Deck design question

Discussion in 'Fiberglass and Composite Boat Building' started by forestjohnson, Nov 22, 2005.

  1. forestjohnson
    Joined: Aug 2005
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    Location: Merritt Island, FL

    forestjohnson Junior Member

    I am designing the new deck for my 32' express sportfish w/ twin diesel inboards and have a question for you, do you think that access to the exhaust system is important? I would like to glass in the decks and this would cover the exhaust system. The only way to access it in the future would be to cut the floor or pull the engine. I guess my question is how often do mufflers, couplers, and pipes have to be serviced. Any ideas of alternative ways of providing access? I have looked at many boats and it seems that very few have access to the exhaust system.
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Most boat manufacturers care little about the sometimes exhorbitant cost of servicing the boat because of lack of access. I can't see why you would do that to yourself. Can you make a flush hatch that is caulked and screwed down?
     
  3. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    There is NO hard & fast rule that the exhaust MUST come out at the transom.

    Many north sea trawlers that don't use dry stack have a large exhaust pipe that runs athwartships with exits on both sides of the boat.

    The exhaust is dumped into the cross pipe and the exhaust coolant goes out which ever side is low.

    Slightly below the water line (if you dare) and displacement speed noise is tiny.

    FAST FRED
     
  4. gonzo
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    Location: Milwaukee, WI

    gonzo Senior Member

    That setup is known as a "North Sea exhaust". It works very well, specially on boats with low freeboard. The drawbacks are dirty sides and more fumes in the cockpit.
     
  5. forestjohnson
    Joined: Aug 2005
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    forestjohnson Junior Member

    Thanks guys. I think I will make a flush hatch that is caulked and screwed down. It may not look as good, but I might thank myself later.
     
  6. Vince Hosea
    Joined: Dec 2005
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    Location: Port Orchard, Washington, USA

    Vince Hosea Junior Member

    Exhaust Accessability

    Whatever you decide to do I would strongly encourage you to make the exhaust system accessable. An exhaust run isn't something you seal up and forget about. It, like any other system needs to be inspected on a regular basis. Also, there is much you can't see. The hose might be subject to vibration and premature wear in a place you do not even suspect.

    When time comes to inspect or replace the hose run, do you really want to pay even more for a fiberglass guy or marine carpenter to cut out decks, interior fixtures, etc. and replace them? I changed out an entire wet exhaust run on a 1980 Grand Banks 42 (twin diesels) a couple years back. It was nearly 60 feet of 3.5 inch hose. For the following year, I returned to the boat 30 days after the install and quarterly thereafter, to check the connections and various places along the runs to make sure everything was ok. This required less than 30 minutes to remove and reinstall bunk mattress boards, some closet and cabnet panels. Had I not been able to access these out of view areas I would have turned the job down. The install and follow up checks would have been almost impossible. It turned out this was original hose, almost 25 years old. It was dripping into the boat all throughout the run. The worst part was within 6 feet of the engines where it had severly delaminated into this gray mush.

    Inspecting the exterior of the wet exhaust hose run and various pipe connections for leaks and rubbing should be done several times a year. Inspecting the interior of the water injection elbows/exhaust manifolds, Verna-Lift, mufflers, whatever you have system, etc. hose run, especially near the engine, should be done yearly, maybe every two years depending on the condition of your system. When you get a feel for what kind of condition the system is in and know of its weaknesses, then you can stretch out check time frames, but no longer than four years for the risers or manifolds where seawater is injected. If you have an overheating issue or you suspect the sea water impeller took a dump, then immediately check the wet exhaust hose. A wet exhaust hose without water will crack and ruin the hose (allthough J2006 hose is suppose to handle two min. of run time without water). Perhaps the idea behind a boat's maintenance schedule is best summed up and described by what Harrison Ford said in the U-Boat movie where he played a stern U-Boat captain. I do not recall the exact line, but he said something to the effect that a captain knows every bolt, every weld of his ship. The same applies here.

    I have worked as a marine mechanic and I'd swear some boats were built by dwarfs. Don't box things in. It will make maintenance easier. I would also consider very much the boat's resale value with such a system boxed in.
    Good luck,
    Vince
     
  7. captword
    Joined: Jan 2004
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    Location: Morehead City North Carolina

    captword Junior Member

    do the dacron hatch

    take a a length of doulbed up 130 pound test dacron long enuf to go around the hatch. Lay the dacron in the crack around the hatch. apply 5200 fast set. whipe very clean with denatured alcohol. you can either paint over as it is or you can fair it even more on top of the caulk. wich ever is more pleasing to the eye. when you get to the point of removing the hatch, dig into the caulk in just one spot. pull straight up and you unzip the hatch doing less damage.
     
  8. gonzo
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    gonzo Senior Member

    That's a smart idea.
     

  9. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    Manufacturers don't care too much about future servicing, they don't do it. They want profit, hatches cost money and mess with the "looks", which is all most boat buyers know about, money and looks. Everything in a boat seems to eventually crap out, including the structure of the boat itself, so the more easy access you have to things the less it costs to fix them. Bad exhaust systems sink a lot of boats, overheat it one time and if you can't inspect it, technically you should have trouble sleeping at night, if your boat is in the water. The simplest system with a muffler has 8 stainless steel hose clamps, it's nice to know when they rust up and fall off, it's even better if you can access them for replacement. A handy thing to do before the deck is installed is to put some pvc tubes in place in inaccesable areas for wires, cables etc. It keeps the present stuff in better condition and allows easy replacement, and easy installation of future doodads. A 4" pipe from the console to the aft end can fill up pretty quick on a big boat, one on each side can be handy also. Sam
     
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