help lightest boat you can build
- Thread starter tx river rat
- Start date
Bellybuster said:
That is what always interested me about the Balsa Wood. Something so light and easy to work with was so strong. The planes were covered with silk or paper and some airplane (Testors ) Dope to tighten the covering and seal it.
Now if the darn stuff was just not so expensive. It would be interesting to see how a boat made of it and covered with fiberglass would do.
Another thing to think about... Balsa is a solid piece of wood not like the plywood which is made up of layers. Epoxy saturate the balsa ...how far would the saturation coat soak into the wood. If it would go half way when doing one side by doing both sides the whole piece would be preserved and epoxy impregnated.
Using 1/4 in balsa and doing that then a light glass on it , the weight should be on the really light side with strength on the positive side. 1/4 inch wood so lighter glass could be used then thinner wood with heavier glass , glass does add a lot of weight , actually it and the combination of several coats of epoxy to wet it in and then to fill it.
Chuck.
making a DIY vacuum bagging system would triple the depth of saturation me thinks. There is a ton of info online about building vacuum bag systems with fridge compressors, mind you, that would mean doing flat panels like a pirogue
Bellybuster said:
:lol: :lol: :lol:
That is exactly the boat I was thinking about. All flat panels , no stitching , just mating the seams together. I don't think untreated Balsa and copper wire would be the best of things. The copper wire when snugged down might go threw it like a hot knife threw soft butter.
If brown kraft paper is ruled "not wood", is there an inexpensive veneer that could be used with a skin-on-frame or birchbark-style frame? The frame could be made of cedar or birch, with balsa ribs.
PS - Stumbled on this while googling: Voyage of the Paper Canoe
2500 miles in an 18 foot, 58 pound, paper canoe. Then he traveled from Pittsburgh to Cedar Key, FL via the Ohio and Mississippi rivers in a 12 ft cedar duck boat.
PS - Stumbled on this while googling: Voyage of the Paper Canoe
2500 miles in an 18 foot, 58 pound, paper canoe. Then he traveled from Pittsburgh to Cedar Key, FL via the Ohio and Mississippi rivers in a 12 ft cedar duck boat.
Greybeard
My boats I build now are lighter than that,if you get to thin you will have to use so much epoxy and cloth to get the strength
it would probably be hevier . I think this boat will be a balance of the thinest wood and glass to strength you can get . I dont think you can go overboard on either one of them.
Ron
My boats I build now are lighter than that,if you get to thin you will have to use so much epoxy and cloth to get the strength
it would probably be hevier . I think this boat will be a balance of the thinest wood and glass to strength you can get . I dont think you can go overboard on either one of them.
Ron
It would seem, without tests to confirm, that epoxy would literally be soaked up by porous wood such as balsa. This would negate much of the weight savings of its light weight. Maybe, a light coat of something to limit saturation of epoxy? But, then, even the prevention coat would add weight.
density of various woods
http://www.simetric.co.uk/si_wood.htm
looks like the next best for light weight is bamboo
or perhaps cottenwood
Wood - seasoned & dry kg/cu.m
Afromosia 705
Apple 660 - 830
Ash, black 540
Ash, white 670
Aspen 420
Balsa 170
Bamboo 300 - 400
Birch (British) 670
Cedar, red 380
Cypress 510
Douglas Fir 530
Ebony 960 - 1120
Elm ( English ) 600
Elm ( Wych ) 690
Elm ( Rock ) 815
Iroko 655
Larch 590
Lignum Vitae 1280 - 1370
Mahogany ( Honduras ) 545
Mahogany ( African ) 495 - 850
Maple 755
Oak 590 - 930
Pine ( Oregon ) 530
Pine ( Parana ) 560
Pine ( Canadian ) 350 - 560
Pine ( Red ) 370 - 660
Redwood ( American ) 450
Redwood ( European ) 510
Spruce ( Canadian ) 450
Spruce ( Sitka ) 450
Sycamore 590
Teak 630 - 720
Willow 420
http://www.simetric.co.uk/si_wood.htm
looks like the next best for light weight is bamboo
or perhaps cottenwood
Wood - seasoned & dry kg/cu.m
Afromosia 705
Apple 660 - 830
Ash, black 540
Ash, white 670
Aspen 420
Balsa 170
Bamboo 300 - 400
Birch (British) 670
Cedar, red 380
Cypress 510
Douglas Fir 530
Ebony 960 - 1120
Elm ( English ) 600
Elm ( Wych ) 690
Elm ( Rock ) 815
Iroko 655
Larch 590
Lignum Vitae 1280 - 1370
Mahogany ( Honduras ) 545
Mahogany ( African ) 495 - 850
Maple 755
Oak 590 - 930
Pine ( Oregon ) 530
Pine ( Parana ) 560
Pine ( Canadian ) 350 - 560
Pine ( Red ) 370 - 660
Redwood ( American ) 450
Redwood ( European ) 510
Spruce ( Canadian ) 450
Spruce ( Sitka ) 450
Sycamore 590
Teak 630 - 720
Willow 420
Kayak Jack said:
You are so right , everything and anything added to it will increase the weight of the boat..that is a given fact :roll: ...... a 50 / 50 mix of the epoxy and acetone would be a lot lighter and be absorbed a lot quicker into the wood strengthening it. Providing that would happen then the Balsa could become a lot stronger then the plywood since it is epoxy impregnated and still be lighter then any plywood......
