I’ve been at this business for over 10 years. I’ve made some good decisions and wasted many, many dollars on bad ones.
For better or worse I’ve shared them all with millions of people as one of the stars of Discovery Channel’s Bering Sea Gold.
Teaching you to build a dredge in almost 5,000 words may be more difficult than dredging itself. So in this guide I hope to teach you how to size your dredge to your skill level and how to think about the systems your dredge needs.
With a little experienced guidance at the start of your journey you can avoid 80% of the most common mistakes new dredgers make.
And if you have patience, persistence, and you’re willing to start with what works instead of pursuing a crazy idea, then you can be the Bering Sea’s next successful gold miner.
Who knows? Maybe you’ll even star on Bering Sea Gold with me and the the rest of the cast…
How does a gold dredge work?
A suction dredge is basically an underwater vacuum cleaner that sucks (hopefully) gold-bearing gravel up and runs it through a sluicebox.
In more technical terms, suction is created by a motor-driven centrifugal pump moving high pressure water into a jet system, creating a low pressure area that creates suction at the nozzle via the venturi effect.
I can’t explain the science anymore elegantly than that. But the important effect is that suction is created without some kind of impeller that can obstruct the flow of large rocks and boulders.
That allows the diver to suck up boulders of all sizes, gravel, and sand off the Bering Sea floor. That material passes through a sluice box to recover the gold and dump the rest, AKA the “tailings,” back into the ocean.
Most diver dredges our size run a two-man team. One diver underwater sucks gold and one tender up top monitors the systems, the weather, anchors, and helps the diver get on the gold.
Size matters: how big does my dredge need to be?
Size really matters in this business. More power means more gold. Full stop.
Every year it gets more challenging for new entrants because the easiest gold has already been found, and smaller operations are less economical.
Unfortunately, more power also means more expense and more danger. So the key is to build up to your skill level and financial ability but not beyond – with a view to the future of the industry and what’s going to be working 10 years from now.
We size dredges based on the inside diameter of the suction hose. Commercial gold dredges working the Bering Sea range from 6″ to 14″.
6″ is for hobbyists
A 6″ dredge is going to be powered by a 20-30 hp motor. At this point a 6″ is pretty much for hobbyists. You can make a few shekels with a 6″ in the recreational mining areas but unless you are dedicated to the dirtbag gold miner lifestyle and you have good ground, it’s probably not going to pencil out.
If you’re a good diver and a competent operator, you’re probably going to be thinking about upgrading after a season.
8″ is a good size for a start, but is getting obsolete
For people who are single operators or are just starting out, I think 8″ is a decent choice. That’s typically powered by a 40-50 horse motor and it’s fairly easy to work underwater.
I can think of several guys who are making a living with an 8″ dredge and don’t have to run a big team, or even work with a tender. With that said I think it’s exceptionally dangerous to dive without a tender and we’ve never done it on The Eroica. But some people are comfortable with that risk.
My big problem with an 8″ is that I think it’s heading towards extinction, and quickly. To get good gold close to town you need to do something different than most.
The best 8″ dredgers I see usually have some special characteristic. There’s a guy Kevin with an unusually fast dredge that travels far to his own claim that most people dredges can’t reach quickly. Glen Lebaron works deep with his underwater sluice. There’s a guy Larry who has a beach launcher who recovers fine gold really well.
All of these guys work alone.
The last 8″ dredge on our lease (lease 14), who runs a standard 2-diver team and dives at similar depths to us, recently upgraded to a 10″ to get more gold.
10″ is our preferred size
The Eroica is a 10″ dredge that’s powered by a 100 hp Cummins 4bt.
A 10″ can support an owner-operator and a diver or two. They can still make enough gold working close to town to support a team, but it’s getting tougher to do so.
It’s also not so big that a new diver can’t learn how to operate it. My husband Alex and our diver Dan basically began their diving careers this summer on The Eroica. We’ve been trying out other new divers with no gold diving experience who have been able to learn on the job.
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12″+ you’d better be a stud diver
Notice how the horsepower has roughly doubled every 2″ bigger the dredge hose gets? From 25 to 50 to 100.
