Alternative to replacing stringers?

[davaugust]

My boat had a couple of soft spots in the floor, and I decided for various reasons that it was time to go ahead and tear it up and replace / patch it. It's an ongoing project, which can be seen here:<br /><br /> http://www.shareaproject.com/projectThumbs.php?p=1 <br /><br />Turns out there is a little rot in the stringers directly under the affected floor area. I REALLY don't want to replace them. I had hoped to keep the cuddy intact, and in order to replace the stringers, I'd have to tear it apart. I've got the new floor sections cut to size and ready to glass in, as soon as I figure out a good solution for this.<br /><br />I was considering using Git-Rot on the directly affected area of stringer, and maybe shoring a newly epoxied and glassed 2x12 across (alongside) the repair. <br /><br />Any thoughts on whether this would work or any alternatives?

 

[wallbanger2]

Re: Alternative to replacing stringers?

If there is no way you are going to replace the entire stringer, then I would remove the damaged section and use Seacast ( http://www.transomrepair.com/ )to replace it with. You could also sister replacement wood next to the repaired area on each side to improve the streangth between the repaired area and the old stringer.<br />I would first ensure that you don't have any rot developing in the stringers farther up under the cuddy cabin though.

 

[Winger Ed.]

Re: Alternative to replacing stringers?

Throw a few layers of 'glass' over the rotted area and move on.<br /><br />Some boats used to be made where the stringers were hollow. The builder put about 1/8th" of fiberglass mat over a wooden 2 x 4, then when it had set, pulled the board out and put the stringer in the hull with a layer or two of fiberglass mat over the molded hollow rectangle that they pulled off the board. That was their stringer.<br /><br />There is nothing majic about the wood being in there. If its rotted and structurally worthless, you can just overlap it with a few layers of 'glass & resin to regain the structural strength it used to have.<br /><br />It would save a pound or two if you could get the rotten wood out first, but if that isn't a big deal-- leave it. The layer or two of fiberglass overlaying the rotted core of the stringer will give at least as much strength as you lost when the wood rotted.<br /><br /><br />The stringer gets its strength from the sides & top/bottom in resisting a 'bowing' load like a piece of square tubing. Or, when its new, its more nearly like a solid bar. <br /><br />If the bottom is the hull, the center is filled with wood-or whatever, then the top can be sort of thin. The rest of its strength is made up by the sides... Like a square pipe.<br /><br /><br />Here's my logic on adding 'glass to the sides & top:<br /><br />If the bottom of the 'tube'- or stringer (the hull)is sound, and the center (the wooden board)is essentially gone,,,,,,,,,,,<br /><br />Then, the lost strength of the 'missing wood and the 'thinness' of the existing top, can be made up or even exceded by strengthing the sides & top. <br /><br /><br />This has worked for me on a few Fiberglass hulls I have had in years past. But don't tell anyone I recomended this, or I will lie and deny everything. When the pureists see this, and start pounding their pitchforks on the ground and lighting thier torches in preperation for buring us at the stake---- I'll point over,, and blame it all on you. <br /><br />Ed.

 

[BillP]

Re: Alternative to replacing stringers?

I'm with Ed on this one. There is no structural reason bulking up the existing glass with more layers to make up the strength won't work. It is more expensive than wood but the labor and time to complete is way less. My only problem doing this is the top of the stringers get higher and can pose other problems with fitting new floors.

 

[lawyertob]

Re: Alternative to replacing stringers?

Daveaugust,<br /><br /> I was checking out your project pictures and I saw your Nautolex Ivory Deco Dot flooring. I was wondering how thick and how flexible the product is. Is it more like vinyl flooring or vinyl upholstery? I had intended to put a bedliner material on my floor, but this product looks great and is pretty economical. My only worry is that it isn't tough enough. After having played with it, what do you think of the material?<br /><br /> Oh yeah, I also love the sharaproject.com site. I will be posting my project pics on it when I am done.<br /><br />$0.01 for your thoughts,<br />Joe

 

[crab bait]

Re: Alternative to replacing stringers?

i'd cut out the rot an 'scab'/sandwich the stringer with at least the grade wood it is.. ofcoarse epoxy everything an all.. <br /><br />( how easy an a good fix can this be )

 

[Solittle]

Re: Alternative to replacing stringers?

I'm with Crab Bait on this as a minimum. Check out seacast as a filler - - (I'm not a fan of Git-Rot).<br /><br />Ed's method may be OK for some boats used in some waters but I would not feel comfortable trying to run in or out of Government Cut in Miami in my 23'er with such a "repair" holdin it together.

 

[BillP]

Re: Alternative to replacing stringers?

Originally posted by SoLittle:<br /> I'm with Crab Bait on this as a minimum. Check out seacast as a filler - - (I'm not a fan of Git-Rot).<br /><br />Ed's method may be OK for some boats used in some waters but I would not feel comfortable trying to run in or out of Government Cut in Miami in my 23'er with such a "repair" holdin it together.

Pound for pound poly/glass is about as strong as steel...check the specs. All you have to do is bulk up the layers enough to make the stength of rotted wood. Even when glassing stringers down the glass needs to be as strong as the wood. If you glass it right an all glass repair will be better (but heavier and more $$$) than wood...except for absorbing vibration.

