technical layout

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  • cookie
    LPBC wearer
    • Aug 2008
    • 493

    technical layout

    I would greatly appreciate your opinion on the technical layout of my 27' sailboat. There is a sloppy drawing of the current situation below, but there are some thing I like to change. As I will be rebuilding pretty much the whole deck, cockpit, bulkheads, etc, I might as well do things right

    Some of the questions I have are:
    • Where to put the diesel tank and does it need to be stainless?
    • Where to put the propane tank
    • What heating system is preferred, gas or oil burning?
    • Would it be a good idea to move the batteries from under the bed to somewhere where I don't breathe charging fumes, for example in the aft storage box or engine compartment? The fuses and main switches are located rather far forward, at the end of the kitchen on starboard side.
    • The engine currently gets air through a gap in the cockpit sole, but I want to make a sort of respiratory tube system. Any suggestions?
    • Is for and aft weight distribution critical, or can I move things like batteries, fuel and propane tanks around a bit?

    I am also thinking about having the cooler and "the can" switch locations, as the cooler is now in the bathroom

    When you're chewing on life's gristle
    Don't grumble, give a whistle...
  • floatingkiwi
    country member
    • Nov 2008
    • 3603

    #2
    Re: technical layout

    I don't know if there is any such thing as a fully qualified layout technician, but if there is, I am not one.
    However, the batteries where they are, seem to me, couldn't be in a place that gets thrashed about as much as they do there.
    I would put them in a low place where there is least rocking and rolling.
    Centreline aft of keel, in front of the engine, perhaps.
    Those Gougeon Brothers have good ideas for making built in spaces that use the shape of the hull efficiently. Square corners but not at the bottom.
    Last edited by floatingkiwi; 04-17-2010, 08:33 AM.
    ..don't judge a man till you've walked a mile in his shoes..

    Comment

    • Peerie Maa
      Old Grey Inquisitive One
      • Oct 2008
      • 62422

      #3
      Re: technical layout

      Try and keep the heavy weights near midships, and keep the variable weights there as well, or you will experience changes of trim as you empty and fill the tanks. The designer will have considered trim when he positioned everything, so if you move something forward, move something of similar weigh the same distance aft.

      Ensure that your gas bottle compartment has a drain to allow leaking gas to flow out from the bottom of the stowage to outboard.

      Your engine intake can be run through a duct, just ensure that it is of sufficient cross section to avoid choking the engine.
      It really is quite difficult to build an ugly wooden boat.

      The power of the web: Anyone can post anything on the web
      The weakness of the web: Anyone can post anything on the web.

      Comment

      • Ian McColgin
        Senior Member
        • Apr 1999
        • 51639

        #4
        Re: technical layout

        The propane tank may be as good as it gets - presumably isolated from the interior and vented overboard.

        Batteries should be boxed with a lid to keep tools or junk from falling in and shorting across the terminals. But really, outgassing is not a huge problem and the normal gaps in the lid allow the light gas to waft away. If you don't like sleeping over them, move them up to the cockpit where they will be the last thing covered with water in the event of catastrophy. Nice to have juice to the radio for that last mayday.

        I like a main panel near the companion, which if you move the battery boxes to one each side of the cockpit under the seats, is convenient also for the selector switch. This makes a neat configuration. You're ripping up enough that designing and laying down a really righteous wireing is good. Be sure all the leads are labled - best those shrink-on number labels and a key at the diagram which is posted inside the switch-breaker panel - and by labeled I mean at BOTH ends.

        I have lived through three boats where the wiring was evolutionary under previous owners and forget the myth of intelligent design as all evolution is chaotic, messy, random and confusing. Nothing worse than chasing down wires to nowhere. Do this correctly and God, as well as any future owners, will love you.

        Air to the engine compartment from the accomodation and bilges is a good thing - keeps those spaces sweeter and may allow your air filtres to last a nudge longer. Venting out can be enhanced with a blower. Good thing. Only power vent out, never in. Instead of the gap you describe you can make a slightly baffeled path to cut down sound transfer.

        Fuel tanks can be aluminum, stainless, black iron, plastic, built-in glass, and built-in rubbery flexable. Much depends. Are you looking at an odd space? Would you want to build it or have it fabricated?

        Fore and aft weight matters. Depending on the design, you may notice that she sails poorly with that foreward water tank empty but that on the mooring she seems a little down at the bow, coming to her right lines only when there's crew in the cockpit. Moving a couple of biggish batteries for a small boat, 4D or something, is a couple hundred pounds but under the berth to forward edged of the the cockpit is no biggie. Moving tanks around or moving batteries much further could be an issue. Try to make your moves symetrical - towards the center.

