hatch or portlight

Discussion in 'Multihulls' started by rberrey, Sep 10, 2011.

  1. rberrey
    Joined: Oct 2010
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    rberrey Senior Member

    I plan on two 10" glass hatches on my 31' tri build , I have planed on three portlights, port and starboard. If I were to add three more 10" glass hatches what would be the pro,s and con,s of doing away with four of the six planed portlights? Rick
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    10" hatches are useless for anything other then passing a beer to the skipper. Do you mean an opening port rather then hatch?

    Opening ports can be a leak point, so it's important to get good ones, particularly if heading off shore. Generally, you'll want as much light as you can get down in a hull, so replacing the port lights with opening ports (all or partially) is the wise choice. As to how many, well it depends on the design, where you'll be sailing, etc. In my area, you want as many opening ports as practical. Don't forget storm shutters for all ports (opening or fixed).
     
  3. rberrey
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    rberrey Senior Member

    Thanks PAR, I didn't explain myself well. Small hatches topside for light and ventalation,in place of opening ports in hulls port and starboard. Hatches would be heavy duty off shore, any opening ports would be as well. The design is a tristar 31 so I need as much light as I can get , also I am on the Alabama gulf coast so ventalation is high on the list. I want to stay within my budget and get the most light and ventalation for my money. Adding two or more small bluewater hatches gets into some money . Thanks , Rick
     
  4. cavalier mk2
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    cavalier mk2 Senior Member

    Jim Brown always recommends fixed ports, preferably plastic-cast acrylic or polycarbonate for light and dedicated ventilators for airflow. Good ones let in the air and keep out the water. Think airplane instead of boat and you will be closer in terms of weight and use to the concept. Searunners have the back window opening and offshore its the only one that could be opened. I saw some neat wing vents on Newick plans that used plastic plumbing 45 angle Ts. The top and bottom are piped straight through and the 45 is angled up letting in the air while the rain and waves run straight out. Solar ventilators can pump air through on days without a breeze. You could make decent basic hatches yourself that will let in the air without ventilating our wallet!
     
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  5. rberrey
    Joined: Oct 2010
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    rberrey Senior Member

    I may make some of my hatches in areas that dont need lighting . There are vents designed for the boat, the extra hatches would just add more light to a dark boat. I have been thinking glass on the deck would give me more light per sq inch than glass in the side of the hull. I did think airplane, I bought a tristar design. I will install at least two solar vents, head and galley. Do you have any vents on your underwing ? Thanks, Rick
     
  6. cavalier mk2
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    cavalier mk2 Senior Member

    Yes, The under wing has vent/drains that have a fairing to keep the water out forward and aft that give good circulation without letting in water. Like a attic or roof a wing must be vented to prevent rupture, for example blow up a bag and then hit it with your hand, the wave. A wood boat needs the air circulation too for rot prevention.
    Hatches can be made as skylights with plastic too. Current bonding goops allow 50-60% expansion/ contraction without fasteners to keep things dry. Our old cabin windows with the rubber seals added 100 pounds to the boat , the cast acrylic weighs in at about 35. We will be installing them soon, I'll let you know how hard it is.
     
  7. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    Hatches for less money

    I have made a few hatches in different ways. The best by far is to make them out of cheap polyester resin and a mould.

    The people who made a sistership to my cat did this and they had heaps of hatches. They would have saved many thousands by making theirs.

    Get a piece of glass or melamine. Put surrounds around it with chamfered edges. Then coat the entire thing with some resin and wax. Then you glass the thing. I put foam in the large flat areas as I was making deck hatches. The builders I saw put perspex in theirs. Really strong. I bought hatch hardware from Maxwell.

    Don't make timber hatches - I am replacing all of mine. At the same time you should also make a mould for the hatch surrounds so you can glue that on.

    BTW - I have Gougeon brothers hatches on my boats too. If the bulkhead is vertical then you pop a piece of perspex into washboard like surrounds - its in their book on boatbuilding. My little cats have Gougeon hatches under the Searunner style brim at the aft cabin.

    We also use our lockers as vents as well. I took this idea from another cat. The front two hatches are at the foot of our beds. So I put some dinghy inspection hatches (and mossie screens) in the bulkhead. So to get more ventilation we pop the hatches up (even in the rain) and get breeze in.

    We also have dinghy inspection hatches in the galley. I open these and the pressure in the underwing breathes air mostly in but sometimes out.

    cheers

    Phil
     
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  8. cavalier mk2
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    cavalier mk2 Senior Member

    Thanks Phil, I'll try fiberglass hatches down the road. Wood epoxy still holds up though especially if you epoxy bond the hinge fasteners in. Where people don't rot starts in the screw holes.
     
  9. rberrey
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    rberrey Senior Member

    The hatches I will build will be all foam, glass, and epoxy. Vents in the underwing are something I have been thinking about for awhile, I have'nt looked at the plans on vent placement so Ed might already have one designed. Building a form is a good idea , even if I do use store bought hatches I will build storm covers. Rick
     

  10. cavalier mk2
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    cavalier mk2 Senior Member

    Something I forgot to add about underwing vents is that they be close enough to the center hull to be above the waterline if the ama is punched under. In the old Searunner books you'll see those boats diagrammed with the mainhull with a cruising load coming out of the water with the wing towards the ama and ama immersed in a extreme knockdown.I'll have to dig out the old AYRS issue for Doug with a Lock Crowther letter complaining about racing Nicol's with the interior stripped starting the dangerous trend toward main hull flying in competition...
     
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