The highest-performing diver dredges are also the biggest. They’re the most expensive to build and also the most dangerous to operate.
There’s only one 12″ dredge (High Noon) and one 14″ (Synergy) in town. I don’t know how big the motor is on the 12″, but the 14″ is powered by something ridiculous like a 350 hp John Deere. That may be overpowered – I don’t really know.
I do know this: a lot of the divers that have worked on The Eroica and have also dove on The Synergy come back to work on The Eroica because a 14″ is just too big. Even guys with tons of experience and seem fearless underwater feel like the juice just isn’t worth the squeeze at that size. It’s very difficult and very dangerous. So you quickly top out the larger you get.
Systems that need to work
One thing gold miners seem to forget is that offshore gold dredges are boats.
Don’t make the mistake of focusing completely on the diving and gold recovery systems and treating the rest like an afterthought, because you’re going to lose a lot of gold if you don’t get the boaty stuff right.
It’s hard to overstate how important a good anchoring system is. You can spend all that time building the dredge, hunting for gold, and getting on it, but if you can’t set on the spot you want consistently – or you get blown off by every current or 15 knot wind – you won’t make any gold.
Over the years we’ve gone from two anchors that we pulled up by hand, to two electric drum winches powering two anchors, to three drum winches and three anchors, and now run two capstans that power four anchors.
Your anchor needs to be big enough for the dredge size, but more importantly your chain needs to be big and long enough to help hold the dredge in place during strong currents and wind.
That means you can’t have tiny winch drums that won’t hold much chain, especially on a 40-foot vessel.
You also need to be able to set quickly, which means free-spool capabilities, and you need to be able to pull them quickly and reliably.
Hydraulic and electric are your two power choices – both have their own issues.
We run electric off the battery system but need to be continuously charging the battery banks with a generator while we’re pulling and setting anchor or we’ll run out of power. It can be slow, and is only as reliable as that generator.
Hydraulic requires some kind of power, too. You either need a power pack, which is an extra motor, or to run hydros off of your pump motor. But if you don’t clutch your pump motor you can’t run your hydraulics without running your suction. That makes your order of operations challenging.
Each choice is a trade-off.
Two anchors are quick to set, but you can only work in a straight line, and you’re a slave to the direction of the current. If you’re set broad side to the current it will blow you off your spot when it changes direction, and that could cost you thousands of dollars an hour.
If you’re not broadside, you may get murked out when the tide changes; meaning your tailings off the sluice box are coming over the diver’s head. No bueno.
Three anchors is probably the most common setup. Two in front, one in back gives you a side-to-side axis to work on and the ability to set into a strong current and hold on two picks.
Four anchors are slower to pick, but I love how big of an area we can set in and the control it gives is in any direction. We’re never going back to three or less.
Flotation is insidious because you likely won’t realize you made a mistake until after a few seasons.
Most guys try to get achieve flotation as cheaply as possible. I’ve seen 55-gallon drums, plastic tubs, pieces of foam ratchet-strapped to the dredge frame, and even fuel jugs used as flotation. There’s one big barge that used connexes welded together as flotation. It’s madness. (I’d love to know how much rum was consumed before that idea was “floated.”)
All of the serious working dredges either have custom made pontoons, or a platform that was once an actual boat, or barge.
If you have deep, skinny pontoons like we do, they act like sails underwater and make you susceptible to blowing off your spot in a strong current. Although the deeper pontoons give us a nice keel for better control and more efficiently cutting through the waves while we’re underway.
If you have a flat-bottom barge, you’d better have bulkheads and a way to bilge water or it’s a major risk for sinking.
Will you build them custom or pull them off another boat? If you can’t access the pontoons or bilge them out you’ll be filling them with foam, which has its setbacks, as even if you get closed cell marine grade foam, it is still susceptible to becoming water-logged, and it ruins the pontoon.
How much freeboard will you have? For some reason everyone in the business decided to have like 6″ of freeboard.
