Pump intake grates- thinking of trying something taboo

[jcyamaharider]

So I got to do some testing with our new pumps. I still cannot come on plane on each engine ( single ) with my L13's in but I do have more traction then I did last year. Port pump is all 3 washers, Starboard was only the blue washer I do believe.

Last year it was a struggle to maintain 11 with the ski locker bag full, transom bag full, and my 2 daughters sitting in the rear of the boat while my wife was driving.

Yesterday I filled my transom bag, center locker bag, and filled my port bag 100%. With all of that full, my 2 daughters, wife, and myself in the boat we were able to not only maintain surf speed we were able to hit 15 mph before it started to lose traction. I didn't put on the wedge and I didn't shot video since it was just a quick test.

 

[swatski]

So I got to do some testing with our new pumps. I still cannot come on plane on each engine ( single ) with my L13's in but I do have more traction then I did last year. Port pump is all 3 washers, Starboard was only the blue washer I do believe.

Last year it was a struggle to maintain 11 with the ski locker bag full, transom bag full, and my 2 daughters sitting in the rear of the boat while my wife was driving.

Yesterday I filled my transom bag, center locker bag, and filled my port bag 100%. With all of that full, my 2 daughters, wife, and myself in the boat we were able to not only maintain surf speed we were able to hit 15 mph before it started to lose traction. I didn't put on the wedge and I didn't shot video since it was just a quick test.

That's great!
(It really is hard to believe sometimes what Yamaha lets through its (non?) existing QC process... I guess they make sure there are things for us to fix as hobbists; my boat was a hobby-lobby special no doubt!!!!)
(but then again, we look at poor guys with 2014 Scarabs... and we cry for them, lol)

Anyway, my bondo looks great after about 10 hours on it!
I'm very encouraged this is the way to do it. It will need a finish to last a long time but I am very happy with the results so far. I will wait few more hours to make sure, before supermetalgliding the pumps (see post #95 on previous page), want to make sure the fiber-bondo holds well. It should be the bomb.

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[jacoviii]

Nice now it looks like I need to pull the pumps and do some bondo too.

 

[swatski]

Nice now it looks like I need to pull the pumps and do some bondo too.

My results are holding really good after the last round of Bondo porting.
Surfing fully ballasted with about 2,000lbs of ballast the boat jumps out of the water and pulls like a mule at 10.5mph with 6,400RPM on the tachs.


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[jacoviii]

I have not got the the Bondo yet. I have been working on sound proofing. The only thing I have a issue with is the pump to fiberglass flexing and the bondo getting hair line cracks that leak air again.

 

[swatski]

I have not got the the Bondo yet. I have been working on sound proofing. The only thing I have a issue with is the pump to fiberglass flexing and the bondo getting hair line cracks that leak air again.

Yep, I plan on Supermetalglide'ing it for that very reason. Will report back.

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[CrankyGypsy]

So, the intake grate removal idea has been abandoned/untested?
I see talk of this for boats on SeaDoo forums, but no application and results. I'm planning to remove mine on my Challenger 180. As far as detriment to stability, I'm questioning if a boat is as susceptible as a ski? But, I chuckle when I read the guys on Green Hulk saying "you'll suck up a stick" - as if sticks always approach the pumps perpendicular. May not be their only purpose, but I feel their main purpose is arm-sucking prevention - I'll take my chances with the lightning-strike possibility of a giant @swatski rock. My reasoning for wanting to try it is I sucked up a rope after 1hr on the water and had to call it a day because I couldn't get my hand in there far enough (no cleanouts) diving under the boat. I cut off what I could and had to limp it back to the dock, making matters worse. Unfortunately, during the rope removal, I opened up a can of worms deciding to clean and replace some additional driveline stuff, so I'm waiting on parts ...will report back.

As for the pump shoe smoothing, I think I used 4200 on my AR230 that held up well and used acetone to clean before application. I would also consider regular 3M silicone - I know it says "not below waterline" but I tend to believe that is for moored boats and I have never had an issue with it where I "shouldn't" have used it. Besides, it is what Yamaha uses to seal the pump shoe and those things are tough to get off! I think it's malleability compared to 4200/5200 makes it more tenacious against the vibrations. It is messier, so I usually put painter's tape down, smear it on, smooth it out, and remove the tape for a very clean application. SeaDoo uses something black they refer to as "Adchem Sealant" which looks and feels similar to clear silicone.