        Heating - depends on what you're up to. If you want to live-aboard in winter, it's hard to beat oil but the units I've used all need either a low pressure pump or adequate gravity feed from a dedicated tank, which could be an installation fiddle issue of the first water. I am prejudiced against propane as I don't like things that go boom in the dark. If intermittant use, like taking the chill off while the coffee brews on an autum morning or while you enjoy the stew at the end of a blustery spring day, it's hard to beat a solid fuel unit feed by driftwood and perhaps some charcoal (expensive for permanent heating but worth the ease for a couple hourse here and there).

        G'luck
        Last edited by Ian McColgin; 04-17-2010, 10:07 AM. Reason: heat

        Comment

        • cookie
          LPBC wearer
          • Aug 2008
          • 493

          #5
          Re: technical layout

          Thanks all, that's very helpful and makes a lot of sense.


          I think I'll move the batteries toward the companion way. One to be placed where the diesel tank is now located. The other on port side, and install a small (plastic) fuel tank aft of the engine.
          The boat came with a gas heater, but if I can find an affordable oil heater, then oil it will be.



          The only problem left now is how to properly ventilate the lower area of where the propane tank is located.
          When you're chewing on life's gristle
          Don't grumble, give a whistle...

          Comment

          • JimConlin
            Senior Member
            • Oct 2000
            • 10678

            #6
            Re: technical layout

            Read THIS BOOK

            Comment

            • cookie
              LPBC wearer
              • Aug 2008
              • 493

              #7
              Re: technical layout

              Another book

              I plowed through 3 books today, and none had the answers. Or at least not as good as the answers I got above.

              Still, I think it will be difficult to find a good solution for ventilating the propane storage area, as it is so low, the bottom of the tank probably being a couple inches below the waterline.....
              When you're chewing on life's gristle
              Don't grumble, give a whistle...

              Comment

              • Peerie Maa
                Old Grey Inquisitive One
                • Oct 2008
                • 62422

                #8
                Re: technical layout

                Originally posted by cookie
                Still, I think it will be difficult to find a good solution for ventilating the propane storage area, as it is so low, the bottom of the tank probably being a couple inches below the waterline.....
                If you can't build a stowage with a gas tight base above the waterline in the counter, look fore somewhere else for the bottle. Will it fit right up in the bow, with a wt bulkhead behind it and a hatch in the deck? Some designs stow the ground tackle there with an ob drain.
                Last edited by Peerie Maa; 04-17-2010, 04:20 PM. Reason: For clarity
                It really is quite difficult to build an ugly wooden boat.

                The power of the web: Anyone can post anything on the web
                The weakness of the web: Anyone can post anything on the web.

                Comment

                • donald branscom
                  Senior Member
                  • Nov 2004
                  • 5197

                  #9
                  Re: technical layout

                  Originally posted by floatingkiwi
                  I don't know if there is any such thing as a fully qualified layout technician, but if there is, I am not one.
                  However, the batteries where they are, seem to me, couldn't be in a place that gets thrashed about as much as they do there.
                  I would put them in a low place where there is least rocking and rolling.
                  Centreline aft of keel, in front of the engine, perhaps.
                  Those Gougeon Brothers have good ideas for making built in spaces that use the shape of the hull efficiently. Square corners but not at the bottom.
                  FLOATING KIWI is right.
                  The battery location is not good.
                  They should be down low close to the engine as possible or closer to the center of the boat. Also Try to put them together if possible.
                  You want to keep the battery cables short.
                  The ONLY reason to have a battery in the forepeak of a boat is to avoid the cost of a heavy battery cable going all the way to an electric winch, and that is NOT a good reason to have a battery up there.
                  The Coast Guard requires a cover over the batteries and if they are together you will only have to make one cover. Or one box.
                  You do not want cable crossing under the walk way. It creates problems.

                  Opposite the batteries put something heavy like a tool kit or other heavy items to balance the boat.

                  Use the old battery location to store things you do not need often.
                  I love the smell of fresh cut plywood in the morning.

                  Comment

                  • donald branscom
                    Senior Member
                    • Nov 2004
                    • 5197

                    #10
                    Re: technical layout

                    There are many good boat books about the layout of the interior of a boat.

                    You also need to move that water tank.
                    Right now you have the batteries AND water tank in the bow of the boat. Crazy.
                    The galley(kitchen) is it the right place. It needs to be near the conpanionway.

                    Whoever made that drawing was not a sailor.
                    Things are labeled like a house ie, BED,Kitchen, etc.,.

                    The one thing that is RIGHT is the denny's style dining area. It will be VERY useful for charts and sitting with a friend for coffee and a meal.
                    The seats are shown as being different sizes. Not good.
                    Seats should be comfortable. I won't get into all the dementions but the table has to be at least 12inches above the seat cushion. Also the table edge should be directly above the seat front edge. The BEST book for those measurements is Tom Colvin's "Cruising as a way of Life" book. There are others too.

