Thursday, October 29, 2009


When Sean Jamieson of The Gondola Company near San Diego noticed one of his gondolas was experiencing the symptoms of a leak, he investigated further, and found a wooden boat owner's nightmare. Worms.

I've got to give Sean credit here for allowing me to post these photos. There are some problems we, as gondola owners, would rather not share.

I know Sean and have seen his tenacious approach to maintenance. If Sean can end up with something like this, any of us can.

Here's what the inside of the boat looked like when they first discovered that something wasn't right: Here's a close-up of the same spot: After some further poking and prodding, here's what they saw on the exterior of the hull: And a close-up: The culprits here are most likely members of the family Teredinidae. Sometimes refered to as "Teredo Worms", most folks in the english speaking world call them "Ship Worms" - a term used for several species of the waterborne pests.
Funny thing about these little buggers - they're not worms at all.

Venetians call them by another name, which when translated means "water termites". They do eat wood, but they're not termites, nor are they members of any insect family.

Believe it or not, Shipworms are bivalves; members of the same family as oysters and clams. They are similar in shape to worms, and their digestive tracts can metabolize wood somewhat like termites, but they are molluscs.

Once I bought a gondola which had a sort of "aftermarket keel" bolted on below the already fiberglassed hull. The previous owner didn't know about Shipworms, and within the first year I found myself removing what was left of that wooden keel.

It was one big slimy, stinky mess. As these things eat their way through the cellulose wood, they leave behind calcificate tubes which remind me of the interior of some oyster shells.

Here are a few photos taken after the gondola had been hauled out and further inspected.

What started out as a small area of soft wood became a bigger problem.
Sean told me:
"The hole in the boat you see was created by breaking off pieces by hand, like cracking a graham cracker. One picture is just a small piece that shows all the worm tubes."

Here's another view from the outside, showing an interesting angle on the frames inside. And in this photo, we can appreciate the length of the plank in question.
I don't envy Sean and the task he has ahead of him.
But I can honestly say that there are few people west of the Atlantic as qualified to undertake such a repair.

According to Sean, the moral of our story here is:
"make sure your diver lets you know when your bottom paint needs replacement".
I say:
Keep an eye on your boats.
Shipworms can exploit the smallest opening and once they're in, they can be quite destructive.


Tamas Feher from Hungary said...

Guess you can't put copper plating on the gondola's hull and paint it over because of the prohibitive weight increase? But maybe adding a few exposed copper nails would help repel the wood termite?

I heard creosote (a kind of tar coating that can be scraped off old wooden telegraph poles) kills shipworms very well if ijected into the wood, but it is carcinogenic and has been officially banned for years.

By the way these teredo things are eating whole american cities alive!

One must wonder if water quality enhancement programmes in the venetian lagoon will also cause the collapse of Serenissima city due to skyrocketing shipworm population?

Bob Easton said...

Arrrgh! What an unpleasant development. Best wishes to Sean for a speedy and cost effective repair.