what does catastrophic stringer failure actually look like when it happens?

[GHBAY]

I dont mean rotten stringers, Im talking about when someone decides not to replace rotten stringers, what eventually happens to their pleasure craft while under way?

I was just talking to someone about the need to repair the obviously rotten stringers in his boat, and he said 'meh- when I cant keep her afloat any more i will get rid of her'. He implied he could not fathom a situation where some immediate, catastrophic failure would present a significant issue.

he uses his 20' runabout on inland lakes in relatively calm water.

anyone have any good pics I can share with him?

 

[greenbush future]

Re: what does catastrophic stringer failure actually look like when it happens?

The quickest way to consider what could happen is to think of your stringers as your spine on your body. If it was mush and you smash up against a wave with no spin, how well would you do?

And knowing you have rot and doing nothing about it, kind of puts lives in harms way. That's a lawyers dream right there. Not to mention the lives of anyone who shares that boat.

Based on the casual comments your friend offered, he most likely doesn't even have insurance or fails to understand what could happen if neglected boats continue to be used. I don't have any pictures handy, most boats that have failed are at the bottom of the lake.

 

[jasoutside]

Re: what does catastrophic stringer failure actually look like when it happens?

A while back there was some video and photos of a big black go fast boat (Baja maybe) that took a good size wave and basically destroyed that boat. It was a new boat if memory serves me. It would be cool if somebody could reference that. He made it back to shore but the entire structure was trashed.

That was a newish, solid, strong boat. Take one that has mush for stringers, that can be a quick trip to the bottom under the right conditions.

 

[Brian 26]

Re: what does catastrophic stringer failure actually look like when it happens?

There was a post on here a few months ago by a guy who bought a $20k go fast boat and had the transom rip off his first few times out. Sank the boat, and insurance did not cover it. I wish I could find it but can't, maybe someone else can. When you read that you start thinking differently about how important boat structure is.

 

[racerone]

Re: what does catastrophic stringer failure actually look like when it happens?

The vast majority of folks think----" it is a fibreglass boat, what could possibly go wrong with it "----The truth is that most transoms and stringers are cored with cheap plywood.--Have even seen some with chip board in the stringers.------------My own 30' centre console started shaking too much and I stopped using it.----Stingers were nothing but powder and " beaver puke " and failure was immenent.------------But you would get " blisters on your tongue " convincing some folks to inspect / fix that.------Boats were never engineered / built for easy inspection and maintenance of these items.

 

[smokeonthewater]

Re: what does catastrophic stringer failure actually look like when it happens?

I was ON a boat with a ply floor attached to 2x runners that had been scabbed to the side of rotten stringers.
I felt the floor moving under my feet each time we crossed a wake and repeatedly asked my friend to slow down.
A few minutes later I looked back to see water partially covering the exhaust manifolds and seconds later we were dead in the water.


We managed to keep it afloat long enough to get another friend to tow it to the shore where we ran it aground. With the use of a 2500 gph pump and group 31 deep cycle from my boat we managed to get it floating again for the tow back to the ramp.

The hull had split lengthwise down the bottom for about 6 feet. My friend was very lucky that while the water came in VERY fast underway it was slow enough sitting still and at idle speed tow that my pump could keep up.... After getting the water out of the engine he pulled it, sold it, and trashed the hull We were all very luck that nobody got killed that night.
Things could have been a LOT worse if it had busted crosswise. The hull could have come apart a 50 mph....

 

[Watermann]

Re: what does catastrophic stringer failure actually look like when it happens?

This should sum it up for him...

 

[agallant80]

Re: what does catastrophic stringer failure actually look like when it happens?

My first boat, which back then I knew nothing about boats had a rotted deck which was covered by 1/4 inch plywood. The stringers were so rotted they would not hold a screw and the person I bought it off of had to liquid nail the "new" decking down. The boat had a tone of flex in the hull. Chances are on a small lake with no big waves you would just feel the boat flex. A hard run aground or big waves may present a whole set of other issues. I can easily see the hull cracking.

The whole thing is nothing good is going to come of a boat which has lots and lots of rot. Sooner or later somethign will give and she will take on water or the engine will sag to the point where things bind up.

 

[spdracr39]

Re: what does catastrophic stringer failure actually look like when it happens?

Would you ride with your friend on the freeway at 70 mph knowing the frame of the car was almost rusted in half or the wheel was about to fall off? I would stay away from this friend's equipment at all cost. That includes his vehicles too if that is the way he approaches his maintenance. If he wants to expose himself to harm that's his business but there isn't any reason for you to get killed or injured with him.

 

[lncoop]

Re: what does catastrophic stringer failure actually look like when it happens?

Sadly he thinks his boat will just "be fine til it ain't" and there's nothing you can say or show him to convince him otherwise, so any additional effort will be wasted on your part. I have a friend like that. Good as gold but stubborn as a mule and has an old Ouachita trihull that needs a transom. He's resolved to do the same thing as your buddy. I just told him that was his choice but my daughter wouldn't be tubing behind or riding on his boat in that condition. Fortunately we're still friends.

 

[Home Cookin']

Re: what does catastrophic stringer failure actually look like when it happens?

I guess the follow-up question is, how strong is a fiberglass hull itself on a 20' boat underway? I see the hull as more than just a skin but an integral part of the structure--an exoskeleton if you want to extend the spine metaphor. Would a fiberglass hull of decent quality, with gunwales attached, be strong enough to handle smooth or moderate conditions?

