posted 01-05-2013 03:00 PM ET (US)        

--the typical Hamilton Water Jet goes not change the direction of the pump shaft rotation when going into reverse. This means that the propulsion can be shifted to Reverse from Foward without concern for a crash shift in a gear box, as is typical in outboard propulsion;

--that the reverse deflector can be lowered into intermediate positions which will permit a combination of foward, sideways, and reverse thrust to be produced, which can be useful in maneuvering a vessel.

I highly recommend watching the presentation on the Hamilton Water Jet to learn more about its operation and features.

posted 01-06-2013 12:21 AM ET (US)            

Water jet propulsion is of course also used on thousands of boats priced for ordinary consumers for use in shallow and white water rivers, typically for fishing, but also for workboats and law enforcement.

Hamilton from New Zealand is one of the major suppliers of water jet pumps for consumer level boats. Our 22 foot Fish-Rite welded aluminum boat had a Hamilton 212 pump coupled to a multiport fuel injected 5.7 liter V8 GMC 325 HP Vortec. We used it for salmon fishing in the upper Sacramento River where white water rapids are ubiquitous.The models of this size use manual steering and bucket controls instead of hydraulic.

The vast majority of these consumer level craft don't have the jack shaft pictured in the video. The pump is bolted directly to the engine, which is in the stern, similar to an outdrive setup.

In addition to the fact that the direction of pump rotation is constant and that the bucket is what causes the vessel to go into reverse (similar the thrust reversers on a jet aircraft), there are a couple of other things that are different in handling one of these boats.

First, there is no "neutral". If the engine is running, the pump is rotating. The vessel is held stationary by lowering the bucket partially such that forward and reverse thrust are equal, usually with the engine idling. There is no "detent"in the throttle lever position for neutral. One has to look at stationary object, such as a tree or a dock and move the throttle lever into a position that results in the desired effect.

Secondly, when backing, the steering wheel must be moved in exactly the opposite direction compared to backing a propeller boat.

These two things take a little getting used to, especially the backing part when one has been running a propeller boat all summer and suddenly switching to the jet pump boat in the fall.

It was great fun learning to master one of these things and learning to run white water and do high speed shallow river travel in general.

posted 01-06-2013 11:42 AM ET (US)            

My first exposure to "jet propelled" boats was back in the 70's during water ski days on lakes. There were quite a few "day cruisers" typically powered by the largest displacement carbureted Oldsmobile V8's coupled to first generation Berkeley jet drives. In water ski applications these setups were said to guzzle fuel compared to propeller boats. I owned an I/O prop drive then.

By 2003 when we bought our Fish-rite with the Hamilton 212 pump, water jet technology was on about the third generation of design. The rpm profile in salmon fishing was 95% up on plane at 3700 rpm and 5% at idle. The kicker was used to maintain position while fishing. There was no need for GPS so speed was never known. As best as I could determine, my fuel consumption was 4.5 gallons per hour. That's pretty decent for a 3,000 lb boat.

To clarify my comments in the post above about neutral and reverse, some of these boats come with separate levers for throttle and bucket position. They are different in length to avoid errors. Ours had a single lever setup which controlled both the throttle and bucket.

When approaching a dock one just turned the wheel toward the dock in forward, then when the bow is where you want it, shift the bucket into reverse position, keep the wheel turned toward the dock, and the stern tucks in to the dock. Pretty slick.

posted 01-08-2013 10:56 PM ET (US)            

We had been using all fiberglass boats (Bertram etc.)with conventional props and shafts.The very shallow water on the South shore was always a challenge .There were no jet boats anywhere near us that I could find but the Corps of Engineers had a survey boat in Savannah Ga.I spent two days with them and came away convinced this was the way to go.

We ended up going with Kvichak Marine in Seattle to build two 38x15 boats with 3126 Caterpillars and Hamilton jet drives.Both companies were great to deal with .I took a lot of heat from the Division of Puchase...why did I have to go across the country and why did we need "jet engines".And there were some skeptics.among the cops too.No more!

The maneuverability afforded by those jets and "buckets"(deflectors)in the hands of a skilled pilot is incredible not to mention the ability to operate in shallow water and the safety when working with the search and rescue team.

I was very happy to learn that Kvichak got the contract for the new USCG utility boat...jet and I understand NYPD has also ordered a jet boat from Kvichak.