Preliminary Sketch

Discussion in 'Option One' started by Willallison, Sep 10, 2002.

  1. Willallison
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    Willallison Senior Member

    As a starting point, here's a preliminary sketch for a Head-up O-1.
    It uses a number of the elements shown from previous points and (hopefully) ties them together to produce a boat to meet our objectives.
    As one should with all things in life, lets start at the front....
    Aft of the anchor locker (could be open at top, though I've shown it closed) is a pair of v-berth, with infill to for a double. Headroom here is at least 1.5m. A drop-down ladder provides safe, easy access to the foredeck, reducing the need to use the necessarily narrow side decks (250mm). Then come a pair of storage cabinets or draws, the stbd side doubling up as the instrument binacle for the helm, which is immediately behind it. Up one step into the saloon proper and the aforementioned helm is to stbd, a convertible dinette to port. The backrest flips back to provide a double, forward facing navigators seat. The top of the cabinet in front providing chart room. Immediately aft of the helm seat is a small (1.25m long) lounge. With a leaf from the dinette, this will provide additional dining space. The fridge / freezer could be located under here - possibly in a top loading or draw style. Aft of this is the Galley - 1.25m long. Opposite is the head - not overly large at 1 x 0.9m. Headroom throughout the saloon and head is a minimum 2m.
    The aft cockpit is 2m long and has a seat running the full length on the port side, providing good rope and fender etc storage and a separate, externally vented gas locker. A wet locker is to stbd, immediately outside the rear door to the saloon. There is a gate to the stbd boarding platform. The outboard pod is sufficiently wide to accomodate a main and auxhillary.

    Ok - lets see what you've got in the way of darts......
    And while we're at it, perhaps we should open up the somewhat thorny topic of styling. Personally, I'll vote for a "classic" look - not too traditional, but at the same time, not some attempt to keep up with the latest design fad (or is that traditional?...;) )
     

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  2. tom28571
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    tom28571 Senior Member

    Will,

    Not many darts. In my opinion, this is the best offered so far.

    Can you explain the trade offs that go into deciding on a pod mounted engine versus a transom mounted one? I know these pods are in vogue now but are they an over-all positive feature?

    One sharp dart is the top overhang in the cockpit. It will need to be pretty high to have both headroom under and a self draining cockpit.
     
  3. Willallison
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    Willallison Senior Member

    As always, there are pros and cons in using a pod. 1st and most obvious it greatly increases cockpit space. Boats tend to be a little quicker onto plane, but also run at a slightly higher angle of attack (higher trim). If they extend too far back, they can induce porpoising in some boats. I must admit, my knowledge is somewhat limited on the subject, but they seem to work well.
    The latest trend here seems to be to use what they call a 3/4 pod, so you still get most of the cockpit space but the pod doesn't extend so far back. From an amateur builder point of view, however, this becomes a much more complex build.

    As far as the extended cabin roof goes, it's confession time.....I've put the cockpit sole (and cabin sole) at chine level, so it wouldn't be self-draining. But with the pod and subsequent full height transom (about 1200mm), this isn't quite as big a problem as it would be with alower transom....
     
  4. tom28571
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    tom28571 Senior Member

    Ok Will, now I will chumk a dart.

    I could not abide a non self draining cockpit. The C Dory comes to mind (a friend has one). Stepping into water in the cockpit just doesn't get it for me. Adding a grate helps but you are still hostage to a bilge pump, stuff always falls in the cracks of the grate and it's always scuzzy under there. If it never rains where you cruise, it better but ....

    Now for the pod. I've not had too much experience with them but on one occasion in following waves, the prop kept ventilating, requiring a slow down to get the prop working again. This happened over and over and was a real nuisance. On another boat, porposing was a problem. I expect better design would help avoid these tendencies but it's obvious that the tendency is there.

    My view is this. I don't understand the extra cockpit argument. The pod is part of the boat and increases the length for all things but available waterline length AND available room. I say that because I think it would be much easier to build the boat longer with consequent greater room somewhere than to build a transom strong enough to take the increased stresses of the engines out there on that extended moment arm. I can understand a short pod with extended hull bottom that gives a good boarding and swim platform but even that is taking room from the cockpit, not adding it.

