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PostPosted: Wed Aug 01, 2018 5:32 am 
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Jim_MI wrote:
niswanger wrote:
Whoa, trying to picture this is hard, but I kind of get your thinking. So at the forward cross member of the trailer you bolt down the 3" then at the aft end you bolt down the 3.5" This must mean the 3" end sticks out of the 3.5" one, otherwise you would be bolting both pipes down.


Yes. Sorry if that was not clear.
2x6 cross pieces are 8' apart (max for trailer bed). 3.5" OD and 3" OD pipe bunk pieces are each about 8' long, but that includes several inches of each extending beyond the cross pieces. So when properly telescoped with the 3" ends bolted only to the front cross piece and the 3.5" bolted only to the rear cross piece, they are free to "bow-and-grow" to fit the hull without producing excess inward tension on the cross pieces.


I understand the concept, just wondering if the end of the 3.5" piece at the front is resting on the cross piece or only the 3" piece that's bolted on that cross piece? I also wonder if there was a way to just use one piece of pvc where the fixed area (bolt etc.) was slotted to allow for more movement/flexing (use a fender washer that can bend to conform to the inner contour of the PVC)? I was at home depot last night and the largest tee they sell is for 2.5" pvc but I was idea gathering and thought that I cold use my oscillating barrel sander and ream out the inside where a 2.5" pvc pipe would actually slip all the way through. Then cut and shape down the 90 degree tee leg (so it doesn't interfere with the bunk profile resting against the hull) and use it for fixing (bolting) to a cross piece (this way the main piece could slip under pressure and the tee piece would keep it anchored to the cross piece). I think I would actually do this if I could find a 3" tee, use 3" main pvc bunks and then 2.5" inside the main which would be a snuggish fit that wouldn't slide in and out easy because of a bolt head inside the pvc (this is where the tee union would shine as it would eliminate hardware inside the main pvc pipe). In this setup the main 3" would be a clear straight-thru piece allowing for another one size smaller piece to slide all the way in. This way I could make a much longer sled/skid to slide off the PA all the way down to the water. Again, from my previous post with a link to a post about my trailer build explains this.

If you have any pictures please post them, or PM me if you are motivated to help out :)

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PostPosted: Thu Aug 02, 2018 7:35 am 
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Unable to post pics at the moment, but a few more comments:
1) The 3.5" tube does not rest on the front cross piece. It butts up against it but is free to slide backward.
2) I like your ingenuity about a pull-out rear ramp design. But from my experience, the flexing of the PVC tubes under load will tighten things up to the point of making that feature useless for unloading at the lake. And if you store your PA on the trailer, with time the tubes will take on some permanent curvature and make your pull-out ramp too difficult to use even when reloading for the trip home.
3) I make a point of keeping my trailer hubs dry when backing down the ramp to load or unload (in order to minimize bearing problems). Consequently, my PA never floats off of or onto my trailer and I must push it off and pull it up onto my bunks by hand. But despite being 63 years old and no body builder, this has not been much of a challenge. You might consider a simpler rear end design for starters before engineering a complicated solution to a "problem" that just isn't that bad.

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PostPosted: Thu Aug 02, 2018 9:22 am 
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Jim_MI wrote:
Unable to post pics at the moment, but a few more comments:
1) The 3.5" tube does not rest on the front cross piece. It butts up against it but is free to slide backward.
2) I like your ingenuity about a pull-out rear ramp design. But from my experience, the flexing of the PVC tubes under load will tighten things up to the point of making that feature useless for unloading at the lake. And if you store your PA on the trailer, with time the tubes will take on some permanent curvature and make your pull-out ramp too difficult to use even when reloading for the trip home.
3) I make a point of keeping my trailer hubs dry when backing down the ramp to load or unload (in order to minimize bearing problems). Consequently, my PA never floats off of or onto my trailer and I must push it off and pull it up onto my bunks by hand. But despite being 63 years old and no body builder, this has not been much of a challenge. You might consider a simpler rear end design for starters before engineering a complicated solution to a "problem" that just isn't that bad.


