are we building boats backwards

[seedtick]

think you're on the right track Mick,

impact resistance is improved in a couple of ways

1. absorb the shock, bend but don't break - this is why cars have plastic panels, they absornb the impact

2. be stiff enough to not bend, IIRC stiffness of wood goes up by the cube, so twice as thick is 8 times as stiff

while wooden boats can be flexible, pinning the panels down with epoxy and glass tends to make it stiffer. for the style boats ya'll are building, you need to be stiffer (option 2)

 

[tx river rat]

Mick
Mate just to make sure I wasn't criticizing the Laker are your build at all. and she did get you home can't ask for more than that.
My point in this thread was at the same weight what was the most impact resistant hull.
Now a few things come up in the discussion on here that I really agree with
4mm or 3/16 ply is my ply of choice for bottom and sides ( as Matt said thicker core less glass same strength) and very little added weight
I do believe the inside should have the heavier cloth .
Mick the t-v built with 4 mm sides and bottom is tough and another thing it floats so much shallower it really takes a lot of strain of off the hull , on my trip my boat was loaded with around 450 lbs so it took a lot of abuse when I hit a rock or high centered it You are going to love that boat the T-V
Oh yea I had 1/8 sides on mine
Bear might take you up on that little deal on the thirty lb boat , how long is your boat , mine is 15 ft hatches tie downs cooler compartment folding seat extra bulkheads for the cooler and It weighs in at 44 lbs and in some places we were bouncing off rocks at 7 and 8 miles an hour by my gps that was in sections where the Brazos might narrow down to twenty yards.wide and that was with 450 lbs in it. :lol: I believe we could build that boat ..


Ron

 

[sheena's dad]

Hi guys,

I was talking to Ron on the phone a little earlier and know his opinions and all but I have a question I didn't think to ask him so I might as well ask it here as I think it pertains to this topic. I KNOW that a wood canoe, or kayak can survive the whitewater, rocks and all. When I was running the Guadaloupe River I know of several wooden kayaks and canoes that made the run, dancing off rock and tumbling end over end. They were glassed inside and out, but with a double layer of 6 ounce glass on bottom, one layer run as straight weave pattern and the other run on the bias (that 45 degree angle that Ron mentioned). It was those boats that were behind my thinking to buy the 6 ounce cloth that I plan to use on my builds. Now, to be perfectly honest, I hadn't thought about the cloth running bias but I am thinking that might be an option for me because I want to the strongest sandwich I can get out of my cloth and wood. I am not concerned about the weight. With all due respect, sometimes when I read your posts it almost appears to be an unmentioned contest of who can build the lightest boat....something I enjoy reading and learn alot from...but it's the strength and durability that I want to achieve so if I'm building a bit heavier than some of you please excuse me for that. I can see where the weight factor can be important, don't get me wrong....I'm just tossing in my two cents. My question is this: what about that two layers of glass on the bottom? I mean we're talking 12 ounces outside and 6 ounces inside. Any opinions?

 

[hairymick]

G'day Ron,

Mate I know you weren't criticizing my Laker or my build of her

The fact is that I used the worst imaginable ply on this boat. It was the stuff I had rejected from other builds and it was only ever intended to be used on still water. I also used the lightest weight glass I could find. In spite of this, she held together well enough for me to paddle her home.

I would defy any store bought, fibreglass boat of similar size and weight to do the same after the belting mine got.

I think the T-V would outperform my laker in these conditions and the fact that T-V also draws so little water would also help a lot.

Steve, your input is as valuable here as it is anywhere else mate. Thank you for joining in!

At the moment, I am just considering options. I intend to build a boat that will stand up to this river (and me) and all thoughts and suggestions are greatly appreciated. I am confident my Sasquatch will stand up but would be gutted if I were to destroy her. She is just way to pretty to bounce off rocks.

Ticky & Matt, Good points - as allways. Thank you

 

[Wannabe]

Fellas,
I can't quote any facts, but if you research it you will probally find that laying the cloth on at a bias will make a stronger boat than running the weave straight down the boat. But then, Rons little expearment proved that.
I Wannabe quiet now.
Bob

 

[Kayak Jack]

... For running in white water with rocks in a wooden boat, something rounded, with plenty of panels would survive the best.

