Wheelhouse windows

Discussion in 'Boatbuilding' started by Johns1152, Oct 11, 2010.

  1. viking north
    Joined: Dec 2010
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    viking north VINLAND

    I don't normally nit pick on the price of corn but i feel this is important enought to do so to set a comparison base here where individuals can make an informed decision on whichever style they wish but know the basic pros and cons of each. So lets get rid of the murky waters and compare apples with apples. Given, two identical vessels with only one difference. One has a forward sloped windshield the other a reverse sloped windshield. If we expose both to an identical big boarding sea,that encounters the windshield with the same force.Which is more suseptiable to having it's winshield damaged. From logic you have to choose one or the other. Geo.
     
  2. TeddyDiver
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    TeddyDiver Gollywobbler

    In most designs it's given by the function and there's not much to choose from. Like DS sailboat vs North sea trawler. :)
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    If the windscreens are spec'ed to the same strength, then the raked fore or aft point is moot, as both will survive. Granted one may require different scantlings, but this is a typical engineering solution and has little bearing on the reality of the window's life at sea.
     
  4. Boston

    Boston Previous Member

    interesting thread guys
    while I cant comment on the raked forward or aft question ( although I like Marks Logic on this one ) I might add a word about installation, and mind you my experience in this area is limited to terrestrial applications.
    You always want the window to float in the frame. It should have room to move a bit to both dampen vibrations of impact and to allow twist in the surrounding structure. Also a quick word about laminate glass. Auto lami is annealed glass by law, I'm sure you can get it tempered but whats used in the auto industry is exclusively annealed, otherwise it would be your face that broke rather than the glass. Temp lami is the bomb, triple lami 1/4 will stop most caliber of bullets, if properly installed it will stop multiple strikes. It might be posible to find bent tempered Lami used in rear windshields so don't let me discourage anyone but the forward wind screen will always be annealed laminated glass, highly prone to cracking.

    cheers
    B

    PS
    the glass configuration with the highest strength that you can typically order is 1/4 tempered over 3/8 tempered over 1/4 tempered with 3m blast resistant film on the inside. Your going to have to keep your fingers off the film cause its prone to scratching. I'm not particularly fond of polycarbonate for a number of reasons but one simple one is that it breaks into razor sharp shards, so I'd hesitate to use it on forward facing exposures.

    carry on
    B
     
  5. michael pierzga
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    michael pierzga Senior Member

    Yes, you want the glass to float. The way I do it is by using these little stick on rubber "drops " in either clear or black that you purchase at a hardware store to keep doors from vibrating. Stick them on the edges and on the mating surfaces. The rubber drops keep the glass suspended in the frame and insure that the caulked joint in not starved.
    I cant remember , either Bostik or Sika has a good glass fitting tutorial.

    I generally use a two step process. First adhere the window to the frame, let cure, then finish caulk the seam. Difficult to do both simultaneously , stay inside the skin time of the caulking and difficult to avoid bubbles during the fitting stage.
     

    Attached Files:

  6. mark775

    mark775 Guest

    Bos, thank-you. You've got a guy that has been fishing where the Gulf stream rips and upwells in the North Atlantic, and a guy that has been on the ocean 8,000 days of his life on (mostly) the not so "Pacific"... both of these guys are telling you something different than what some school book says about how waves hit a window.
    Here, have a look-see.
    http://www.pukuk.com/MVpukuk.html

    This is a friend of mine who grew up working boats in Alaska and fished Bearing Sea crab in the seventies. He once took a wave on a boat that folded the steel cabin back three inches (it actually buckled the steel). He is acutely aware of the power the sea can have so because of the configuration of his new boat with the working foredeck, and needing forward raked window for good deck visability, he did this;
    http://www.pukuk.com/P7240007_op_800x600.jpg

    I honestly don't know what his windows consist of but I do know that he plies the Aleutians (crazy, if you ask me) in this little boat so he specified 3/8" steel cabin construction, fully expecting that solid water will one day make it past the dodger and hit his cabin. Were it you, would you want what a classification society specifies as a minimum (probably 3/16") or would you feel better believing you might survive the force of a Suburban head-on?
    For the life of me, I do not know what the drawings of a wave, a little bigger wave, and a "fully developed wave" have to do with anything. When the front of your boat scoops solid water, you can divert it like with the dodger on the Puk Uk, you can let it run parallel to your windows as it comes aft and up (particularly if you have a forecabin) or you can make a deadend with foreward raked windows where the water has nowhere to go. I'm betting that the books don't specify much of a difference in glass for forward, vertical, and aft. Why would that be - because the guy writing the book hasn't experienced burying the front half of his boat into a wave traveling in the opposit direction as the boat? Picture it... You are falling off of one wave crest (you had to keep a little headway on to maintain steerage. You are just "jogging"), building up speed at the acceleration of a falling object (I don't know, you are now doing 15, 20 knots in a fall?) when you touch down, you continue down for a moment, until the next wave rises to smash headlong into the front half of your boat at 15 or 20 knots in the opposite direction. It is absolutely a heavy wall of water traveling exactly perpendicular to a forward raked window at a combined speed of say, 35 knots.
    Big boats get away with this, aft cabin boats somewhat get away with this. A small boat with forward raked windows? Bloody stupid - I don't care what some guy who hasn't been there says.
    I'm putting way more time into this than should be necessary but sometimes it takes a little longer. I'm okay with it... for now. Here:
    window rake.jpg

