How to avoid clogging your engine with sand

[Scottintexas]

I know this thread is specific to Yamaha and a thread search didn't find any references to Scarab, but in case someone owning a Scarab is concerned then don't be. Scarab uses a self contained closed loop engine cooling system with anti-freeze. On many many occasions I have dragged the sandy bottom and had to power through to get back into sucking clean water. I have never had an engine cooling system filled with sand nor an engine overheating issue. I have many complaints about Scarab boats/trailers but cooling is not one of them.

doesn't the scarab use raw water for the exhaust cooling ?

 

[Joatmon]

doesn't the scarab use raw water for the exhaust cooling ?

Yes you are correct. For some reason I was only thinking about the internal engine cooling. The exhaust system is cooled via an intake with raw water. Surprisingly I have never had an issue with sand in the exhaust. Boating in the “skinny” waters of southwest Florida I know I have pumped sand through the exhaust. Since I boat in salt water I do flush the exhaust water system afterwards.

 

[Julian]

Yes you are correct. For some reason I was only thinking about the internal engine cooling. The exhaust system is cooled via an intake with raw water. Surprisingly I have never had an issue with sand in the exhaust. Boating in the “skinny” waters of southwest Florida I know I have pumped sand through the exhaust. Since I boat in salt water I do flush the exhaust water system afterwards.

There have been examples of Scarabs overheating due to clogged cooling systems.
Both brands are susceptible to this.

https://jetboaters.net/threads/scarab-255-ho-impulse-resonator-melting.16758/

 

[Shipbuilder]

Ok, this is mostly on subject, when beaching the boat I have been backing in and then using a Sand Anchor up on the beach. Today when inspecting the boat after putting it back on the trailer I noticed (hard to miss) that the rudder had snapped off and was hanging from the two steering rods. (I have two rods because I have the Cobra Jet Fangs. Surprisingly I did not notice any loss of steering performance even while putting it back on the trailer. I have already ordered a replacement rudder ( they call it a steering plate).

Lesson learned! set a bow anchor first when backing in and don't let the rudders etc hit the beach!

 

[Prodock]

Ok, this is mostly on subject, when beaching the boat I have been backing in and then using a Sand Anchor up on the beach. Today when inspecting the boat after putting it back on the trailer I noticed (hard to miss) that the rudder had snapped off and was hanging from the two steering rods. (I have two rods because I have the Cobra Jet Fangs. Surprisingly I did not notice any loss of steering performance even while putting it back on the trailer. I have already ordered a replacement rudder ( they call it a steering plate).

Lesson learned! set a bow anchor first when backing in and don't let the rudders etc hit the beach!

Thanks for the heads up, especially for newbies. I learned about backing up to the sand bar because I sucked in sand, fortunately didn’t break the rudder or do any lasting damage to the engines, but it’s good to share these experiences.

 

[Shipbuilder]

pictures of the broken rudder

 

[FSH 210 Sport]

Ok, this is mostly on subject, when beaching the boat I have been backing in and then using a Sand Anchor up on the beach. Today when inspecting the boat after putting it back on the trailer I noticed (hard to miss) that the rudder had snapped off and was hanging from the two steering rods. (I have two rods because I have the Cobra Jet Fangs. Surprisingly I did not notice any loss of steering performance even while putting it back on the trailer. I have already ordered a replacement rudder ( they call it a steering plate).

Lesson learned! set a bow anchor first when backing in and don't let the rudders etc hit the beach!

Thats called a Med tie… set the bow anchor way out, be sure and back down on it to make sure it holds fast, then pay out the rode until you get to where you want to be, then pull taught on the shore anchor(s). In a Med tie you put out two shore anchors at 45* off of each aft corner and pull them taught and your boat will not sway.

 

[Adrian @ JB Solutions]

lol where are all the people that say Cobras will rip your pumps off.
You should have no issues backing in. Keep stern knee deep.

 

[Susanna]

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.

Thanks good to see what it does.
Is there anyone come up with a solution to prevent the grass from entering into the intake grates?.

 

[Julian]

Thanks good to see what it does.
Is there anyone come up with a solution to prevent the grass from entering into the intake grates?.

No solution I've seen. Have you learned the reverse maneuver to clean out your intakes?

 

[Susanna]

I have tried reverse to no avail. I hear about a tool to use. What is that?
Anyone have a solution to keep the seaweed and debree out?

 

[Susanna]

The sea doo switch has a device on it. We need that on a jet ski!!

 

[Dixemon]

Ok, this is mostly on subject, when beaching the boat I have been backing in and then using a Sand Anchor up on the beach. Today when inspecting the boat after putting it back on the trailer I noticed (hard to miss) that the rudder had snapped off and was hanging from the two steering rods. (I have two rods because I have the Cobra Jet Fangs. Surprisingly I did not notice any loss of steering performance even while putting it back on the trailer. I have already ordered a replacement rudder ( they call it a steering plate).

