Raised Helm Deck for Inlet Surf Running Idea

Discussion in 'Boat Design' started by DouglasEagleson, Mar 9, 2016.

  1. gonzo
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    gonzo Senior Member

    There were some crews that abandoned their boats and drowned. The boats were found floating later with no significant damage. At least two abandoned because of broken rudders. That is what I mean by inexperienced.
     
  2. CT249
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    CT249 Senior Member

    Yep, some crews certainly abandoned too early and suffered tragically - but they weren't on "boats designed as daysailers". Yep, there certainly were rudder problems, involving people like world champion and life-long cruiser Harold Cudmore (certainly NOT inexperienced), Hobart winner Ted Heath (also not inexperienced) and I think David May (highly experienced).

    I'm not trying to be picky, but when we're trying to work out such important lessons it seems that we should be accurate.
     
  3. gonzo
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    gonzo Senior Member

    I've been at sea a large part of my life, and find it hard to understand why they abandoned a boat with a damaged rudder. The only explanation that seems to make sense is that they gave in to panic.
     
  4. DouglasEagleson
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    DouglasEagleson Junior Member

    Sealed Pilot House Design

    I was thinking further about the need for torsional strength in my raised deck helmsman pilot house. Up and down forces can be managed by a strong beam to the deck and/or the hull. The hull has up and down strength.

    But a sideways force challenges the connection bolts. Sideways on a bolt compared to up/down is a issue.

    But I have a solution. But a "X" frame on the pair of support beams. This locks the two beams together so a force of "away" from a bolt has a matching force of "toward" the opposite beam mount.

    With real carbon composite design an acceptable raised sealed helmsman station is allowed. In fact it will be strong enough to survive direct wave hit and full boat rolling. It will be legal as a component of self-righting calculation.

    Four foot wide and four food long would be about a person and a halve weight.


    66666666666******** asterisk means carbon station
    6666666666*666air
    666666666*6666
    @@@@@@hull deck
     
  5. gonzo
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    gonzo Senior Member

    Are you saying your boat is bolted together :)? Bolted structures are largely held together by friction. When the force is parallel to the bolt, localized stresses are much higher; the opposite of what you appear to be saying.....or maybe not. It is really hard to tell; amusing though.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Douglas, what type of engineering background do you have, as some of the questions and assumptions you've made in recent and previous posts suggests, not as firm a grasp as would be required? What type of stability calculation will you be employing? How are you calculating element modulus for your proposed carbon fiber tower (my assumption)?
     
  7. gonzo
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    gonzo Senior Member

    It is the "torsional strength" which manages the "up and down forces", duh.
     
  8. TANSL
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    TANSL Senior Member

    In the calculation of structures, and any other calculations, it is very important to analyze and understand the problem. Only then you can design the most appropriate solution. Forces perpendicular to hulls, or to deck beams, can not produce efforts on those elements related to their "torsional strength".
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    What an "uplifting" thread. It should be re-named the "Tower of Terror"
     
  10. CT249
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    CT249 Senior Member

    No.

    The two boats that I know of that abandoned ship due to rudder loss were Gunslinger and Golden Apple. Gunslinger abandoned because the boat had rolled and appeared to be taking on water. The crew were bailing but the water was gaining on them. In fact it appeared that the water that was gathering .in the bilge had probably been taken on in the roll, and was then running out of cupboards, mattresses etc. They then readied the raft but it was lost overboard, in another roll I think. With no raft and a chopper nearby, getting taken off is arguably a reasonable decision - who would risk five lives when a chopper is overhead?

    Morning Apple was in no danger but again, a chopper was overhead and it seemed to be a more reasonable option.

    One of the lessons from disasters is that it is all too easy for those who were not there to sit back and blame those who were there for the decisions they made. It's a factor that has been studied and recognised. Logically, we must understand that we who are sitting on the sidelines have a tendency to say "it wouldn't have happened to us" when we criticise others and what they did. What seems like panic to us sitting in our nice warm chairs is not panic when seen in context.


    PS- You're dead right, of course, about the bolt issue....perhaps Douglas needs to read some J.E. Gordon, at the very least, to understand the way basic mechanical fastenings work.
     
  11. TANSL
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    TANSL Senior Member

    CT249, I totally agree with you. It's amazing how many people throw opinions, with complete joy, no data and no rigor, on issues or problems that are very serious and difficult to clarify.
     
  12. gonzo
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    gonzo Senior Member

    Is that an opinion ;)?
     
  13. DouglasEagleson
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    DouglasEagleson Junior Member

    concerning my engineering.

    Yes I can not do structure calculations. The general result is that I over design concept wise. Engineers working with a 1.7 factor of excess strength scare me. Squeeze all excess out for the eloquence.

    I can do a trial design for demonstration only, though. The bolt issue is confused. I think the term is bolt glass-sheer for one force direction. And peeling for the sideways direction. I eliminated peeling force by locking the two mount beams together with an "X" sub-beam frame.
     
  14. DouglasEagleson
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    DouglasEagleson Junior Member

    All things considered yes I am making something odd. So going back the beginning again.

    Putting on a pilot house is my main goal. So simply extending the hull with an add-on section would look better. A "Stretch" addition. You would have a new section mounted behind the backstay. It could be elevated over the water or have subsurface hull also. A rather artistic design of extension is possible.

    The bolt/beams to attach the two is a real engineering trial. Some designs such as long overhang main hulls would likely use overhang section. Some hulls would be more conducive than others for Stretching/Add-on.

    Finding a place for a true pilot houses on 30 footers and less is problematic. So this method will work for real, but need a scantling like approach. Or just wing-it?

    I would also take the chance too make a lightning safe pilot house. An aluminum box inside a fiberglass section simply needs to be grounded. The inside would need to be covered with insulative materials like automobiles are. And have its own ground plate in the water. A plate separate from the mast/rigging ground plate.

    It would still be waterspout proof is given window covers and ventilation.

    So it is a ballast free add-on. And would not effect self-righting negatively. I would then allow a place on the roof for the inlet running. It could be an open helm position on the roof, or once again given a second story for the upper pilot house.

    Formal small sailboat work is this intention.
     

  15. gonzo
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    gonzo Senior Member

    What eloquence safety factor would you recommend for glass-sheer?
     
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