Help recovering a valuable hydrofoil that sank at Crissy Field, San Francisco


Hello OpenROV community!

My good friend dropped an expensive and hard to replace windsurfing hydrofoil at Crissy Field (a few meters from the shore). He spent hours searching for it with no luck. Do you think that a Trident would find it? If so, anyone interested in helping with this? I am sure he would be willing to pay a bounty :-).

Below is an image of a similar hydrofoil as a reference.


Ariel Poler



Hey Ariel,

Bummer, man!! How dense is the foil? Do you think it would have sunk to the bottom and stayed there, or is it likely that it got carried by the current?

We could certainly throw a Trident in the water and poke around, or it may be better look around with a side scan sonar if the area it was lost is fairly large.

Always looking for an excuse for an adventure!



Hi Eric,

The foil is pretty dense carbon fiber, so it weights a few pounds. I think that while it might have moved a bit as it fell down, it would have soon settled in place (almost like an anchor). But your idea of a sonar (Fishfinder?) is a good one. Probably much simpler, so it might be a good idea to try that first… I’ll suggest that to my friend and report back.

Thank you!



My pleasure. If you have some specific spots you’d like to look around with using a Trident, let me know. Best of luck!



We know approximately where it fell (at Crissy Field). The challenge is that it gets relatively deep all of a sudden (10-30 feet). If that wouldn’t be too deep for a Trident, and you guy are up for giving it a shot, that would be awesome. We don’t think it moved too much, but it might be covered by sand. It fell last Wednesday afternoon…

BTW: I checked with a couple of people who have sonars and they don’t believe that would work.



Hi Eric
First off, thanks for taking an interest in the project.
It’s my foil that sitting on the bottom of the bay just off Crissy field. I’d love to get your help in locating it.
So far it’s been like searching for a needle in a haystack but the openrov sound like it could shed some light on locating it. Let me know when you might be available.
You can contact me at the email associated with my login.



Here’s some more info on the contours of the slope & where I think the foil is. It came off 10’ from shore at low tide in about 4-5’ of water. What I don’t know know is if it is still in that area or has drifted with tide and/or is partially buried in shifting sands.
So far I have done a grid pattern with a 16-20’ windsurfing mast poking at the bottom with no luck.
The visabality is quite low and there is a sandbar to the west where the former estuary mouth breeched last month but is closed now.
Next potential task is to try to sweep the area with a tethered weighted rope secured from shore and dragged across bottom with the help of a boat.
I’m up to any ideas on how we can use the OPENROV to help find the foil. Let me know if you have any thoughts.
Many thanks & much appreciate your time and expertise.


This is the area where the foil was lost. I had 2 sight lines to shore between the wind sock and large palm tree to the east


Hey Steve,

This is great data to have! I may be able to get hold of a bonafide sidescan sonar which could be appropriate for this search, but that would have to happen after Thanksgiving. In the meantime (although the likelihood of success is very small) I’d love to try deploying Trident in the area you’ve described. I’m trying to see if there is a time this weekend or early next week that could work.