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Stringer replacement help

LeifThor

Member III
I’ll summarize the problem, and then give more details.

I have a 1972 35-2 that needs at least one stringer completely replaced located under the floor in the middle of the cabin.

I may need to replace the only other stringer running across the cabin located just in front of the engine (the engine is under the seatee in the cabin area instead of being located under the cockpit).

And I need to repair at least 3 of what appears to be sheared partial stringers (I say partial because these 8 only run from the side of the boat in a couple or few feet).

Somewhere in the boat’s history it may have run aground, and I found one report of a vessel assist 3 miles offshore taking on water, outcome being water pumped out and she was towed to port. The reported situation may have been an outcome after the unreported first situation.

I need to know-
1. If this job is better done while the boat is in the water, or on dry dock given the hull flex from either situation. I’m aware of the problems that can come from repairing a stringer if the hull shape isn’t in its right or natural shape (which can result in bulges in the hull or the repair popping out).

2. Should I use marine ply or a solid piece of teak, or if another material what and if so, where best to purchase it?

3. Could there be hull stress fractures on the outside of the hull at the joint between hull and keel if a sailboat is sailed without proper stringers attached. No rigid brace between hull and keel resulting in possible flex of keel. The bottom was painted prior to purchase so won’t know for sure until old paint is stripped a year out from now.

4. Is a stringer replacement/repair so difficult a problem to solve (getting the hull to its right position for the replacement/repair) it’s easier to get another boat?

Now for more detail about this 35-2 which may provide clues to one or two answers here.

Two owners ago, (when the incidents happened) she was owned by a woman who had a reputation of not knowing how to sail. She spent a fair bit of money on some good hardware for the boat, yet also had a number of repair jobs done by kind neighbors that we’re executed in the worst way possible.

When I bought the boat she had-
1. A cracked at base mast.
2. An engine that barely ran and was jury rigged and ready to explode (atomic 4).
3. Cracked floors around the bilge access plates (2).
4. Creaky floors

Since purchasing her, I’ve-
1. Replaced most of the engine (water pump, alternator, gas tank, control cables, carburetor, fuel pump, fuel filter, hoses, added water strainer, and replaced the entire exhaust system.

Engine runs fine though she’s been through a lot of shotty jury rigged fixes, so she’s a wee bit tired and will need a rebuild in a couple years.

Shortly after purchasing her, while cleaning out the area below the floors, which were thick in engine grease and soot or dirt making up a layer throughout the bottom of the hull under the cabin floor (no grease was found on the underside of the cabin floor), the stringer for which this post is responsible, lay in delaminated pieces, leaving only fiberglass tabs where it was attached to the hull still in place. Spraying water below the floors simply knocked over the already detached and delaminated remnants left. Once removed it also exposed a section below the cabin floor that had not been seen since the boat was built. To even get to this area to spray below the cabin I had to remove a water bladder that laid below the floor that I can only assume was a back up for long journeys some decades prior. It was leaking and attached to the water system so as long as there was water in the tank, it was partially filling the bladder which had been leaking for possibly decades. The result being a waterlogged worthless rotted stringer that was completely delaminated.

I have no idea how many times she’s been sailed without effective stringers. I have no idea how many owners she’s had. But I’m positive I was the first eyes to see under the floors between the stringer next to the engine and the stringer that fell over in pieces which amounts to a section roughly 4x7ft.

Inside was a section of hose going nowhere, odd nuts and bolts laying on the floor, a glasses case completely rusted, and a whole lot of wet moldy rotten smell. Combining a slow leaking water bladder with a section of bilge area underbelly completely cut off from access created the rotten delaminated stringer.

I know I’ll need to cut a hole in the floor to replace the stringer, and I’d do it anyway since a boat shouldn’t have inaccessible areas. I was surprised at purchase it didn’t have an access plate there.

Anyone who’s dealt with this problem and solved it successfully or unsuccessfully I’d really like to hear from the most. And if so as much detail of your success or failure replacing your stringers.

Thanks!
 

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gadangit

Member III
It appears that your stringers were not bonded to the one piece sole and only provided support across the span. I can't imagine they are doing anything that affects the shape of your hull.
Our boat did not have those stringers, but was built in a similar way. The bilge area filled with ugly crud underneath is essentially inaccessible which drove me crazy. So I cut out the whole sole and started over. Our solution included adding epoxy coated plywood stringers to support individual floor panels.

I've posted pictures of what it looked like with the sole cut out and the eventual fix. I'll look for the posts later, but if you search by my postings you'll find some examples of how we solved the problem.

