Just have to ask...About sailboat cabin height.

Discussion in 'Boat Design' started by SoNew, Dec 1, 2012.

  1. PAR
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    PAR Yacht Designer/Builder

    It's all in the goals of the SOR, nothing less or more. Sailors want to have some sailing ability when sailing, it can be generally assumed. Place a 3' tall, 6' long and wide box on the fore deck of a Catalina 22 and see how well it goes to windward. It becomes obvious pretty quickly and it has little to do with aesthetic considerations.
     
  2. michael pierzga
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    michael pierzga Senior Member

    Boats with high topsides and a low cabin house solve the interior volume issue in a more eye pleasing manner than ones with low topside hulls and tall cabins.

    Most modern boats follow this routine.

    Unfortunately tall topsides create their own usability problem. Some of these new 40 and 50 footers are so tall that its impossible to come alongside with a dinghy and climb aboard without some kinda boarding ladder.
     
  3. PAR
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    PAR Yacht Designer/Builder

    Modern boats have high freeboard because they employ canoe bodied hull forms, which limits below the LWL volume, so they have to get accommodations somewhere. Previous to the canoe body trends, more built down shapes where employed, which offered considerably more below the LWL volume, for accommodations and of course the associated drag that comes with these hull forms as well.
     
  4. tom28571
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    tom28571 Senior Member

    All true.

    Easy to miss an obvious factor like this.
     
  5. moTthediesel
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    moTthediesel Junior Member

    This shows one great advantage of the Seabright, or box keel hull form. They are an example of a boat that can be designed & built light, yet still get the cabin sole low enough to give good headroom without excessive freeboard.

    Tom
     
  6. Steve W
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    Steve W Senior Member

    Of course on many smaller canoe bodied hull forms you can walk on the hull skin as another means of maximizing available headroom, its very easy to lose 3 or 4" or more by trying to build a flat level cabin sole you dont need. Obviously if you build a giant box on the deck you will suffer from windage issues but on a lot of mid size sailboats that have, say, 6ft headroom and you just want a few inches more for comfort you can sometimes cut the top off and raise it a bit and/or lower the sole a bit and achieve what you want without unduly effecting the looks too much and to be honest you would never be able to notice any performance difference, its only when you want to gain a lot that that windage would come into play. I knew a guy who did this with a Peterson 34.Like i said before the designer needs to utilize all of the various tricks to maximize headroom in smaller boats. I once built a Bingham Allegra and it had something like 6ft headroom on a 24ft boat without looking out of proportion because you were standing down in the keel somewhat and lots of camber.

    Steve.

    Steve.
     
  7. PAR
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    PAR Yacht Designer/Builder

    Lots of tricks Steve. The American 25 used this trick, where a wide keel stub permitted 6'+ headroom, but you where standing on the ballast casting, below the fairbody of the hull/keel stub interface. Of course, this is precisely where boarding water would also accumulate. Excess roof crown is how the 20' Flicka gets away with it, plus a lot of hull rocker, built down garboards and cute little tricks to hide the 12" crown.

    I've found you need a 3 ton hull form to get enough volume for standing headroom. Flicka is 3 tons, on an 18' LWL, which is pushing the envelop quite a bit and she pays a dear price for this, with a D/L over 400 and she still looks a bit odd with her deckhouse proportions.
     
  8. Steve W
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    Steve W Senior Member

    Yes, the Flika looks a bit cartoonish but not ugly, the Fred Bingham Allegra was very similar but a bit better proportions with the extra length, My old Macgregor 36 catamaran was good example of a boat design that used no tricks and only had about 5ft or less with the hatch closed,it could have easily have achieved 6ft and the boat would have looked better for it. The boat had length to work with so it could have easily handled 6" more freeboard and looked more proportionate, it was too low for its length, it had plywood cabin soles which were always waterlogged and it didnt need(which i removed on mine) and the big hinged hatch had very little camber so it could have had a fixed top with a full radius, these three things would have given it an easy 6ft and the boat would have been more proportionate for the type. Of course it could have used a few tricks to get more interior width in the hulls too as the hull to deck joint wasted 3" each side of each hull that it could have sorely used plus the hulls themselves could have been 3" wider and still been road legal unless the trailable width was 8ft back in the 70s. Great boats though, blazing speed and better built than one would expect for a Mac.

