B&G Foward Scan Questions

[joelm100]

Good day all, I'm gonna run with Scott T-Bird's hi-jack of Barryl's post . I'm looking for real advise on installing a B&G Forward Scan on my H380. The boat also has two existing transducer holes, just fore of the keel and on either side of centerline. One throughhull has a DST810 and the other has a blanking plug, ~8" away. It would be lovely not to drill another hole in my boat if I can get away with it, so I'm wondering:
1) how real is the interference between the Forward Scan and the traditional sounder. Is B&G concerned about return echos or turbulence.
2) If the interference is real, can I somehow disable the depth function on the 810 and still keep the paddle wheel for SOW.
3) Can I do this quickly and on the fly?
4) What is the power consumption of the Forward Scan vs the 810.
5) does anyone know what the 810 uses as a frequency vs the Forward Scan. Am I gonna be messing with the orca whale echolocation?
I'm using a newer Zeus3 and a couple of older Tritons for the user interface and processing. Thanks for your consideration! j

....
So it appears that you are shooting thru the hull with it and it may be located some distance from your DST 810. I'm thinking more about how to utilize the existing hole right next to my DST 810, which is now filled with the old depth transducer (I had separate depth and paddlewheel ducers basically side-by-side.
....
Sorry for thread hi-jacking, but sometimes interesting info comes out of a thread that goes in a new direction!

 

[jssailem]

Your questions seem to be answered in the equipment specifications for the two systems.

Here is the data from the Forward Scan transducer.

• The ForwardScan® transducer operates at 180 kHz to reduce interference from traditional 200 kHz echo sounders.

Here is the data from the DST810

• Depth Frequency: 235 kHz
  Minimum Depth Range: 0.5 m (1.6')
  Maximum Depth Range: Up to 100 m (330')—NMEA 2000®

That being said, you would need to contact B&G for actual performance specifics.

If I may ask, what motivates the desire for a forward scan sonar? Are you planning on entering shallow waters often? Most of the exploration I have done in the Pacific Northwest finds limited application for such hardware. More often than not, anytime you are within 50 yards of the shoreline, you can be in 8-plus fathoms.

 

[dLj]

I question why you would put a forward scan unit in. All the ones I've experienced have very limited usefulness. I had one on my boat i removed. Others that I've looked at and talked with owners all say they are nearly useless. Several had the B&G unit you are talking about. Great idea, but in actual use very limited in function. I would think you would need a pretty specific application to justify the expense and Installation. If you don't mind answering, why are you putting one in? What is your expected usage?

dj

 

[joelm100]

Your questions seem to be answered in the equipment specifications for the two systems.
...
If I may ask, what motivates the desire for a forward scan sonar? Are you planning on entering shallow waters often? Most of the exploration I have done in the Pacific Northwest finds limited application for such hardware. More often than not, anytime you are within 50 yards of the shoreline, you can be in 8-plus fathoms.

Brilliant, and thanks for that summary. To your question, and to DLJ's, I'm hoping it will help my anxiety when we do stern ties up in Canada. As you know, the anchorages in the Gulf Islands, Desolation Sound, and further north can put you close to shoreline. Often there is often plenty of water under--often to much water. However, this season I tapped the keel on a rock as I was poking around for a stern tie while gunkholing. No big damage, but it might drop my anxiety a notch or two, especially as the summer light starts to fade. Your opinion?

 

[dLj]

Brilliant, and thanks for that summary. To your question, and to DLJ's, I'm hoping it will help my anxiety when we do stern ties up in Canada. As you know, the anchorages in the Gulf Islands, Desolation Sound, and further north can put you close to shoreline. Often there is often plenty of water under--often to much water. However, this season I tapped the keel on a rock as I was poking around for a stern tie while gunkholing. No big damage, but it might drop my anxiety a notch or two, especially as the summer light starts to fade. Your opinion?

As it's forward facing, not sure how you are dealing with stern facing tie-ups. But I guess you could be scoping out the Anchorage prior to setting anchor. That might work.

I used to sail in an area that had a lot of boulders. I used a lead line to check for boulders. I know it's an old technique, but it's quite powerful and I find faster (much) than a hand help depth gauge. I would check all along my boat, a depth gauge only gives one point, then get in my dinghy and set the lead line to what I considered a safe depth and them row around over the area i was expecting to move while anchored. Takes a little practice but setting it in a way that I can see the line move indicating I've hit something makes it possible to cover a lot of area very quickly. I actually just did this when I was in South Caicos. I had to get to the fuel dock and was told I could only do it at high tide. I set up my lead line and rowed several possible routes to the dock. It turned out in fact I could go in almost anytime except dead low tide. And I found the best route to do that. It only took me about half an hour and I covered a huge area.

Now in your case, if you are scoping out an area to look for rocks or other obstructions, it could work. Do bear in mind most folks feel you can't be moving much over about 2 knots (as I recall) in order to "see" and be able to avoid an obstruction .. But sure seems like a pretty major expense for not a lot of payback...

dj

 

[Ralph Johnstone]

I don't know what you have for navigation gear, but just a friendly warning, if you're don't have CHS large scale charts for the area in which you are sailing, you can't sail for very long before having a touch or much worse. DO NOT, and I repeat DO NOT rely on charts in a chartplotter. You need the detail found only in CHS paper charts.