If you use plywood ( may favorite the 1/8 th inch ) in place of the 1/4 inch Balsa there would be a lot more weight..... Balsa is extremely light and an epoxy saturation will add weight but I believe a 1/4 inch piece of Balsa , saturated , would weigh less then a 1/8th piece of plywood that is saturated. Plus the Balsa would offer more wood and strength.
To sum my thoughts up into a nut shell.........
We are just guessing / speculating / grasping at straws, till someone does it and finds out the up's and the down's of using Balsa.
Chuck.
Balsa is very brittle. I wouldn't trust it as a "core" of a composite sandwich if you expected that core to add strength to the overall hull.
But check this out:
http://www.airfieldmodels.com/informati ... /index.htm
But check this out:
http://www.airfieldmodels.com/informati ... /index.htm
But bamboo is NOT wood :twisted: Have thought for a long time that bamboo would (not wood) be a fantastic material for a lightweight and very strong boat.
Regards John
Regards John
The balsa core even though brittle would add strength because of its thickness.JEM said:
Quote from Wikipedia:
Jimmy
The Mosquito was the fastest airplane in the world at the time. I suspect its balsa pieces may have been thicker than we are discussing here.
As thin of a panel as we are discussing, glue would likely soak in all the way through, completely saturating it, and adding more weight than wanted. I'd mentioned a light coat of something (shellac? varnish? something else?) to prevent epoxy soaking in too deeply. Maybe if it were sprayed on in a very light mist? This method of application would seem to have a better chance to remain near the surface.
As thin of a panel as we are discussing, glue would likely soak in all the way through, completely saturating it, and adding more weight than wanted. I'd mentioned a light coat of something (shellac? varnish? something else?) to prevent epoxy soaking in too deeply. Maybe if it were sprayed on in a very light mist? This method of application would seem to have a better chance to remain near the surface.
Jimmy W said:
yes it will add some but to get the lamination to perform like a composite made with a marine-grade species of plywood, more layers of fiberglass will be needed, adding weight, and ending up heavier than just using marine grade plywood.
Balsa seems more damned trouble than its worth. Cedar is a time-proven material for a compromise of weight and strength, and it doesn't soak through with epoxy.
this has been a much welcomed distraction from my incredibly boring work day.
Balsa is probably the most common core material for allot of racing boats including 1000+ horsepower offshore boats. Most of the world cup sail boats also use a balsa core. Albeit i'm sure the coverings are very high tech materials.
Bamboo would indeed be a light weight alternative for skin on frame but you're right, it is a grass, not wood.
This would be so much easier if the contest was for the heaviest boat that floats, I suggest a rule change.
Balsa is probably the most common core material for allot of racing boats including 1000+ horsepower offshore boats. Most of the world cup sail boats also use a balsa core. Albeit i'm sure the coverings are very high tech materials.
Bamboo would indeed be a light weight alternative for skin on frame but you're right, it is a grass, not wood.
This would be so much easier if the contest was for the heaviest boat that floats, I suggest a rule change.
what if one was to build a strip panel boat with alternating strips of balsa and cedar. A 50/50 mix of both would decrease the weight by aprox 30%. The decks could be all balsa as they would not have to carry weight.
I could easily envision a craft like the Okwata or a decked pirogue fitiing the bill and possibly coming in around 20-25 lbs maybe less with lighter cloths
Actually, looking at the mass chart balsa (170) is less than 50% the mass of red cedar (380), it would effectively cut the weight in half
I could easily envision a craft like the Okwata or a decked pirogue fitiing the bill and possibly coming in around 20-25 lbs maybe less with lighter cloths
Actually, looking at the mass chart balsa (170) is less than 50% the mass of red cedar (380), it would effectively cut the weight in half
At this point I think I'll go back to the top of this section and reread 'The Wood is the Filling, Not The Boat. 
Bob
Bob
Read it, Bob, but believe it at your own risk. To think that wood does not only contribute, but makes up a majority of hull strength is not clear thinking. Think "Old Ironsides", Bon Homme Richard", "Pinto", "Nina", etc.etc. A laminate of epoxifed fiber glass over, say, cardboard will never produce the strength of the same laminate over good plywood.Wannabe said:At this point I think I'll go back to the top of this section and reread 'The Wood is the Filling, Not The Boat.
Bob
I cant stand it. :twisted:
Jack talks about the good wood in his yak being supreour ,but on our trip I was in a boat built from 3/16 laun bottom and 1/8 sides and deck painted bottom out of poly . Looking at the boats at the end of the run there was very little difference in the shape of the bottoms. Mine made it just fine. Well I have to admit I didnt hang up on as many rocks as Jack did. :lol: :lol: :lol:
Ok going to throw this out ,take a piece of 3/4 ply 5 1/2 inches wide and 3 ft long. then take a piece of sold wood 3/4 bye 5 1/2
see which one is stiffer and breaks first.
I was amazed at how much stiffer the strip built duck is compared to a ply boat.
Boy that should fire it up. ducking going to the bunker.
Ron
Jack talks about the good wood in his yak being supreour ,but on our trip I was in a boat built from 3/16 laun bottom and 1/8 sides and deck painted bottom out of poly . Looking at the boats at the end of the run there was very little difference in the shape of the bottoms. Mine made it just fine. Well I have to admit I didnt hang up on as many rocks as Jack did. :lol: :lol: :lol:
Ok going to throw this out ,take a piece of 3/4 ply 5 1/2 inches wide and 3 ft long. then take a piece of sold wood 3/4 bye 5 1/2
see which one is stiffer and breaks first.
I was amazed at how much stiffer the strip built duck is compared to a ply boat.
Boy that should fire it up. ducking going to the bunker.
Ron