                    There are TWO ways to design a boat interior. One way is for people who do NOT live on a boat, and the other way is for people who DO live on the boat.
                    When the people who do NOT live on a boat go on a boat that is a live aboard style boat they always like it MORE. So there is ONE way to design the boat.
                    LIKE YOU WILL LIVE THERE.

                    The lockers in the cockpit should NOT be open to the interior of the boat.
                    You can read about all the boats lost at sea for that reason alone.
                    All lockers have to have latches. And you can read about all the people hurt at sea by things getting loose from lockers.

                    If you have a nice dining table you will not need a chart table.
                    And in real practice you need those charts on deck a lot of the time especially on inland waterways. That is why they make waterproof charts.
                    Out in the ocean you will not need the charts on deck.

                    You do NOT need a refrigerator.
                    You do not need a built in toilet like a house has.
                    You do not need a built in shower like a house has.
                    I love the smell of fresh cut plywood in the morning.

                    Comment

                    • donald branscom
                      Senior Member
                      • Nov 2004
                      • 5197

                      #11
                      Re: technical layout

                      Now I will tell you about fuel tanks.

                      You need a main fuel tank and a DAY TANK.

                      The day tank can be plastic 11 gallons. Or smaller. They are Coast Guard approved,
                      Polypropolene.


                      The main tank can be stainless. Aluminum condensates 3.5 times more than steel. Not good. Aluminum has to have fitting that are steel or aluminum NOT brass or you will have a lot of corrosion problems.
                      So that means when the aluminum tank is not full, it can get a lot of moisture in the fuel from condensation.
                      A steel tank is only slightly cheaper than a stainless tank but is not worth it unless you have a steel boat.
                      The steel tank has to be sanded to clean metal when fabricated and lined with special fuel proof epoxy paint. Steel tanks should have steel fittings.

                      Rember that if you are carrying a few hundred pounds of fuel on a 27 foot boat the performance under sail will be lousy in light air.


                      The truth is if you had a perkins 4-108 size engine and a 11 gallon day tank and the engine uses 1/4 gallon of fuel per hour you could go a long way before ever needing to transfer fuel from the main tank. That is 44 hours @ boat speed!


                      All fuel tanks have to have a fuel vent 1/2 inch diameter minimum going to the highest point above the deck and that is usually near the companion way, because it is just above the engine and the location of the fuel filters etc.,.


                      If your boat is for day sailing you may not need anything except the 11 gallon day tank.
                      A day tank is very useful if the main tank gets contaminated with growth, so you can run off of the day tank until the main tank can be filtered when you get to a repair facility.

                      And most important the day tank is above the engine so if the fuel pump quits or gets contaminated the DAY TANK gravity feeds the engine. Very Imprortant.
                      Last edited by donald branscom; 04-17-2010, 03:35 PM.
                      I love the smell of fresh cut plywood in the morning.

                      Comment

                      • donald branscom
                        Senior Member
                        • Nov 2004
                        • 5197

                        #12
                        Re: technical layout

                        BTW....You did not tell us what the boat is going to be used for.

                        Layouts of boats are in reference as to what they will be used for to a certain extent.
                        The remarks I have made so far are based just on a 27 FOOT boat.
                        Last edited by donald branscom; 04-17-2010, 03:40 PM.
                        I love the smell of fresh cut plywood in the morning.

                        Comment

                        • donald branscom
                          Senior Member
                          • Nov 2004
                          • 5197

                          #13
                          Re: technical layout

                          Originally posted by Peerie Maa
                          If you can't build a stowage with a gas tight base above the waterline, look fore somewhere else for the bottle. Will it fit right up in the bow, with a wt bulkhead behind it and a hatch in the deck? Some designs stow the ground tackle there with an ob drain.

                          You CAN if the space for the tank has a vent at the bottom of the space that will not get water in it. Propane is heavier than air so the fumes go to the bottom of the space.
                          I love the smell of fresh cut plywood in the morning.

                          Comment

                          • Peerie Maa
                            Old Grey Inquisitive One
                            • Oct 2008
                            • 62422

                            #14
                            Re: technical layout

                            Originally posted by donald branscom
                            You CAN if the space for the tank has a vent at the bottom of the space that will not get water in it. Propane is heavier than air so the fumes go to the bottom of the space.
                            My point is that the space needs to vent overboard at its lowest point, to allow any leakages of the flammable gas to drain to atmosphere out side the boat.
                            It really is quite difficult to build an ugly wooden boat.

                            The power of the web: Anyone can post anything on the web
                            The weakness of the web: Anyone can post anything on the web.

                            Comment

                            • donald branscom
                              Senior Member
                              • Nov 2004
                              • 5197

                              #15
                              Re: technical layout

                              Originally posted by Peerie Maa
                              My point is that the space needs to vent overboard at its lowest point, to allow any leakages of the flammable gas to drain to atmosphere out side the boat.
                              Yes we agree, Peerie
                              I love the smell of fresh cut plywood in the morning.

                              Comment

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