Jet Boats

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Permalink Reply by John K. on September 20, 2009 at 9:51pm

Tammy, we had a discussion about jet boats a long time ago that is still in our forums. You can find it at http://www.boatbrevard.com/forum/topics/jet-ski-or-jet-boat. It might help you out...

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Permalink Reply by Randy Wilhite on September 21, 2009 at 10:38am

Tammy,

I have watched the traffic on your post concerning what type of boat to buy and stayed quiet as this is, in my opinion, all dependent on what you plan to do with it - i.e. fish, just cruise, ski, overnight, etc. - and how much money you have to spend. In this case though, after looking through the post that John K. referred you to, I think you might appreciate a little more information.

Looking at your message I see where you are looking at a jet boat and not a jet ski.

Jets use a stainless steel impeller (looks sort of like a long thick screw) that takes in water from in front of it and then throws the water out the back through a steerable nozzle. This provides forward propulsion for the craft and since the impeller is usually inside the hull of the craft, you end up with a shallower draft as there is no "lower unit", either outboard or stern drive, with an attached propeller hanging down in the water. Reverse propulsion is provided by a reversing bucket that slides over the jet nozzle and diverts the water back towards the front of the craft.

The advantages of a jet drive are: a. There is no dangerous propeller hanging down in the water to impact swimmers, sea life, the bottom or debris; b. They have a shallower draft and can run in pretty skinny water; c. jet drives are simpler in design without all the gears, bellows, and other things necessary for outboards or stern-drives, and simpler is usually ( but not always) better, especially when you are talking salt water propulsion; d. Since again, there is no propeller, jet craft have none of the problems with dinged, bent or broken propeller ears, although they can be vulnerable to sucking up weeds, plastic and sand in the water intake that then can damage the impeller.

The disadvatages of jet drives are: a. They use more gas per mile than a prop driven craft, sometimes as much as 27% more when comparing a two-stroke jet to a four-stroke outboard or stern drive; b. Jet boats are very difficult to handle at slower speeds, such as around docks and launch ramps, because all steering is dependent on that jet pumping water so when you slow down your manuverability suffers greatly (and I have never seen a jet boat that has any degree of predictibility when manuvering in reverse); c. Jet boats in the 16 foot and up range usually use two motors (there's that loss of efficiency when compared to a prop) to make enough propulsion to propel a boat with three or four passengers or when pulling a skier, so that means any gain in reliability through simplicity is more than lost; d. Jet boats are louder than prop driven boats, usually because they are using two stroke motors rather than four stroke motors; e. That ability to run in very shallow water can be a liability because some folks think they run in one or two inches of water, and they don't.

So, that's my take on jet boats versus propeller boats. A jet ski is an entirely different animal and I am not addressing those. To make matters more confusing, you can also get a jet unit to bolt to the lower unit of almost any outboard as replacement for the propeller. I saw lots of these in Alaska which were used for running on the rocky rivers there, but talking with those folks revealed that while more reliable than a prop hanging down in the water, they lost a lot in efficiency - both speed and fuel consumption.

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Permalink Reply by Tammy Bousquet on September 21, 2009 at 12:24pm

Thanks for the information. I did some research yesterday and saw the same pros and cons listed on various sites as well. I am looking at a 2001 challenger Seadoo. I read that there is some sort of grate that comes with it to prevent objects from being sucked up, but the one that comes standard is movable and it was suggested that it be replaced with one that does not move. I also read that going slow has it's challenges with maneuvering, but that the newer models are better in that regard. I don't know...I still have a lot of research to do :)

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Permalink Reply by Henry on September 21, 2009 at 2:24pm

Tammy,

I had looked at a Whaler Jet Boat at one time, and did some homework myself. The hydrodynamic
effecency is considerablly less as mentioned by Randy White, and in our waters, suspended sediment
if abundant, which is a concern. The ability to run in shallow water though correct, is not necessarily
a good idea, with the sand injestion particularry hard on the drive. Back to earlier post, an outboard
is probably the best overall option. Any hole that must be cut in a boats hull is an oppurtunity for
failure, weather an outdrive, or a jetdrive. The jet boats I've looked at have the water pickup just
rear of the midship point of the hull, and if you were to "beach" the boat at an island or sandbar, well
a problem with huge amounts of sand injestion, wheras an outboard or sterndrive has all running
gear at the stern, and can tilt up to mitigate shallow water. For strictly skiing activities, the jet boat
has some perks, but for an overall multi-use boat, simplier, and more traditional may be better. Also
the simple outboard has parts avalible from many dealers, and can be serviced by many shops,
wheras a Seadoo Jet Boat may be limited with such options, which usually means more $$$.

Henry

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Permalink Reply by Nancy Eberlin on September 23, 2009 at 10:42am

We own a 15' jet boat sportster which seats 4 people - we sold our 23' IO and bought this boat so we could go into shallower water. It is a fun little boat - goes around 50 mph, is not bad on gas, and doesn't take too long to clean up!
We have also had jet skis so we were familiar with the jet technology. It is a little trickier to dock, but it is just the matter of getting used to it.

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Permalink Reply by Norman Gardner on October 26, 2009 at 7:45pm

I have a Yamaha SX230 and Love It. The is also a forum that have all the answers http://yamahajetboaters.com/
Let me know if you have questions

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Permalink Reply by Shawn M. McCoy on October 27, 2009 at 4:22pm

I have a 20 Sea-doo Challenger sport boat with the 240 Merc. My experiance with these types of boats are: Never let them sit for long periods of time without atleast starting them up., follow routine maintenance schedules, Also, like most boats, keep the throttle linkage, steering components greased, stay out of shallow water, (bad for impeller housing). flush the motor after eash use in salt and occasionally spray and the engine down with some sort of protectant. Ive done that for the past 4 yrs and the boat runs like a champ. Oh yea, unlike outboard, IO and inboard boats your steering relies on engine power, meaning it does not stop and turn like most other boats once you let off the throttle. Hope this helps Shawn

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Permalink Reply by Mark Haggard on January 25, 2010 at 8:59am

Tammy I would not recommed a jet boat for your first boat. Although jet boats are a lot of fun they have higher maintenance cost the engines rpms run higher you use more fuel. The engines wear out faster they are harder to work on. Jet pumps require extra maintenance. Just talk to any marine technicain. Go with an outboard for your first boat.

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Permalink Reply by Mark Haggard on January 25, 2010 at 9:35am

Tammy I was looking at your page. You are looking at getting a boat up to 22 ft. What kind of tow vehicle do you have?

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Permalink Reply by Mike Minutella on February 5, 2010 at 3:14pm

Alot of pro's- but I have owned a couple. The 4 stroke seadoo's are the best, just a little pricey. They handle great.

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