Choice of Equipment for Underwater Surveys to find Wrecks and Map Bottom Underwater

[BoltSnap]

I am working on finding and exploring shipwrecks and antiquities buried under the Mediterranean sea off the coast of Libya. I am fairly new to this type of adventure myself. I have been visiting some websites for companies that manufacture Side Scan Sonar and magnetometers (JW Fishers for example) to determine the type of equipment and models that would be necessary in this project. I have looked at Side Scan Sonar and magnetometers but can’t determine which product(s) would be required in our case.

In principle, do we need just the Side Scan Sonar by itself or do we need the Side Scan Sonar in addition to one type of the detectors/magnetometers?


Note: In addition to scanning the sea bottom to find sunken wrecks and antiquities underwater, we want to map the sea bottom to determine potential dive sites (rocks and reef structures). We are not looking for a specific wreck but actually surveying the bottom for signs of any wrecks without knowing about specific wrecks in the area surveyed in advance.

 

[Wookie]

I have done a fair amount of survey work for professional oilfield survey companies. Basically, they use the mag to tell them where to look harder for bottom features. The real stuff to use is multibeam sonar for the best profiles. A poor man's multibeam (real survey quality multibeams are in the millions of dollars) is called WASSP. Look it up, it's from New Zealand, but Furuno is the US distributor.

A mag is difficult to fly, as they must be kept within a few feet of the bottom, meaning that every time you turn, change speed, get current, etc., it either flies up off the bottom or noses into the dirt. Depending on depth, a hull mounted side scan is very cost effective, it will show you bottom anomalies, giving you a place to come back and look with more expensive equipment.

 

[BoltSnap]

Capt. Frank,

Does the WASSP product make it unnecessary to use the Side Scan and magnetometers products from JW Fishers? Is it an all in one type of solution whereby we don't need the other products?

---------- Post added July 11th, 2013 at 01:32 AM ----------

Also, what price ranges are we talking about here for the WASSP solution?

 

[Wookie]

When I made inquiry last year, the WASSP 160F was about $50k for the transducer and operating software. For survey quality data, you would need a heave compensator ($150k-$1M), a GPS good to within 6" (most folks rent these, you don't even want to know, including the monthly subscription at about $10k per month), and a mosiacing software like Hypack or ArcGIS to put a large area picture together for you.

You don't want that. You're looking for bottom features, so the WASSP 160F as it stands alone for $50k will do the job for you, at least down to 100 meters or so. Now, the WASSP has a 112 degree beam width, so you will cover a swath 300 meters wide in 100 meters of water depth. If you are only in 10 meters of depth, you'll run a lot more lines. You don't care about mosiacing your data, if you get a hit, you mark it and then make runs in all directions using the raw data. That works well enough for what you (or me when hunting bottom features, for that matter) need or want.

The WASSP data will be far prettier than anything you would collect with a sidescan sonar, and it's easier to see features on it. I hate interpreting sidescan, because of the data gap in the center.

The NOAA fisheries lab in Beaufort, NC has a pole mount they use on a 25' Parker, so it doesn't have to be a through hull transducer.

Short answer is that I feel that the WASSP will do exactly what you want (as long as you don't need to look deeper than 100 meters, the limit for most recreational divers) without anything else. The Kiwis that run the company are very responsive to your questions. They love to talk about their equipment (what man doesn't), so give them a ring or drop an e-mail.

 

[adziev]

Maybe u can use the informations from this article: In water survey of ships afloat