There's a saying I trying to recollect that my father-in-law often says when building stuff about the lesser of good or perfect etc. etc. and it basically comes down to KISS principle. So I agree about the telescoping idea, if the main bunk flexes too much the inner pvc pipe might bind...hummm, wonder how much it would bind if just a 1/2" or so of deflection. I guess if it doesn't work then I'm just out two pieces of inner pipe and some shorter pieces/fitting for the leg. I feel it's worth a shot as a concept prototype. I'm getting down to lots of sketches, consulting, measuring etc. and this is what I'm going to do (yet another "complicated" engineering design):

Based on the thread talking about which size PVC to use here: https://www.hobie.com/forums/viewtopic. ... 37#p304137 I will be going with 2.5" main PVC bunks. Home Depot doesn't sell this size but it's available for similar price at a local plumbing store. This will allow for 2" inner bunk ramp sleeve POC test.

The bunk cross members are going to be 7' apart. At the front of the trailer I'm welding a piece of steel rectangular tube under the upper angle iron rails of the trailer. Next I'm going to affix (using pins so it's removable) a 5" section of 1 1/4" sch40 steel pipe (this is 1.25" ID with about 1.66" OD, sturdy stuff) now this will be done on each side of the front. Then the main cross member will be a 6.5' long piece of 1" sch40 steel pipe inserted into this 1.25" bushing-like pipe. Atop the 1" pipe I will affix an ~5.5' piece of 6" PT deck board by means of welding a flat bar strap to the bottom side of the 1" pipe and bending it back to the under side of the deck board and affixing with HW like a bold and t-nut on the top side of the board (so it's flush, no bold protruding). This will now act as a main cross member platform that tilts (allowing affixed pvc with a slot in the pvc and good bolt and fender washer, to flex better, I think?). The busing will NOT be welded to the rectangular tube stand-off but instead I will weld a bracket to the bushing with tabs to use locking pins (reason for this explained later).

I will do the exact same for the rear. Now the main bunks should be able to flex with undue strain on the area it's affixed/bolted. Though I plan to make a slot so the both (captive with a fender washer which should bend to the inner contour of the pvc) end can shift some as there's flex/load introduced.

Reason I'm making all four corner bushings removable is two fold: 1. the main cross member 1" sch40 steel pipe will protrude further outboard by about 10". I'm wondering if I could make wood lift stands such that I can remove all pins and lift the whole rig up about 4" and support it this way. I could then pull the trailer out and use it as a normal utility trailer. 2. When launching, I could unpin the front, this would allow the whole rig to tilt back as I push the kayak off to the rear. As I test this prototype I can adjust as I go...add chain stop so it doesn't tilt too far etc.

Concerns:

1. This is like a frame where two sides are steel pipe and the other two sides are 4 pieces of 2.5" PVC. When on the trailer I will have to cotter pin etc. all four corners just to the outboard side of the bushing through the main 1" sch40 steel pipe, so it doesn't shift left or right. Need to expose other risks I'm not thinking about here?

2. When launching need to keep side-sway left/right to a minimum. Same goes when lifting on garage wooden lifts at each corner.

Sounds crazy, but I really do want to make something that has true utility, don't care about looks, just needs to work and be reliable.

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PostPosted: Thu Aug 02, 2018 8:45 pm 
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Please don't take offense to my reply as this topic has been flogged over the past several years.

In 2013 I bought a PA-14 after fishing for 3 years out of my first Hobie, a 2010 Outback.

Since the PA-14 was too heavy to car top, I bought a Hobie Trailex trailer with the carpeted bunks....I was lead to believe the bunks would do a good job supporting the PA-14.
That was not a good solution owing to the kayaks shape.

Tom Kirkman had a simple solution using 2" PVC. I too believe in the kiss principle, so I "shamelessly stole his idea". My only change was to use 2.875" OD schedule 40 PVC.
I mounted the PVC directly to the Trailex carpeted 2 x 6 boards spaced 67" on center apart using 1/4 x 20 SS bolts, a large fender washer under the bolt head and a second fender washer and nylock nut under the 2 x 6.......but I also slotted the PVC about 1" length wise so the PVC could "sag/move over over time"....and as Jim_MI noted, it does sag to fit the hulls shape.

