# Jet drive VS Prop



## Shady Walls (Feb 20, 2014)

Been asking about jet drives ( thinking about putting one on). What are the pros and cons. The few people I've talked with have different views, like power, gas consumption, etc.


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## jjordan (Sep 6, 2006)

Great for shallow water. Lose about 30% horse power and they do drink alot of gas


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## TheRooster (Jul 15, 2012)

I agree with jjordan, but that goes out the window when you get into some vegetation, jet drives hate the veggies, just get a jack plate and prop your motor right and you can run stuff you wouldn't have dreamed you'd ever be able to run before

Sent from my SM-N900T using Tapatalk


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## Smackdaddy53 (Nov 4, 2011)

Depends on what hull you are putting it on, how many grates you leave in the intake, correct height etc. Many people run outboard jets in the marsh around here. Im about to be running mine as soon as I finish rigging my hull and getting the Tuffcoat on the deck. If jets were so horrible I doubt Sonny (Sonny 's Marine ) would rig them and sell them in POC. If it isn't for you all you have to do is unbolt the LU and put the prop drive back on. 
Here is my jet tunnel hull I have been working on for a couple of years. Just got the GatorGlide on the bottom and painted it. 
























http://www.fishingscout.com/scouts/SmackDaddy


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## pmgoffjr (Jul 30, 2009)

Here's the facts on squirt motors:
They like light hulls.
There's no comparison on how shallow you can take off in compared to a prop.
There's no comparison to how shallow you can run.
Grass is not an issue when you remove the grate. But an oyster shell will shut you down. Easy fix, but it happens.
They do not like big rough water.
Slow speed maneuvering is poor.

They aren't for everyone, if you HAVE to drag four biscuit heads, 400 lbs of ice, pops and groceries around, it's not your rig.


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## Shady Walls (Feb 20, 2014)

Thx for the info- nice boat smack! Already got jack plate, shallow blaster. Wasn't sure about the hp, or gas consumption.


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## Smackdaddy53 (Nov 4, 2011)

Shady Walls said:


> Thx for the info- nice boat smack! Already got jack plate, shallow blaster. Wasn't sure about the hp, or gas consumption.


What size motor do you have? You don't need anything but a manual jackplate because once you get the height set you leave it.

http://www.fishingscout.com/scouts/SmackDaddy


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## Shady Walls (Feb 20, 2014)

60 e-tec on a 14.5 shoalwater cat, got manual on it and it runs skinny. Getting lots of hours on it and was thinking about selling it and build a boat like yours or pmgoffjr. Or just wait an get another motor when this one plays out.


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## gunsmoke11 (Apr 30, 2012)

Shady Walls said:


> 60 e-tec on a 14.5 shoalwater cat, got manual on it and it runs skinny. Getting lots of hours on it and was thinking about selling it and build a boat like yours or pmgoffjr. Or just wait an get another motor when this one plays out.


You will.blow out to much fo cat haul! If you get in the slightest chop.you will sell


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## Smackdaddy53 (Nov 4, 2011)

gunsmoke11 said:


> You will.blow out to much fo cat haul! If you get in the slightest chop.you will sell


Yup, an outboard jet needs a flat bottom or a little deadrise to work correctly. Something like these:








http://www.fishingscout.com/scouts/SmackDaddy


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## Shady Walls (Feb 20, 2014)

Great info. Thx!


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## pmgoffjr (Jul 30, 2009)

You're more than welcome to take a ride on my sled any time. Only when you know...will you know.


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## trout250 (Aug 24, 2005)

i have a tahatsu 30 that is a jet drive,had it on a 16ft lowes 48" btm. it would run in only a ffew inches of water, if boat would float it would run, took me a while to get it adjusted because it was not a tunnel, hated berry weed.

was a good rig for getting into places that you could not get with rregular rig


good luck


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## TrueblueTexican (Aug 29, 2005)

*I've run jet forty years*

We started in the Laguna a looong time ago - from experience if you have sand or mud the boat will travel in 1/2 " water on plane, however your draft on a loaded boat is what you generally need to get on plane again - in other word if you are running skinny and shut down you will be sitting high and dry.

There is now a weed cutter attachment attachment for OB jets that will cut weeds - you can remove the grate - but you risk locking up and ruining your impellars/linings - to a point you will be able to run in salad but only for short distances - you are really better off leaving your grates in and sharpening them to a knife point.

Cavitation is a jets enemy - as in any water pump(doesn't make any difference what kind) cavitating impellars lose metal each time they cavitate, so you actually wear the impellar out most times before the wear ring - we modified pumps years ago to stainless wear rings and close impellar tolerances (these mods make the pump more efficient) Understand that water is not compressible a pump ACCELERATES the water stream to work, feeding clean unaerated water is what you have to do, the the impellar need to be efficiently made - Solas has the best impellars out there.

With ALL OB pumps there is a 30% loss from head horsepower to pump horsepower - and the hull design is CRITICAL, the jet tunnel itself should be no WIDER than 1/2" each side of the intake foot and no LONGER than 16". The leading edge of your pump foot should be within 1/4" of the TOP of the tunnel - ANYTHING that will create bubbles feeding TO the intake needs to be scrubbed FLAT - taking a stamped aluminum hull designed for outboards is asking for trouble or a lot of mods - any center keel before the tunnel has to be scrubbed FLAT - or you pump will be ingesting AIR. Well designed OB jet hulls that work PROPERLY generally will have a reverse chine bottom.