    Steve.
     
  9. yipster
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    yipster designer

    Living in a box.
    Aint no boat but a car you can park after a long ride, walk to a diner and continue the journey.
    Big hatches on cat hulls I've seen, think even a raising saloon but dont recall seeing camper poptops on a smaller monos.
     
  10. TeddyDiver
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    TeddyDiver Gollywobbler

    Nobody builds doghouses anymore..
     
  11. daiquiri
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    daiquiri Engineering and Design

    The windage, the aesthetics and the ease of access to sheats is the main reason.
    Of course, if one is building a boat for himself and doesn't mind having a huge ugly doghouse bulging from the deck, it's ok - he doesn't have to ask for anyone's opinion. But if the boat has to be mass-produced and has to meet the taste of the general public, the aesthetic plays a huge role.

    The smaller the boat the boat gets, the more difficult it is to make the aesthetics and the functionality meet each other, when it comes to internal accomodation. It is especially true if one aims at designing a boat with modern look. Here's an example of a 5.5 m sailboat, with visually pleasing proportions, but with an inevitably low deckhouse:
    5.5 m sailboat - original.gif

    And here is a hypothetical alternative look of the same boat, stretched to have a full height in the cabin:
    5.5 m sailboat - full cabin height.gif

    They both have a fixed max beam for trailerability. To me the 2nd one looks like it just came out of some Disney comics, but it might be just a matter of personal taste.... ;)
     
  12. Steve W
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    Steve W Senior Member

    I dont think anyone would expect to get standing headroom in a 5.5m trailer sailer, there are no amount of design tricks to achieve this and still look accepteble, you need to get up to perhaps 7.5m and 2000kg before you can pull it off unless you can stand down in the keel, unless you have a fair bit of displacement you dont have enough boat under the water and therefore require even more freeboard. I have a boat sitting in my yard waiting for attention which i think is actually the minimum size to get 6ft headroom and still look good, its an old Lindenberg 26, the designer,Lee Creekmore used just about every trick in the book and i think came up with a good looking boat, i accept that some may disagree but it has considerable freeboard, quite a bit of displacement at 5300lbs, a nice amount of deck camber,a narrow trunk cabin which has the effect of getting the visual line of the cabinside to deck joint higher up than it would be if the cabin was wider which allows the cabin side to be lower, the cabin side is about as high as it can be, (he could probably have got away with a bit more crown to the cabintop, maybe), and to cap it all you stand on the hull, no cabinsole at all. So if the boat were any shorter it would be out of proportion.

    Steve.
     
  13. CDK
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    CDK retired engineer

    A couple of years ago I met a bald guy with a small sailing boat who moored in our bay for a few days. His head had been bleeding so I asked him what happened.
    He said every now and then he banged his head against a beam in the cabin because there was insufficient headroom.

    Two years later he showed up again, now with a crater-like indent in his skull, where a surgeon had removed a large amount of tissue. Repeated skin abrasion and subsequent exposure to the sun had lead to skin cancer.

    So yes, headroom is very important!
     
  14. Frosty

    Frosty Previous Member

    Surely the obvious is fatigue of stooping all the time. It will give you neck ache and make you tired.

    It may permenantly alter your stance.
     

  15. PAR
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    PAR Yacht Designer/Builder

    I use to live aboard a lovely 63' wooden ketch and of course I slept in the aft cabin, which had standing headroom for most of it. Between the beams I could stand, until just at the berth, which of course I forgot each morning as I woke, stretched and smacked my head. It wasn't long before a length of well padded carpet, was stabled to the offending beams, as I realized I wasn't ever going to be awake enough, to remember the headroom was only between them. No chainsaw was necessary, nor surgeons.
     
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