 

[JeffVans]

GREAT... Now I have something else to add to the list of stuff that I "NEED" to do. lol

 

[satovod]

 

[swatski]

So, the intake grate removal idea has been abandoned/untested?
I see talk of this for boats on SeaDoo forums, but no application and results. I'm planning to remove mine on my Challenger 180. As far as detriment to stability, I'm questioning if a boat is as susceptible as a ski? But, I chuckle when I read the guys on Green Hulk saying "you'll suck up a stick" - as if sticks always approach the pumps perpendicular. May not be their only purpose, but I feel their main purpose is arm-sucking prevention - I'll take my chances with the lightning-strike possibility of a giant @swatski rock. My reasoning for wanting to try it is I sucked up a rope after 1hr on the water and had to call it a day because I couldn't get my hand in there far enough (no cleanouts) diving under the boat. I cut off what I could and had to limp it back to the dock, making matters worse. Unfortunately, during the rope removal, I opened up a can of worms deciding to clean and replace some additional driveline stuff, so I'm waiting on parts ...will report back.

As for the pump shoe smoothing, I think I used 4200 on my AR230 that held up well and used acetone to clean before application. I would also consider regular 3M silicone - I know it says "not below waterline" but I tend to believe that is for moored boats and I have never had an issue with it where I "shouldn't" have used it. Besides, it is what Yamaha uses to seal the pump shoe and those things are tough to get off! I think it's malleability compared to 4200/5200 makes it more tenacious against the vibrations. It is messier, so I usually put painter's tape down, smear it on, smooth it out, and remove the tape for a very clean application. SeaDoo uses something black they refer to as "Adchem Sealant" which looks and feels similar to clear silicone.

IIRC I sucked the giant tick through the unmodified factory grate. So there is that.

No, I would not modify it again, my two new grates went on stock. I think thevgsins are fairly minimal and I feel those are already fairly weak alloy.

I am not aware of any top-loader grates that work so well in jet skis help alleviate cavitation in boats or increase top speed. The loading is just different.

Maybe @satovod is leading us in the right direction? Any results with those, yet? I’m very curious.

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[satovod]

Toploader intake grates have long history in pro/sport jet ski industry and well proven effectiveness. I set mine in 2011 and have never regretted the money spent.

google it toploader grates +jetski

The Technology Behind Top Loader Intake Grates - The Watercraft Journal | the best resource for JetSki, WaveRunner, and SeaDoo enthusiasts and most popular Personal WaterCraft site in the world!

So you want to gain more performance out of your personal watercraft but don’t want to break the bank. Well one of the easiest ways to do so is going to be to install a top loader intake grate. A relatively cheap item, this single part can help increase the performance, handling, and overall...

watercraftjournal.com

 

[swatski]

Toploader intake grates have long history in pro/sport jet ski industry and well proven effectiveness. I set mine in 2011 and have never regretted the money spent.

google it toploader grates +jetski

The Technology Behind Top Loader Intake Grates - The Watercraft Journal | the best resource for JetSki, WaveRunner, and SeaDoo enthusiasts and most popular Personal WaterCraft site in the world!

So you want to gain more performance out of your personal watercraft but don’t want to break the bank. Well one of the easiest ways to do so is going to be to install a top loader intake grate. A relatively cheap item, this single part can help increase the performance, handling, and overall...

watercraftjournal.com

Yep.
What about jet boats?

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[satovod]

what the difference between jetski and jetboats? none actually. On boats with twin jet setup at V hull toploaders shall be even better.

 

[2kwik4u]

what the difference between jetski and jetboats? none actually. On boats with twin jet setup at V hull toploaders shall be even better.

Engine/Pump load, Depth in the water, likelyhood of exiting the water, overall speed vs engine rpm. Lots of differences between the two that will inherently affect the fluid dynamics associated with the pump.

With that said, So far "most" mods for the ski have translated well to the boats. L13 cone, and pump sealing are two notable ones.

