can it work?? dream at stake here...

Discussion in 'Boat Design' started by tugboat, Dec 5, 2012.

  1. Number4

    Number4 Previous Member

    Hi Tugboat,
    I can't help you with your boat, but I hope I can help you with your back.
    Almost a year ago I suffered the same thing, probably from 20 years of rugby and hard labour.I have broken bones, been burned, even stabbed, but nothing can compare to the pain of a prolapsed disc.
    The quacks prescribed me surgery, anti inflamatories, and pain killers.
    I looked at a video of the surgery and nearly fainted. The anti inflamatories gave me a terrible stomach ulcer. The pain killers turned me into a prescription junkie.
    Try to lose some weight, you will feel better.
    Always adopt a good posture, sitting, walking, lifting.
    Try to do press ups. If you cannot do a full press up, just do half press up, ie, leave your waist on the floor and raise your torso.
    Eat lots of garlic, it is a natural anti inflamatory.
    Sleep on your back on a blanket on the floor. I place half a pool cue under my back right at the spot. It works!
    There also is a certain green herb you can smoke or eat that will make you feel much better. The quacks don't prescribe it and it is not very legal, but it works much better than booze or anything they will give you.
    One year later I get only an occasional twinge in my leg, and some times even forget about it all together.
    Oh the joys of growing old!
    Best Wishes Mate,
  2. tom28571
    Joined: Dec 2001
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    Location: Oriental, NC

    tom28571 Senior Member


    Yes the subject of the thread is core material but if the back problem is not solved, it doesn't matter. My problem is a combination of age and a lifetime of poor posture and careless activity. When I saw the MRI showing cross sections of the spinal column, the poor thing was being pinched into almost zero space by failing vertebrae . Nothing short of physical intervention was going to help that and so I elected the surgery. Not fun, for sure. Six weeks in a hard cast.

    Best of luck to you with the project.
  3. BertKu
    Joined: May 2009
    Posts: 2,480
    Likes: 43, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    You got now 3 good solid advice from us. Most people forget that even the backbone does change and can grow slightly with the right supplements. A lot of people will probably disagree and will think that backbone does not grow or change , but that is their prerogative. I will agree that if you get older that a person shrinks, but with the right supplement, you can shrink for the better.
    Sorry Doug it was about 30 years ago that I got hold of that book from your Canadian doctor. I cannot even remember his name. Maybe a search on the net could help you. At least you see that you are not the only one. Probably half of us have back problems.
    If you solve your back, you can fix your hull in no time.
  4. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Doug I forgot to ask you. Do you take MSM? or Devils claw? MSM is either made from plants for those who are allergic for shellfish or MSM made from shellfish extractions. Get hold of that book. MSM helps to form a layer between joints. I give my horse Devils Claws (don't laugh !) there must be something also for human consumption available. Bert
  5. Eric Sponberg
    Joined: Dec 2001
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    Location: On board Corroboree

    Eric Sponberg Senior Member

    Tugboat--It seems like you are getting a lot of pain relief advice from most of the responders, and that's OK. To throw my hat into the ring, I don't suffer so much from pain--I have had issues with my back over the years, but chiropractic help a long time ago helped me with exercises that I do daily to keep it under control. I am also a double cancer survivor--8+ years out from stage 3 colon cancer, and recently had a tiny melanoma cut out of my back. So much for the medical issues. Good luck on your care.

    As for cores on your tugboat, as you probably know, there are various pros and cons to using any core material, and they all come with different shear strengths. Their purpose is to separate the laminate skins so that they will be stronger by virtue of their geometry being further apart, but in the process, the cores have to resist shear. The inside skin is stressed in one direction, the outside skin in the opposite direction, and the core has to hold them together. Cores do this in two ways: 1) by their inherent shear strength and modulus (stiffness), and 2) by their thickness. Foam cores are the least strong and stiff but they are very light and expensive. Wood cores like balsa, plywood or solid timber are the most strong and stiff, but they are heavier and are cheaper. Honeycombs come in a number of different materials, are very strong and stiff, are very light, and generally kind of pricey. Inherent strength and stiffness go up with density--denser cores of any material are stronger and stiffer than less dense cores. Thick cores will have more overall strength than thin cores, and generally the thicker the core, the thinner the skins can be. But you can get too thin on both core thickness and skin thickness. If the core is too thin, it will fail before the skins can reach their full load carrying ability. And if the cores are too thick and the skins too thin, the skins can buckle off the core and fail at low loads. Ideally, you want the maximum strength of the core to correspond to the maximum strength of the skins without the skins buckling, and in the case of polyester laminates, from leaking too much--polyester laminates are porous.

    Weight and price also go up with density. So the trick of any boat design and engineering job is to pick the correct core material and thickness with the right amount of weight, cost, strength and stiffness that will do the job. And if there are special considerations like preventing balsa or plywood from getting wet, then those have to be taken into acccount. Honeycombs, depending on the type, can be difficult to laminate in a wet lay-up situation. The best honeycombs like aramid and aluminum are used only in pre-preg molding operations because a special glue layer is used to grab onto the edges of the core walls to help it bond to the skins. Some of the plastic honeycombs are not very strong, but they do have a ready-made layer on which to laminate the skins without filling up all the cells with resin.