I did mount a 600# capacity, $32 Atwood winch on the frame to help load the PA on a steep ramp......I am a bit older than Jim_MI :wink:

My kayak has been used now for 5 years and never leaves the trailer unless I am fishing. I have not had any issues with the hull changing shape while cradled on the trailer.
The following photos will give you some idea of how I approached the supporting issue.......note that some "wiggle room" with the PVC does in no way cause any issues.
Image Image Image

When securing the kayak to the trailer, I don't tightly secure the straps.....snug is good enough as the low pressure tires (12 psi) don't cause the whole rig to bounce around on the road.

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PostPosted: Thu Aug 02, 2018 9:34 pm 
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*Trying to visualize where your main bunks end. I can make out the fwd approx but the aft is hard to picture. Can you tell me specifically where on the PA the fwd/aft bunks end, say n inches from aft and n inches from fwd or just reference a stock item on the deck?

Dr.SteelheadCatcher wrote:
Please don't take offense to my reply as this topic has been flogged over the past several years.
No offense, not sure I'm following the flogging part.

Dr.SteelheadCatcher wrote:
Since the PA-14 was too heavy to car top, I bought a Hobie Trailex trailer with the carpeted bunks....I was lead to believe the bunks would do a good job supporting the PA-14.
That was not a good solution owing to the kayaks shape.
I'm a little confused here, bunk is "NOT" a good solution?

Dr.SteelheadCatcher wrote:
Tom Kirkman had a simple solution using 2" PVC. I too believe in the kiss principle, so I "shamelessly stole his idea". My only change was to use 2.875" OD schedule 40 PVC.
So 2.875" OD is that simply put 2.5" schedule 40? I'm trying to figure out if I should use 2.5" or 2" and I really think either would do but I prefer to use the 2.5" so I can use a sleeve size that works for my application.

Dr.SteelheadCatcher wrote:
I mounted the PVC directly to the Trailex carpeted 2 x 6 boards spaced 67" on center apart using 1/4 x 20 SS bolts, a large fender washer under the bolt head and a second fender washer and nylock nut under the 2 x 6.......but I also slotted the PVC about 1" length wise so the PVC could "sag/move over over time"....and as Jim_MI noted, it does sag to fit the hulls shape.
So 67" apart on center you mean the cross members are that far apart? I was thinking 7' or 84" but I could certainly tighten it up some. Exactly my thought on the slotting, allows for movement. My cross member will pivot too...this will be a fun project this weekend.

Dr.SteelheadCatcher wrote:
I did mount a 600# capacity, $32 Atwood winch on the frame to help load the PA on a steep ramp......I am a bit older than Jim_MI :wink:
Old or not, great idea and I will do the same if possible.

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PostPosted: Fri Aug 03, 2018 7:34 am 
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Quote:
Trying to visualize where your main bunks end. I can make out the fwd approx but the aft is hard to picture. Can you tell me specifically where on the PA the fwd/aft bunks end, say n inches from aft and n inches from fwd or just reference a stock item on the deck?

Ans: About 12" from the center of the front bunk and about 6" from the center of the aft bunk...this is where I have the 22° coupler attached.


Dr.SteelheadCatcher wrote:
Please don't take offense to my reply as this topic has been flogged over the past several years.
Quote:
No offense, not sure I'm following the flogging part.

Ans: There is numerous past posting that cover the topic....that's all.

Dr.SteelheadCatcher wrote:
Since the PA-14 was too heavy to car top, I bought a Hobie Trailex trailer with the carpeted bunks....I was lead to believe the bunks would do a good job supporting the PA-14.
That was not a good solution owing to the kayaks shape.
Quote:
I'm a little confused here, bunk is "NOT" a good solution?

Ans: No, since the hull would be supported on the outer part of the hull and not through the mid section.

Dr.SteelheadCatcher wrote:
Tom Kirkman had a simple solution using 2" PVC. I too believe in the kiss principle, so I "shamelessly stole his idea". My only change was to use 2.875" OD schedule 40 PVC.
Quote:
So 2.875" OD is that simply put 2.5" schedule 40? I'm trying to figure out if I should use 2.5" or 2" and I really think either would do but I prefer to use the 2.5" so I can use a sleeve size that works for my application.

Ans: The 2.875" OD is sold as 3" PVC in my area.

