Jet Drive zodiac

[firefrog]

Just a question to those of you in PSD using boats . We have a few call outs through out the year that are in areas with shallow water and were thinking of getting a jet drive for use on our zodiac . During some flooding last year we pretty much wasted our prop driving over roads and under water hazards . Just interested in any thoughts , pros & cons ......

 

[Wildcard]

Jets loose 40% of the power that a wheel would have but sometimes are one of the only options. Are you looking at inboard or out board and how big? If it's just a little 12-14 footer you might want to look at stump jumpers also.

 

[medic1657]

This is my first post to the board. Glad to be here. I've spent about 20 years using boats as a police officer/paramedic to patrol inland lakes and streams in Virginia. I've used a few set ups for different situations. I've used both aluminum jons and inflatables with both props and jets.

Maneuvering a jet drive in swift or moving water can be a bear. Used both set ups in rivers and streams and even a few highways during some flood events. For some reason I feel I need to keep making minor corrections to keep the bow into the current. I love using the zodiacs during flood events, and with a jet drive I can go just about anywhere. I like the jets for allowing access to shallow areas and also like them when operating in water with a lot of submerged hazards. Didn't like them when they suck up debris like rocks and stones that damaged the impeller. They don't give you the same thrust for the same horsepower that a prop drive would give you. However an inflatable has a shallow draft and in most cases it does not need the thrust. They can be a little sluggish to maneuver though. They just don't respond as quickly as a V- or a chymed flat bottom jon boat would. The inflatables are stable and are great in moving or swift water.

I would also suggest that you make sure that any bowlines for the boat are not long enough to reach the transom. I once sucked up the bowline into the intake. Made for a tense situation until we could paddle to a landing site and remove the rope. Also was a little costly as it we wound up replacing the impeller. I also like jets when I'm towing divers to and from the downlines. Less worry of an accident, but you still have to be careful.

Props give more thrust for the same horsepower. We rigged a pitchfork to the front of the lower units for the boats we routinely use for river assignments. It allowed the water to pass and blocked debris without causing cavatation. It even keeps us from grinding or bending the skeg. The prop drives also give me more thrust if I have to tow another boat. The drawback is that we couldn't access really shallow water to access victims unless we trimmed the motor up. I can hold the boat at station in swift water better with a prop drive than I can with a jet drive. With jet drives though, I can usually access shallow areas very well to the point that I can almost exit the boat without getting my shoes wet.

Both have their pro's and con's. I guess it's something that you will need to practice with to get the perfect set up for what you plan on using the boat for.

Hope this was helpful.
Medic1657

 

[bridgediver]

We rigged a pitchfork to the front of the lower units for the boats we routinely use for river assignments. It allowed the water to pass and blocked debris without causing cavatation. It even keeps us from grinding or bending the skeg. Medic1657

First off, welcome!

I'd also like to know more about this pitch fork idea. It sounds great! Do you think it would work for jet motors? We've got a couple of really weedy lakes where we're always sucking weeds up.

Mark

 

[BigJetDriver]

Folks,

I've used both jets and props on varying kinds and sizes of boats over the years. I would have to agree with Medic's comments.

One suggestion, though, is a rig we use here in Tejas called a "Flats Boat". A lot of them come with a flat bottom, but with a large tunnel down the center of the hull from bow to stern. The tunnel is open on the bottom.

At the stern, where the tunnel exits, the shaft of the outboard is placed so that the prop is centered on the tunnel. The motor is usually mounted on a hydraulic jack-plate, so that the prop can be raised or lowered as necessary.

These boats will function in spots that only an airboat could go otherwise, but with the motor down, they have all of the power and "steerability" of the conventional prop. Another plus is that the decks are flat, so they leave a lot of working space available.

Just a thought.

Cheers!

Rob Davie

 

[cool_hardware52]

As an alternative carry a couple of these http://www.compositeprop.com/

You can replace just one blade, and you can stow the spares unassembled, i.e. just the blades.


I've used them on an Avon. I like the fact that I don't have a heavy, sharp, spare prop to secure in the boat.


Regards,



Tobin

 

[Wildcard]

Folks,

I've used both jets and props on varying kinds and sizes of boats over the years. I would have to agree with Medic's comments.

One suggestion, though, is a rig we use here in Tejas called a "Flats Boat". A lot of them come with a flat bottom, but with a large tunnel down the center of the hull from bow to stern. The tunnel is open on the bottom.

At the stern, where the tunnel exits, the shaft of the outboard is placed so that the prop is centered on the tunnel. The motor is usually mounted on a hydraulic jack-plate, so that the prop can be raised or lowered as necessary.

These boats will function in spots that only an airboat could go otherwise, but with the motor down, they have all of the power and "steerability" of the conventional prop. Another plus is that the decks are flat, so they leave a lot of working space available.

Just a thought.

Cheers!

Rob Davie

Most Mfgs call them tunnel boats and are great for rivers with jets. Damn fine idea.
There are commercial skeg and prop guards out there that do the same thing as the pitch fork Idea, which is another fine idea.
Here is a link for stump jumpers, all the pros of both jets and props, and they are reasonably priced. Sorry I don't know how to make it clickable.
http://www.stump-jumper.com/pages/features.html

 

[medic1657]

The pitchforks were attached using big radiator clamps to secure them to the lower units of the prop driven boats. The mechanic that installed them wouldn't weld them in fear of damaging the lower unit housing. I'd tend to agree with him and the radiator clamps held the pitchfork in place well. If we lost one, no big loss. They were fairly inexpensive. It beat the alternative to replacing shear pins and lower unit gears.
I don't think they would be of much assistance on a jet drive in grass. The intakes on them would still pull the grass in around the tines of the pitchfork. It would probably get in the way of removing the grass that may get hung in the intake. How about a smaller intake screen? It wouldn't let the grass in but on the other hand, it would also be more likely to become blocked with silt and debris.
We don't have many grassy areas in the parts of VA that I've patrolled. I'll check with a couple of the guys down in the eastern part of the state where they deal with that sort of thing and see if they have any suggestions.
Thanks
Medic1657

 

[Wildcard]

One aditional bonus of jets is if you have the need you can put a diverter in the jet and use it as a fire pump. This is for inboard jets only.

 

[Wildcard]

I had another thought, what about an air boat? I wouldn't want one for patrol duty type stuff but for emergency use it may be a good idea.