It is better with the pictures. but this is boat related
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that is (2)pieces of 3" PVC pipe the lenght being the width of the saddle, think of a letter C laying with the openind in the letter again the bottom of the boat. I know after I cut the pipe and lay it on the side walk the way it will go in the boat I can stand on the pipe and not bend or distore it and with two there ain't no way you can convenice me that I have weaked the saddle any at all. About standing on the pipe , remember I am in better physical shape and leaner that the two above mentioned self appointed experts.
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- C Maven
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Craig, excellent diagrams!
Brian
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- Craig Smerda
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ugh...Louie wrote:I have been usin (2) 3" pieces of PVC pipe all the way back to the Encore day, that was before you started boatin there Yankee boy and Phil wasn't any good. I cut the 3" PVC pipe on a badn saw so it is no longer a circle but a cresent only having taken about a sixth of the circle away this privide a flat surface for the pipe to rest again the bottom of the boat and allow for total water transfer, but hey I've only been doing it since the late 80's so what do I know.
- Craig Smerda
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we're talking about hull flex and cracks in the hull buddy... under the cutout's... not about the cutout's affecting the saddle.Louie wrote:that is (2)pieces of 3" PVC pipe the lenght being the width of the saddle, think of a letter C laying with the openind in the letter again the bottom of the boat. I know after I cut the pipe and lay it on the side walk the way it will go in the boat I can stand on the pipe and not bend or distore it and with two there ain't no way you can convenice me that I have weaked the saddle any at all. About standing on the pipe , remember I am in better physical shape and leaner that the two above mentioned self appointed experts.
do i need to draw you a special picture?
That is one way of sayin I am right. You might know a little boat design but I've been outfitting boats. since back when it involved two tractor intertubes and a 4 ft X 3 ft X 2 ft block of stryrofoam. Andrew brought the first Zoom and Teaureau made down here for outfitting and took ack what we came up with.
SF hull convexity
Wow. That started quite a discussion.
Interesting points.
The intent is to confer longitudinal rigidity to the saddle, allowing the upward forces from the bottom to be spread to the thwarts.
The thwarts and their attachment points are the weak points, I agree.
The foam under the stiff steel bar helps absorb some of the force from underneath. The steel bar does not touch the hull. All the foam from the saddle between the bar and the thwarts also absorb part of impacts.
Weak points are also created with this system along the saddle, longitudinally. But, again, the foam buffer under the bar absorbs the blows from that area.
Inevitably, by reducing flex in the hull, I increased the stresses it is subjected to. Time will tell if it can stand it.
Nice outfitting, Craig.
What do you guys use to glue foam to PE?
Martin
Interesting points.
The intent is to confer longitudinal rigidity to the saddle, allowing the upward forces from the bottom to be spread to the thwarts.
The thwarts and their attachment points are the weak points, I agree.
The foam under the stiff steel bar helps absorb some of the force from underneath. The steel bar does not touch the hull. All the foam from the saddle between the bar and the thwarts also absorb part of impacts.
Weak points are also created with this system along the saddle, longitudinally. But, again, the foam buffer under the bar absorbs the blows from that area.
Inevitably, by reducing flex in the hull, I increased the stresses it is subjected to. Time will tell if it can stand it.
Nice outfitting, Craig.
What do you guys use to glue foam to PE?
Martin
I've got a Royalex Ocoee with stress cracks in the cross section where the straps were anchored to the bottom. They partly happened because the ABS core was cut into.
I'm replacing the straps with a bulkhead to reduce the flexing.
Any predictions how well that'll prolong the life of the boat?
I'm replacing the straps with a bulkhead to reduce the flexing.
Any predictions how well that'll prolong the life of the boat?
Craig Smerda wrote:not as much with royalex... then again the entire hull on a royalex boat flexes all over the place for the most part and i haven't seen many people tie a bulkhead style saddle system into the hull on a royalex boat the way it's done with a rotomolded boat.gumpy1114 wrote: Is this an issue with royalex canoes too? or just PE?
what i do see happen in royalex boats with a saddle is this in time... the hull wears through just in front of the saddle where all the paddlers weight rests and there is no support.
- Craig Smerda
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i stand by my convictions and assertions... and i know a lotta' bit about outfitting.Louie wrote:That is one way of sayin I am right. You might know a little boat design but I've been outfitting boats. since back when it involved two tractor intertubes and a 4 ft X 3 ft X 2 ft block of stryrofoam. Andrew brought the first Zoom and Teaureau made down here for outfitting and took ack what we came up with.
Totally agree for longevity, when outfitting it's best to not have anything stiffening one area of a hull more than another.... which also means in essence, one area should not be less supported than another.... that's one reason why the Inuits merely tied pieces of found wood and bone together, so they would remain flexible enough to withstand the external forces of ice, surf, and possible critters... however there a certain performance reasons to have a more rigid boat than a flimsy floppy one
I do like the idea, of widening AND tapering off the base of saddle though... hadn't seen or noticed that before.
I used to do it that way, but stopped as it creates a stress riser either side of cut... a direct blow in the cut out area, might just cause problems.. like rebar or one of them cut tree spikes on the Cheoah
I do like the idea, of widening AND tapering off the base of saddle though... hadn't seen or noticed that before.
been there with truck intertubes (them tractor tubes were way big and heavy), styrofoam blocks (with the little bits and pieces that floated off ), and one of my favorites partially filled ice chests (w/beers for the rescuers) hooked in with bungee cords ( they come a running ) ...Craig Smerda wrote:i stand by my convictions and assertions... and i know a lotta' bit about outfitting.Louie wrote:That is one way of sayin I am right. You might know a little boat design but I've been outfitting boats. since back when it involved two tractor intertubes and a 4 ft X 3 ft X 2 ft block of stryrofoam. Andrew brought the first Zoom and Teaureau made down here for outfitting and took ack what we came up with.
ugh...Louie wrote:I have been usin (2) 3" pieces of PVC pipe all the way back to the Encore day, that was before you started boatin there Yankee boy and Phil wasn't any good. I cut the 3" PVC pipe on a badn saw so it is no longer a circle but a cresent only having taken about a sixth of the circle away this privide a flat surface for the pipe to rest again the bottom of the boat and allow for total water transfer, but hey I've only been doing it since the late 80's so what do I know.
