new Great lakes heavy weather cruising houseboat!

Discussion in 'Boat Design' started by assycat, Jan 14, 2013.

  1. assycat

    assycat Previous Member

  2. assycat

    assycat Previous Member

    Gonzo- i agree- bolger was a genius-true they werent the most beautiful but have you seen his little microtrawler?.its very cute...i own a set of plans.

    I love his designs. just to correct any misunderstanding the boat is @waterline 24' cb is at 12 ft and the L.O.A. is not 38 ft its 32.
    I have designed many boats,.. it isnt my first. they all worked great.

    I understand you work with a lot of ply- whats your thoughts on MDO? is it stiffer than other marine types? was checking out some and it seemed very stiff...? but i did not have any meranti to compare.
    also i got some ply from the lumber yard- its like 9 or 11 layers thick at 3/4 inch...no voids. its labelled fir? but acx fir always seems to have voids...is it possible they gave me marine by accident? it has a couple small knots both side- no football patches. and no voids..looks almost lke birch ply?

    cheers!
     

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  3. peterAustralia
    Joined: Mar 2006
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    peterAustralia Senior Member

    I will express this point of view in good nature,, thats my intent anyway,,, just expressing a polite opinion, nothing more.

    The north west motor yacht at 48,000 pounds that is 22 tonnes.

    Now the top cabin that makes it look top heavy, might only have a weight of say 2 tonnes.

    That means 20 tonnes is down low and not too high, and only ten percent of the weight is up high. Additionally for boats like this they get qualified naval architects that spend a good three years at university or more doing very involved mathematical calculations in order to provide the stability calculations.

    What i am getting at, is that yes that boat has a fair bit of height to it, but it also has a lot of weight, a good 20 tonnes down reasonably low. I think its easier to add topweight if a boat is too stiff and roll period is too quick than it is to add ballast down low if stability is insufficient and roll period is too slow
     
  4. assycat

    assycat Previous Member

    the weight of the upper superstructure would maybe weigh 500 lbs so -crew weight - 1 berth and the steering,- maybe a small portable w.c. is the only weight above 6 ft. the beam of the vessel makes it very stable- barge hulls are able to carry huge sail areas. if a sailboat. and lots of weight up top. however most of the weight will be below decks such as tankage- engine-accomodations-crew-berhs stowage etc... have you seen a BC log barge?



    they stack all thier weight aloft!...never rollover- we are talking 80 ft high - the barge is ballasted true- but- it still has high freeboard. I have seen 27 ft'ers v hulled which is less stable- that have flybridges on them with more weight than my proposed accomodations- and they have more windage than mine would...cant see a problem. have you been on a flat bottomed barge? you cant tell you are on a boat. windage?..not an issue - the top wheelhouse is 6ft 2" high and 8 ft long by 5 wide. decreasing the possibility of a rollover issues. the wheelhouse is alos designed for honeycomb. maybe if the wheelhouse was heavier than the hull i could see it.

    would i take her out in 12 ft seas- no. 6 ft? yes...
     

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  5. NavArch Student
    Joined: Mar 2011
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    Location: South West Pennsylvania

    NavArch Student Junior Member

    Weather on the Lakes

    I know I am a little late to chime in on the conditions out on the lakes but last summer I sailed as a deck cadet on board the S.S. Alpena on the lakes. Throughout the summer we sailed through some pretty heavy weather. Even when loaded with 12,000 tons of cargo, the 505 ft vessel was pitching and rolling. If i was in a pleasure boat, I would certainly keep her near the coast, especially since some storms whip up in only a few minutes.
     
  6. peterAustralia
    Joined: Mar 2006
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    Location: Melbourne Australia

    peterAustralia Senior Member

    this thread is starting to get exceedlingly daft

    my boat is stable,, hey look at this one,, its high too, mine is high, that boat is stable, thus my boat is stable. What is ommitted is beam, what is ommitted it weight, what is ommitted is metacenter calculations

    thats the word.. metacenter. If your boat is stable,,, learn to do the calcs and publish them...otherwise ur blowing smoke
     
  7. assycat

    assycat Previous Member

    no argument there in those conditions...;)
     
  8. assycat

    assycat Previous Member

    what does this smoke signal say?!??? can you read it?

    Peter seriously- you are saying that no boat - unless its done to

    rubber stamp standards should get built? Ill wager - if I built this boat it would perform just as i expect. and if it did- then what about your metacentric heights and stability calcs?- yea I know all about those....
    I would argue- rather than numbers- perhaps simple common sense can come into play-
    problem with this site is if i succeed then Im a threat to all "educated" designers...and if i fail- then - its- I told you so!

    I cant win no matter what--

    so what Im hearing is- there has there ever been an non NA approved boat built when everyone said dont.. and it worked? yet i can give you a many examples.

    can you give me an examples of one that failed when they said it shouldnt?? I can!
     
  9. JRD
    Joined: May 2010
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    Location: New Zealand

    JRD Senior Member

    What Peter is saying to you looks like good advice to me assycat. If I had as much common sense as you, I would accept it.

