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Thread: Do I need to glass it?

  1. #16
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    Another question for you oh so knowledgeable folks. The plan I'm using is mostly marine ply for the sides, bottom, transom, etc. But all of the other smaller pieces (benches, seat risers, knees, gunwales, etc) the recommendation is fir. I've looked around and I haven't been able to source any douglas fir locally. Big box stores aren't carrying it and my favorite local lumber mill doesn't have it either. They deal mostly in hardwoods and have a great selection of that, but the only softwood I usually see them carry is white pine. Can you guys recommend any substitute wood for these types of components? I'd like to keep it cheap, but don't want poor quality.
    THANKS
    Last edited by Owen Stefaniak; 02-10-2017 at 12:19 PM.

  2. #17
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    Fir is lightweight and strong, but for thwarts and seats and other items you can use many woods. The trade off will be weight. Sapele, spruce, cedar, and cypress are all good options.

  3. #18
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    I spared no expense and used mahogany on my boat. Most cypresses is new growth and just doesn't hold up in my view. I've had to repair a lot of rotten Adirondack chairs made with new growth Cypress. I would try to find some sinker cypress, the old growth stuff if you want cypress. And that stuff cost as much is good hardwood or more.

    I would try to get an excellent piece of wood for the stem. That's where everything fastens too and will hold all the plywood together. White oak would be a good wood for that. I would use a really good wood for the transom. There's where you're going to have your handles to pick up the back of the boat. White oak would be good and won't break the bank. But I've seen boats made out of double three-quarter marine plywood for the transom too. Everything connects to the transom so you're going to be drilling into plywood if you use plywood for the transom. The Epoxy is what gives it the real strength though with a strong fillet in the corner.

  4. #19
    Quote Originally Posted by Robin Frierson View Post
    I spared no expense and used mahogany on my boat. Most cypresses is new growth and just doesn't hold up in my view. I've had to repair a lot of rotten Adirondack chairs made with new growth Cypress. I would try to find some sinker cypress, the old growth stuff if you want cypress. And that stuff cost as much is good hardwood or more.

    I would try to get an excellent piece of wood for the stem. That's where everything fastens too and will hold all the plywood together. White oak would be a good wood for that. I would use a really good wood for the transom. There's where you're going to have your handles to pick up the back of the boat. White oak would be good and won't break the bank. But I've seen boats made out of double three-quarter marine plywood for the transom too. Everything connects to the transom so you're going to be drilling into plywood if you use plywood for the transom. The Epoxy is what gives it the real strength though with a strong fillet in the corner.
    Hold on there, Cap'n. We're talking 10 foot OA designs here. Not too many 10 footers need a 1.5 inch transom. We're also talking glassing and/or epoxy encapsulation here. Almost any wood, including cypress, will be unlikely to rot if properly built and maintained. I don't recall seeing a lot of Adirondack chairs getting fiberglassed or epoxy encapsulated. Or getting a whole lot of maintenance, either.
    Fair winds and following seas,
    Jim Waldron

  5. #20
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    Quote Originally Posted by Owen Stefaniak View Post
    I've looked around and I haven't been able to source any douglas fir locally.
    Home Depot in Milwaukee certainly carries Douglas Fir. Quality is another question, but picking through stock you can find tight straight grain. You may need to keep at it for a while as you gradually accumulate what you need over several visits.

  6. #21

    easily found wood for your purpose

    Quote Originally Posted by Owen Stefaniak View Post
    Another question for you oh so knowledgeable folks. The plan I'm using is mostly marine ply for the sides, bottom, transom, etc. But all of the other smaller pieces (benches, seat risers, knees, gunwales, etc) the recommendation is fir. I've looked around and I haven't been able to source any douglas fir locally. Big box stores aren't carrying it and my favorite local lumber mill doesn't have it either. They deal mostly in hardwoods and have a great selection of that, but the only softwood I usually see them carry is white pine. Can you guys recommend any substitute wood for these types of components? I'd like to keep it cheap, but don't want poor quality.
    THANKS
    Most local wood suppliers have African Mahogany and its usually about $5/bd ft. Its not as good as Honduras Mahogany but much cheaper and lasts fine. Sometimes you can find Douglas Fir dimensional lumber at a architectural wood supplier which is a good wood for your purposes. We have that here is Dallas, but mostly I'd use mahogany or quarter sawn Yellow pine.

  7. #22
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    Aug 2016
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    Quote Originally Posted by Alan Schwabacher View Post
    Home Depot in Milwaukee certainly carries Douglas Fir. Quality is another question, but picking through stock you can find tight straight grain. You may need to keep at it for a while as you gradually accumulate what you need over several visits.
    Thanks a bunch Alan, you are indeed correct. The closest stores to me are Lowes and Menards. Lowes had nothing and Menards only had doug fir in some crappy looking 4x4. Figured the Depot would be more of the same so I didn't bother to make the trip until today and as you say, they do have it. Thanks for that intel, I appreciate it.