I used to do it that way, but stopped as it creates a stress riser either side of cut... a direct blow in the cut out area, might just cause problems.. like rebar or one of them cut tree spikes on the Cheoah
- Craig Smerda
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Re: SF hull convexity
seeing how Louie likes pictures...mtalbot wrote: 1. The intent is to confer longitudinal rigidity to the saddle, allowing the upward forces from the bottom to be spread to the thwarts.
2. The thwarts and their attachment points are the weak points, I agree.
3. The foam under the stiff steel bar helps absorb some of the force from underneath. The steel bar does not touch the hull. All the foam from the saddle between the bar and the thwarts also absorb part of impacts.
4. Weak points are also created with this system along the saddle, longitudinally. But, again, the foam buffer under the bar absorbs the blows from that area.
5. Inevitably, by reducing flex in the hull, I increased the stresses it is subjected to. Time will tell if it can stand it.
6. What do you guys use to glue foam to PE?
Martin
1. unecessarily increasing upwards pressure on to the thwarts and their mounting tabs isn't a desire i would prefer. imo what you are doing is increasing the rigidity the long way on the saddle in a small area and it will most likely have the greatest effect of added stiffness mainly under the weight of the paddler... in other words... the middle of the saddle where the bulk of your weight rests. sitting in the boat on your saddle in water alone will begin to concave the hull a bit. add five gallons of water along with that and it will concave it even more. you can perform this test by doing a roll and watching how much further the saddle is from the thwart dry versus with water. i've seen the thwart move up to 1/4" or more away from the thwart when a boat is full of water... in some boats even more than this. (you do want a little flex going on believe it or not... and the minicell saddle is a good conductor of just enough flex imo)
let's also keep in mind that the boat's hull is concave from front to back and side to side as well... not dead flat to the ground. so if the plate is extremely rigid, stiff and straight how will it conform to the shape of the hull?
2. the thwarts and mounting tabs shouldn't really be an issue as a great deal of upwards pressure and inertia would be required to break either of them from my viewpoint
3. & 4. the bar itself isn't a terrible idea... but for the best effect it needs to be at least as wide as the saddle and not as narrow as you used. (i'll make another drawing to show my ideal saddle beam) the foam between the bar and the hull isn't doing much from my perspective other than giving you a surface area to glue it all together. there are now four smaller pockets to flex rather than two larger ones.
5. as i stated above... i feel a bit of hull flex is alright to have as i feel it's important to disperse the inertia and energy of an impact over a greater area and not pinpoint where the bulk of it is directed to. (imagine you are walking barefoot on a beach that is full of rocks... which rocks are less painful to walk on?... the rocks that are large and bigger than the sole of your foot or the tiny rocks that focus pointed pressure in small and specific areas of the bottom of your foot?... i'd rather walk on the large rocks that spread out my mass on a broader surface area personally.)
6. Weldwood... the red can... we're working on a free t-shirt deal if we can buy enough cans of it this year.
maybe someone should get Weldwood to co-sponsor ALF'd
i apply the same principals to my C1 outfitting...
this boat was just rough cut and not finish fitted for a buddy of mine so he could tailor it exactly to himself on the final fitment... and don't ask me what those piece's of wood inside the hull are for... they're mock-up's and are extremely sensitive and classified by the Kazakhstani goverment.
- Craig Smerda
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Re: SF hull convexity
Oh, and your were doing so good...Craig Smerda wrote:...3. & 4. the bar itself isn't a terrible idea... but for the best effect it needs to be at least as wide as the saddle and not as narrow as you used. (i'll make another drawing to show my ideal saddle beam) the foam between the bar and the hull isn't doing much from my perspective other than giving you a surface area to glue it all together. there are now four smaller pockets to flex rather than two larger ones....
The reason I didn't go off on this post initially - (beside starting to sound like Louie) - was exactly because the iron rod was completely encased in foam. As long as the piece of iron is narrower and shorter than the saddle, then really it shouldn't create as bad of a stress riser. If the iron was anyway near as wide as the saddle, then plastic to either side of it would be breaking before very long (if the boat is paddled hard). I did start to suggest using a shorter piece of iron, as it's nearly out the end of the foam. Which most like will be the demise, of this hull. But give the guy a break! He's stepping into uncharted territory, and most likely will be charging full steam ahead. I commend your attempt. Keep thinking out of the box, just remember sometimes the lid slams shut. But who knows, you may just be on to something?
Ok, with that said...It seems to me the same results would be achieved, by simply adding the extra foam to the saddle.
Maybe I'm missing the point, but why in the world would you want a piece of metal in a saddle in the first place (even a plastic laminated one)? I'm unaware of any need for extra longitudinal rigidity in the saddle? And especially why Craig would consider a wider piece to be better, when he's already increased the footprint of his saddle because of uneven loading across the bottom?
I have added internal pieces to keep footbraces in place (as in Wendy's saddle), but never to achieve overall stiffness. And yes, I use petroleum based contact cement also.... any brand.
- sbroam
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I say fill the entire boat with minicell except for exactly where you fit. Didn't somebody post essentially a boat carved from a block of minicell here years ago? Edwin Datshefsky maybe? Like that, but with a skin of PE.
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