Chris
 
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gadangit

Member III
See post #27
 

LeifThor

Member III
It appears that your stringers were not bonded to the one piece sole and only provided support across the span. I can't imagine they are doing anything that affects the shape of your hull.
Our boat did not have those stringers, but was built in a similar way. The bilge area filled with ugly crud underneath is essentially inaccessible which drove me crazy. So I cut out the whole sole and started over. Our solution included adding epoxy coated plywood stringers to support individual floor panels.

I've posted pictures of what it looked like with the sole cut out and the eventual fix. I'll look for the posts later, but if you search by my postings you'll find some examples of how we solved the problem.

Chris
Thanks Chris for your reply! No they aren’t or weren’t attached to the cabin floor, only to the hull. And I’d swear I read the fiberglass floor was part of the rigidity of the hull, to say the one piece floor acts as a partial piece of the structure holding the hull to a consistent shape. Any idea where I’d find your earlier post with pics?

I like your ply/epoxy solution. Has it held up well, and how long ago, or how many sails has your boat had since?

Thanks again, this helps!
 

gadangit

Member III
In the water.
It was fixed maybe 4 years ago? I think we've sailed approximately 2500nm since in all conditions.

I have looked to see if the gaps in the floorboards change while sailing and I haven't seen anything. We do have structural beams that tie our bulkheads together, which is probably helping. And our new stringers are screwed to the remaining one piece sole that is still attached to the hull.

I will be honest and say my gut tells me the one piece sole bonded to the hull on each side does provide structure to the hull, kind of a TriAxial Grid V1.0. But you can tie it all back together as we did.

Take all this with a grain of salt. I'm just a dude on the internet... :)
 

LeifThor

Member III
Love that last line Chris! But hey we all help each other here, and your thoughts and repairs were really good.

I've been thinking a lot about this repair, and realized some things you mentioned earlier and they finally clicked.

The fact that these supposed stringers were only tapped to the floor indicates it totally wasn't a structural stringer. Even when it was attached and the wood was in good shape that piece never helped the hull maintain it's shape. Which really makes me scratch my head as to why they did that, and I can only come up with one reason. The stringer that holds the shape is elsewhere, but where? And then it hit me...The floor (under the cabin floor, the real floor of the boat, is flat, and the flat area is feet wide, far wider than the width of the keel...

They built up such a thick layer of glass going up from the keel top, that that's the lateral stringer, about I'm guessing 6-8 inches high of fiberglass, which makes the boat super solid.

If the floor continued it's V to a point where the top of the keel was that would mean no extra glass there, but this big flat area is a dead giveaway it's a big solid piece of fiberglass work, or the keel has an big flat area at it's top which I can't believe.

What are your thoughts on my observations??
 

gadangit

Member III
Let me start by saying I think that your rotten stringer was there to support the one piece sole. That is a long flat span that is only about an inch or so thick? No material can span that without sagging under feet or feeling bouncy. So they stuck a stringer under to support the middle. That is my theory.

But that flat section under the sole is actually the top of your keel lead. In our boat the lead at the top was a series of large blocks. How the heck they got in there I have no idea (we have 9500lbs total and I couldn't even budge a block). It appears they then added a bunch of 2 part foam to hold it all together and glassed across the top from one side of the hull to another. We do not have any thing like you describe as a thick layer of glass acting as a beam.

So I think the hull is keeping it's shape by a series of horizontal structural planes: the one piece cabin sole and the glass across the lead. I think there is a vertical element, at least on our boat, just aft of the lead in another hefty layup of glass that is tying the two sides of the keel together from the deepest part of the bilge up to the top of the lead.

I also think the hulls shape itself with it's wine glass cross section inherently adds to the structure and hull stiffness.

Seriously, I have no idea if any of this is even remotely right.
 

LeifThor

Member III
So we’re in dry dock now getting a leak that had been going since before we bought the boat just outside the shaft log, that I thought was a cracked log, but wasn’t. And while here, I’ve decided to address the stringers issue and here’s what I’ve done, and what I’m considering doing, especially since reading your replies again, and talking to others here in dry dock about it.
Aiming for goals-
1. To ensure the hull maintains its shape under sail.
2. remove the creak in our floors (ideally not creaking while under sail too).
3. That whatever solution is used, no impression of the job is left as a visible bulge on the exterior (an apparent issue that has happened to people repairing or replacing stringers).
Its taken two days to cut the hole in the cabin sole to access the areas, remove the remaining oil and waterlogged stringer just in front of the engine, and clean a seriously fouled area. I’m positive something terrible happened to the prior engine, as I learned while at this yard, this atomic four is a rebuild and just six years old. From bow to stern, the bilge area going up to just under the underside of the sole/floor was caked in an 1/8 inch of oil and possibly melted plastic? I don’t know, but whatever it was, it took two days to scrape it off (pics attached). So now I can see my engine from the access panel at the V berth, that prior was blocked by the two rotting pieces of wood.