The transom strength is a separate conversation b/c it takes the whole force of a pushing motor (outboard); it's strength to the hull only is at the corners. I suppose with an i/o, the pushing force is transfered at least somewhat to the bottom of the hull where the motor is attached, but frankly I don't know anything about the structure and the hull/motor tie-in.

There are boats with no stringers that do fine. One design is the aluminum open boat with ribs at latitude rather than stringers on longitude. And there are fiberglass boats like old privateers, whalers and carolina skiffs with solid (filled and sealed) hulls at the bottom and nothing on the sides. Of course they are designed that way so there are other structural compensations.

 

[crabby captain john]

Re: what does catastrophic stringer failure actually look like when it happens?

Actually, that boat should be for sale in Craigslist ~~ needs TLC but very clean

This should sum it up for him...

 

[crabby captain john]

Re: what does catastrophic stringer failure actually look like when it happens?

Your friends boat is like an eggshell~~~ with the egg removed.... A wave or wake from the right direction and it will crumble.

 

[Frank Acampora]

Re: what does catastrophic stringer failure actually look like when it happens?



Here are a couple of photos of my little 14 foot flat bottom go-fast. When I was rebuilding/reinforcing it to take the higher horsepower engines I intended to put on it, I removed the stringers. Just for S*** and giggles I decided to try to run it without a floor or stringers.

While fiberglass is very strong, it is also very flexible. My hull bottom is only about 1/4 inch thick. When I went to run it, at anything over an idle, the pressure of water against the hull would bubble it up about 6-8 inches from the transom to about 3 feet forward. Needless to say, I never got it over 5 MPH.

While a deep vee might fare a little better and a thicker bottom might also fare a little better, and while Fiberglass has a greater tensile strength than the same weight of steel, I imagine that at some speed the bubble will exceed tensile strength and burst.

 

[tazrig]

Re: what does catastrophic stringer failure actually look like when it happens?

This should sum it up for him...

Thats only if he's lucky and it doesn't break in half before it sinks! :facepalm:

 

[smokeonthewater]

Re: what does catastrophic stringer failure actually look like when it happens?

I guess the follow-up question is, how strong is a fiberglass hull itself on a 20' boat underway? I see the hull as more than just a skin but an integral part of the structure--an exoskeleton if you want to extend the spine metaphor. Would a fiberglass hull of decent quality, with gunwales attached, be strong enough to handle smooth or moderate conditions?

No ..... there are animals without vertebra but that doesn't mean humans would be fine without one in calm conditions

The transom strength is a separate conversation b/c it takes the whole force of a pushing motor (outboard); it's strength to the hull only is at the corners. I suppose with an i/o, the pushing force is transferred at least somewhat to the bottom of the hull where the motor is attached, but frankly I don't know anything about the structure and the hull/motor tie-in.

The transom transfers the bulk of the forces it sees to the STRINGERS and they carry that force throughout the boat

There are boats with no stringers that do fine. One design is the aluminum open boat with ribs at latitude rather than stringers on longitude. And there are fiberglass boats like old privateers, whalers and carolina skiffs with solid (filled and sealed) hulls at the bottom and nothing on the sides. Of course they are designed that way so there are other structural compensations.

The aluminum boats DO have mechanisms that take the place of the stringers.... Usually riveted or welded outside the hull but also sometimes inside.. and the foam filled boats if built without stringers have two shear panels (inner and outer hull) attached by foam providing structure

The real key tho is that while there may be boats in existence that do not need stringers, they are not BUILT with stringers..... just as a worm doesn't have a spine. You can not just remove the stringers (even through years of neglect) and expect success.

 

[Slide]

Re: what does catastrophic stringer failure actually look like when it happens?

Stringers carry compressive stresses and bending loads. Imagine your boat as a piece of paper - you can pull it in any direction without deforming it (tensile and shear loads) but if you compress or torque it, it immediately deforms. Without stringers, the fiberglass hull will continually deform until it fails catastrophically.

Source: I am a structural engineer.

 

[Scott Danforth]

Re: what does catastrophic stringer failure actually look like when it happens?

there are not many pics because in many cases, I believe the boater did not survive.

think of it this way. stand on a full unopened beer can. you can put 300+ pounds on it. now take the same beer can, drink its contents and try to stand on it. The beer in this case acts as the structure. That is what the stringers do in a boat.

I have a friend of mine that owned a charter fishing boat. was about 5 miles out on Lake Michigan, port engine mount or mounts or stinger failed when under-power to get to the reef. The big block dropped and caused a huge leak at the transom. Water came in quick enough to sink the boat within about 15 minutes even with boat pumps running. luckily he managed a mayday and there was another fishing boat near by to pick him and the customers up.

Here is prior thread that has a pic of a boat being hauled out without the transom or rear half of the boat.

http://forums.iboats.com/boat-resto...-does-happen-hull-failure-due-rot-549862.html

 

[tazrig]

Re: what does catastrophic stringer failure actually look like when it happens?

anyone have any good pics I can share with him?

How about this:



... if he survives going full speed when the boat splits in half. :facepalm:

 

[Texasmark]

Re: what does catastrophic stringer failure actually look like when it happens?

This is not a "could" it's a "did".

Was in Crystal River Florida (N. Florida on W. side just below the pan handle) for business and decided to get a guide and do some local fishing.

This senior gent shows up with this antique skiff of sorts, plywood with wood stringers, about 20' long, 90 Rude for power.....never ran it over about half throttle.

In answer to your question, the floor pulsates with the waves. It moves up and down and up and down.

Want more of a definition, ask.

Oh, the rest of the story was he said not to pick up anything floating....................

Trip cost me $200 cash and couple of thousand off my hide being scared s........less. Haven't been back.

Mark