    A is the worst case scenario as far as design. I know of many boats with glass removed with this design. I know of a passenger on a boat that was hit by water and glass as the 1/4" laminated glass imploded.
    B is infinately better, other than it doesn't give you much of an overhead space to hang your radios and it rains on your glass.
    If you must have forward raked windows, C is a fair compromise and will you believe me... even though I don't have a case study... will you believe me, that the little forward cant of the cabin front will act as a dodger and possibly keep you alive one day? No, it isn't pretty. One has to be creative to make it blend with any other line on most profiles, but it seriously may save you by diverting a volume of water with the same shape as it from hitting your window.

    Small craft generally simply cannot afford the weight of heavy enough glass to make a forward raked window a seaworthy alternative.
     
  7. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Being the guy that fished the north atlantic i can front line attest, the Labrador/South Greenland / North west Alaska ocean area as Mark pointed is meet your maker anytime fishing. Been there done that don't want to go back. EVER !
    Teddydriver you are probably correct not much out there in pleasure craft and probably for two reasons the risk,and the extra cost to try and compensate for the risk. Looked at your build last night, nice work.
    PAR,i agree that forward sloping windows must be engineered differently than vertical or reverse but I can't seem to find any of these engineering studys or specs specifically related to the forward slope verses the vertical(straight) verses the aft sloped. I am going to search it out a little further and contact the Marine Division of Memorial University in St John's, NFLD. Surely someone has done a study.
    Mark775, Good point on the boat speed factor when beating into it, in addition to the wave dynamics. Wave dynamics being a huge factor in determining all marine specs.While i never actually mentioned it one envisions the two as a boarding sea approaches. Also sounds typical ,the people in the field(fishermen) whom this is a big concern are modifying their vessels to compensate. Geo.
    P.S.
    Bloddy good thread, DAM important topic and Great info, thats not been really been presented or explored to any extent on this forum. I also have a small confession RE my intense interest and debate on this topic, I have a relative thats in the planning stage of building a new north atlantic shrimper and the fishing area could also include the northern Labrador coast.

    A yacht is not defined by the vessel but by the care and love of her owner
     
  8. TeddyDiver
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    TeddyDiver Gollywobbler

    Thanks:) I hope to gain some progress this year.
    One thing about wheelhouses and forward raked windows... they used to be (in the good old days) allways well above the deck and the front was rounded.. for obvious reasons mentioned in this thread.
     
  9. SeaJay
    Joined: Jun 2007
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    SeaJay Senior Member

    I'm still curious on what you guys think about vertical windows that form a bow shaped configuration, shedding water to the sides?

    http://setsail.com/fpb-64-avatar-final-trial/#more-12092

    Somewhere on Dashew's site are some photos of them taking some heavier seas, and a discussion regarding the window construction? As has been stated earlier; in the final analysis, it is really an engineering issue and I know Dashew addressed it properly, but if we're discussing the relative pressures felt by various window orientations, then I'd be interested in how you feel this general configuration measures up.

    I'm interested in using it as I feel it is an appropriate compromise for me between sea-worthiness, aesthetics, solar gain, glare, etc.
     
  10. michael pierzga
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    michael pierzga Senior Member

    Perpendicular windows are nice to look out of . No glare...day and night...no sunshine heat..perfect. they also free up space on deck and in the wheelhouse. Will they blow out on a small yacht...sure !!!. WHO CARES. Simply design your wheelhouse with blown out windows in mind. Self bailing via jumbo drains with a companionway arrangement that has regulation sill height, wash boards and is one hundred percent watertight even if your missing windows. This is the only way on a small vessel. . All windows, no matter what angle, size, material, are fragile.
     
