Anyone have SF with under gunnel air intakes?

[madhatter1]

We get soot on the transom and in the cockpit areas over time. Was looking into mechanical issues and tune up but decided that's probably not the issue. Engines (8-92TI's) start with no smoke and run super clean. Zero visible exhaust on plane. Clean air filters, intercoolers, and good turbo's.

But we still get the soot buildup on the paint. If we go into a strong headwind it builds up quicker. Calm days or wind behind us much less. Also we get salt mist spray in the same areas more in head wind and less in tailwind.

So basically seems like a big station wagon effect compounded by the under gunnel air intake. Not sure if the amount of air drawn into ER is enough to be a factor. Also we have a full 4 sided enclosure with no openings ion the back other than ladder area.

Wondering if others experience the same. Most SF's have the ER vents on the side. Guessing responses will be limited.

[Wiredup62]

My 60 GT has the under gunnel vents and no vents along the outside of the hull. I have not had any issues, but the CAT C32 acerts don't smoke much anyway.

[racclarkson@gmail.com]

We get soot on the transom and in the cockpit areas over time. Was looking into mechanical issues and tune up but decided that's probably not the issue. Engines (8-92TI's) start with no smoke and run super clean. Zero visible exhaust on plane. Clean air filters, intercoolers, and good turbo's.

But we still get the soot buildup on the paint. If we go into a strong headwind it builds up quicker. Calm days or wind behind us much less. Also we get salt mist spray in the same areas more in head wind and less in tailwind.

So basically seems like a big station wagon effect compounded by the under gunnel air intake. Not sure if the amount of air drawn into ER is enough to be a factor. Also we have a full 4 sided enclosure with no openings ion the back other than ladder area.

Wondering if others experience the same. Most SF's have the ER vents on the side. Guessing responses will be limited.

I got some high hour Detroit 71's, and mine intake under the cockpit coaming as well. But, I've not experienced sooting around the transom.

[madhatter1]

Maybe Its just the 46 design. I wanted to dig into injectors and tuning and such but my mechanic questioned why on perfectly clean running engines. And he is not the kind of guy who would turn down work. I run kind of slow at 22 MPH when it can run 26-27 MPH all day long. Cruise at 1750-1800 RPM's. Maybe I should run them at 1900 to burn a little hotter and cruise faster. Strange since they run so clean by the eye.

[madhatter1]

Just to clarify when I say soot i mean stains in paint that wash right off with spray-9. Not actual heavy soot buildup.

[pdog]

My 46 has under gunnel air intakes as well. I have had zero issues with soot on transom. I do get the mist at times depending on wind direction.

[madhatter1]

Perhaps I do need to address this from a mechanical standpoint. Just seems odd with the exhaust so clean to the eye. Thanks for the responses. Answered my question.

[Jim saco]

We get soot on the transom and in the cockpit areas over time. Was looking into mechanical issues and tune up but decided that's probably not the issue. Engines (8-92TI's) start with no smoke and run super clean. Zero visible exhaust on plane. Clean air filters, intercoolers, and good turbo's.

But we still get the soot buildup on the paint. If we go into a strong headwind it builds up quicker. Calm days or wind behind us much less. Also we get salt mist spray in the same areas more in head wind and less in tailwind.

So basically seems like a big station wagon effect compounded by the under gunnel air intake. Not sure if the amount of air drawn into ER is enough to be a factor. Also we have a full 4 sided enclosure with no openings ion the back other than ladder area.

Wondering if others experience the same. Most SF's have the ER vents on the side. Guessing responses will be limited.

I get the same results on my 41. Especially with a strong headwind as you’ve described. I’ve always blamed it on the cockpit air intakes pulling exhaust back into the cockpit.

[madhatter1]

My tanks and fuel are so clean I never see any hint of goop or water in the Racor bowls. In fact the seals started to leak since it had been so long since they were serviced other than filter changes. The guy they sent thought they had just be cleaned recently.

But I guess that has nothing to do with fuel quality. We buy from local municipal marina that does plenty of volume. What additives are good to use? of volume.

[ageless]

Have you run load numbers? What's your engine temps? Possibly overloaded?? I use the Opti-lube Summer because the volume to ratio is AMAZING and my fuel is pretty clean with all the injectors in my 12/71's rebuilt by RPM in the last year, so worth it to have the assurance there's no reliajunk injectors in my ER

I have cockpit intakes and had soot when I was overloaded, after the injectors were done and I was 100% there was nothing mechanical I was 250 star/400port overloaded that I fixed with prop service. Soot gone