Smoother intake?

[FSHER]

Hello,
Another miss regarding assembly/build quality on my Yamaha 210 FSH is the intake in general. Both intake screens/grates have gaps where they meet the hull and the back sides of the intake ducts are 1/4 or more higher than where it connects to the impeller housing(I think that's what they connect to). Am I wrong in thinking that the intake should be 100% smooth flowing? I'm sure the affect is very little to negligible but maybe it s not? Maybe if the intake was smooth the water could flow better and decrease issues slightly. Is the flow disturbed just enough to make it easier for weeds to get tangled up?

Is it crazy to want to fill the gaps to smooth them out and or maybe file the intake ducts down to make them level with the impeller housing?

-Mark

 

[David Martin]

Give us some pictures........but you are correct most gates use caulk to smooth out the gaps......I getting ready to pull my jets for maintenance and recalk the gate gaps ..........my port engine is picking up the sea grass in the gaps a little more than I like.

 

[anmut]

I fill mine with silicone by hand and smooth them out - it won't last super long, but it'll help for the season.

 

[AZMark]

A few different attempts at what you’re looking to do in this thread:

Pump intake grates- thinking of trying something taboo

So I still haven't gotten a set of replacement grates so I didn't want to do anything crazy yet. I decided to "blueprint" what was there. I cut the crossbar out of the stock grates and knife edged the bars. I also cleaned up the intakes a bunch, there was a pretty good ledge that the water would...

jetboaters.net

 

[FSHER]

Give us some pictures........but you are correct most gates use caulk to smooth out the gaps......I getting ready to pull my jets for maintenance and recalk the gate gaps ..........my port engine is picking up the sea grass in the gaps a little more than I like.

Not my pics but you get the idea.

The black arrows on mine have little to no squeeze out so I thought to start, filling those gaps and smoothing them out a little better.
The red arrow points out the worst IMO, where the aft side of the intake sits above the impeller housing more than 1/4 inch.

From research, it sounds like a lot of boats will cavitate when launching from a stop and when they port and polish it goes away. I've even read that some get a little more speed. I'm in aviation and i think air works similar to water so it makes sense to me. if you can have clean air in, you'll get clean air out and if the air is disturbed or turbulent, it wreck all kinds of havoc.

I'm thinking each one of those seams, gaps and misaligned parts have an amount of tiny disturbances that add up. After reading into it more i realized, if I'm at a stop and I go wide open, it does cavitate for a second. ITs something I don't do often so it hasn't been an issue. I'm also curious about top speed. I've only ever been able to hit 40 and I've read that it should top out at 43. I couldn't care less about an extra 3mph but if its there for the taking than id like to take it.

Thank you @AZMark for the link.

Some have used 4200, 5200 or whatever else that was in the shed with it seemingly lasting a season or 2. I'm in aviation and I'm leaning towards fuel tank sealant, specifically PR-1750 B 1/2. This is an integral 2 part polythioether compound specifically designed for fillet sealing and filling gaps. The stuff is tough, doesn't peal off like most sealants do, stays flexible to some degree. It is, however, expensive, messy to work with and you need mechanical devices like a sealant removal disc (below) to get it off.

Not sure when ill get to it but ill do my best to post updates.

-Mark