    So the decision to use any particular core material has a myriad of considerations that have to be designed to. You cannot switch out one core for another at the same thickness and hope that the laminate will work. If you are considering foam on the one hand, or plywood on the other, the foam core is necessarily going to be thicker than a plywood core. They may best be matched with different laminates--you don't generally hold the skins the same and just switch out cores of various types and thicknesses. You have to match the skin weights and thicknesses to the core at hand. It's all an engineering problem--it can all be calculated ahead of time, but it is not necessarily a simple process to do so.

    Ideally, you have to decide what kind of construction technique you want to use. I think Core-Cell strip planking with fiberglass skins is a relatively easy way to go--it will give you the shapes that you are looking for that, before laminating the skins, can be easily faired for the shapes you want, easier than plywood core, and overall more imperivous to water migrating through it should you have a skin failure or anomoly that allows water in--it won't go through foam easily if you have been careful with your jointing, but it will travel easily through the inner grains of plywood. Figure out the overall thickness of the core plus the thickness of the corresponding skins and stick to that. If you need some engineering help, consider hiring someone who knows what they are doing to do some engineering calculations for you.

    I hope that helps. Good luck.

  6. tugboat

    tugboat Previous Member

    Bert I had to laugh- I wish i was as lucky- I might be prone to gallstones and/or kidnrey stones--which are from drinking too much milk..ugh...I understand whny it works--its because calcium strengthens bone...But I do drink alot of choc milk--cheers Bert--thanks for the support its always appreciated as you know...
  7. tugboat

    tugboat Previous Member

    Im sure my lifestyle hasn't helped my back..i used to be a real worker bee when i was younger..but i was in my thirites whjen my back sgtarted to give.
    Im really hope it doesnt come down to surgery--
    Thanks Tom- cheers!
  8. tugboat

    tugboat Previous Member

    Hi Adam! thanks and i appreciate your support also.
    The weigth issue is on the will help--but even when i lost weight before--and then gained it back- my back still hurts -actually as of writing im in severe pain..but dont want to harp on it...thats life...

    i want to wait till i get further into my build, technically it (my back pain)should be a priority- but i am determined, back pain or not, to finish this boat.
    you too mate!
    thanks for the input.
  9. tugboat

    tugboat Previous Member

    Eric-- I enjoy reading your posts- you are very knowledgable and as with the this thread- you dont judge or try to tell me what will or wont work you just give the facts-something i appreciate the the "enth degree...
    It obvious you have worked with these materials where as ive done only some experimentation using samples..which is why i really like the pp honeycomb.
    The scrim really gets a bond to the core..ive tried epoxy and core-cell...and in my experience-and im not saying i was a scientific about them- the core cell skins pulled apart easier than the honeycomb which i could not puill apart and had a great bond... but i did want to ask you what you think of strip planking that hull? you see any issues using 1/2 inch ply strips? and then epoxy on both sides laminated on both sides with 4 layers of triax???

    im thinking strip planking..??..core or ply...what r your thoughts? anyone is welcome to join in on a strip plank discussion..seems like a possible route...?
    thanks again Eric!
  10. tunnels

    tunnels Previous Member

    I used to have lots trouble with my back as i said last time i have a disc that worn badly. So i desided to take care of my self . i always stretch really hard in bed first thing i wake up and lay flat on my back and totally relax after the stretch then i sit up and wivel round on my bottom and place both feet flat on the floor and stand up strsaight then walk . How many times do we stand in one leg and lean on a wall or a bench ? , never lean !! always carry your body weight evenly on both feet !!, when carrying anything walk half the distance on one side the other half on the other side . when getting down on a floor bend your knees and squat first with you back straight . 9/10 of back problems are of our bad habits !!! give up the bad habits and the body will repair its self . also drinking and smoking if you do either !!,give it away and bekind to yourself if your friends give you a hard time about not drinking with them and dont like it find new friends !! :mad:
  11. Eric Sponberg
    Joined: Dec 2001
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    Location: On board Corroboree

    Eric Sponberg Senior Member

    Personally, I would strip plank with Core-cell core and then fiberglass over, outside first, then inside.

    If you want to use plywood, that's fine, and use epoxy resin for the laminate. Again, as I stated above, no matter what core you choose, you have to use the correct thickness.

    A common way to build plywood boats, actually, is to use multiple layers of thinner sheets of plywood for the areas that have little to no curvature, or simple curvature (bending in one direction only). In areas of compound curvature such as around your transom, strip plank with solid timber. Pick your species of solid timber to match the species of plywood. So if you are using Okoume ply, also use Okoume timber. The reason for using solid timber is that it is a lot easier to cut the strips to shape in solid timber than it is in plywood. Solid timber cuts easily, plywood shatters at the edges if you're not careful. The best strip plank shape is a bead and cove shape, where one side of the strip is slightly convex, and the other side is slightly concave to the same radius. Using bead and cove strips necessarily keeps the glue joint from strip to stip uniform in thickness regardless of the amount of curvature in the panel. The same applies to Core-Cell strip planking, by the way, as Core-Cell strips are also available in a bead and cove shape--you can buy them that way (at least you used to be able to) or you can buy an appropriate cutting head for your table saw or planer and cut them that way yourself.