I heard about and bought some coosa board as an alternative to marine ply and right before I began cutting it up to lay it in it occurred to me-
If the wood was there to simply hold up the floor, can I use something much simpler, possibly allowing me better access to my engine. So using about $2 of pvc pipe, and wedging them only over the top of the keel against the underside of the cabin sole, I’ve effectively removed the creak from the cabin sole.
And as I was patting myself on the back for coming up with such a simple solution, it just feels too simple, and I’m concerned the hull has only the cabin sole and lengthwise couch and dinette members to maintain her hull shape under sail.
So here I am on the hard wondering if I should build in stringers across the boat for added structural strength, or wait and see how the pvc pipe fix does first.
I’m pretty sure the piece next to the engine was not held to the fiberglass tabs.
By using the pvc, I’ve at least eliminated the potential for bulge in the hull as some have experienced when replacing stringers. And if I do add the coosa board, I think it better I do it in the water.
if the PVC does the job, then I’ll glass them in, the tape is just to hold them temporarily.
 

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Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
Not sure I really understand this issue, but I'd say if there was a stringer there before, replace it to the original design and probably the original material.

The PVC idea, well....it is unusual.
 

LeifThor

Member III
It’s wrong for me to call this a stringer, it’s what I thought it was when I first found them.
A proper name for would be sole support, as in the only purpose it served (given how they were connected by 4x6 long fiberglass tabs at the bottom, there’s no indication with such a minor attachment they could serve as a stringer would. It just didn’t dawn on me till later, they could have only served to keep the floor from flexing.
I totally agree with you if a stringer comes out a stringer should go back in. And yeah the PVC is unusual but for holding the floor/cabin sole it works just fine. If I wanted to distribute the load I could add a piece of wood along the top.
I really wish an Ericson owner who had a stringer fail and the boat suffered or doesnt have a stringer running port to starboard and who’s hull is fine sailing to weather in high winds could speak to this.
Thanks Chris:)
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
On every boat the sole is part of the structure. Boats move, flex and twist. The sole has to withstand that just to be a viable sole, with inspection hatches that open reliably and a floor that doesn't sag or squeak. The bilges below the sole have to be contained and drained. All the components are in a wet, hidden environment requiring traditional materials selections and fastening.
 

LeifThor

Member III
Well said Christian! One thing that drove me mad when we bought the boat was the lack of access to the area below the sole. A decades old bladder blocked access next to the head. When that was removed, a rotted delaminated board blocked the view. After removing that I could see the other end of the blocked area which was another less rotten piece of wood just in front of the engine. None of the wood was attached to anything. When it was originally installed it was attached to the boat bilge floor via four (per board) tabs of fiberglass, but had long since separated.
To your point, there lies a mystery. Ericson sailboats are if nothing else well made. I’ve owned two, and it never stops amazing me on their incredible design and build.
Yet...
They chose to insert raw wood, with no fiberglass to protect it, in the bilge area where as you mention it wet all the time.
This makes me think that maybe this was done after she was built by an owner later on. It just doesn’t fit the Ericson styling.
The only Scenario where those boards could have been used as an actual stringer would be if the tabs of fiberglass were only put on the bottom so that the word itself could flex wall under sale, but that makes no sense either because they used plywood.scenario where those boards could have been used as an actual stringer would be if the tabs of fiberglass were only put on the bottom of the boards so that the wood itself could flex while under sail, but that makes no sense either because they used plywood.
And I totally agree with you about the sole being an integral part of the stress design.
 

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gadangit

Member III
While recognizing the financial considerations that come into play with these repairs, I echo what Christian said: try to stick with traditional materials and construction methods. Any shipwright reading your post about PVC supports will be crying themselves to sleep tonight. :)
Chris
 

LeifThor

Member III
How about this, can anyone who owns any size Ericson show me any photo of a stock stringers that runs port to starboard underneath the floors in their boat? I’m just curious to see what’s out there because the open celled wood to that environment seems odd.
 
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