Dr.SteelheadCatcher wrote:
I mounted the PVC directly to the Trailex carpeted 2 x 6 boards spaced 67" on center apart using 1/4 x 20 SS bolts, a large fender washer under the bolt head and a second fender washer and nylock nut under the 2 x 6.......but I also slotted the PVC about 1" length wise so the PVC could "sag/move over over time"....and as Jim_MI noted, it does sag to fit the hulls shape.
Quote:
So 67" apart on center you mean the cross members are that far apart? I was thinking 7' or 84" but I could certainly tighten it up some. Exactly my thought on the slotting, allows for movement. My cross member will pivot too...this will be a fun project this weekend.

Ans: Hobie has recommended that their nice, but spendy cradles be spaced 67" apart, on center for PA-12 and 14's.

Dr.SteelheadCatcher wrote:
I did mount a 600# capacity, $32 Atwood winch on the frame to help load the PA on a steep ramp......I am a bit older than Jim_MI :wink:
Quote:
Old or not, great idea and I will do the same if possible.

Ans: You won't regret adding the winch. I added a 9" wide rubber roller to make it easier to winch on my PA.

Roy, good luck with your project.

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PostPosted: Fri Aug 03, 2018 8:53 am 
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Dr.SteelheadCatcher wrote:
Ans: About 12" from the center of the front bunk and about 6" from the center of the aft bunk...this is where I have the 22° coupler attached.
Sorry I'm confused. I'm making it more simple, see below image. Can you provide the marked "lettered" measurements in inches? I think "C" is 67" correct?

Image

Dr.SteelheadCatcher wrote:
Since the PA-14 was too heavy to car top, I bought a Hobie Trailex trailer with the carpeted bunks....I was lead to believe the bunks would do a good job supporting the PA-14. That was not a good solution owing to the kayaks shape.
I'm a little confused here, bunk is "NOT" a good solution?
Ans: No, since the hull would be supported on the outer part of the hull and not through the mid section.
I'm still confused and now it must be terminology as my thinking of "bunks" must not be correct. What you have right now, in my mind are PVC bunks, but that must be wrong because you wouldn't use a solution that's "not" good.

Dr.SteelheadCatcher wrote:
Ans: The 2.875" OD is sold as 3" PVC in my area.
That's really odd to me. PVC is sized on ID. I measured the OD of 2.5" sch40 (ID is 2.5") and it's exactly 2.875" OD so your numbers indicate 2.5" sch40 PVC. How could 3" PVC even if it was the OD have an actual OD that's 1/8" less?

If I had to guess here on this forum, based on other threads, about 60% are using 3" PVC, 30% using 2" PVC and 10% using 4" or 2.5". I personally plan to use 2.5" sch40 grey/electrical (which has UV inhibitors) that's exactly 2.875" OD.

I also think I want to place my cross members a little bit further apart because the Hobie Cradles lack any support between them which is find as it will allow normal relaxing of the hull. With 2.5" PVC bunks there's support all along the scupper lines of the hull and I don't want ridged, I actually want the PVC to flex some which is why a farther spread of the cross members will allow this more than tighter together cross members. Lot's of work upcoming for me this weekend.

*Oh, one more question just came to mind. I don't think I will have the luxury of being able to mount my bunks with my SS hardware such that I can simply access it by the open ends, so, if I have to mount it, just drill a large enough hole through the top so the screw fits in and a screw driver will hold the bolt? For the SS fender washer I will have to slide it into the bunk with a stick and line it up that way and get the bolt to drop down through the fender washer.

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PostPosted: Fri Aug 03, 2018 1:49 pm 
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These posts about PVC really trouble us, we've seen so many damaged hulls due to this type of storage and transport - We specifically warn against doing this - what happens if the hull distorts (it gets compress on the sides and the deck pushes up - and scuppers and sometimes decks break)

Cradles are best - PVC has caused so many issues over the years - you really should avoid.