    That's my story and I'm sticking to it.

    I'd love to see a full and objective explanation of pros and cons of the pods and where they might be best applied.
     
  5. Willallison
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    Willallison Senior Member

    hmm - had a sneaking suspicion that might be coming - and I have no valid argument for what you say - I agree - self draining is the way to go....that's why they're called preliminary sketches:D

    And your comments re the pod are also valid. I suspect that the boat you refer to does indeed suffer from a poorly designed pod. I can also see where you're coming from as far as cockpit space is concerned, but I'm not too sure that I can completely agree with you - if you extend the cockpit out to where the pod ends, then you still need to add boarding platforms, making the boat longer overall. Where pods really come into their own, of course is for repowering a previously inboard powered hull - you simply bolt a pod on and away you go. That's not the case with O-1, I realise.

    The cost of building an extra 3 feet of boat would far exceed the cost of 3 feet of pod, I would expect.

    A number of designs I have seen have a running surface slightly above the boats bottom - a little like a step. This provides additional lift at lower speeds, but reduces wetted area once the boat is up and planing.

    I did read a fairly basic technical article in a mag a number of years ago about the benefits of using a pod and the design considerations that must be taken into account for them to be successful - hopefully I'll still have it somewhere, but in the meantime, perhaps someone else might have some info......
     
  6. Portager
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    Portager Senior Member

    Will;

    I like the new layout, except for the non self-bailing cockpit. I like the chart area too. I think you should extend the deckhouse out on the port side, it will provide more room for the head and dinette. If you leave the side deck on the starboard side you don't loose access to the foredeck but you do loose some symmetry.

    I found the discussion on pods interesting and very confusing. I thought performance would be better with a longer hull length. In addition, I learned that a main disadvantage of outboards was the CG was too far aft and the pitch moment of inertia was too high which causes porposing. It seams to me that the pod would only agrevate these problems.

    I have decided to start a Masters Science degree in Systems Architecture and Engineering (MSSAE) at the University of Southern California (USC), so I won't have as much time to spend on the list as I used to. It seams my daughters have high educational expectations, so I'm going to be underwriting their tuition longer than I had originally planned. Therefore getting the MS will allow me to increase my income to counteract this financial drain so I'll be able to afford "Portager".

    Cheers;
    Mike Schooley
     
  7. ErikG
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    ErikG Senior Member

    Unsymmetric?!?!

    Mike->
    I can't imagine building or owning a boat that I would feel is ugly (Sorry Mike). An unsymmetric profile is just ugly to me.
    I mean looking from ahead of the boat it would look to weird in my opinion.

    But I too agree that the cockpit needs to be selfdraining.
    So what/how could we use the space under the cockpit sole for (if it is to be raised I mean)?

    Will->
    I do like the profile of your drawing!
    The big window area makes me a bit concerned, don't they need more support than in the prel. sketch?

    Erik
     
  8. tom28571
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    tom28571 Senior Member

    Thinking back on the construction of my latest boat, I do think that adding a pod would be costlier and more work than adding the extra length. My comments on the length referred to making the LOA of both choices the same, including engine. I ditto the comments about repowering inboards with outboards on a pod to maintain weight ballance. On a new design, I have a suspicion that the longer hull with proper ballance is better every time.

    I have also seen a number of boats with pods with that shape. I have to wonder if there is real data behind the supposed lift that the little step gives. If the boat is a real heavy, deep-transom thing, maybe, but for a boat like we are working for, I very much doubt any advantages in lift.
     
  9. Portager
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    Portager Senior Member

    ErikG;

    You have a valid point and you have a right to your opinion, but a good designer needs to keep an open mind and consider unconventional ideas before instinctively tossing them overboard. Allow you mind to venture outside the box once in awhile, otherwise all that is left is rehashing old decisions.

