesive, typically used with plastics.

Jim,
Good luck on the stringer jobs. Most find it easier than it looks. It's just time consuming. We are always around for any questions that may come up. Keep us informed and of course post plenty of pictures.

Best tool on my '80 ski was a jam saw to cut the stringers. Set it at 3/4 of an inch above the floor and it left the "walls" of the old glass. This allowed me to fit the new stringers directly into where the old ones were removed. Found a used one and it was the Best $30 I spent!

Mix small amounts of resin at a time in the summer heat. It will help pace you so you don't try to go to fast and get sloppy. Also, it allows you to get out of the boat and stop bending over so long.

When i decide or have to start this project i want one of you old timers to come spend a few months down south with my free Rent. But must work on Boat for food. You guys rock! It would be nice if someone could put a how to pamplet together for the total stringer floor replacment with materials and types of epxy and glass an etc.

BAT5 wrote: Hello all. I have a 1989 Nautique 2001, that I just bought. Boat has 329 hours on it, and seems in great shape. I am noticing a soft spot in the floor, what seems to be about 10 inches from the passenger side of the motor cover. (soft sport seems like it runs in between the stringers for about 18 inches.)   Does this mean a Stringer is rotten, or could it be that the flooring in that area is weak or rotten?

Your floor has rot, that is what is causing the soft spot. Your stringers more than likely do as well. I had a soft spot right in front of my pylon and right behind the drivers seat. Once I got in and looking at it all 4 stringers has rot in them. They were not completely gone in all 4 but there was rot that would have eventually rotted the whole things in all 4.

I wish the best for you that it is just in the floor but I doubt it.

I documented the whole process of taking the floor and stringers out and replacing them if you would like to see it. Link is in my signature.

Bat - Your boat has epoxy resin vs '88 & older had polyester. The epoxy is less likely to absorb water so your stringers may be fine. The floor is plywood, so the edges & holes let water into the plys.

Search for the 'hammer test' on this site (from Morfoot) as that may give you some insight into your status.

Thanks for the feedback guys. I'll check out the hammer test and let you know what i find. Appreciate the help. Thanks,

Would be nice if those who have done the stringer and floor job to post how its holding up and performing.    Im especially interested in the composite jobs to see how much weight was saved and how the job is holding up.


also it would be a good idea for someone to make and save templates for the stringers. for forum members to use.    In my case there was No wood left in the main stringers at all and due to condition of the rest it is a little difficult to make a good template. My main stringers broke up in a few pieces through removal.   Im going to set them in place again and glass the fragments together then make a template. if its good, ill save it. Glass the cardboard so it will last and offer it up.   

It's about 20-30% lighter and I'm not complaining about that. Still solid as a rock ~5yrs later. Joe's is the same- we're not particularly easy on our boats. We did use epoxy and a generous glass and bulkhead schedule though.

Food for thought after doing a stringer and floor replacement on my 89 Nautique 2001.

There are 2 types of fiberglass shops. One's that have burnt down and one's that will...

Do your research on the resin that you buy. Some boats were made out of SMC fiberglass and standard resins do not stick to them. Cheaper is not better. The cheaper variations, available at most box stores and marina's, have a filler comparable to limestone mixed into the resin. This makes wetting your fiberglass mat very difficult compared to the higher quality resin. I used about 6 gallons of resin and an entire roll of mat. 3.5ft wide by 50 ft long? or longer...

You will burn through a lot of material and a lot of rubber gloves. I went through 2000 pairs of rubber gloves by the time I was completed...

Paper Dixie cups are great for mixing and they are cheap. Don't use plastic... They tend to melt.

Fiberglass creates heat as the chemical reaction occurs. The combination of warm ambient air temperatures, atomized solvents in the air and high reaction temperatures can make a recipe for disaster. Be careful, Make sure you have enough ventilation and if you can afford them sparkless tools, and heaters. Ye old torpedo furnace isnt recommended.

Your boat will have open cell foam used in its construction. Replace it with closed cell expanding foam. 2lb foam is fine. Your boat will be much stronger and will n ever sink....

Some basic protective equipment makes you look like a huge dork but will make your job a little more tolerable. Throwaway jumpsuit, tape the legs and arms closed if you have to, comfortable respirator and goggles to keep the fumes out of your eyes. It gets pretty thick in the bottom of the hull after glassing the floor together.

Cardboard templates are a lifesaver before cutting into that $60 sheet of marine grade plywood.

Use bondo or similar filler to round inside corners or anything else to help the fiberglass lay down. Fiberglass mat does not like sharp angles. This will ultimately make the repair stronger and more reliable. After applying filler to the inside corners take the glossy surface back off before applying fiberglass. The resin won't stick to a glossy surface. Same goes for the old fiberglass. If the surface is glossy or dirty the new stuff will not stick and you are wasting your time. Do your prep work!

Seriously consider hanging your boat during this process. If your boat is on the trailer the hull will deform as you remove structural components. Hanging the boat with the hooks designe by Correct Craft will allow the hull to relax.

Lastly. Get creative and make your boating life easier. Move that battery compartment out from underneath the bow. Put a cup holder in the floor by the drivers seat. Yes they fit. trust me on this one.

Congrats. you are now qualified to replace stringers...

p.s. 3m 80 grit 8 inch grinding disks fit on your high speed buffer with a cheap adapter.