 

[crab bait]

Re: Alternative to replacing stringers?

with that method lets<br /> hope we/us/the people who use this board / ammetures DO it right..!!<br /><br /> an know how to eningineer the right thickness.. an not be to weak or to brittle..<br /><br />go for it..!!

 

[Buttanic]

Re: Alternative to replacing stringers?

Face it guys, which do you think would break first a wood 2X4 or one made of glass. As far as I am concerned the wood is only a form for the glass. You don't have to lay the glass over the top of the stringers if hight is a problem, it's the thickness of the sides that provide the strength. <br /><br />Buttanic

 

[G DANE]

Re: Alternative to replacing stringers?

Interesting thread. <br />First of all, when repairing, lots of overkills are done, but why not. Ed is right, glassfiberreinforced poly has a strength equal to ordinary steel, but is a lot more flexible which is a challenge to the construction it supports. To comment the construction method, try to compare a square tube to a u-profile, you will find the tube is much stronger. If you examine the way a tube collapses, you will see that the sides deform and buttom and top bends, that makes reason for a core material, bonded to sides of profile. That being said, this kind of repair method is useable, done the right way.

 

[Bill Matuscak]

Re: Alternative to replacing stringers?

I spent last summer replacing the floor and transom on a 14 foot Sea Star tri-hull. The stringers were just as Winger Ed. described. They are a single layer of heavy roving that appeared to have been molded over a 2x4. They are hollow and really not very straight. The original floor was held to the stringers with random, large globs of some form of epoxy. There is no cross bracing or flotation under the floor. <br /><br />They seem to have done the job nicely and have held up all these years. Although the floor was rotted and the bilge area held standing water, these glass stringers were strong and dry because there was no wood inside to rot away.<br /><br />It seems like just glassing over the bad spots in the stringers would be a safe repair. I think I would make a close inspection of the glass in these areas to be sure it was still solid enough to bond the new material.

 

[davaugust]

Re: Alternative to replacing stringers?

Originally posted by Joe Glastron T186:<br /> Daveaugust,<br /><br /> I was checking out your project pictures and I saw your Nautolex Ivory Deco Dot flooring. I was wondering how thick and how flexible the product is. Is it more like vinyl flooring or vinyl upholstery? I had intended to put a bedliner material on my floor, but this product looks great and is pretty economical. My only worry is that it isn't tough enough. After having played with it, what do you think of the material?<br /><br /> Oh yeah, I also love the sharaproject.com site. I will be posting my project pics on it when I am done.<br /><br />$0.01 for your thoughts,<br />Joe

I have found the material to be a really great choice for my new floor...Here are some pros and cons:<br /><br />Pros:<br /><br />1) Pretty cheap for alternative flooring. Not really any more expensive than good marine carpet.<br /><br />2) Very flexible and easy to work with. In answer to your specific question..I'd say it's somewhere about halfway between upholstery vinyl and floor vinyl.<br /><br />3) Very strong. So far it seems to be very strong and tough. I haven't really put it to the test yet though, so it's hard to say.<br /><br />4) Easy to clean. I got it really dirty while putting it in. I sprayed some household cleaner on it, then sprayed it down with a hose and it came very clean.<br /><br />Cons:<br /><br />The only downside I've found so far is that it REALLY shows imperfections from below. I'm kind of a novice fiberglasser, and wasn't as careful as I should have been during the sanding phase of my flooring project. The nautolex, after applied, shows EVERY imperfection in my fiberglass job.<br /><br />As for the shareaproject.com site...Thanks! Can't wait to see your pics!

 

[Jungleboat]

Re: Alternative to replacing stringers?

Gotta admit, the idea of simply reinforcing the square section of stringer by fiberglassing over it strikes me as a LOT easier!

Compared to cutting off the top of the old glass, digging out the wood, cutting, shaping and treating new wood, then sticking it back in - then fiberglassing over it anyway...

Or just fiberglass over it - I like that idea

How many layers would one need to substitute for the missing/rotten wood?

Any particular technique or just slather loads of glass all over?

My boat is a 20ft V hull cabin cruiser, if that's any help. I'm not too worried about weight; I doubt it would come close to the weight of a 3rd person on board and it doesn't seem to notice that.

For those that remember I'm in Borneo, complete with rainy season. I am thinking of pulling the boat out of the water, ripping out the floor and replacing the stringers - but that seems like a huge job... Nor is there anything in the way of "marine" wood out here, just wood of various types.

The current setup has survived 20mph through heavy chop, so she's reasonably sturdy. However that's with an ancient 32 year old 90hp 2 stroke that rarely runs properly. I'm eyeing up an affordable 140hp (and yes, that may mean a new transom..)

This boat is identical to mine but with 175 on there, so the design should handle it:

http://www.mudah.my/Boat+Escort+19ft-9454002.htm

I'm not so sure the stringers could handle that kind of speed though :redface:

 

[Woodonglass]

Re: Alternative to replacing stringers?

UHHHMMM did you notice this thread was 6 YEARS OLD!!!!!