Could we replace the intake grate with something more effective at filtering but also increase flow?

[Bruce]

This year leaving for Bimini we had to stop three times to clear out seaweed that was stuck in the intake grate. We were pulling soccer ball sized clumps through the intake grate that had never made it into the pump.

The factory design has large open areas with large pieces of brittle, I assume aluminum, keeping out large pieces of trash. The coating or paint often chips off of the factory grates which must contribute to cavitation.

I was thinking that something like the 3/8 stainless round bar grids used on high end grills might be a good alternative. Properly spaced it could allow for the same area for water to flow through and being round in shape it should allow for a greater volume of less disturbed water to pass. Having more bars more tightly spaced would reduce the size of object that could pass through. Using a less brittle metal would make them less likely to break, although more likely to bend.

@Speedling I am particularly interested in your thoughts on how this would effect the jets efficiency.

@justason, how difficult would such a grate be to manufacture?

 

[Speedling]

Oh sure, on my daughter's birthday.
When I can sit down I will type, lol

 

[Bruce]

Oh sure, on my daughter's birthday.
When I can sit down I will type, lol

Happy Birthday to her!

 

[justason]

Oh sure, on my daughter's birthday.
When I can sit down I will type, lol

It must be daughter day! We're at a pub in new bern nc scopeing out marina's

I like where your going with this @Bruce Whats there now is a casting. A large one if i recall. Let me noodle this and find investors. And type when i'm not on my phone

 

[Murf'n'surf]

I've always dreamt about a secondary "grate" that hangs down 8-10" below the oem grate. It would deflect a high percentage of weeds.

No matter what kind of grate you have, it can get clogged by the high volume of water flowing into the cavity which is carrying the weeds. So, deflecting, mechanical cleaning or back washing are the only options as I see it.

Can Yamaha design an electric cleaner that moves the grate out of the way and somehow expells the clump? How about by reversing the water flow somehow?

 

[Bill D]

You mean like reverse the jet pump by reversing the engine rotation? Like snowmobiles.

 

[DieselCamel]

Sea doo offered a cool feature for weeds. Sadly my boat doesn't have it.

 

[Englewoodcowboy]

That is slick! Something like that in combinationwith the cleanout plug could make about any clog a reletively quick and easy clear. It would be very beneficial if it was something you could keep one engine running to keep direction etc and clear the other and vice versa.

 

[Speedling]

Ok, I'm about ready to go to bed, but I'll give you the short version of my take on the intake.
The stock intake grate obviously lets a LOT through. Especially sticks etc can just jam their way through. I had this extensively in Lake Cumberland, Kentucky. However, i found that being on plane significantly decreased the amount of debris I would get stuck in there! The problem isn't logs and sticks floating at the top, it's the half water logged woodchips floating a little below the surface.
This is the same spot your seaweed would be as it is essentially a a waterlogged plant.

A lot of seaweed can get pushed through the impellers no problem. It can get chopped sliced and diced. From what I am seeing however is you guys are getting it all stuck on the intake grates.

Now, this is much different than sticks or debris, because with sticks or debris, the smaller the holes are, the more stuff can be deflected. Sea weed, however, won't get deflected, it'll simply wrap around the intake guard of whatever kind you make, and clog it up. So, if you used something like a grill grating, more sea weed will just get stuck on there instead of getting pushed through the pump at all. For sure you would want to have the "rungs" going in line with the boat so that it would have a possibility of sliding off. But I doubt it would work that way.
Many other pump manufacturers have finer intake grates.

Hamilton

Berkely

So you can see that the "big boys" of jets have a finer tooth comb in effect.
But again, I don't feel that will be effective for sea weed.
But as far as top speed and efficiency goes....

IF you didn't get a wad of sea weed stuck on the grates, then you can look at efficiency.
You can't just duct tape some window screen on there. It will not work. The grill grate idea is probably best.
If you want to know what it will do for performance etc. not much. It will create some turbulence, for sure, but as long as you don't go crazy with it, it won't hurt you. There is a lot of theories about actually reducing the intake area for a higher velocity water entering the pump, and therefore it takes less energy to push that water at a higher velocity out the pump. Companies like http://www.iijet.com/IntelliJET Technology.htm have been trying to work with this adjustable intake idea to increase the velocity at higher speeds for quite some time.
I do NOT think, however, that with the load of a boat, that it will make a large enough difference to matter. You may experience a couple mph loss due to the turbulence of the whole setup, but I highly doubt it would effect your basic on plane performance for the crossing.

I hope that tackles most of it.
Go ahead and start fabbing something up and I can try to analyze what ya got!

 

[waterboy]

@Bruce you just have to do a better job dodging the weed piles. I know I probably looked like a drunk heading over to Bimini this year. I got nailed by a huge clump in 2014 so my eyes were peeled this year watching out and weaving to avoid the weeds. I didn't have any problems this year but I drove 80 miles to go 60 miles by zig zagging. In your case, I'm going to blame the driver for hitting the weeds...

 

[jetboater4life]

We need to 3d print some poly carbon intake grate prototypes to test this out.

 

[rkluck]

This is interesting since this is pain point for us all. There are many much larger jet boats (military, etc.). How do they prevent this? Is it because they are so large that debris goes through but what about rope. If you go into any large harbor there is crap everywhere. How do these large ships avoid the same kinds of problems. I guess they could just keep divers on board but I doubt it! HA