How to locate sunken mast in marina? sonar?

[Pete7]

Do you a sport diving club nearby. Organise a BBQ and offer a prize of $100 to anyone finding it.

If 38 boats sank in the marina along with all the other stuff that might of broken up in the storm there is going to be a lot of junk on the bottom.


Pete

[mbianka]

An underwater camera and monitor from Ebay might help you scan the bottom pretty easy if visibility is adequate from you dingy. I guessing two feet or more. Even if the mast is in the muck a spar might be sticking up if you are lucky. Worth a shot anyway.

[David M]

A side scan sonar would see it quite easily. The resolution on them is amazing. The higher frequency sonars can tell what model of car that is sitting on the bottom. Side scans are tens of thousands of dollars and it takes special training to be able to interpolate the image on the screen. We have used them from the research vessel to find all kinds of things. The more practical alternative is to rent one and the person who is trained in using it. This would cost you 2-3 thousand per day....possibly more than the value of the mast.

A magnetometer would never detect a stainless and aluminum mast, for obvious reasons. We use those as well. A company out of silicon valley charters our boat to field test their magnetometers and sub-bottom acoustic profilers. The latter are used for seeing the Earth's strata.

With an underwater camera you might get lucky. It sound like the water in your marina is too turbid to be able to see more than a meter or two, otherwise you would be able to see the mast sitting in 9 feet of water. This makes a camera a needle in a haystack situation....the greater the turbidity, the bigger the haystack. For a camera to work in that turbidity it would have to be flown a very precise 1 meter or so above the bottom in order to see the bottom otherwise all you would see on the monitor is solid green. Doing this would be nearly impossible without a camera mounted to an instrument with controllable diving planes and an altimeter. In doing this you also take the chance of running the camera into the mast or some other junk on the bottom....not good.

A recording depth sounder would probably not work either because you would never be able to tell the mast from a fish's air bladder sitting at the bottom from any other sort of debris at the bottom.

The best inexpensive way would be to do transects dragging a grapnel hook by setting up a grid on your electronic chart. We have done this as well for recovering lost instruments. We usually find them...knock on wood.

We had a couple custom grapnels made because what the boating supply stores were selling was inadequate. With the wide rather than circular (cross section) flukes the anchor would tend to grab rather than plow. Which is understandable since that is an anchors job. The grapnel for boats would hop along the bottom possibly missing what we are looking for rather than plowing along the bottom.

[Greg4cocokai]

Many, many years ago I had removed the pushpit (whole stern rail) on a Catalina 38 to install a new improved one. We were in a very calm marina with 11' of water. Somehow the thing got knocked in. Shoulda settled right where it fell in. A week or two later when the diver came to clean the bottom I asked him to tie a line to it so I could pull it up. After his first check he said it wasn't there! I had him check again doing a larger circle and he came back and said that it was nowhere to be found. A rather large item to sink in the silt! Good luck with your search.

[zeehag]

lemme see--a storm demolished a marina and insurance is paying to rebuild. your mast is lost in same storm. why not add the mast to insurance claim and go for it.

[model 10]

Originally Posted by zeehag

lemme see--a storm demolished a marina and insurance is paying to rebuild. your mast is lost in same storm. why not add the mast to insurance claim and go for it.

Because if he saves the friendly insurance co $5k it would be noble and trickle down to you, maybe. I personally would not benifit as I don't carry hull insurance but perhaps in the total scheme of things it would be better to re-use your old mast.
Is it going to be usable though? You are right get all new stuff.

[zeehag]

if there is a storm policy being paid off and if the boat is included in this pay off, on is not smart to ignore it as the insurance company is going to raise your rates anyway--is their job, anytime a pay out is required, insurance rates rise anyway--it isnt gonna save anyone anything not to get a new mast.

if you NEED the old one--DIVE for it

[LakeSuperior]

I have dove for eye glasses that have fallen in next boats tied at the dock. It boggles my mind that in 50% of the time I can't locate the glasses. No tide, no current, etc. They should be sitting on the bottom next to the boat. I have even checked to see if they were caught on the cribs and pilings. For context I have searched for shipwrecks for 40 years.

I guess the glasses must take on a stable attitude and sail laterally as they fall through the column.

On the other hand, maybe they are scooped up and reused in someway by forces below.

[SkiprJohn]

I know you've already decided on a different mast but here's my suggestion about the old one.
I'm a real cheapskate so I'll offer my this. Get a grappling hook or make one. Take some bent pieces of cheap rebar and tie them together to offer a treble hook. Tie a piece of nylon line to it and launch your dinghy and drag it around until you hook something. You're probably going to hook a lot of stuff so be prepared to haul a lot of stuff ashore or rehook the same stuff on your next pass.

[Cheechako]

I second the grappling hook. They are often sold in the marine stores or hardware stores near marinas up here. Usually made of rebar. Take a dingy and drag it along.... hard to miss a 45 ft mast will spreaders and rigging! I am assuming the water is muddy not clear... otherwise you should have not much problem seeing it... although seeing it or grappeling it after a hurricane... it may be buried i suppose. The other choice is pay a diver to circuit the marina... Worth it to repair if you find it....

[bgallinger]

All of these threads for a busted mast in a measly 9 feet of water!!??

[Cheechako]

Originally Posted by bgallinger

All of these threads for a busted mast in a measly 9 feet of water!!??

Yeah.... scratching my head too.... must be real muddy water. I forgot to mention a fish finder might work for something that big. Like a Hummingbird for $100 or les for a used one.

[Sailor_Hutch]

Originally Posted by Cheechako

Yeah.... scratching my head too.... must be real muddy water. I forgot to mention a fish finder might work for something that big. Like a Hummingbird for $100 or les for a used one.

Muddy?

The Cuyahoga river - the one that started itself burning spontaneously in the seventies - pours into this lake.

[Cheechako]

Originally Posted by Sailor_Hutch

Muddy?

The Cuyahoga river - the one that started itself burning spontaneously in the seventies - pours into this lake.

Cool.... that mast should be nice and clean from the "acid wash"!

[Captain Grandpa]

Originally Posted by Dennis.G

In just 9 foot of water could likely locate just using:
Bathyscopes – Underwater Viewing Fun | Ocean Fare

Of course you would still need to dive in and tie a rope to it. In 9' should be able to just hold breath and swim on down to it. Hardest part likely hauling it up from bottom and getting it to shore.

That looks fun!