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Follow up to the Sport Locker question #99841
02/27/07 10:56 PM
02/27/07 10:56 PM
Joined: Nov 2006
Posts: 30
Lake Norman, NC
D
Doug_P182_LKN Offline OP
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Doug_P182_LKN  Offline OP
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Joined: Nov 2006
Posts: 30
Lake Norman, NC
A while back there was a thread about Sport Lockers and storage tubes. I got a few e-mails asking me to post some pics of what mine looks like. I know this isn't much in the way of a DIY project considering what a lot of you guys do. But when a trailer Sport Locker can cost $900 - more than the cost of some trailers, necessity becomes the mother of invention. Here are some pics of the storage tube I made for the trailer of my Prindle 18-2 from a scrap piece of sewar pipe from a construction site.

The pipe is 1/2-inch thick pvc and is strong, strong enough to stand on... but heavy! Another nice thing when it's long enough... ditch the original rollers that came on the trailer. They'll put dents in the hull over time and mark up the bottom of the hulls. Cradles with carpeting and padding are much nicer and better. So just lop off a couple of 18-inch pvc sections, cut them in half and mount them with galvanized steel. I even have little pvc vertical pieces at the stern to help guide the hulls into the cradles when retrieving the boat.

Like I said, it may not be much compared to what many of you have done, but I'm proud of it. You just have to remember to remove BOTH end caps when you launch the boat at a ramp and dunk the trailer. They seal pretty well and I learned that for as much air volume contained within the tube... 375-lbs of boat and about 200-lbs of trailer can float very easily! Learned that one the HARD way! <img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

[Linked Image]


Doug Bernstein
Prindle 18.2 'Special Treat' #590
Lake Norman, NC
-- Have You Seen This? --
Re: Follow up to the Sport Locker question [Re: Doug_P182_LKN] #99842
02/28/07 08:01 AM
02/28/07 08:01 AM
Joined: Jan 2004
Posts: 330
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srm Offline
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srm  Offline
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Posts: 330
Is that hull cradle mounting bracket (the piece of vertical steel bar held on with a single U-bolt) very secure? It doesn't look like it would inspire much confidence. Your hull cradles look like they're way up there. I might be a little worried about bending or breaking the mounting bracket during hard braking or cornering.

sm

Re: Follow up to the Sport Locker question [Re: Doug_P182_LKN] #99843
02/28/07 08:44 AM
02/28/07 08:44 AM
Joined: Jun 2001
Posts: 890
Dunedin Causeway, FL
David Parker Offline
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David Parker  Offline
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Posts: 890
Dunedin Causeway, FL
A few years back I read on this forum (the OLD one, remember?) that you can put PVC pipe in a warm oven and get it to soften to the point that you can press it against your hull and make it conform to your hull shape yielding custom cradles.

Does anyone know how hot you must get PVC to bend but not melt or stink up the wife's oven? Can you do this with the thick wall mentioned here?

Re: Follow up to the Sport Locker question [Re: srm] #99844
02/28/07 09:29 AM
02/28/07 09:29 AM
Joined: Jan 2007
Posts: 71
Lake Norman, NC
Special_Treat_P182 Offline
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Special_Treat_P182  Offline
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Lake Norman, NC
It's actually very secure. Heavy guage galvanized steel bolted to the L-brackets and three bolts through with epoxy on the pvc. Yes it is held to the frame by that single u-bolt. I've been meaning to replace them simply because the bolt is stainless and the mounting plate has some surface rust. I would prefer it to all be galvanized and of course, "anything worth engineering is worth over-engineering".

However, it's currently strong enough to support my 225-lbs standing on the hull cradle. I've tested it on all four, so that's almost 2.5 times on each compared to the weight of the boat.

Re: Follow up to the Sport Locker question [Re: David Parker] #99845
02/28/07 09:31 AM
02/28/07 09:31 AM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
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yes, you can do it with the thick stuff. but I don't think there's anyway you will avoid stinking up a sink. You can also use an outdoor grill on low with the PVC on a sheet of aluminum or something. Heat slowly, check often, keep fire extinguisher nearby. Not sure on the temperature.


Jake Kohl
Re: Follow up to the Sport Locker question [Re: Special_Treat_P182] #99846
02/28/07 09:39 AM
02/28/07 09:39 AM
Joined: Jan 2004
Posts: 1,884
Detroit, MI
mbounds Offline
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Detroit, MI
It's not the vertical load capacity I'd be concerned about - it's the ability to resist cyclical transverse (sideways) loads.

Over time, the weld at the bottom of the vertical piece is going to crack and break unless there's some kind of transverse restraint.

Re: Follow up to the Sport Locker question [Re: David Parker] #99847
02/28/07 09:41 AM
02/28/07 09:41 AM
Joined: Sep 2005
Posts: 1,187
38.912, -95.37
_flatlander_ Offline
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Posts: 1,187
38.912, -95.37
David,

I'd be interested in replies also. From experience heating and bending Schedule 40 PVC conduit up to 5" (with a 0.188" wall) it takes a constant and consistent heat. For the big stuff we use an electric blanket of sorts. Could possibly use an electric space heater? The real trick would be NOT burning one side to get the 1/2" thickness soft enough to bend. Maybe two heaters (with fans) set close together heating both inside and out at once?


