are we building boats backwards

[tx river rat]

Bear and Mike
Maybe I am around some cheap boats tupper war ones what is the difference in the roto mold boats and the daggers maybe it is the quality of the different brands or how they are stored but I have help fix several boats with a plastic welder.
Educate me here fellows
Ron

 

[JEM]

Type of plastic has much to do with it. It you ever pressed your hands on a white water boat, you'll find it gives way pretty easy. It flexes and bends just enough to deflect energy. Combined with the shape, they last a long, long time.

In order to save some $, manufacturers are coming out with stiffer plastic but it's more brittle. They use it on recreational boats not meant for whitewater.

 

[Jimmy W]

I have around here somewhere a piece of Royalex that I picked up outside the Bluehole Company in Sunbright, Tn. That material has a plastic foam core with several layers of plastic over that and a layer of vinyl on the outside and inside. I know that it is at least 7 or more layers overall. My old OCA has some deep gouges, but, I never saw one get punctured or split.

 

[bearridge]

Friend Ron,

I aint sho I kin explain, but my Dagger iz Royalex too. Once upon a time I seen a Blue Hole Sunburst II which wuz foolishly on the Nantahala without floatation. This kid blew out 'n the canoe filled with water, turnt sideways 'n bent round a big rock. It hung up good.

We all pulled out 'n walked back ta where the canoe wuz pinned. It wuz near bout bent double. I jest knew that canoe wuz gone, but not fergot. It wuz hard ta git it loose....the side wuz all smushed in, but after we got it loose, it begun ta find its shape....like it had a memory of what it wuz supposed ta look like.

We mite have had ta replace a thwart, but I figger that canoe iz still on a river somewhere today. It come away frum that rock with a dent/wrinkle, but nuthin' ta keep it frum paddlin' okay. I reckon that wuz what my canoe done after I run it inta the carport.

The Dagger Caption I paddle haz some deep slits frum sharp rocks....some of 'em purty deep, but no rock haz cut it deep enuff ta leak.

regards
bearridge

I believe that all government is evil, and that trying to improve it is largely a waste of time. H.L. Mencken

 

[hairymick]

Mike,

mate, I am not really bagging out on the plastic, dedicated white water boats. Smarter minds than mine have built them and I have no doubt that they work and last well and better than timber in that environment. I just would prefer to build my own - is all

There were two plastic boats on this trip, neither of them were white water craft but they were the only ones to come through relatively unscathed. Actually, there was a moment (fleeting) when I was wishing my boat was made of plastic.

Then, we reached the end of the rapids with several miles of flat water, still to paddle and the plastic boats started to lag behind. This is also very important to me, after paddling and playing in white water for allmost 5 hours, having a boat that is still easy to push forward over flat water for a couple more hours.

 

[Kayak Jack]

Royalex is reputed to be able to return from nearly any misshaping event. It may need a hair dryer or trouble light to heat it up a bit, then push it into shape and turn off the heat.

It is slippery on the outside, and gives good traction on the inside. Very good material for an all around boat.

 

[kengrome]

Ken I disagree with some of the things you say here :lol: respectfully

No problem tx river rat, disagreements are often followed by enlightenment ...

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.

Well, I can see that this is not one of our points of disagreement since I agree with this statement.

Abrasion cloth is not much help here the glass wears much better than the cloth does

Sorry, you lost me here. I never mentioned any type of cloth other than fiberglass fabric in this thread.

I can see some benefit to the sandwich Chuck was mentioning

So can I, but only 'some' benefit ... not maximum benefit. The technique of using fiberglass fabric as the bread (instead of the meat) in a composite wood/glass sandwich will clearly make the sandwich stronger than without the glass, but it also wastes some of the most commonly sought after advantages of the fiberglass.

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

This technique will provide lower puncture and impact resistance that using the glass as the innermost layer. It may work when the energy is imparted slowly rather than quickly, but then so would using the glass inside the hull where it can better resist higher energy impacts.

I've researched this technique before -- because at one time I thought it might make more sense to put the glass in the middle too -- but in every case it seems the experts recommend using the glass as the outer skins, never in the middle. Better yet, they prefer kevlar as the outer laminate inside the hull since it has far greater tensional strength than glass.

 

[tx river rat]

Ken
sounds like we basically agree on things . and if you will look under the boat bragging forum you can see the lay up I am doing on my new boat
This thread might have been worded wrong my point was for the same weight beef the inside up not the outside.
Ron

 

[kengrome]

Ken, sounds like we basically agree on things

Yes I think we do.

This thread might have been worded wrong my point was for the same weight beef the inside up not the outside.

Absolutely!

 

[digr57]

Tx River Rat I agree with you that putting the extra glass on the inside will help with the impact resistance But its been my understanding that the glass on the outside is needed for abrasion. What will happen when you get a gouge or scratch down to the wood. It will let water soak in to the wood,. A definite problem. Just my opinion but if i wanted a stronger bottem i would use thicker wood and still glass both sides. Like i said just my opinion.

