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Old 31-10-2020, 23:12   #1
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Teredo worms and epoxy boats

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?
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Old 01-11-2020, 01:52   #2
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Re: Teredo worms and epoxy boats

What material is underneath the epoxy?
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Old 01-11-2020, 01:08   #3
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Re: Teredo worms and epoxy boats

This vessel is composite. Had what I believe to be teredos eaten their way past the layers of epoxy and epoxy fiberglass they would have eventually been home free into a wooden core.

Overall a problem vessel since it is too wide for any travel lift in SE Asia. Only giant commercial.slipways could handle width but I didn't want to haul in those type of yards. I finally convinced a yard with rollers to roll her out on balloons. The racing dagger board had to be cut down. It was pretty scary to see her tilt forward and backward as weight shifted on to rollers. A team of ten spent 1/2 a day getting her on to hard.
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Old 01-11-2020, 12:39   #4
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Re: Teredo worms and epoxy boats

We had a place on our skeg that delaminated, and got teredos in it. The holes were on the order of 1 mm diameter. She was on the hard for a week, and about the 5th day, they started to come out of their holes, and died, drying out on the surface. Which we then sanded off, and repaired and painted. That boat should not have been left without bottom paint on it.

To me, those holes look like serious trouble, turning the timber into Swiss Cheese. No, fiberglass boats [despite stories about polyester mites], cannot be eaten into by teredo worms.

No, your weekly cleanings were not preventing the worms. They will go to the wood whenever they can, it is what they eat.

The boat needed to have an antifoul on it that that prevents the worms. I can't tell for sure from the picture you posted, but, a proper repair would include waiting for all the worms to die, then re-glassing all the wetted area with epoxy and glass, and then priming and anti-fouling it.

Sorry to be the bearer of bad tidings.


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Old 01-11-2020, 15:44   #5
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Re: Teredo worms and epoxy boats

The photograph I posted is 100% epoxy. In this case no wood was exposed.


The solid West System epoxy was clearly drilled by something capable of drilling round holes.

I do not use the word eating. Teredo worms do not require wood to live. I suspect wood is not their primary food source. Wood provides them a place to hide.

Wikipedia....microalgae, are extracted from the water passing through the gills where gas exchange also takes place


I found several posts claiming they also saw damage on fiberglass boats. Everyone reading this post should also stop saying it is impossible.

One person said they worked in a shipyard in Australia. My vessel was in Langkawi waters of Malaysia.

I think the photo is proof enough. However, I failed to say I personally saw what looked like white worms on the hull when the vessel was initially hauled out.

These *worms" appear to have been living in the spongy growth. I believe they were able to hide from fish in this matting.

I still do not claim 100% certain that teredo worms did this damage . Are there other molluscs that drill round holes?
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Old 01-11-2020, 16:22   #6
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Re: Teredo worms and epoxy boats

Quote:
The solid West System epoxy was clearly drilled by something capable of drilling round holes.
That does not look like "solid epoxy" to me. More like some manner of fairing compound, ie some resin (epoxy or other) with a lot of microballoons or other filler suspended in it. Many such compounds are quite friable... so they are easy to sand to the desired contour and finish... and thus are quite a lot easier for some organism to penetrate than solid epoxy would be, let alone a glass/epoxy composite.

How deep are the holes in your boat? Teradoes continue to bore for long distances (compared to the diameter of the hole), often turning and digging parallel to the surface of the wood. Do your holes do that?

And for what it is worth, I'm in Australia and have spent a lot of times in boatyards and have never encountered anyone who claimed that there were organisms eating into FRP hulls. I find that very hard to believe and until some substantive proof is offered, will discount the tale as apocryphal nonsense.

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Old 01-11-2020, 16:34   #7
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Re: Teredo worms and epoxy boats

Teredo worms can leave 24 in. long tunnels, with holes of up to 1/2". they are actually a bivalve, and when they exit the holes, they keep boring them out, and lining the hole with excreta. (from wikipedia)

suggest you take a springy bit of wire (7x7 s/s will do), and probe some of those holes, and compare what you find to the picture in wiki. Or, try injecting a mild acid solution, and see if they will come out so you can see for sure what you're dealing with. Or let the boat sit in the sun and bake them out.

First, you'll have to accept that there is a serious problem there, and that it is due to not antifouling. I can imagine that will be a bitter pill. But, you will have to accept what you cannot change and deal with the situation you have. I am not trying to be mean to you, but you have a serious problem there. Our worms were only there for ~ 6 weeks. The holes in your picture look like they belong to bigger worms than we had, Wiki says there are 30 species of teredo navalis.

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Old 01-11-2020, 16:44   #8
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Re: Teredo worms and epoxy boats

Quote:
Originally Posted by pbmaise View Post
...the boat was attacked by teredo worms .
Teredo worms do not eat or otherwise live in fiberglass or other non-wooden environments. They are a wood-boring species, and spend their entire lives from larvae on, living inside of wooden objects and only wooden objects, nothing else. Do a little research and you'll find that whatever caused the damage to your old boat, it wasn't teredo worms.
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Old 01-11-2020, 16:48   #9
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Re: Teredo worms and epoxy boats

Jim,

This photo was taken near the front of an ama. Holes were found mostly along the bottom of all three hulls where the epoxy and fiberglass was thickest.

