Teredo worms and epoxy boats

[pbmaise]

Originally Posted by jimbunyard

Additionally the freeswimming hatchlings have to have wood to begin their lifecycles (and to begin building a 'house' on/in, without which they cannot survive or live), and since the suspect holes are roughly the size of an adult worm, one has to wonder how the 'worm' got from microscopic larva to adult without the benefit of the protection of their normal woody burrow.

Of course if it's some other species of teredo --- other lifestyles are possible...

Another reply was from a professional oceanographer who confirmed they are filter feeders and..

"There has been documentation of them burrowing into Concrete pilings."

The vessel was initially cleaned before the photograph I began this thread with. Here is a detail from that photo.

Notice bottom right something that escaped the initial cleaning.

It is my contention that....

#1 This appears to have been a home of a teredo worm.

#2 That even though they also "eat" wood that they can do damage to other things in the water.

#3 Yes the epoxy may have contained an organic filler. I cannot say for sure it did or didn't. Both the builder and the designer have died.

#4 The "home" in this photograph is quite large. This would not have escaped my weekly cleanings. Therefore, I believe all the holes were drilled into the vessel after the new owner purchased the vessel and stopped cleaning.


I tried to search for more references to teredo damage to non-wooden structures and found

"Some mollusks can damage concrete, too, though not so severely." Source
A Century Ago, Wood-Eating Worms Devastated San Francisco Bay
The battle against them is still being waged today.
By Matthew Taub OCTOBER 15, 2018

I also confirmed they are filter feeders and they don't "eat" exclusively wood.

Teredo navalis demonstrated that this species is mainly feeding on seston by filter feeding in contrast to wood consumption. T. navalis showed similar stable isotope values (δ13C, δ15N) as Mytilus edulis and Crassostrea gigas, which species were attached to the wood instead of boring into.

Source: What is the main food source of the shipworm (Teredo navalis)? A stable isotope approah lPeterPaalvastaGerardvan der Veldebc

[jimbunyard]

Originally Posted by pbmaise

Another reply was from a professional oceanographer who confirmed they are filter feeders and..

"There has been documentation of them burrowing into Concrete pilings."

The vessel was initially cleaned before the photograph I began this thread with. Here is a detail from that photo.

Notice bottom right something that escaped the initial cleaning.

It is my contention that....

#1 This appears to have been a home of a teredo worm.

#2 That even though they also "eat" wood that they can do damage to other things in the water.

#3 Yes the epoxy may have contained an organic filler. I cannot say for sure it did or didn't. Both the builder and the designer have died.

#4 The "home" in this photograph is quite large. This would not have escaped my weekly cleanings. Therefore, I believe all the holes were drilled into the vessel after the new owner purchased the vessel and stopped cleaning.


I tried to search for more references to teredo damage to non-wooden structures and found

"Some mollusks can damage concrete, too, though not so severely." Source
A Century Ago, Wood-Eating Worms Devastated San Francisco Bay
The battle against them is still being waged today.
By Matthew Taub OCTOBER 15, 2018

I also confirmed they are filter feeders and they don't "eat" exclusively wood.

Teredo navalis demonstrated that this species is mainly feeding on seston by filter feeding in contrast to wood consumption. T. navalis showed similar stable isotope values (δ13C, δ15N) as Mytilus edulis and Crassostrea gigas, which species were attached to the wood instead of boring into.

Source: What is the main food source of the shipworm (Teredo navalis)? A stable isotope approah lPeterPaalvastaGerardvan der Veldebc

'Oceanography' covers a rather wide category of study; I'd be a little wary of putting a great deal of credit in one on-line individual's unsupported assertion, even though they may well be correct.

https://www.researchgate.net/publica...0via%20siphons.

This study supports the hypothesis that T. Navalis may, in certain situations gain a portion, or even the main portion, of its sustenance from seston (plankton, bioseston, tripton, nekton) , though that certainly doesn't mean they always or most often do.

Atoll's aneccdote seems to lobby against the idea, since I find it unlikely that a whole keel's-worth infestation could be fed by plankton through a square inch aperture.

