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  1. #1

    Anyone have SF with under gunnel air intakes?

    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.
    1966 34c
    1982 46 HP

  2. #2

    Re: Anyone have SF with under gunnel air intakes?

    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.

  3. #3

    Re: Anyone have SF with under gunnel air intakes?

    Quote Originally Posted by madhatter1 View Post
    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.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

  4. #4

    Re: Anyone have SF with under gunnel air intakes?

    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.
    1966 34c
    1982 46 HP

  5. #5

    Re: Anyone have SF with under gunnel air intakes?

    Just to clarify when I say soot i mean stains in paint that wash right off with spray-9. Not actual heavy soot buildup.
    1966 34c
    1982 46 HP

  6. #6

    Re: Anyone have SF with under gunnel air intakes?

    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.
    Jason
    Orange Beach, AL
    1984 46C

  7. #7

    Re: Anyone have SF with under gunnel air intakes?

    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.
    1966 34c
    1982 46 HP

  8. #8

    Re: Anyone have SF with under gunnel air intakes?

    Hatteras went to the cockpit combustion air intakes when salt ingestion became a problem. Most of the convertibles were hard fished in the day. Beating your way offshore to the offshore canyons would result in spray getting sucked into the intakes. I delivered several 46’s to Ben Hurley back in the day for the Hurley treatment one of his most popular mods was eliminating the side vents and adding cockpit intakes. I think Hatt went back to the side vents because of engine room noise being transferred into the cockpit. I understand the new vents are much larger and slow the velocity of the air coming in to give the spray a chance to drop out in the plenum box. As far as soot as long as there is no smoke behind the boat when your running just run it. Could be crappy fuel also. I’ve had loads of fuel over the years that smoked more than others. Who knows what’s going on at the refinery. We used to spend the month of June at Marsh Harbor. Fished 25 days back to back. The fuel there was clear as gin and burned cleaner and the boat preformed better than it ever has. Fuel guys said that their fuel came from Venezuela. I never really considered before where the oil came from and how it was refined.
    "DON'T BELIEVE ANYTHING YOU READ OR HEAR AND ONLY HALF OF WHAT YOU SEE" - BEN FRANKLIN




    Endless Summer
    1967 50c 12/71n DDA 525hp
    ex Miss Betsy
    owners:
    Howard P. Miller 1967-1974
    Richard F Hull 1974-1976
    Robert J. & R.Scott Smith 1976-present

  9. #9

    Re: Anyone have SF with under gunnel air intakes?

    Robert, what is your opinion on servicing fuel injectors. As far as I know these are original from Dave's install on the new engine (950 hours) and the in frame rebuild (850 hours). I know injectors were done on the rebuild because original issue was an injector issue.

    And yes, downside to air intakes is engine room noise. The generator sound is loud enough in the cockpit to be irritating when on the hook.
    Last edited by madhatter1; 07-20-2021 at 08:15 AM.
    1966 34c
    1982 46 HP

  10. #10

    Re: Anyone have SF with under gunnel air intakes?

    Quote Originally Posted by madhatter1 View Post
    Robert, what is your opinion on servicing fuel injectors. As far as I know these are original from Dave's install on the new engine (950 hours) and the in frame rebuild (850 hours). I know injectors were done on the rebuild because original issue was an injector issue.And yes, downside to air intakes is engine room noise. The generator sound is loud enough in the cockpit to be irritating when on the hook.
    Easy question. Consult the injector guru Derek a/k/a Avenger on the forum.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

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