Frequently Asked Questions
- What type of hull makes a good jet boat?
- Why should I consider a jet?
- Specifically, why should I buy a HamiltonJet?
- How much efficiency do you loose with a jet?
- Can you tow with a jet boat?
- How about reverse? People also say jets don’t back-up well.
- What about low speed control?
- Does HamiltonJet offer electronic controls?
- What kind of preventative maintenance does a jet require?
What type of hull makes a good jet boat?
Waterjets are suitable for a wide range of hull types, including monohulls, barges and landing craft, catamarans, trimarans, amphibious vehicles and more. Waterjets work particularly well in planing hulls with constant or near constant dead rise over the aft half of the planing surface and a gently rising bow. Some warp is permissible in slower crafts but may cause bow steering in vessels that approach 40 knots. Some deadrise is required, a totally flat bottom craft is not appropriate, neither is a deep bow. Hull loading should be light to moderate; heavily loaded hulls may not be suitable. Please check with us before making a decision.
Why should I consider a jet?
Jets offer numerous advantages:
1) You can run in much shallower water and go places a prop wouldn’t dare!
2) You can beach your boat with without worrying about a prop shaft, sterndrive or outboard leg.
3) Because the jet is at the aft of the boat and is normally still in the water you can get the boat back off the beach just by lowering the reverse bucket and giving it some throttle.
4) They’re simple and durable and have very low maintenance requirements. This means less downtime and longer life.
5) Better reverse and low speed maneuverability than with a prop.
6) They’re easy to trailer and launch. There’s nothing hanging down to drag on the boat launch.
7) Swimmers, divers and wildlife are much safer around a jet.
8) Lower drag adds to overall efficiency. A jet generally lowers your hull resistance by 8-12%!
9) Impellers rpm’s are not sensitive to boat loading so a jet can’t overload the engine once they are correctly matched.
10) They’re smooth and quiet.
11) Simple installation procedures save time and money.
Specifically, why should I buy a HamiltonJet?
HamiltonJet has been the leader in water jet technology for many years. This has allowed them to develop a very wide range of precise and highly efficient jet models as well as extensive sales and service network. This results in the most refined product with the best support in the industry. In the time that HamiltonJet has been the industry leader, most other jet companies have come and gone or changed ownership–some several times. A well-maintained jet will last for many years. So, if you’re considering a jet, be sure that the jet manufacturer will be around as long as it will.
How much efficiency do you loose with a jet?
This is a very common question. The answer is that you don’t necessarily loose any. A modern HamiltonJet, applied appropriately, will deliver about the same efficiency as a propeller and may actually exceed propeller systems at 25+ knots. Note that many factors influence efficiency. Some hull designs are appropriate for a jet, andsome aren’t. Weight is also a critical factor in determining if a particular vessel would be a good candidate for a jet drive. Contact HamiltonJet for your specific application.
Can you tow with a jet boat?
Sure, it’s very common. There are numerous companies using jets in towing and rescue operations. In fact, if you compare a medium to high speed prop boat to a jet boat, assuming they are both designed to reach the same non-towing speed, you’ll find that the jet boat will usually out tow the prop boat.
How about reverse? People also say jets don’t back-up well.
This is a very common misconception. Older jets with small “clamshell” or “gate” style reverse ducts are the cause of this misunderstanding. Modern, split duct reverse systems have far more reversing power that virtually anything else. A HamiltonJet will typically have about 55% of its forward thrust available in reverse. In fact, applying full reverse at planing speeds will bring the boat to a complete stop in about 1-1/2 boat lengths. Because of the forces involved we strongly recommend that people only do this maneuver in an emergency.
What about low speed control?
A single jet using the HamiltonJet reverse and JT nozzle system can pivot in its own length, or in the case of twinjets, crab walks. With twins, maneuverability is so good that generally bow thrusters aren’t needed. Bottom line, if you’re in a tight situation a jet will probably impart more low speed maneuverability to your vessel than a prop.
Does HamiltonJet offer electronic controls?
Yes, we offer the MECS system for jets ranging from the HJ364 to the HM811 and the Blue Arrow system for the HJ292 through HJ403 models. Both systems can control the engine, jet, gearbox and steering. See the Steering Systems & Controls page on this Web site.
In addition to electronic controls, HamiltonJet also offers rugged, cable-actuated power hydraulic systems on all HJ models except the HJ212.
What kind of preventative maintenance does a jet require?
Jets require very little day-to-day maintenance. Schedules vary slightly depending on jet model, but in general it’s a matter of checking or changing the oil or grease in the main bearing housing, power hydraulic system and driveline. Keeping your anodes and anti-fouling paint in good shape is also required. Under normal operating conditions, more extensive overhauls are not required for many, many hours. As with any mechanical systems, there are limits to what you can subject them to without incurring some kind of damage or additional upkeep. If you have questions on this, or anything else regarding a HamiltonJet, please contact us.
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