Lesson learned! set a bow anchor first when backing in and don't let the rudders etc hit the beach!

I never back into the beach for that reason. I toss the bow anchor about 100' out then having an assistant pay the rode out without any slack in the line i drive straight forward and lightly beach the boat. Just prior to landing i shut the motors off. We turn the boat around and deploy the stern anchor and make all our adjustments to the lines. Way easier than backing up, especially when there are other boats present.

 

[Adrian @ JB Solutions]

I never back into the beach for that reason. I toss the bow anchor about 100' out then having an assistant pay the rode out without any slack in the line i drive straight forward and lightly beach the boat. Just prior to landing i shut the motors off. We turn the boat around and deploy the stern anchor and make all our adjustments to the lines. Way easier than backing up, especially when there are other boats present.

I do the same, minus the beaching, I won't let the get boat get that shallow. I let the bow anchor spin the boat for me. I turn off engines, bow anchor catches and spins me while I grab rear anchor, and jump off and tie up rear.

 

[Joatmon]

I used the reverse clean out when vegetation clogs the jets. I have not tried with mud or sand. I know it also works for a stick in the intake grate. The Gulf area and bay where I boat can get a of top water vegetation in the spring and blue/green algae in the summer.

You have to go hard in reverse for 30 feet or more until the boat is pushing a wall of water then switch to neutral so the back flush is strong enough to push out the debris. I found going to neutral instead of forward works best for me. Jamming from reverse to forward just thrusts the water back the same direction as the clog. Sometimes it takes several attempts. The trick has yet to fail for me. Hope this helps.

 

[Julian]

I used the reverse clean out when vegetation clogs the jets. I have not tried with mud or sand. I know it also works for a stick in the intake grate. The Gulf area and bay where I boat can get a of top water vegetation in the spring and blue/green algae in the summer.

You have to go hard in reverse for 30 feet or more until the boat is pushing a wall of water then switch to neutral so the back flush is strong enough to push out the debris. I found going to neutral instead of forward works best for me. Jamming from reverse to forward just thrusts the water back the same direction as the clog. Sometimes it takes several attempts. The trick has yet to fail for me. Hope this helps.

You should be switching to reverse after you kill the engines, not before. That opens up a straight shot for water to push backwards through the intake. That said, my boat has servos on the buckets, and I can't remember what their default position is when engines are off.

 

[Joatmon]

You should be switching to reverse after you kill the engines, not before. That opens up a straight shot for water to push backwards through the intake. That said, my boat has servos on the buckets, and I can't remember what their default position is when engines are off.

On my Scarab the buckets immediately default to the neutral position when the engines are shut off. That is why when flushing I don't shut off the engines even though I transfer the gear level into neutral. The nozzles have enough exposed opening to back flush the pump. The perfect situation would be if I could go hard in reverse then kill the engines and the buckets would automatically lift into the forward position to fully expose the clogged pumps, but the sequence is not possible on my Scarab.

Leaving the engines running probably also helps prevent water from backing into the engines.

 

[Julian]

On my Scarab the buckets immediately default to the neutral position when the engines are shut off. That is why when flushing I don't shut off the engines even though I transfer the gear level into neutral. The nozzles have enough exposed opening to back flush the pump. The perfect situation would be if I could go hard in reverse then kill the engines and the buckets would automatically lift into the forward position to fully expose the clogged pumps, but the sequence is not possible on my Scarab.

Leaving the engines running probably also helps prevent water from backing into the engines.

If you don't shut off the engine(s), then the reverse maneuver really isn't working the way it could. You will get a little flow of water past the intake on the bottom of the boat, but you will get ZERO water flowing back through the intake tunnel to push weeds etc off the intake. You must shut off the engine to get backflow through the pump and intake. There is no such thing as neutral (prop not spinning) on a jet boat as they have no transmission. Neutral simply pumps water straight down...and as a result, the reverse maneuver cannot flush stuff out of the intake as water is always being pulled through the intake when the engine is running.

 

[Joatmon]

I understand what you are saying but the procedure I use works for me every time and I don’t shut off the engines. Enough back flush gets into the pump, impeller and grate via the nozzle to break the clog loose and it then blows out the back after I power forward. Mostly sea grass and algae blooms.

It would be interesting to hear how others clear their pumps using the reverse procedure.

 

[Julian]

I understand what you are saying but the procedure I use works for me every time and I don’t shut off the engines. Enough back flush gets into the pump, impeller and grate via the nozzle to break the clog loose and it then blows out the back after I power forward. Mostly sea grass and algae blooms.

It would be interesting to hear how others clear their pumps using the reverse procedure.

Zero backwash is getting into the pump and nozzle if the engine is running. Not sure you fully grasp how your jet pump and engine work. I'm on a plane about to take off....so perhaps someone else will help....?