  8. #23
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    I'd say don't glass it because you'd save weight, effort and expense. Good paint and good runners will get you a long way. There's also the risk of leaks in the glass trapping moisture. That's especially bad with plywood, and the cut edges of plywood. But I've never built one.

    I have, however, spent a lot of time in a lot of dinghys in sort of a job capacity, including a lot of time standing up and doing things. Not duck hunting or fishing but there are some similarities. That design doesn't look very stable to me. I'd expect it to rock like a chair if you step toward either end and thwartships is not much better. I'd also expect it to be miserable to row.

    I'd seriously consider a larger and/or different design. Even the right canoe might be light but more practical.

  9. #24
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    Owen: Late to the party here. I'd recommend taking a look at some of the kit boats not necessarily to buy, but just to see what materials they're using (type and thickness), the size and shape of the boat, and the expected weight. The issues you are fighting with are size and weight. There is nothing like experience to put those together in the right formula. So for instance, I have rowed a Dyer 9 (9 foot glass boat - 112 lbs) many times and they move acceptably well. But I am no longer strong enough to pick one up and carry it from water to car top. Rod suggested the 10' Devlin design which actually looks great ... and at 52 pounds would be fantastically transportable! If you look at the construction notes for that boat, they are taping just the seams ... intuitively that would have been my recommendation. There are other similar designs by CLC Boats which list the anticipated weight. I would think something at 75 or 80# or less would be pretty transportable. Of course the lighter the better. Good luck!
    "the mechanic that would perfect his work must first sharpen his tools.” Confucius

  10. Considering the mission defined for this boat, duck hunting and near-shore fishing, light weight enough for single-handed car topping, there are some delicate issues to address:

    If the upper limit of weight is set at, say 80 lb. or less, both small size and light construction are necessary.

    Size can't be too small, as the stability has to be great enough to function as a gunning platform when duck hunting. You can't guarantee that the birds will come in over the bow; they may be perverse enough to be on your beam. Between your body motion to come on target and the recoil of the gun, a lot of lateral force can be involved. Ten feet may be adequate for LOA, but a decent amount of beam is also required for form stability. I wouldn't want to go gunning in a canoe or kyak, for example, as I don't like wearing a wet suit and I sure don't want my shotguns to take up swimming. I'd say a B(max) of around 42-45 inches would be reasonable in a design with good form stability. Less is inviting swimming lessons.

    As to construction, unless you are an anorexic supermodel, minimum scantlings for planking would be quarter inch (6mm) marine ply. If corners are cut and a lesser grade is chosen, it would be more prudent to go to 9mm ply, but in that case, the weight would sky rocket, so that's not a viable choice. If you don't glass the boat (or use Dynel, which hasn't been mentioned so far, I think), you may only get one season out of the boat before it starts to fall apart. Or, if your construction is really good, you may get two or three seasons. But it's a lot of money for a three year life. A layer of Dynel in epoxy or 4-6 oz glass in epoxy and you've got a boat that can last.

    Going back to the original post, easy towing behind a small car was mentioned. If that is, in fact, a possibility, I'd look at things a lot differently: a bit bigger boat with a light weight trailer that you can push or pull to and from the water by hand when necessary would open up a much easier task to meet the mission requirements. Duck hunting in a fifteen foot boat that weighs in a 120 or even 200 pounds is going to be a lot more comfortable and a lot more stable than a ten footer. I think you should give that scenario a lot more thought before you decide.

    For the record, the skill levels for keeping to minimal weight for any given design are demanding. Many builders have failed to bring in their projects at design weight. When building ultralight, the demands are all the more difficult to satisfy. Be realistic about your skills or you may be disappointed in the result.
    Last edited by James Waldron; 02-17-2017 at 9:42 AM.
    Fair winds and following seas,
    Jim Waldron

  11. i suggest dont glass it coated ply is good for that and well epoxy the edges.

  12. #27
    Join Date
    Feb 2013
    Location
    Massachusetts
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    Hello, for the lumberyard skiff I built (see related thread right near this one) I used Meranti plywood and used the West system for all the seams and screw holes. But I didn't glass it. I painted it with Interlux primer and paint.

  13. #28
    My most recent ultralight dinghy: 90 lb. 11' build in 1/4" ply, 4 oz glass inside and topsides, 6 oz glass on bottom. Stitch and glue construction.

    IMG_1630A.jpg
    Fair winds and following seas,
    Jim Waldron

  14. #29
    Quote Originally Posted by James Waldron View Post
    My most recent ultralight dinghy: 90 lb. 11' build in 1/4" ply, 4 oz glass inside and topsides, 6 oz glass on bottom. Stitch and glue construction.

    IMG_1630A.jpg
    What is the beam on this dinghy? Your own design? Very nice BTW.
    Mac

  15. Mac:

    Beam is 4'2"; design and precut ply parts from PT Watercraft, to a design by Russel Brown and friends in Port Townsend, WA, particularly Paul Bieker and Eric Jolley, as I understand it. http://www.ptwatercraft.com/ptwatercraft/PT11Home.html
    Fair winds and following seas,
    Jim Waldron

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