Russ

 

[tx river rat]

Russ
In my feeble mind the cloth doesnt really help in abrasion if you wear off the resin and get down to the glass cloth it wears much faster if the glass wore well it would be included in the graphite coat that is all resin.
And I have some questions about cloth wicking moisture which just the resin want do it will just have water in your crack :lol:
Hope my feeble attempt makes sense
Ron

 

[Kayak Jack]

this thread has a lot more meat in it than normal. Maybe, it could be spiffed up a bit and put into a sticky?

Ron, I need to loan you some punctuation marks to sprinkle here and about in our sentences. A comma - a period every now and then breaks it into separate thoughts. :lol: I'll send some down to you fer free.

 

[tx river rat]

Jack
I have a good supply !@#$%^&*()_ they just get confused where they belong.
Ron

 

[Kayak Jack]

You just go ahead and sprinkle'em along the way, Ron, like salt and pepper on your mashed potatoes. We'll sort'em during reading.

You're a treasure, Ron. A real treasure. Did ya ever locate that old badge you were telling me about?

 

[tx river rat]

Jack
Sorry I forgot to look for it.
Now if I could just remember what I was looking for.
:roll:
Ron

 

[Too Busy]

I've been sitting on the sidelines during this one, but here are my thoughts on sandwich construction.

The wood really shines as the "meat" of the sandwich. In composite construction the stifness of the panels goes up exponentially as the distance between the layers of fiberglass increase. This is demonstrated far better in surfboards than in wooden boats. The "meat is a very lightweight foam that is quite flexible until it is sheated in glass and resin

The plastic resin is very hard when fully cured, but it needs the tensile strength of the fiberglass cloth in order to provide maximum protection to the underlying substrate. So if we just coated a surfboard blank with resin, it would be waterprrof and rigid, but it would break very easily.

It appears the problem on the laker which got this thread started was a tension failure. This was because as the plywood bent, the stress exceeded the tensile strength of the glass coth. I honestly believe that if the laker had a heavier cloth on the INSIDE this would not have happened.
With that being said, it is entirely possible that under the same conditions with a more rigid hull (from heavier glass inside) that the outer glass layer would have punctured...
I believe a more likely outcome would have been either a solid grounding without damage or a spill into fast water.

If you want really good abrasion resistance on the outside, standard (e-glass) cloth isn't the best choice. Dynel, Xynole, or Olefin fabric....even S-glass are more abrasion resistant.
I haven't coated a boat with the eopxy graphite mix that many of you are using, but it cetainly looks to do a good job.
If I'm building a boat that will be dragged or have a lot of grounding, I'll put on a layer of Dynel.

The toughest choices for us as builders is deciding which characteristics are most important? Do we worry more about durability, ultimate strength, total weight or total cost?
Personally I like a pretty boat that is light enough that I don't mind loading and unloading. I sacrifice a little durability and strength to keep the weight down.
Besides, if I break it, then I have an excuse to build another one.

disclaimer: :roll:
These are my opinions, your mileage may vary, .....

 

[oldsparkey]

The toughest choices for us as builders is deciding which characteristics are most important? Do we worry more about durability, ultimate strength, total weight or total cost?
Personally I like a pretty boat that is light enough that I don't mind loading and unloading. I sacrifice a little durability and strength to keep the weight down.
Besides, if I break it, then I have an excuse to build another one.

disclaimer: :roll:
These are my opinions, your mileage may vary, .....

Too Busy , you brought up some good points. Not much mileage from me , about only a quarter or so.
It appears to me this whole thread is a quest for the Holy Grail of boat building, ranks right up there with building the one perfect boat for all occasions. It ain't possible to accomplish such a feat. :roll:

Chuck.
PS. I like to settle for the light weight.

 

[sheena's dad]

It appears to me this whole thread is a quest for the Holy Grail of boat building, ranks right up there with building the one perfect boat for all occasions. It ain't possible to accomplish such a feat. :roll:

Chuck.

Maybe it is, Chuck, mostly likely is...but the meat of the thought do merit discussion,don't it? 8)

I be enjoying this thread.

Steve

 

[bearridge]

It appears to me this whole thread is a quest for the Holy Grail of boat building, ranks right up there with building the one perfect boat for all occasions. It ain't possible to accomplish such a feat. PS. I like to settle for the light weight.

Sometimes the obvious aint obvious ta everbody. :mrgreen: :mrgreen: :mrgreen: :roll: :mrgreen: :lol: :lol: :mrgreen: :lol: :lol:

 

[tx river rat]

There has been a lot of theory thrown around on this thread, I have enjoyed and learned a lot.
The point of my post wasn't the perfect boat or perfect hull it was how to build the best hull at the same weight.
I have come away with some good thoughts and ideals
Thanks guys
Ron