Follow up to the Sport Locker question

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="" />

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

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?

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.

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.

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.

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?

>>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

The glass transition temperature of PVC is 81°C; the melting point is 212°C.

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

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

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!

I have been inspired to build hull cradles like those!

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.

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.

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.