Cat hulls won't work with jet pumps neither will outboard tunnel hulls -

As a general rule you have to get a shallow drafting LIGHT hull in the first place, the more displacement the more load you can efficiently carry -

I would put nothing less than a 115 head horsepower on a 16' boat, and nothing less than a 150 HP head on boats to 20' - that is IF you want reasonable performance and fuel economy (fuel economy and OB jets are an oxymoron)

EVERYTHING you do with an OB jet requires 30% more power, to get on plane and stay on plane - if you UNDERPOWER a hull you will use MORE fuel and cook out a head before its time.

Your hull LOADED needs to float LEVEL - so how you LOAD the boat with people, gear, sitting positions, battery storage, helm station is CRITICAL to efficient performance, a jet sitting down in the transom will be long time to plane and a dog on the water.

Personally I would run only two strokes as jet motors, but I do know of a few who run heavy four bangers.

Jet boating is all about efficient design of your power and hull - a properly set up boat will go just about anywhere - BUT they are for back bays - not crossing open bays like Matagorda.

OB tunnels will now travel ALMOST as shallow as a jet - FYI - I quit jets when the surface running hyperdrives came out - I can go a looong way on a little gas, no worries about grass or bottom composition,

Look at the pics of Pat Goffs boat - its properly set up to float level


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## gunsmoke11 (Apr 30, 2012)

Hey smack jw but why is there a plate welded to your pods? Is that for a jp set back?


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## TrueblueTexican (Aug 29, 2005)

*Smack*



Smackdaddy53 said:


> Depends on what hull you are putting it on, how many grates you leave in the intake, correct height etc. Many people run outboard jets in the marsh around here. Im about to be running mine as soon as I finish rigging my hull and getting the Tuffcoat on the deck. If jets were so horrible I doubt Sonny (Sonny 's Marine ) would rig them and sell them in POC. If it isn't for you all you have to do is unbolt the LU and put the prop drive back on.
> Here is my jet tunnel hull I have been working on for a couple of years. Just got the GatorGlide on the bottom and painted it.
> 
> 
> ...


Nice build, but I think you will find you will need to scrub all three ribs leading into jet tunnel back about five more feet.

You can only push the skinny envelope so far friends properly set up jet boat


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## Shady Walls (Feb 20, 2014)

Man o man lot to contemplate on. Thx for all the info, think I'll just stick to what I got now. Pmgoffjr I do want to take a ride, gotta go to Seguin Tuesday for a few days.


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## Smackdaddy53 (Nov 4, 2011)

TrueblueTexican said:


> Nice build, but I think you will find you will need to scrub all three ribs leading into jet tunnel back about five more feet.
> 
> You can only push the skinny envelope so far friends properly set up jet boat


They are already three feet back, about 90% of the jet hulls I have seen have ribs that close or even closer. I understand why you say that but I will find out for myself I guess. Even the OBJ website and all the people that work there say remove the center rib about 36" back from the front of the tunnel.
No way Im removing that much more of my ribs unless the jet won't load up because of ingested air. Thank for the heads up, we will see soon I hope. I am blowing the Tuffcoat on the deck next week.

http://www.fishingscout.com/scouts/SmackDaddy


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## Smackdaddy53 (Nov 4, 2011)

gunsmoke11 said:


> Hey smack jw but why is there a plate welded to your pods? Is that for a jp set back?


Yes. I designed the tunnel based on a 6" setback manual jackplate for several reasons. The rear of the tunnel is actually 12" past the transom. The pods add floatation for the extra weight of a larger outboard if I end up repowering with a 115, which I probably will if I am not happy with the performance of my 60 Merc Jet.
It will be easier to set the height right where I want it without slotting my motor mount holes. 
The bulk of the tunnel volume is behind the transom so I don't lose very much floatation like I would with the bulk of the tunnel cutting out more volume. 
The weight of the motor is further back so I don't have to mount my console so far forward. 
The tunnel's measurements came from another guy's design with his consent. He sells rigged outboard jets with this tunnel all the time and for many years on the Texas coast.

http://www.fishingscout.com/scouts/SmackDaddy


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## pmgoffjr (Jul 30, 2009)

I don't think you'll have any issues, there's plenty of room for the water to regroup and get clean in the tunnel. The little cavitation wings will cure any ills that might show up anyway.


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## gunsmoke11 (Apr 30, 2012)

Smackdaddy53 said:


> Yes. I designed the tunnel based on a 6" setback manual jackplate for several reasons. The rear of the tunnel is actually 12" past the transom. The pods add floatation for the extra weight of a larger outboard if I end up repowering with a 115, which I probably will if I am not happy with the performance of my 60 Merc Jet.
> It will be easier to set the height right where I want it without slotting my motor mount holes.
> The bulk of the tunnel volume is behind the transom so I don't lose very much floatation like I would with the bulk of the tunnel cutting out more volume.
> The weight of the motor is further back so I don't have to mount my console so far forward.
> ...


Nice I would like to see a skinny video when your done. Also if you ever want to sell that jet to repower pm ill take it off your hands


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## Smackdaddy53 (Nov 4, 2011)

pmgoffjr said:


> I don't think you'll have any issues, there's plenty of room for the water to regroup and get clean in the tunnel. The little cavitation wings will cure any ills that might show up anyway.


The top of the tunnel has a little spoon to it so the aerated water will stay on either side of the jet foot. I have wings too...
If you look close at the reflection in the top of the tunnel it is a little bit concave. I did not weld the bracing on top so when the welds cooled they pulled the middle up perfectly. The bubbles should channel to the left and right.








Fancy wings













Bracing








http://www.fishingscout.com/scouts/SmackDaddy


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