  11. mark775

    mark775 Guest

    "well above the deck and the front was rounded." - Those were designed before there were naval architects. They had to work and each boat evolved differently in specific regions. In case it is not perfectly clear the force I am talking about, I killed another 45 minutes on Paint:
    wave window..jpg

    The volume of water in green is something well mounted 3/16" glass survives. 1/4" will not survive this on boats anything like the one in the drawing at 40' LOA. School bus glass (3/16) is marginal, at best, if the windows are forward raked. I have seen them implode both into pieces and as an intact piece of glass on a poorly fitted rubber frame. If the bow buries another few feet, there is an impact like a head-on collision with the entire ocean. That's the one where one wants to minimize perpendicular frontal area, particularly of glass. Notice how the fronts of serious sportfishermen don't have glass in the lower cabin any more?
     
  12. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Mark, your drawing and description is reality, don't know who else out there have ever experienced this but i have and i have to be honest 90% of your brain is occupied trying to control the remaining 10% not to panic and once you do control these waves of nausia and fear your screaming at the guy next to you to keep both him, yourself and anyone else not under total shock semi alert and into angry survival mode. It's really not nice and as i vividly recall during these nightmares the constant murmuring "she can make it, "she can make it","hope the glass holds" "hope the glass holds" over and over one sea at a time. So I think we owe those out there and those that will be out there to
    do our best to present good productive input and come up with some recommendations and solutions to improve upon some of the wheelhouse window designs that are now going to sea. In my opinion and this is just my opinion thus far there has been some really good input here and from that there seems to be some good recommendations and prevenitive structural design measures.
    Mark775 thank you for having the gumpsion for bringing it up, being the new guy amoung the group i really didn't want to rock the boat but i'm brave when i see a like minded concernd expressed (smiley face) I'd really like to find out more about the deflector installed on the boat you referred to. Is this a new idea ? Have you gotten any feedback on it's success? Is it a feature now being recommended? Have many other fishermen showed interest in it?
    Boston, posted info on the glass itself. What does others think of this info. Is there a recommendation that could be made to improve this part of the equasion,IE are the products and specs. outdated? Can they be improved upon? Should there a higher minimum standard.
    What about the idea of going back to the old school of windshield being set up in a rounded pattern design. I think it would certainlly reduce impact pressure and give a more panaramic view.
    Just some thoughts on some items posted that with further discussion would definately yield good info for all out there. I for one never underestimate what we are doing here, a safety concern discussion that all the world out there has access to. Geo.


    A yacht is not defined by the vessel but by the care and love of her owner
     
  13. mark775

    mark775 Guest

    Thanks. Glad we're on the same page (of the book I don't like to use)! One other thing. We've got a Russian fleet here that uses Lexan a lot. They seem to get along pretty well with it but it does get scratched up and I see it broken now and again. They have done hundreds of boats with it and will tell you that in "sandblasting" conditions (hiding from seas in a protected spot also often invites what we call piteraqs or williwaws but they are not actually katabatic but only an intensifying of wind pressures because of peculiarities in topography - I think of these winds like an airplane wing - the air has further to travel so it necessaily travels faster. I have hidden from a 60 knot blow only to discover 120 knots in my hide out.) it can become almost completely hazed to the point of invisability. I have even known glass to need replacement after a good blow through a hidey-hole. In general, if it is really gonna smoke, one should find a non-sand anchorage (thankfully, solid rock and clay hold much better anyway), and the coast pilot will tell you which anchorages are subject to this type of wind. I wouldn't get near sand with plastic windows even tho I have considered them to save weight. I think it better to use heavy glass forward and perhaps a little lighter on the sides ( though I once removed every starboard side window from a 53' Hoquiam on the Willapa Bar). It's nice to have the specs of what others think but a rule of thumb for me is "thicker and smaller than what everybody else thinks". My own boat has made me turn around because I wasn't sure the glass could take it. My plans are to get rid of the sliders which I have broken MANY times, and replace the fronts with 1/2" tempered (and never test it!).
     
  14. mark775

    mark775 Guest

    There was another thread talking about clouding of laminated around the edges. It may come up if you search "Windhorse" because his are straight 3/4" tempered, I think. With that design, I think the potential is strong to hit that front hard. The dodgers are common and have been done for a hundred years on some types of boats. A Portuguese bridge does the same thing - protects what is behind it. A beautiful AND seaworthy design but look at the length they went to to keep seas off of that front glass:
    007.JPG
    That is a Portuguese bridge.


    A simple and seaworthy design (high bow, thick glass small and aft-raked) and an expensive and seaworthy design (higher bow, thicker glass, windows out reach of most of the sea.
    013.jpg
     

  15. Boston

    Boston Previous Member

    doesn't anyone ever use storm shutters any more
     
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