Anyone know of someone that has fabbed/tried a top loader intake on a jetboat? I have a spare intake grate, access to aluminum, and a very skilled welder. If anyone thinks it's really worth a try, I'll give it a shot.

 

[yam240sx]

I got the Belzona "supermetalglide" kit, sanding tools, and radiator brushes ready to go for round 2 of pump porting.
If we could only get the rain so stop...
View attachment 93863

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where can i get this online ? .. thanks

 

[swatski]

where can i get this online ? .. thanks

This was my contact. Super nice and knowledgeable.

Ashley Hayes
Administrative Assistant
Belzona Gateway, Inc.
8124 Bunkum Rd. Suite 2
Caseyville, IL 62232
888.774.2984 (Office)
618.593.3084 (Cell)
ahayes@belzonagatewayinc.com

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[Beachbummer]

For planning on one engine I suggest trim tabs. I can do it on my sx230 with a trim tab setting and moving people to the front of the boat. It takes several seconds to reach plane, but I can maintain 17mph on a single engine a little below WOT

 

[gmtech16450yz]

I'm baaaaaaaaaaaaaaaaaaaaaaaaaaaaack. lol.

Ok I'm dredging up a 7 year old thread, but it's one I started so I figured it's ok.

I did end up taking those intake grates off just for kicks. I machined aluminum blocks to fit in the mounting spots so the tunnel was nice and smooth. The blocks at the back can be taken off easily, on the blocks for the front I used regular automotive fiberglass (bondo) to fill in around them so to remove them I'd just need to dig out the bondo. So it's a semi-permanent mod but whatever, I seriously doubt I'll ever put the grates back on.

So the results? One was expected, the other was a complete surprise. Removing the grates gained 1-2mph easy and the accel out of the hole pulls good with zero cavitation. But here's the surprise effect that was super obvious right off the bat... It's WAY quieter!

Ok so I noticed the sound difference the minute I first started the engines at home. At first I actually figured it was because when I painted the tunnels with epoxy paint, I put a light coating in the impeller housings too. It makes sense that the epoxy paint could quiet the impeller noise itself but after running it, any impeller/paint contact would have worn away. Out on the water it's absolutely noticeably quieter at all rpms and speeds.

So here's my theory, those grates were working like a lever on a drum. The noise created in the pump would transmit through the bottom of the pump, into those grates and then into the hull. The hull might be acting like a drum or a speaker in that area and that could be the source of a lot of the noise. Removing that lever/drum connection stops the noise transfer. hmmmmm. Maybe.

So for anyone daring enough to risk ~$80 worth of intake grates, here's an easy way to to this mod. Take a sawzall to them! Seriously. I enjoyed the challenge of making the aluminum inserts but honestly it would be way easier to just chop off the bars without taking anything apart at all. Just sawzall off the bars front and back, then use a grinder to smooth down rest of the bars on the blocks. If you decide you want the grates back, order a pair online and just put them back in. I believe you can get them for around $40 each if I remember right.

So who's gonna say "F-it" like I did and try it? The downsides? I suppose it's possible you might suck up something that the grates would stop, but honestly I'm not sure what that would be. The grates don't stop ropes, seaweed, rocks or small pieces of wood to be sucked up anyway. The other downside? Ok so there's a chance if the engines were running and someone swam UNDER the boat and reached their hand up into the tunnel, they'd get their arm chewed off. But again, it's a helluva lot easier to lose an arm on a prop boat so even with no grates, a jet boat is still infinitely safer in that respect. I mean who the hell is swimming around under a running boat anyway?

The upsides? I'm not guaranteeing any speed increases but I seriously doubt it could hurt top speed or performance, it has to help. Stick your finger under a running faucet and see what happens to the water flow. My theory is that those grates not only cause some amount of disruption, I'm also thinking they might cause some amount of aeration at high speeds/flows. And there seems to be a noticeable sound decrease, which is always welcome in these boats. Again, I'm not saying you'll 100% get the results I got, but who knows, you might be surprised!

 

[Speedling]

Interesting find!
Mine will remain in place because lake cumberland that we frequent has a lot of floating tree parts.
I wonder about painting them and smoothing them to get partial benefit though

 

[zipper]

Then there is this chummy situation. I keep having to take out mangled fish from the cleanout ports
Sucked up a shark yet? LOL.