How to avoid clogging your engine with sand

[Julian]

Thanks to @JetBoatPilot for recording the video below!

So the sales guy sold you your jet boat saying you can run it in 18 inches of water. So you sat at the sand bar and did just that and now have an overheat warning?

Yes, jet boats can run in skinny water, but you must remember that they are like giant vaccuums. If you sit in one spot, they will suck sand off the bottom. And because you have low flow, that sand is much more likely to get stuck in a cooling passage.

Running fast across shallow water wont suck up sand (you just risk hitting something or grounding the boat).

So keep this in mind when running your jet boat shallow. I always push my boat back off the sand bar and THEN start it in deeper water.

 

[Dave burke]

Very helpful guys. Thx

 

[HangOutdoors]

Definitely good information.

 

[Prodock]

Great info. Kind of wish I saw it yesterday. Lol. That is exactly what I believe I did today.

 

[Julian]

Yeah.....its important enough info I made it a sticky. Most salespeople wont tell you this!!!

 

[capt]

When you say deeper water approximately what depth are you referring to?

 

[Julian]

I like to have at least 2-3 feet under the boat before I just sit and run the boat.

 

[Cambo]

That is such a great video . Even better would be showing reverse directing water down blowing everything loose allowing even more to be sucked up. I don’t even know if you could see what’s happening . The big question is at about 20 mph is it pulling clean water when the hull is 1 foot off the bottom . There’s an area that I boat in occasionally and has 18 to 24 “ of water for a few miles . Only issue is the sea grass gets sucked in and starts to cause cavitation there are several dredged channels that I cross and can stop clean out the grass if needed and power back up . You can’t stop in the shallow 18” water the boat needs deeper water to get on plain .

 

[Julian]

The big question is at about 20 mph is it pulling clean water when the hull is 1 foot off the bottom

I have no proof of this, but I would say emphatically yes it is pulled clean water. Think about the physics of the movement, there is no opportunity for the boat to do anything other than scoop the surface 6 inches of water.

The video above is sitting in one spot creating a vortex. Did you see how quickly the vortex stopped as soon as the boat began moving?

 

[anmut]

I have no proof of this, but I would say emphatically yes it is pulled clean water. Think about the physics of the movement, there is no opportunity for the boat to do anything other than scoop the surface 6 inches of water.

The video above is sitting in one spot creating a vortex. Did you see how quickly the vortex stopped as soon as the boat began moving?

Did the boat start moving or did the engines stop. I noticed that too and assumed it stopped. Also, I cringed hard when he put his hand near the grates...

 

[Julian]

Did the boat start moving or did the engines stop. I noticed that too and assumed it stopped. Also, I cringed hard when he put his hand near the grates...

The voice over says the boat was put into forward and started moving.

 

[djetok]

The voice over says the boat was put into forward and started moving.

It looked to still be running as you could see a little debris still moving as his hand is moving to the intake grate.

 

[Bubba7827]

Thanks for the post.

 

[Candlewood Blakes]

So where exactly does that stuff go?

my wife beached the boat the other day on an island - tried to reverse out without pushing off too far, and on enginethrottle got stuck in reverse.

she got it home on the other engine.

I checked both impeller areas, they seem OK. Took boat out, jiggled the stock throttle several times till it let me go back to neutral, then turned that engine fine.

forward works fine both sides but run reverse I’m not sure I’m doing a whole lot other than revving the engine - on either side.

 

[tdonoughue]

@Candlewood Blakes , it goes up into the intake, which means it is then in your impellers, gets sucked into your cooling system, and some gets spit back out the jets.

In your situation, it sounds like you have a rock between the gate and the jet. When you beach with the rear to the beach, that can happen. Go to the back of the boat and giggle both gates up and down. They should move freely through the entire range. Don't try to force it at the helm--that is a good way to break a cable... My bet is one of your gates is stuck because there is a little rock or shell or piece of wood from the beach that got stuck.

 

[WREKS]

So where exactly does that stuff gom

It goes with the flow of the cooling water. A large amount of cooling water goes through channels in the exhaust manifolds; some goes into a reservoir inside the cylinder head, then out through the thermostat; a restricted hose allows flow around the cylinders. It is in the cylinder water jackets where the sediment/sand can build up over time. This is the most difficult area to flush out.

 

[Saltydog]

So where exactly does that stuff go?

my wife beached the boat the other day on an island - tried to reverse out without pushing off too far, and on enginethrottle got stuck in reverse.

she got it home on the other engine.

I checked both impeller areas, they seem OK. Took boat out, jiggled the stock throttle several times till it let me go back to neutral, then turned that engine fine.

forward works fine both sides but run reverse I’m not sure I’m doing a whole lot other than revving the engine - on either side.

The rod that attached the fwd and reverse cable to the fwd and reverse bucket. It has a u shaped bracket. There is a slide that must be pushed toward the bow to separate the rod from the bucket. It's much easier to get to this slide when the u shaped bracket is in the "U" shape- BUT- it gets the bucket stuck in reverse. Rotate the U shaped bracket 180 degrees to now look like an "n" shaped bracket. Harder to get to the slide but now will not get stuck.

 

[tdonoughue]

(also, always use the slide to separate the cable from the bucket. if you don't realize there is a slide there and unscrew the cable, you will snap your cable when you re-attach it... ask me how I know.)

 

[Saltydog]

Oh oh oh how do you know?
I feel you man. With each item completed on the to-do list = 2 items added somedays

 

[tdonoughue]

Oh oh oh how do you know?

Sigh.... BTDT. Got t-shirt...