  12. BertKu
    Joined: May 2009
    Posts: 2,480
    Likes: 43, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Doug, do me a favor. Drink that cocktail what I suggested. The problem is, if a nerve get clamped, it starts swelling and how more it swells how more you feel the sharp pins at the back of your legs. Evening primrose oil reduces the swelling of the clamped nerve and you will feel better tomorrow after a sleep. Because you will not sleep from the pain, you take a tot of Vicks Medinite that makes you sleep relaxed. I haven't a clue why my wife put 2 Aspirin's in the cocktail, I will ask her when she comes home from work.
    Those few minutes to get that stuff from the Chemist, drugstore or where ever you'r Canadians get your medicine from. If it does not work , I will pay for it. That is an offer you cannot refuse. Our cost here, where I am living, would be approx. USA $ 24.00
    P.S. I asked my wife, apparently she only use 2 crunched aspirins, when she cannot get Vick's Medinite. The aspirins clashes with Vick Medinite, thus if you can get Vick's Medinite, don't use aspirins. Unfortunately using asperins with Vick Vapor is not as effective.
    Last edited: Dec 7, 2012
  13. tugboat

    tugboat Previous Member always- your care shows through with kindness- as does the others here--i never expected to have so many people be so supportive -- it warms my heart--
    btw--i DONT drink or smoke--never have -- i experimented in my teens..but i outgrew those things--I like to keepy my mind clear.
    i know you know more than most on here about cores and glass- whats your opinion--
    1. core thickness?
    2. core type?
    3.(ok i know you like solid laminates below the water line but i really love my honeycomb core...) what would you suggest as a thickness and type of laminate dfor the core
    4. do you think it will be easy to cover those tricky spots with 1" thick core?
  14. tugboat

    tugboat Previous Member

    Eric- your beginning to get a reputation around here as being truly gifted in these matters-

    The core cell- that you speak of sadly does not exist to my knowedge--it did-- Noahs used to carry it here, but for some reason when core-cell stopped making the a-foams- (now called M-foam) they stopped the bead and cove so i'd have to manufacture my guessing this would involve a bench router??
    I do think ill still go with the honeycomb just because the price of the core cell is about three times the costs of pp honeycomb- and i dont think its three times better but thats all my uninformed opinion- i think in the end i like the stiffness of 1 inch thick pp hc. against what i could afford in c.c. which would be maybe 3/8ths @ 5 lbs/cu ft.
    but if i run into issues im sure i can find a solution and i credit everyone here with giving me the confidence to try this method-
    the project in steel just seems undoable in my present state- but i have been feeling better so i dont want anyone to worry about going to be fine- i just have to lose some weight p-try berts brew, and not do too much at first...Steel requires a lot of muscle--thats fine im strong- but the idea of lifting and positioning heavy plates seems out of my reach for now...
    so core it is! plus to be honest- my boat design as shown on here- has evolved from a flat botted design into my masterpiece- well for me anyway- as i am not a pro. but im happy and confident with this latest design and there is not another one i can find that i like better that will function the way i want. For instance- I have worked on tugboats. most have very full bows- but I like to cut through the waves- if you se ken hankinsons design the fred murphy -see attached- this cuts through i designed my bow in a similar fashion...
    another development was the accomodation space-- I have tried so hard for so many mnonths to fit accomodations i.e. a berth into a small tug wheelhoue and most of the lower space is dedicated to the steanm engine so its difficult to have a tug-(a true tug- ill get into that later!) that cruises..
    so the tool box at the back of the upper wheelhouse is actually a 3 x 6 ft berth. there have been many evolutions in my design - the radius was the latest- i like having the round bilge because i KNOW its going to move through the water with less effort. maybe not by much but there are subtle nuances i love-- like the sound of the water when you cant hear the engine while standing on the bow and the smooth sound of water going over a well formed hull..those types of things really tweak my passions...blah blah sorry didnt mean to take up so much time...there has been other "evolutions too..
    thanks Eric!

    Attached Files:

  15. tugboat

    tugboat Previous Member

    Bert old freind- i apologize for not responding sooner--i was out all day today and wanted to save my reply to you for last since you have been so gracious in your offer. I got your emial earlier and i will repsond tomorrow(my time|) since its late here and i need to rest--my leg is starting to get the familiar "bruning pain of a hot wire running up it..arrrrghh!
    Ill take time to read over everything in your feel good cocktsail and see if i can source this out somewhere here..your wife is suich a blessing--i am not married but i would trade my boat and my next five lives for a good woman...there is no boat worth the price of having a good woman and i wish i could say that i had a permanent one in my life-that took good care of me like yours does-- you are truly a blessed man-ill send you some mail tomorrow..until then take care...
    your replies are never forgotten and always appreciated.
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