forward scanning sonar for container alarm

khbritten · #1 11-29-2006

Anyone have any real-world experience with forward-scanning sonar actually working or failing in detecting containers at sea? I have heard the range of some units (e.g., Interphase Twinscope) is less than advertised. And it seems like any pitching in a sea would further hinder signal/noise.

thanks!

Ken

Cruisingdad · #2 11-29-2006

Hey Ken,

I am curious of the "real-life" experience too. I did speak to Interphase, and that seems to be their claim to fame. I was acutally going to try and use it to find my way down the ditch and it apparently really does not work well in less than 15 or 20 feet.

I do have to ask one question: I have NEVER seen a floating container at sea... but have heard about them. I am curious who has actually seen one??

khbritten · #3 11-29-2006

Good question, Dad. I think it was Blue Water Sailor that cited insurance figures a few months back, and the number of containers reported missing is staggering. Sure, some of those are fraud, but I am sure a lot are real. I got to thinking, and did a little back-of-the-envelope calculation of how likely it would be to actually come within 100' of one. Even making pretty ridiculous assumptions about how long they float, the odds were really low - less than one in a million for a circumnav. The ocean is big! So, I am guessing I won't get any answers to the post. But it never hurts to ask. ;-)

Cruisingdad · #4 11-29-2006

There is a passagemaker post for trawlers and they discussed this (as this is often seen on high end trawlers where $ is not a limiting factor). The person I talked to about it was quite negative on the product to the point she did not even use it anymore. I think she had a Nordhavn... as I recall, so power was not an issue.

Valiant puts them into some of their boats periodically, but less and less as of late it has seemed to me.

Also, I bet most of those containers that go overboard sink. But like you, I have always worried about them. I guess a FF Sonar is like a liferaft: One of things you hope you wasted your money on.

jassing · #5 11-29-2006

Quote:

Originally Posted by Cruisingdad

I have NEVER seen a floating container at sea... but have heard about them. I am curious who has actually seen one??

It's not the ones you see that matter, it's the ones that you don't see -- sometimes they "float" a foot or two under the water.

Cruisingdad · #6 11-29-2006

jassing,

Yep, that is what I have heard... but I have never seen one still except in pictures. What is that solo sailors name... the female from England (Crap, I forgot her name, Emily... )... I think she hit one while crossing the Atlantic one time. It was either that or a whale. I will say, if you hit one you are going to do a bunch of damage.

Giulietta · #7 11-29-2006

Brasil One on their qualifying Atlantic crossing from Brasil to Portugal, hit a sleeping whale!!!

They took the boat out for inspection, and nothing was damaged. In fact some guys got hurt and the damages minor were inside.

I was lucky to climb aboard and see the inside on that occasion.

They were going pretty fast, I was told.

http://www.sailing.org/default.asp?I...r&format=popup

During the race another boat hit a whale,and.. well, read it here

http://www.sailing.org/default.asp?I...r&format=popup

Cruisingdad · #8 11-29-2006

You see, Giuletta, another reason to buy a Catalina: You go so slow the impact will not result in any damage!

Giulietta · #9 11-29-2006

AHAHAHAHA

Hey the way I see it, containers are really the best Sonar customers. They need them to avoid the catalinas!!!!

Just kidding, ok?

Johnrb · #10 11-29-2006

Here is one recent example of a collision with a container:

"Orange Project hits container"

"The Marc Lombard-desgined trimaran Orange Project skippered by Stève Ravussin hit a container earlier today causing damage to the central hull."

"The incident happened while competing in the Route du Rhum at 1000 this morning 140 miles north-west of Azores while sailing at 20kts under full sail."

"Early inspection indicates that the damage from the impact is fairly high up and as far as Ravussin can see there is currently no water ingress. However, there are indications that the rudder stock has been damaged and Ravussin's technical team is currently en-route to carry out repairs."

http://www.ybw.com/auto/newsdesk/200...115ywnews.html

How does 20 knots sound Cruisingdad? FWIW - Orange Project later capsized although there was no suggestion it was related to the collision.