The warm-ocean ecosystem is nothing if not diverse; I remain unconvinced that the culprit was t. navalis, simply because of the atypicalness of the environment where they were postulated to live. Could be wrong though.

If you're really curious, I'd look for other sources as well; some species of Pholadidae (angelwings) seem a more likely suspect to me, at least at first glance...

[fstbttms]

Not related, but related:

https://www.iflscience.com/plants-an...QCELoPkmtEqWRo

[atoll]

Originally Posted by Jim Cate

^^^^

Interesting (and sad) story. Just out of curiosity, how badly fouled was the rest of the copper clad hull? I've seen a few coppered boats hauled in yards here in Oz and they were pretty badly fouled... right on the copper, and after much shorter exposure times than what you describe.

Jim

there was a reef growing on the bottom!
unfortunate as she was a fine classic yacht in otherwise excellent condition but would have required a total restoration similar to what leo gould is doing on the samson boat project

[oldersalt1944]

Beware of polyestermites! They love to eat epoxy and fiberglass.

Originally Posted by pbmaise

Former epoxy boat owner. This summer I helped the new owner haul out and bottom paint. For ten years I user a plastic scrapper to remove any hard growth before it was larger than about 3mm.

Weekly was usually frequent enough. Sometimes every five days was required.

This past year the new owner failed to keep up the scrapping and the boat was attacked by teredo worms . They drilled perfectly round holes about 6mm in diameter and up to 10mm deep
My theory is either the short time or glass fiber is the only thing that prevented total loss of vessel due to the hole depth getting deep.

Tons of questions.

#1 Do the holes in picture look like teredo damage?

#2 Do teredo worms chew past a layer of fiberglass? I suspect the worms only drilled into layers of filler and fairing.

#3 Is an FRP vessel attacked like my epoxy vessel was attacked? I have seen FRP vessels.sitting for years in the water with no cleanings.

#4 Were my weekly cleanings preventing teredo worms?

#5 Would a layer of epoxy laced with copper powder kill a teredo when it ingested it?

[LWatson]

These look more like polyester mite holes, doubtful that toredos would actually drill into the hull. Also I bet that a production boat would not have a hull entirely built of epoxy but merely have a thin coating of epozy to stop osmosis and at best a layer using vinylester before going to polyester resin. Polyester mites are a problem and can be eradicated by a good drenching of raid.

All joking aside these are probably from osmosis and organisms just used the cavities as a convenient home.

[topmast]

Snapping shrimp .

[Kaimana]

I've run boatyards in the tropics for the last 45 years, and have repaired tens of boats that had hull damage. I've never seen teredo damage in anything but wooden boats with no epoxy/fiberglass. Never in fiberglass boats, or composite boats.

I've had my own boats, all built with marine plywood covered with epoxy and fiberglass, in the water the entire time. The ONLY time I've ever seen teredo damage on a wooden boat that was covered with fiberglass and epoxy was on a part of the boat that WASN'T covered with fiberglass and epoxy.

This was a skeg protector on one of my boats: this was a 3/4" piece of marine plywood screwed/glued to the bottom of a 16-foot long by 8" wide skeg. The purpose of the plywood was to protect the fiberglassed skeg's wood, when putting the boat on the hard, which in the tropics means the reef, which is pretty abrasive.

When I hauled the boat, I'd replace the skeg protector every two years or so with a new piece of plywood. There was NEVER any damage to the skeg, although a couple of times the skeg protector was about 1/4 gone due to the teredos. One time I hadn't used the boat for 3 years, and when I finally hauled out, I had small SPINY LOBSTERS sheltering in the coral and other growth on the bottom of my 56-footer! (about 6 inches long). There was no teredo damage.

Teredos do not bore through fiberglass/epoxy, period.

Unless you built that boat yourself, and are absolutely certain you put three layers of 6-oz glass and epoxy over the area in the photo that has those holes, I'd suggest that you've simply got a "WEST system boat" with no fiberglass covering the area. The WEST System suggests that 3 coats of epoxy alone is enough of a covering to protect marine plywood boats.