I'm glad you said that, Matt. I was going to say the same thing. A rounded bottom boat will tend to shrug off rocks etc. A flatter bottom boat tends to run up onto a rock, then stop.

 

[nobucks]

Whitewater kayaks used to be made out of fiberglass. Now they're made out of plastic.

If you're going to run WW in a glass boat, expect damage and be happy if you get away with none.

When I was buildling fiberglass boats, my canoe and my sailboat, I put glass inside and out. I didn't take the canoe into the challenging conditions shown, but I felt better knowing that I had complete glass coverage inside and out. Same with my sailboat.

With glass, the exterior reinforcement is important, but the real strength with fiberglass, CF, kevlar, etc., lies in the sandwich effect, glass on one side, a strong core material in the middle, and glass on the inside.

If you're going to run WW, more layers are important.

 

[JEM]

Laying the glass on a 45 degree bias will certainly give you better results.

If you didn't mind spending the extra money, use 2 layers of S-glass instead of standard e-glass. S-glass is at least 20% stronger than E-glass.

I bet you could use 2 layers of 4-ounce S-glass (inside and outside of the hull), layered with a 45 degree bias, and get the results you're looking. It would be like having the strength of 2 layers of 5-ounce e-glass but lighter and using less resin to wet out.

Ron - may I respectfully also suggest using epoxy instead of polyester?

 

[kengrome]

seedtick speaks words of wisdom. Pound for pound, nothing beats what mother nature produces. Exception would maybe be carbon fiber but that's some expensive stuff.

Wood -- nature's affordable, low-tech carbon fiber.

 

[oldsparkey]

Just a thought since the 1/4 inch bottom was mentioned with it being stiff along with the lighter 1/8th sides.

Make the bottom from the 1/8th wood , lay down a sheet of glass then add another 1/8th sheet of wood over it and glass it. A wood and glass sandwich for the bottom then the lighter sides.

The bottom would be from the outside going inside as............ glass , wood glass , wood , glass all epoxied together equaling a 1/4 in sheet of wood but really reinforced.
You would have a 1/4 inch sheet for the bottom but it would have a layer of glass in the center.

Just a Thought...........

Chuck.

 

[tx river rat]

Matt
I am laughing here I never mentioned poleyester always epoxy for all you good folks.
Now my jugs got the lables tore off so someties I get confused :lol:
Ron

 

[Wannabe]

Chuck,
I am the Wannabe here and I'm not understanding what the middle layer of glass is supposed to do. I was thinking that the material in the middle of a composit construction did not matter as long as it seperated the outside layers. The futher apart the outside layers are the stronger the structure would be. If this is wrong please edumacate me cause I Wannabe smart too. Wait a minute. Would the middle layer of glass turn a composite structure into a compound composit structur (if there is such a thing)?
Deflicted minds want ot know
Bob

 

[kengrome]

Wannabe,

You lose the best benefits of fiberglass when you sandwich it in between two layers of plywood. You don't get the best puncture resistance of its being on the inside, and you don't get the abrasion resistance of its being on the outside. This is why, if you're going to use glass at all, it make sense to use it on one surface or the other (or both) and not in the middle.

 

[sheena's dad]

Actually, Chuck, you have a pretty good thought there.... The old PT boats were built much the same way except they used linen cloth between the layers of ply.....always wanted to build one of them bad boys.....

Bob, and someone with more technical background regarding this can correct me if I'm wrong, but I believe that by adding that layer off glass you actually increase the strength of the lamination four or five fold. But, if my thinking is correct, it also would reduce flexibility by a whole other margin.

Steve

 

[Kayak Jack]

Wannabe, the sandwich theory is partly right. Do NOT, however, discount or underestimate the strength of plywood itself. You can build a strong boat of plywood and never use fiber glass. Glass adds strength, it doesn't create it.

 

[dangermouse01]

The plastic boats if run in rocks will cut split and wear out .

