«

»

Jun 16 2011

Hydro Survey: The Jet Boats

In most typical shallow western streams, there are going to be reaches less than a foot deep that you need to get through in order to get to a deeper reach of the channel. This is where the jet boats come into play for hydro survey. A jet boat is different from a propeller boat in that it’s draft is so much shallower. A jet boat essentially sucks up water and then “jets” it out for its thrust. See the figure below. Outboard jets are a bit more useful than inboard jets because they are usually lighter and smaller and therefore can operate in a wider range of conditions.

A good jet boat can go through anything as long as it is at least 4 inches deep and not a sand bed channel. Braided sandy shallow channels like the Platte River will destroy a jet boat engine because of all the sand that will get sucked up into it. There’s only one solution in a braided channel and we’ll get to that fun watercraft in another post. Having the shallow draft of a jet boat is very helpful in a cobble (or larger) bed channel like the upper Sacramento River (north of Colusa) or Salmon River (Idaho, see the picture below); situations in which you could very easily and quickly damage your propeller in a normal watercraft.

Jet boat on Salmon River, Idaho

Jet boats also allow you to survey extremely close to the edge of water. A single beam depth sounder is still, at its best, limited to collecting data in 1 foot or deeper water, but in a typical propeller boat, it’s difficult to obtain data shallower than 3-4 feet.

Jet boat on American River, Sacramento, CA

Another nice thing about using a jet boat is that if it is light enough (less than a 40hp motor), you can launch it and reload it using a power winch. This has come in handy for our crew on the Rio Grande and a few other shallow streams. A jet boat is ill advised on most reservoirs or large rivers (due to the wave action you may have to deal with) and some areas do not have the access needed, but for the rest, a jet boat is quite a nice tool to have for hydro survey.

3 pings

  1. » Hydro Survey: The Cataraft Hydraulically Inclined

    […] a previous post, I discussed the use of jet boats for hydro surveys on shallow western streams. A jet boat is fantastic in how it can get almost […]

  2. » Hydro Survey: The Setup and Software Hydraulically Inclined

    […] talked about jet boats and the cataraft for hydro survey. Now let’s dig into the set up and the software. Above is the […]

  3. » Hydro Survey: The Airboat Hydraulically Inclined

    […] of any boats used for hydrographic survey and reconnaissance, from jet boat to cataraft, this is the one that gets the most reactions when it’s sitting in the parking lot: […]

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>