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PostPosted: Fri Aug 03, 2018 4:10 pm 
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Jbernier wrote:
These posts about PVC really trouble us, we've seen so many damaged hulls due to this type of storage and transport - We specifically warn against doing this - what happens if the hull distorts (it gets compress on the sides and the deck pushes up - and scuppers and sometimes decks break)

Cradles are best - PVC has caused so many issues over the years - you really should avoid.
JBernier, Thank you for joining this discussion. I won't argue, Hobie engineering certainly knows the best way. And this way you describe seems to be like I show in the first image below correct? Basically these ~ 1' wide cradles both conform to the cross-section of the hull and allow a span of about 70" of zero support, this must be the best thing for these vessels?

So I can see using semi-ridged poles/pipe alone the scupper lines certainly doesn't allow much sag and the net effect as you say "pushes" up. Now this behavior, to me anyway varies extremely. Based on the size and pressure rating (sch 40 VS 80) and the span the PVC pipes are supported...more span = less support (more flex), less span = more rigid, sch 40 is much less ridged over sch 80, 2" PVC much less rigid over 3" PVC, PVC mounted firmly (straight hardware, no slotting for movement and on a fixed mounting cross member) vs. how I show below I will mount the PVC (on a pivoting platform and slotted inside the pvc to allow some flex-shifting to occur).

So I'm going with 2.5" (3" is too big and 2" may be too smal)l, but not out of my prototyping material list, I actually have a pair of 2" sch 40 and 2.5" and will know w/in a week which is best and I may even inquire here on some finding to see what you all think.

Image
Image
Image
Image

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PostPosted: Sat Aug 04, 2018 6:24 pm 
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Jbernier wrote:
These posts about PVC really trouble us, we've seen so many damaged hulls due to this type of storage and transport - We specifically warn against doing this - what happens if the hull distorts (it gets compress on the sides and the deck pushes up - and scuppers and sometimes decks break)

Cradles are best - PVC has caused so many issues over the years - you really should avoid.
With all due respect the cradles that I purchased from Hobie for my TI deformed my hulls (the boat was not strapped down too tightly and yes, they were spaced correctly). I switched to PVC over 2 years ago and have not had any deforming issues. Additionally the cradles started to crack and fall apart after just 1 season. I know you guys are great engineers, but personally I think Hobie got it completely wrong with the cradle system.

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PostPosted: Sun Aug 05, 2018 8:22 pm 
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TI_TOM +1

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PostPosted: Mon Aug 06, 2018 6:03 am 
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Food for thought......Ever wonder about the Hobie "Display stands" the dealers use?
They are elevated parallel pipes/tubes :wink:
I have never seen display stands that use the Hobie Cradles :roll:

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PostPosted: Mon Aug 06, 2018 6:32 am 
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Dr.SteelheadCatcher wrote:
Food for thought......Ever wonder about the Hobie "Display stands" the dealers use?
They are elevated parallel pipes/tubes :wink:
I have never seen display stands that use the Hobie Cradles :roll:


My local ACK in Austin, TX uses two custom showroom stands, one is just ply-wood and has feet making contact (2 forward and 2 aft) that's only about a surface area of 1.5 square inches, not good. The other is a flat bar about 1" X 1.5" running along the scupper lines, just like our PVC bunks, just much smaller.

Anyway, I'm making progress. Ninety inch spread on the cross members for the bunks was way too much...I have settled on a spread of 76 inches, 10 more than Hobie recommends, so I'm essentially moving more aft/fwd by 5". I'll post a video later about my build.

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PostPosted: Mon Aug 06, 2018 6:33 am 
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I am not taking side as I see both sides.... but I think what ever you do if you veer away from Hobie’s recommendation you do so at your own risk. If you are going to do the PVC bunks pay attention to scupper areas and make sure you don’t see bulging on the deck.

That being said I have had a PA 17t and now my TI and both have lived on the cradles with no issues. I had a bow and a stern roller for both. Once seated on the trailer the bow sat on the roller but the stern did not. The TI lives in the garage for over a year now getting used every weekend and some week days. The PA did a year in the garage and a year under a tarp in the back yard. Never any issues with the cradles.

That, that being said should I ever see deformation occurring I will be quick to add more support be it PVC or whatever.... so I guess I am in both camps...


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PostPosted: Sat Aug 11, 2018 8:31 am 
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I have stored my PA on the trailer since 2013 using the Hobie cradles and have no issues with hull distortion. I have the original cradles Hobie made out of fiberglass don’t know if that has anything to do with it.


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