These plastic boats have run into rocks, stopped by rocks, slid over rocks, landed on rocks, hung up on rocks and bounced off of rocks, PLENTY since I have owned them PLENTY more before I have owned them. FAR from worn out, not a single split or crack in the hulls yet, Plenty of scrapes & gouges, but that is expected, thats what they are built for. Their material thickness is not any thicker than my 14' & 16' roto molded touring boats.

DM
mike

 

[tx river rat]

Ken
I disagree with some of the things you say here :lol: respectfully
Puncture (hitting a rock) cloth outside does very little to help because it is being compressed inside cloth carries the strain the heavier it is the more
tension it will stand before it breaks.
Abrasion cloth is not much help here the glass wears much better than the cloth does, reason no cloth is put in your graphite coat, also where the nose contacts the beach or rocks once you wear into the cloth it increases
wearing at a faster rate .
I can see some benefit to the sandwich Chuck was mentioning the middle layer would come under tension first then another layer of wood to compress and then the inside layer of cloth would would start to take the strain, the advantage to me would be reaching the fracture point at a slower rate giving the composite a sponge affect ,hope that is clear to yall not saying it well.
Ron

 

[tx river rat]

Mike
I agree with you they are tough but they do split crack and wear, the wooden boats are also ,but have not really been built for what you are doing and as far as i know Micks is one of the few that has failed and it wasnt built for that.
Your boats are good looking and adapted to what they do so I a not putting them down at all.
Ron
What length are they and how much do they weigh

 

[oldsparkey]

Actually, Chuck, you have a pretty good thought there.... The old PT boats were built much the same way except they used linen cloth between the layers of ply.....always wanted to build one of them bad boys.....

Bob, and someone with more technical background regarding this can correct me if I'm wrong, but I believe that by adding that layer off glass you actually increase the strength of the lamination four or five fold. But, if my thinking is correct, it also would reduce flexibility by a whole other margin.

Steve

Exactly... They were some fine boats and took a ton of punishment , I was thinking that the inner layer of glass ( epoxy coated ) would give the wood a back up on the flexing.

They say that by epoxy saturating the wood you can increase the strength of it up to 4 times , what would add more strength then a layer of epoxied glass between the two sheets of epoxy saturated wood.
The discussion was on how to make the bottom stronger but still offer a little flexing.

Basically it is a off hand or off shot of the vests the Law Enforcement (and some crooks) wear. It is a sandwiching of the materials that stops the bullet.
As I mentioned earlier .... just a thought , nothing more , nothing less , just a thought. Might even go as far as to call it a ..... What If. :roll:

Besides that way you don't need a separate sheet of 1/4 inch wood just for the bottom. You make your own 1/4 sheet for just the bottom. I did the same thing in the Swamp Girl by using left over wood , cut into 1 inch wide strips and to the length I wanted on the inside bottom to increase the stiffness of it.

Chuck.

 

[bearridge]

Fellas,

I never had a plastic boat crack 'er split 'n I have hit some mitey big rocks over the years. Worse, I hit the car port back in 2005. It crushed the bottom of the canoe. Left some white paint marks on the outside 'n some wrinkles in the plastic on the inside. After I backed out, it popped back out 'n aint caused me no truble since.

regards
bearridge

ps I seen a 40 year ole Blue Hole OCA that had some cracks in the bottom. That canoe spent its life hittin' rocks 'n bein' left out in the sun. It needed a little duct tape over the cracks ta keep it frum leakin' last time I looked, but I figger it iz still runnin' rapids fer a few more generations....somewhere up in Taxsylvania.

Roy Suggs: What did you find?
Dan Suggs: Nothing but this old watch. Damn sodbusters!
Jake Spoon: You shot those two men for a watch?
Dan Suggs: Shot 'em, now I'm going to hang 'em.
Eddie Suggs: Hang 'em? Dang, you beat all! I've never heard of hanging dead men.
Dan Suggs: Shot 'em, now I'm gonna hang 'em, then I'm gonna burn 'em! Damn sodbusters. Can't ever be too dead to suit me.