John H16, H14
Re: Follow up to the Sport Locker question [Re: mbounds] #99848
02/28/07 10:11 AM
02/28/07 10:11 AM
Joined: Jan 2004
Posts: 330
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srm Offline
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Joined: Jan 2004
Posts: 330
>>It's not the vertical load capacity I'd be concerned about - it's the ability to resist cyclical transverse (sideways) loads

Yea, that's my point exactly. You've got ~400lb raised up on 4 thin (1/4" to 3/8" thick? x 1-1/2"?) bars (6 to 8" high?). Subject to 1/2 to 1 G cornering loads (??) under normal circumstances, more during peak loads (pot holes, hard swerves, accidents).
From the looks of it, the only thing holding that bar vertical is a small flat plate at the bottom held on by a U-Bolt. The U-bolt is subject to increased tension due to side forces (the support tying to fall over). The weld joint is subject to fluctuating shear and bending loads and the bar is subject to bending.

If you grab the boat while on the trailer, do those supports bend or wobble at all?

I think a fairly simple fix or upgrade would be to take some more of that bar, and weld it at a 45deg angle to the existing vertical just below your hull cradle. Weld a base plate at the bottom with holes for a U-bolt. This would virtually eliminate any bending loads and give the bracket a lot more horizontal stability.

sm

Re: Follow up to the Sport Locker question [Re: _flatlander_] #99849
02/28/07 10:12 AM
02/28/07 10:12 AM
Joined: Jan 2004
Posts: 1,884
Detroit, MI
mbounds Offline
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Detroit, MI
The glass transition temperature of PVC is 81C; the melting point is 212C.

The closer you get to the melting point, the softer it will be.

How about just putting it in the oven at 300F (=150C)for a half hour?

Re: Follow up to the Sport Locker question [Re: srm] #99850
02/28/07 10:20 AM
02/28/07 10:20 AM
Joined: Jan 2007
Posts: 71
Lake Norman, NC
Special_Treat_P182 Offline
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Special_Treat_P182  Offline
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Joined: Jan 2007
Posts: 71
Lake Norman, NC
I hear ya and you're probably right. The steel is certainly strong enough, but the weld at the base and the single u-bolt must certainly be a weak point.

The supports and cradles don't wobble at all. If I grab hold of one and shake or lift, the entire trailer moves as one piece.

I've probably cheated fate by not trailering very far over the years. I agree with your last assessment. I'll probably replace the u-bolt and plate and add two galvanized u-bolts to each support. Then weld on a 45deg piece or triangle to resist lateral stress. Good idea!

Re: Follow up to the Sport Locker question [Re: Special_Treat_P182] #99851
02/28/07 11:38 AM
02/28/07 11:38 AM
Joined: Oct 2006
Posts: 902
Norman,OK
gree2056 Offline
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gree2056  Offline
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Norman,OK
I have been inspired to build hull cradles like those!


Once you go cat you never go back! Nacra 5.2 (Elsies)#1499, running an inter17 spin!
Re: Follow up to the Sport Locker question [Re: gree2056] #99852
02/28/07 07:56 PM
02/28/07 07:56 PM
Joined: Apr 2002
Posts: 602
Wilmington,NC
Dlennard Offline
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Dlennard  Offline
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Posts: 602
Wilmington,NC
I put mine on the grill on medium on a sheet of foil for 15 min. worked great. My grill has a ss pan above the flame so it is really like a big oven. If you take a router and round over the edges it looks a lot better. Also take a jig saw and round the corners.

Re: Follow up to the Sport Locker question [Re: Dlennard] #99853
02/28/07 10:17 PM
02/28/07 10:17 PM
Joined: Jun 2001
Posts: 890
Dunedin Causeway, FL
David Parker Offline
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David Parker  Offline
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Posts: 890
Dunedin Causeway, FL
Quote
How about just putting it in the oven at 300F (=150C)for a half hour?


A friend did just this but he used flat sheet PVC. Where would you get such raw plastic stock? Why be at the mercy of scavanged pipe? He is cruising somewhere in the South Pacific so I can't ask him.

Re: Follow up to the Sport Locker question [Re: David Parker] #99854
02/28/07 10:38 PM
02/28/07 10:38 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 12,310
South Carolina
Quote
Quote
How about just putting it in the oven at 300F (=150C)for a half hour?


A friend did just this but he used flat sheet PVC. Where would you get such raw plastic stock? Why be at the mercy of scavanged pipe? He is cruising somewhere in the South Pacific so I can't ask him.


Go to www.mcmaster.com and type in PVC...then click on PVC and go from there.


Jake Kohl
Re: Follow up to the Sport Locker question [Re: David Parker] #99855
02/28/07 10:40 PM
02/28/07 10:40 PM
Joined: Nov 2005
Posts: 5,582
“an island in the Pacific....
hobie1616 Offline
Carpal Tunnel
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Posts: 5,582
“an island in the Pacific....
Years ago I immersed Plexiglas in hot water to form a cover for airplane landing lights. We bent the soft plastic around the leading edge of the wing. I can't remember the temp but it wasn't boiling.

An array of heat lamps should work too.


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