I agree you are indeed seeing epoxy filler. My point was it is not wood.

The deepest holes were about 10mm. Either...

#1 The builder was applying some very thick layers of filler, or

#2 Whatever, animal drilled these holes was capable of getting past layers of fiberglass mat impregnated with epoxy.

Again I do not know if it was only a matter of time before they drilled past the epoxy glass coating.

The attached photo is from another boat hauled out while I was at the hard. You are looking at the two props of a militia speed boat.

I posted this photo to support my claim that teredo worms could hide from fish in the spongy mat of growth. I suspect most vessels do not see this type of growth. Hence fish can eat teredo worms in most locations before they do damage.
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Old 01-11-2020, 16:58   #10
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Re: Teredo worms and epoxy boats

Quote:
Originally Posted by pbmaise View Post

I posted this photo to support my claim that teredo worms could hide from fish in the spongy mat of growth. I suspect most vessels do not see this type of growth. Hence fish can eat teredo worms in most locations before they do damage.
1.- Teredo worms (or "shipworms") are not actually worms, they are mollusks.

2.- In their adult form, they do not live outside of the holes they have bored into wooden structures. Therefore they are not predated upon by fish.

Again, do a little research. You are basing your position on a fallacy.
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Old 01-11-2020, 17:04   #11
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Re: Teredo worms and epoxy boats

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Originally Posted by fstbttms View Post
Teredo worms do not eat or otherwise live in fiberglass or other non-wooden environments. They are a wood-boring species, and spend their entire lives from larvae on, living inside of wooden objects and only wooden objects, nothing else. Do a little research and you'll find that whatever caused the damage to your old boat, it wasn't teredo worms.
I do not say they do. However, they most certainly are filter feeders and do not need wood to live. I quoted Wikipedia to support this.

I do claim they need a place to hide to escape fish. I claim they can hide in the dense spongy mat on the surface. I attached a photo of this mat and attest i saw something that looked like white worms in this mat after hauling out.

If you zoom in closely on the first photo bottom right there appears to be even more evidence these holes were bored by teredo worms. Notice the calcareous tunnel that could have been the home of a worm on the surface.
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Old 01-11-2020, 17:07   #12
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Re: Teredo worms and epoxy boats

There are also rock-boring clams and mussels. Although a few species use acid to help attack hard limestone, most just use teeth-like growths to grind away the rock ... and hence prefer relatively soft rocks ... maybe a fairing compound would be soft enough for them to take hold?
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Old 01-11-2020, 17:09   #13
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Re: Teredo worms and epoxy boats

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I do not say they do. However, they most certainly are filter feeders and do not need wood to live.
"Naval shipworms primarily feed on wood. They are able to do so because of enzymes produced by the nitrogen-fixing bacteria within them. Teredo navalis use their shell to cut into the wood. The pieces are then transported into the mouth via cilia."

https://animaldiversity.org/accounts...s/#food_habits

Quote:
Originally Posted by pbmaise View Post
I agree they need a place to hide to escape fish.
"The calcerous covering they secrete not only act as a lubricant but also deters predators or poisons in the water. Predators include bacteria and parasitic protozoa like Architophrya. Native Australians and snails also eat naval shipworms."

https://animaldiversity.org/accounts...lis/#predation
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Old 01-11-2020, 17:34   #14
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Re: Teredo worms and epoxy boats

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Originally Posted by Jim Cate View Post
That does not look like "solid epoxy" to me. More like some manner of fairing compound, ie some resin (epoxy or other) with a lot of microballoons or other filler suspended in it. Many such compounds are quite friable... so they are easy to sand to the desired contour and finish... and thus are quite a lot easier for some organism to penetrate than solid epoxy would be, let alone a glass/epoxy composite.
............
You might be onto something here Jim. Other filler compounds used might have been organic in nature and could even be a food source. Not likely but possible - just spit out the epoxy bits - like eating a very bony fish.
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Old 01-11-2020, 18:02   #15
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Re: Teredo worms and epoxy boats

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You might be onto something here Jim. Other filler compounds used might have been organic in nature and could even be a food source. Not likely but possible - just spit out the epoxy bits - like eating a very bony fish.
Richard Barrie didn't skimp when building this vessel so I doubt he added something organic into the filler. I am not saying that is impossible.

Jay Kantola designed this vessel and worked very closely with the Gougeon brothers. Build years of the hulls were 1996-1998.

I found an interesting discussion on EpoxyWorks discussing using sanding dust as a filler.


https://www.epoxyworks.com/index.php/thats-a-fact/

West System mentions that sanding dust might be.compatible with their 5 minute cure epoxy.

"An exception to this is our G/5 Five-Minute Adhesive. It is more viscous to begin with, and remains liquid for only about five minutes, which is not enough time for the epoxy to drain out of the added wood dust fibers."

Conclusion... Yes..I agree now there is a chance we are looking at filler made from epoxy and saw dust. Further, the worms stopped eating once they reached the epoxy impregnated glass mat.
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