The pros are our pump doesn’t work as hard and the diver doesn’t have far to climb in or out of the water, but it has downsides. You’ll get wet deck in any kind of swell, which is a danger to your systems, and you have little flexibility to add weight to the dredge.
If you put your sluice under the deck (like it is on The Eroica – which I think is a mistake) then added weight could put it underwater. The nice thing about having your box under the deck, is that it’s out of your way, and close to the water, so your pump is more efficient. The downside is, if you don’t have enough freeboard, your box will fill with water with each ocean swell.
If your pump is higher out of the water it isn’t going to be as strong, but you only lose like 1 psi per foot. I’d take that trade-off for 12-24″ more height off the water.
I think guys just achieve flotation as cheaply as possible, but if you can’t bilge them or service them you’ll be filling those things with foam or replacing them in a few years. And if they’re poorly designed, they can quickly cost you thousands in lost dredging time.
Not too much, not too little, redundancy. This one’s pretty simple.
I think one outboard is a mistake. Redundancy is your friend on the Bering Sea and the last thing you want is to lose all power with a storm blowing up.
Too little power and you’ll spend half your life motoring out to the mining grounds and make a lot of leases uneconomical to work. Too much power and you’re just adding excess weight and wasting money.
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Gold Recovery Systems
The fastest way to lose money is to mess this part up. The most common mistake is messing up the math on your pump, jet, and flare. It’s a finicky fluid dynamics equation to get strong, efficient suction and then deliver that material into the sluice box at a pace that’s optimal for gold recovery.
There are several key features of nozzle design that keep the diver safe. It needs handles for the divers to hold onto. It needs to be short enough for the diver to reach the front of the nozzle from the handles. It needs a breaker flap to open up more suction surface area in the event you get a boulder stuck on the main opening.
It needs a good working angle on it. It needs to be light enough to move around, but have thick enough metal that you aren’t blowing it out more than, say, once a season. We started making our nozzles out of stainless steel. More expensive, but its lighter, and mostly rust-free.
Just go copy one.
And don’t skimp on hose. For one you need some extra length to maneuver underwater. And for two if the hose is too old it’ll get more rock jams. New hose will pay for itself in a hurry once the old hose has degraded a certain amount. We have about 45′ of hose on the Eroica, but some guys have as much as 50′ and as little as 30-35.’ If you’re mining in over twenty feet of water, you’ll need length.
I can’t get into the math here because I’m no expert and it would take too long, but you need to get this right. Getting it wrong means you’re going to end up highbanking on the beach.
You need a reliable pump motor, a reliable (and easily serviceable) way to drive the pump off the motor, strong lay-flat, the right number of jets at the right length and diameter, and a flare that’s long enough and set at the right angle to slow the water down.
Changing one input will affect the performance of the others, so you’d better triple check your math and build a test system before you come to Nome.
If I were to build The Eroica from scratch I’d put the sluice box above the deck. When everything’s under the deck it’s difficult to monitor and service underwater and if you lose flotation or add weight your sluice is halfway underwater.
This is probably where guys waste the most time. Everyone is obsessed with sluice box performance and they think if they’re not making gold the “sluicebox is broken.” It’s not – it’s usually because they’re on bad ground.
If you get a few things right it’s going to work just fine.
You need to slow the water way down before it hits the sluice. That means getting your jet and flare right and putting a rubber flap in the transition between the flare and the box to knock it all down.
You need to set the sluice at the right angle – we do 1″ of drop over 10″ of run.
The box needs to be long enough. Ours 10 x 4.’ making it a good box size for an 8″ dredge, but I’d like 12+ feet for a 10″ dredge.
You need to have miners moss under riffles (we use expanded metal) under some kind of grating that classifies material. We like 1/4″ for the top grating.
There are 100 different sluice box designs that could work. All the debate around sluice boxes is because they’re part art, part science, and part know-it-all miners who are convinced their way is the only right way. I like a box current that is smooth, relatively free of white water, powerful, but calm.
This is the one part I’d encourage you not to overthink. There are some advanced fine-gold recovery systems that are out there, but I don’t know much about them, to be honest. Recovering gold, when it’s there, is surprisingly easy. Don’t chase specks, because that’s all you’ll end up mining.