    In this world you can ussually get a little good advice for free, for the same price you can generally get a whole lot of bad advice. I have read most of this thread and in my humble opinion you have come up trumps here, no one here has offered you any bad advice at all, and you havent had to pay a cent.
    Just a pity no one will tell you are right for nothing.
     
  10. motorbike
    Joined: Mar 2011
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    motorbike Senior Member

    I also think youve had good advice, since you asked for some merely by posting on a boat design forum. But despite all that free good quality advice, if you are still very confident in your skill and judgement, then build your boat. There is another thread here by a religious fellow who is pretty strong minded and seems pretty determined and is likewise damning the torpedoes so to speak. That woud be a good thread to read.
     
  11. assycat

    assycat Previous Member

    haha- its certainly is a pity!:)
     
  12. assycat

    assycat Previous Member

    whats the thread?- Im not religious. but i think I saw a guy on here build a ferrocement tri (or maybe it was a proa?)- after others said he couldnt. maybe its the same guy??

    What I am basing my opinion on is a scale model in scaled conditions far beyond what the full size boat would ever face and it handled fine. thats all.
    I also have built a few barges in my day- and they have worked fine. what I DO find on these forums is a refusal to be open minded. I have seen a few that are but mostly- people here are so stuck in establishment that they are blind to other possibilities. so the first thing that is said- when someone who is not a "formal N.A. " designs a boat is- it cant possibly work....nonsense.

    it took 30 years for cored hulls to be accepted and used. it took 20 years before anyone even recognized swath technology. mariners rightfully are copnservative since boats do cost a lot of bucks so no one wants to experiment. great! but -- we are still stuck in the monohull era which really died out about 70 years ago. there are better hullforms now. but because the treid methods are standardized- people still stay in thier comfort zones.

    as far as my vessel design goes-

    what no one has failed to do- is explain to me in a logical manner or post some numbers as to why my boat wont work?. they tell me things like -" its a rollover thats waiting to happen"- yet these same armchair critics- cannot explain why, anymore than I can explain why it wont.

    however- now that ive tested it. and have a proof of concept- people still tell me that they are correct, likely due to the fact that if they back down from thier opinions it puts them outside thier comfort zones and it hurts ego-

    we are all in the same boat here- no pun intended- it shouldnt bruise ones ego- to be mistaken about a desig?

    and that goes either way- myself included or anyone else. ???:?:;)
     
  13. JRD
    Joined: May 2010
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    Location: New Zealand

    JRD Senior Member

    Assy at this stage you have posted little data or design information for any one to work with. To prove you right or wrong will require a weight study and significant calculations. Your first 3D model looks top heavy at first glance, but without some real dimensions and wieghts all that can be made are friendly observations. 3D sketches can give the wrong idea of proportions, better to provide actual weights and a traditional lines plan.

    No one has said that a non NA design will never work, they are just suggesting a more rigorous approach which is known to work.

    If you want a scale model stability test to be taken with more than a grain of salt, I suggest you publish your data here. No one will bag you for giving it a go, but they will be sure to speak up if they feel your method is not sound.

    Many have said this before, stability modeling doesnt scale well. There are too many factors in the scale up that have counterproductive influences on the final result. As Peter said earlier its all about the beam, centre of gravity and mass. Comes together as metacentric height.
     
  14. peterAustralia
    Joined: Mar 2006
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    Location: Melbourne Australia

    peterAustralia Senior Member

    OK

    This will be my absolute last post in this thread, you can do your own thing. I went back to page one and had a look at your original design. I also put 'motorcruiser' into google images.

    In all the boats that turned up, I could not see one boat with an extra deck on so small a size. Maybe the topdeck is light, maybe the topdeck is not a full 6.5ft high, maybe its lower. Either way it still looks topheavy.

    Hey maybe I am wrong, maybe your right, maybe it is just fine to add an additional deck up high on a boat with a width of 10ft, its just that I cant find an example of a boat with this additional deck on only 10ft beam.

    Maybe you will build your boat, it will go fine and you take it in rough weather and it behaves really well,,,, just maybe.... i am off overseas in 10 days,,, so will leave it to you. When I put in 'flybridge motorcruiser' into google images, the smallest boat I could see that had an enclosed additional topdeck was a rivieria 61 motorcruiser

    I have no problem doing your own thing, to your own design, going for a simpler lower cost vessel seems sound, yours still looks topheavy... but that is just me,,,

    i am sure you know that there is a forum devoted to stability on this website
     

  15. assycat

    assycat Previous Member

    The truth is- I just dont know enough- other than doing test models.. I understand exactly what a metacentric hieght is. but Knowing HOW to apply it or derive some formula- means a lot of investigation.
    I appreciate your METHOD of imparting your opinion- I know its splitting hairs- but its in HOW people communicate things that makes me responsive to valid opinions. go to glen-l- look at the malahini- has a flydeck- also there are many fishing boats in the 27-30 ft range with flybridges. but I dont know if the beam is only 10 ft. grand banks types are 13 ft- so... i admit- I still-even with all my model tests -might not want to invest in something i am uncertain of and for me -reluctantly- thats a dealbreaker- sadly too!- since it would be almost perfect for my needs...
     
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