As you are headed for north of Desolation, you are likely headed for my ultimate all time favorite, the Broughton Archipelago. I carry all large scale charts for that region and I don't want to think of what it would be like going through there without a chartplotter, large scale paper charts charts and a depth sounder. The reason I pick on that area is the water is only about 33F to 34F at best in the summer and very often your're without VHF communications because of the mountains. If you run into problems, you are truly all alone (AKA royally screwed).

 

[joelm100]

I question why you would put a forward scan unit in. All the ones I've experienced have very limited usefulness. I had one on my boat i removed. Others that I've looked at and talked with owners all say they are nearly useless. Several had the B&G unit you are talking about. Great idea, but in actual use very limited in function. I would think you would need a pretty specific application to justify the expense and Installation. If you don't mind answering, why are you putting one in? What is your expected usage?

dj

Thanks for getting back. I also am skeptical but I'm curious why you decommissioned the Forward Scan if it was already installed? Need the space? (still have it and want to sell it?) Hopefully it wasn't THAT useless.
I am truly doubtful that the Forward Scan will add anything over the 810 in deep water. However, I do have hopes it will have utility when gunkholing in shallow water at low speed. My use would be poking around the fjords of northern Vancouver Island, BC Canada. The mountains come down very steeply and continue down. I've been in displayed depths of 150ft but only 30' from shore where we might do a "stern tie", similar to a med-mooring. "Teakerne Arm" in Desolation Sound, BC is a beautiful and classic example of where we might use this technique. This isn't my boat, but is a nice shot of the situation. Good chance that anchor is in 100+ feet of water 30 feet off the bow.
Again, I'd love to hear why it didn't work for you in real life.

 

[joelm100]

Now in your case, if you are scoping out an area to look for rocks or other obstructions, it could work. Do bear in mind most folks feel you can't be moving much over about 2 knots (as I recall) in order to "see" and be able to avoid an obstruction .. But sure seems like a pretty major expense for not a lot of payback...

dj

Yep, exactly! "it could work", but "sure seems like a pretty major expense." So much teeth gnashing for my wife and I. I'm curious to hear real experiences, not the marketing that B&G has provided.

 

[joelm100]

I don't know what you have for navigation gear, but just a friendly warning, if you're don't have CHS large scale charts for the area in which you are sailing, you can't sail for very long before having a touch or much worse. DO NOT, and I repeat DO NOT rely on charts in a chartplotter. You need the detail found only in CHS paper charts.

As you are headed for north of Desolation, you are likely headed for my ultimate all time favorite, the Broughton Archipelago. I carry all large scale charts for that region and I don't want to think of what it would be like going through there without a chartplotter, large scale paper charts charts and a depth sounder. The reason I pick on that area is the water is only about 33F to 34F at best in the summer and very often your're without VHF communications because of the mountains. If you run into problems, you are truly all alone (AKA royally screwed).

View attachment 226999


View attachment 227000

Love, love, love that!

 

[dLj]

My system was old. It was only moderately functioning. The sensor on the hull was large and i felt better to not have that major bump for better hull speed. You (at least your photo showed) are running a trawler - different dynamics. Running on a friend's boat with a modern B&G forward scanning sonar - it was really not as useful as had been hoped. So with that, and an old clunky system on a sailboat - removal was the way to go. Not necessarily your case. But the forward looking sonars seem to just be fish finders on a slant....

dj

 

[jssailem]

The reason we install the sonar transducer near the bow is to enable the return signal to give us information about what is immediately ahead. Here is a link to the 810's acoustic data. The acoustic pattern of the transducer gives us info on how the system can display what is ahead of us. If we go slowly and can understand the information projected by the system, we can know the dangers.

https://assets-7484b3de52.cdn.insitecloud.net/3e88cb786b84edb/235f.pdf

A simple and inexpensive method of entering shallow waters is to take a dinghy into an anchorage or shallow water passage and use a hand-held depth sonar to give us the necessary information.

 

[Ralph Johnstone]

A simple and inexpensive method of entering shallow waters is to take a dinghy into an anchorage or shallow water passage and use a hand-held depth sonar to give us the necessary information.

Done that before but haven't bothered with the handheld sonar as the water is so cold in northern waters not a lot of small stuff grows quickly. We could quickly scope out an anchorage looking at the bottom before bringing in the mother ship.

That's the way Cook sent in the longboats to explore the coastline of BC back in the late 1700's before bringing in the mother ship. Put a hole in the big one and it's game over.

 

[marcham]

I had the B&G forward scan on my Oceanis 31. We used it frequently when anchoring or crossing bars to get into bays in BC. I wished I had it on my current boat, but it's low in the priority list (spinnaker, repair freezer, etc...) but it did do a great job of showing features that are not well charted. It also provides a backup depth measurement means in case your dst810 fails.

We always kept it in standby unless needed, but the menu option to switch between standby and active is a little buried.

Ours was installed about 10-12 inches offset laterally from the depth sounder with no interference.

We only used it a few minutes each day under power, so power consumption was not a concern.

 

[jssailem]

That's the way Cook sent in the longboats to explore the coastline of BC

Same too for the Spanish (Juan Francisco de la Bodega y Quadra) and British Commodore Vancouver explorers.