Just do yourself a big favor and make it easy to pull apart and clean.
Will someone out there please make a decent deep water dive compressor for surface air supply?
We use a Keene 263 driven by a Honda GX-160. It’s sort of reliable?
You’re going to replace or rebuild the 263 every season. One of the other dredge owners in Nome told me he has a graveyard of like 9 of them.
Some guys prefer the Hookamax. Those are the two most common air compressors.
The problem is no one who builds air compressors is willing to slap a label on them that says they’re ok for humans to breathe on. The compressor needs to be “oil-free” which uses a teflon coating or have special breathing air oil lubricating the mechanism.
You’re running these things hard, 10-12 hours a day. There are a lot of “hookah” dive systems but they’re usually for bubbling around for 30 minutes in the Bahamas and are too small and cheap to withstand the rigors of Bering Sea gold diving.
Some guys swear by electric nail gun compressors made by Dewalt or Rigid. I’ve never been able to get comfortable with those things as anything other than an absolute last ditch emergency compressor. Who knows what sort of lubricators or weird additives are to be found in these machines, but I do not want them in my, or my diver’s lungs.
What else goes into the air system? Let’s work down towards the diver.
The first thing off the compressor is a “hot line” or “steam line.” Take a temperature gun to the first 3 feet of line coming off the 263 after running it for 2 hours. We gun it at 150+ degrees.
Most dive line is rated to only 120 degrees.
The scary thing is even the guys who sell “dive compressors” don’t always know what they’re talking about. We noticed last year that Keene Engineering sold “steam line” that was only rated to 120 degrees – no better than normal dive hose.
We use a few feet of pure copper line now. I know a guy who put hydraulic line coming off the compressor and severely damaged his lungs when it got too hot and melted when he was underwater. It’s really important to get this right. Don’t be a dumb-dumb and mess up your lungs.
You’ll also want a pressure tank for the air. It maintains steady air pressure for the diver and holds a reserve of air for when the compressor inevitably gives out at some point during the season. It’s Murphy’s law, which is really about redundancy more than anything else. Have back-ups. Have an escape plan.
We upgraded to a 30-gallon commercial diving air reservoir this season from two 9-gallon Keene tanks plumbed together and the extra air really helped our safety and peace of mind.
You’ll also need to filter the air with a commercial diver air filter system and be REALLY mindful of where the air intake is. Multiple motors means a lot of exhaust and high risk of carbon monoxide poisoning for the diver if the wind switches to the wrong position.
We pipe exhaust up to a high exhaust stack above the Cummins and keep a sensitive carbon monoxide monitor near the intake to make sure the air coming in is clean. It shows us the exact PPM that the air contains as it goes to the diver. This is a no-compromise issue.
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Bering Sea temperatures are in the 40s and for a diver to spend 5+ hours underwater they need hot water continuously pumped into their suit.
Like hydraulics, you can choose to make this a separate system or to run it off the pump motor.
We run our hot water off the pump motor. The motor cooling system pumps seawater through a heat exchanger that gets heat from the exhaust, and the motor itself, and runs to the diver.
The benefits of this are using one system for multiple purposes. No need for an extra fuel source and some kind of power generation. It’s super reliable.
The downsides are the hot water is tied to the motor. Need to idle down or shut the motor down for a rock jam? Diver loses hot water. And if you try to choke the water flow too much to the diver to bring the temp up later in the season you could be overheating the motor. Also, hotter water reduces flow, so it can be difficult to get the balance you need.
We use OTS brand Guardian mask and communication systems. I don’t know how people dive without it. The diver and the tender talking to each other massively improves safety and gold production for a relatively small investment of a couple thousand dollars.
Comms are so important to safety that we won’t dive if they go out. Better have a backup.
Where guys waste the most money on dredges
We subscribe to the KISS method: Keep It Simple Stupid.
Just accept that you’re not going to have a very profitable dredge for the first season or two. Even guys that know what they’re doing need at least a season to work out the kinks in a new operation.