I disagree that it's adequate, and have proof in the many experiences I've had repairing other people's WEST-system boats that disintegrated in the tropics in one manner or another.

Meanwhile, my boat, which was sitting in the moorings next to the damaged boat, for the same length of time, had no damage whatsoever, simply because I'd included a layer of 4-oz fiberglass cloth all over the boat as part of my WEFCT system (Wood-Epoxy-Fiberglass-Covering Technique system). Say WEFCT three times fast, you'll get the idea. It's as hard for a teredo to get through as it is to pronounce.

What you took the picture of on your boat is probably an area that the builder sanded on too much, leaving the epoxy a couple of thousandths of an inch thick. I've seen a lot of this; above the waterline, you get small splits and holes that are hairline at first, but which get larger as rainwater and dew ingresses and the now-wet wood starts to undergo expansion and contraction leading to dry rot.

Below the waterline, you get the same micro-splits and micro-holes, but you can't see them until they develop into a bigger problem, because they're concealed by the bottom paint, and in the absence of bottom paint, the fouling growth on the hull.

In that area of the photo, you've probably got some of these micro-splits or holes; and the teredos got through these when they were small, and set up shop there. Then they enlarged their holes where they go through the hull, because they need water to breathe.

I don't know what you've got, but it's not teredos. They can't bore through fiberglass. I suggest you listen to all the people on this forum who have far more experience than you do.

And put a layer of 6-oz fiberglass on your boat below the waterline (and don't sand it too much!). That will fix this problem forever.

With Warm Aloha, Tim

[Ric Sheridan]

Maybe they are eating their way out?

[Kaimana]

Originally Posted by Ric Sheridan

Maybe they are eating their way out?

Yeah but. The problem is that they have to "eat their way in" first, and if the entire hull is covered with epoxy AND fiberglass below the waterline, there's no way for them to do that.

Now, I have seen teredo damage following hull damage that wasn't promptly repaired.

An example I often see is when the rudder of a boat bangs a rock or reef, tearing through the fiberglass, allowing the worms ingress. They're TEENY when they get in; a tenth of an inch long if that. And they don't need a big hole; they can get in through a scrape through the fiberglass that's only a couple of inches square. Once in, they go to town!
That's why, if you've got a wood/epoxy/fiberglass boat (DON'T FORGET the fiberglass!! LOL!), you need to address repairs to underwater damage right away.

You can always use what's called Marine Splash Zone Compound, an ugly green two-part epoxy that can be mixed, then smeared onto the damage underwater with a rubber glove that you throw away. It's good for years, then when you haul the boat, dry the area out and do a proper repair.

With Warm Aloha, Tim

[jeepers]

How long do you need to leave a boat to dry out to kill off the worms?
Is it fact you can freeze the boat on the hard it kills the wood worms?
I'm curious as I now of an available boat that has worms. Cold molded wood with casien glue holding it together. Used previously to epoxy etc.
Would it be possible to vacuum bag a hull below the water line for epoxy infusion?

I found these earlier today before I saw this thread..
Shocking...

https://www.youtube.com/watch?v=ioFamAP7xKM

https://www.youtube.com/watch?v=LPmCygTI-5E

[Kaimana]

Run away, run away! "Has worms"? How many? How deep? How damaged is the boat? Have a marine surveyor look at it if you're serious and try to quantify the damage. The damage is the problem, not that there are still worms in the boat.

The worms are easy to get rid of: simply have a termite company come tent and fumigate the boat and that will kill EVERYTHING inside the tent: cockroaches, shipworms, mice, rats, and termites, if the boat has them too.

[pbmaise]

I think I finally found what the mollusk is.

It was likely a member of the piddock family.

https://www.newscientist.com/lastwor...he-hole-story/

https://en.wikipedia.org/wiki/Pholadidae

If you are dealing with only barnacles...no worry. Barnacles don't bore. Once you knock the barnacle off you are left with a white hard crust that naturally dissolves back into the water over time.

However, if piddock or a similar mollusk if eating into the boat they appear to be able to drill right into rocks as the article shows. Therefore, I think overtime they certainly would have drilled into the balsa core of my former vessel.