    A cleaver designer would find a way to minimize the visual impact of the asymmetric design, after all we are only talking about .25 m (4"). This .25 m would increase the head from 1 X .9 to 1 X 1.15, a 27.8% increase in area. It would have a similar affect on the dinette. On a boat the size of O-1 I think this is a valuable benefit.

    Cheers;
    Mike Schooley
     
  10. ErikG
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    ErikG Senior Member

    Sorry Mike but...

    To me a asymmetrical boat in this specific way, to me it would be like an airplane with biplanes on one side and a cessna style wing on the other.

    I do agree that a good designer needs to think "outside the box" but to me any successful boat is not only a boat that gives ME what I wan't, it's also a boat that gives a lot of ppl what they want. IE it has to be sellable.

    On the otherhand you ARE right, if no one does anything different from what has been done before, we could all stop trying and just start playing golf instead...

    And I hate golf ;-)

    On the side deck issue, I want to be able to go alongside with any side of the boat, and fastening [fenders] ("bumpers" don't know the proper english word for them). And also handling the lines would be a lot more difficult on one side than the other, and I don't really like that.

    ErikG
     
  11. tom28571
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    tom28571 Senior Member

    Erik,

    While I instinctively agree with you on the virtue of lateral stability, I have to remember what Burt Rutan's Boomerang aircraft looks like. Asymmetric in all coordinates.

    After meeting Burt and listening to his explanation of the design, I found myself thinking that it is one of the most symmetrical planes that I've seen.

    You can probably find the Boomerang on Google. Don't have time to look for it right now.
     
  12. Jeff
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    Jeff Moderator

    Boomerang
     

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  13. Willallison
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    Willallison Senior Member

    As far as the pod thing goes, Ive sent the feelers out to see if we con come up with some data - unfortunately I'm not that good at digging up this kind of stuff, so hopefully someone can come up with some data.

    The assymetrical deck plan is not exactly new - many liveaboard 'trawlers' (hate that term) are being built this way these days and in a vessel which rarely comes alongside a strange dock I can see real benefits. But, as Erik suggested, for a lightweight like O-1, which is highly susceptible to both wind and current, the ability to berth either side-to can be very important. You don't have the luxury of things like covered side-decks to hide what is to most people an ungainly, if not ugly aspect of the boat. However, the upside is that instead of having a head and dinette which are only just big enough, you wind up with considerably more space.
    I would be concerned about lateral stability issues. As the design stands, there is probably a slight weight bias to port and with the bulk of the storage available on this sode, the situation would tend to become worse as owners load up their boats with gear. You could possibly address this issue with the placement of permanent on-board weights (such as batteries). Only a proper weight schedule could establish that. Moving the cockpit seat to the stbd side and swapping the auxhillary, boarding platform etc around would help, but the width beween the side-deck and cabin door is just a tad too narrow for a seat.
    How the assymetrical frontal area would effect higher speed stability, I have no idea.....

    Erik, The windows are maybe a little bigger than others would draw, though at around 550mm deep, they aren't exactly huge. As a home-build, the owner might break them up into smaller sections, making each pane smaller. But one of the the most important aspects of a boat (after safety of course) is how it feels. And there's nothing I hate more than a boat which feels dark and closed in - the ability to sit inside on a cold wet day and acually look out is VERY much underrated these days, I think. But as you suggest - this is simply a preliminay sketch, so all these things must be examined further...
     
  14. Willallison
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    Willallison Senior Member

    Same boat with the freeboard raised about 150mm. This allows sufficient height for the cockpit to be self-draining, but still retain the overhang. Alterations to the transom include lengthening the running surface and sides to effectively eliminate the pod - good or bad who knows.
    With a little tweaking, I'm sure I could improve the looks somewhat....thoughts?.....
     

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  15. Polarity
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    Polarity Senior Member

    Not a very constructive comment, but,,, I like her! :D
    She has a nice balanced feel to her,

    I would want to work on the interior layout and I might just whizz her into rhino and see what she looks like... - sorry I have not contributed but after I lost my evolving design in the HD crash I have not really been able to get back into it. :rolleyes:
    Now where is the coffee!

    Paul
     
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