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STEPS TO SUCCESS IN DREDGING | Tom Ashworth's Prospectors Cache

Tom Ashworth on 8

Tom Ashworth on 8″ Dredge

I am sitting here at my home in Dayton, Oregon at the end of January with a deep sensation of emptiness due to not being behind the nozzle of my suction dredge. It is not the cold weather that keeps me away from the Klamath River, it is the floods we had this year. Some say it has been worse than the 1964 flood. I don’t know, but I know it did a lot of damage this year. The water in the Klamath River is very muddy and I don’t like to dredge when I can’t see. Instead I decided to write a information article on things that I have found to work well when I do get to go dredging.

Dredging for gold for me has been one of the most exciting and profitable recreations that there is. There has been much written about gold dredging. Some of the stuff written works great and other stuff didn’t work. I am going to talk about some of the things I believe to work and some of the things I believe sounds good, but don’t work well at all. Judge for yourself.


Some people think diving for gold is dangerous. I have read some books that the author claims to be an expert on dredging and he suggest the use hip waders and would never dive because of the dangers of diving. Some people say that diving should only be done after hours of specialized training. They are also told that diving is hard work and that you must be young to do it. These people will buy a 2 or 3 inch dredge without hookah capabilities and work shallow areas or where bedrock can be reached easily. What I have found is that they have to work harder to find less gold than if they had bought a 4 or 5 inch dredge with hookah. The main reasons I believe this to be true is that the rocks in the river are larger than 2 or 3 inches and it takes too long to throw the rocks that would not fit in the suction hose and also they usually have one plug up after another in the suction hose or jet tube with this dredge. Sure they can pack them into remote areas, but it has been my experience that a high banker would be a better choice. When you are wearing waders and not diving, you are bent over in an uncomfortable position, pulling rocks above the surface of the water to throw. It is common sense that a rock is heavier out of water than it is under water.
I believe that diving for gold can be dangerous if you don’t use a little common sense. I also believe it is safe if you use common sense. Most of my diving is done in chest deep water. I use protective gear such as a wet suit to keep me warm. I suggest at least a 7mm thick Farmer John Style. When it gets warmer you can remove the jacket and just use a tee shirt underneath the overall bib on the Farmer John Style. Diving is also great because you can see the gold you are dredging up, so you know what layer, or where on bedrock it is coming from. If you don’t get your head under water with a diving mask on you can’t see the gold. I also suggest you buy a diving mask with a purge on it. It makes it easier to get the water out of your mask if it fills up. To get the water out of your mask, just tilt your head forward and blow out your nose until the water is out.

When I am diving, I am in a laying down position for dredging. This is more comfortable than bending over with waders. I believe it is easier to work a 5″ dredge than any other, because they are not much heavier than the smaller dredges, but the will move more gravel, have less plug ups and you can use them for sampling large rivers to determine if a super dredge is needed for a pay streak.


I believe that I have wasted more time dredging by not thoroughly sampling an area. Most of the prospectors I see that are successful do sample an area to make sure it is worth bringing more equipment in. I have some new rules for myself for sampling. (1) Determine the minimum amount of gold I would be willing to work for on a daily basis. For me it is currently 1/2 ounce. (2) Decide how deep you are willing to dredge to recover the minimum with the equipment you are using. I typically say that I will remove 1 foot of overburden for every 1 inch diameter of my suction hose. If I use my 5″ dredge, then I would be willing to dredge up to 5 feet of overburden to recover 1/2 ounce of gold in an 8 hour shift. If I use my 6″ dredge then I will dredge 8 feet of overburden to recover 1/2 ounce of gold in an 8 hour shift. (3) Decide where you would like to start. I usually listen to people, read reports and look the area over to verify that its accessibility is going to be acceptable to me. If it takes you a week to pack a dredge in to sample, may be fine if you dredge full time, but I only have 3 or 4 days off from my job per week, so this would not be acceptable for me. (4) Draw out a sketch of the area. Plan a sampling pattern that will allow you to discover any pay streaks on the claim. (5) Dredge a sample hole of a fixed size and determine how much you dredged. For example if you dredge a hole 12′ long X 9′ Wide and 3′ Deep you have just dredged 12 cubic yards. Measure the gold and determine if you can obtain your minimum amount with your equipment per day. For example, using the above hole with 12 cubic yards. If I am using a 5″ dredge with a rated capacity of 12 cubic yards per hour, I multiply the rated capacity of the dredge by .667, which means the 5″ dredge will move 8 cubic yards per hour. Then I say I want a 1/2 ounce in 8 hours the formula works like this:

((True Dredge Capacity = (8 Cu. Yds.)) X (Number hours worked = (8 hours))) = (Total Cu. Yds. Per day = (64 Cu. Yds.))

Then you divide the Total Cu. Yds. Per day by the sample size.

64 divided by 12 = 5.33 Sample factor

Then you take the amount of gold you want in 1 day and divide it by the sample factor. In this case we want 1/2 ounce or 10 Dwts. Per day.

10 Dwts. divided by 5.33 = 1.88 Dwts.

In the above illustration we would have needed to find 1.88 Dwts. in the sample hole to be of interest to me.

If I find an acceptable sample I dredge several other sample holes that help me determine the direction and length of the pay streak. Also it is a good idea to drop back behind the sample hole to see how far back and how far forward the pay streak extends.

The key to being successful at dredging is to sample.


These are just a few of things I have found to work. If you have any suggestions please Email me and I will try to add them, so we can help other miners.

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