But as someone new to the business, if you don’t let your costs run away with your imagination and you get a few key things right you can set yourself on the path to profitability.
If you make a major mistake it could be difficult or even impossible to fix, and you’ll make a contribution to Nome’s large and growing dredge graveyard.
Bad suction math
Like I said above, building your core suction system right is one of the non-negotiables to a working dredge. A shocking number of people mess this up right from the jump.
When you buy a dredge off the shelf from Dahlke or Keene they already have the math and measurements done for you. But those guys don’t sell 10″ dredges, so if you’re going to build bigger you need sit down at the drawing board and do it right.
A couple seasons ago I rebuilt my jet and flare system and only changed one thing: the size and number of jets. Three simple metal tubes dramatically increased the suction and performance of The Eroica’s gold recovery system. If I went the wrong way it might not have worked at all.
Fluid dynamics is really finicky – you only have to be a little wrong to be really wrong. I strongly recommend you build and test this system before it ever reaches Nome.
Live-aboard space/going too big
Look, you’re not going to “live at sea and run 24 hours a day.” For some reason, excited new dredgers think they’re going to do that, and they waste way too much money building the cabin space to fuel that delusion.
And if you’re an owner-operator you’re also not going to live on your dredge in the harbor.
A bunk and a microwave may work for a diver or crewmember, but you just need too much infrastructure as an owner to really make this work.
Getting a bit of land, filling in a gravel pad, and plopping a couple connexes and a porta-potty down for a camp is cheaper and much nicer than adding 20 feet and a huge cabin to your dredge.
I’ve seen 60-foot boats basically powering 8″ dredges. It’s an incredible waste of money and boat.
Plus using the Nome harbor outhouse all the time is disgusting. That alone might make you want to quit the business. Seriously, it’s a living, breathing health violation in there. I am very practiced at holding my breath for the rare times I have to enter that house of horrors.
One thing people underestimate is just how difficult the mental game is living in Western Alaska 6 months a year, including preseason, which no one ever thinks about.
It’s cold, stormy, and dreary. If you have some money, invest in some space to get away from the harbor and learn to enjoy the open country. You’re going to be here for 6 months and only dredge 50 or 60 days.
There’s something about gold that just attracts…crazy.
Too many guys come up with some speculative idea that they drew on the back of a napkin and blow their whole retirement on it.
Maybe it’s arrogance and maybe it’s ignorance. Maybe it’s both?
But it’s hard to see how these guys don’t understand what a massive gamble they’re taking, and how unlikely they are to succeed, when they’re trying a new idea.
I’ve only seen two or three real innovative operations succeed in the last 12 years I’ve been in Nome. They were all started by guys who had deep experience mining offshore, who were already proven operators, and were well capitalized. If this is you, congratulations, why are you reading this?
One Last Thing: Don’t Be a D*ck
This is essential. Nome is a small community. The dredging fleet is even smaller.
Over the dozen years I’ve worked in this industry, I’ve seen many bros come up here and act like they know what’s what, and that we’re all a bunch of idiots. They’re rude, dismissive, and they end up at the bars getting all sorts of terrible advice from others like them.
Granted, there are some real intellectually-challenged individuals who have operated (and still do) up here, but also, You. Do. Not. Know. Anything. Be kind, be polite, shut your mouth, and listen.
If you’re friendly, humble, and cool, you will be able to get essential information from successful gold miners that may be the difference between success and failure.
Also, be decent, respectful and kind to the local Nome community. This is an isolated part of the world, and they’re not crazy about outsiders, and miners in particular.
Unfortunately, a few bad apples over the years have soured some of the locals against us, and I don’t want to see anyone adding to the anti-miner sentiment. Even the local business owners will make your life harder if you’re difficult to work with.
Except Clark at Builders Industrial Supply. He’ll take your money, regardless! (Love you, Clark!)
Thanks for checking out my tips for starting your own dredge! Let me know what you think, and if you have any questions.
Want more dredging advice? Check out the 5 biggest mistakes new gold dredgers make.
Or watch my video on Youtube!
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