Converting trailer to double stack

I currently have a galvanizes trailer for my H20, I want to stack a 17 on top. Has anyone done this, what did you do, how did you do it?
I want it to be something I can use long term so I don't want to stack directly with just padding between boats.

I'm thinking I would need to weld/attach two uprights between the hulls on front with a crossbar, and then have something similar at the back that can be removed ?

Any help would be greatly appreciated.

Do you want to do this on a permanent basis, or is this a one-time deal? For a one-time use, you can use padded 2x4s across the trampoline frame of the 16 on the bottom. But I wouldn't go very far with that set-up.

However, you need to be mindful of the load-carrying capacity of the trailer (usually there's a plate or sticker that has that info on the trailer). You may need to upgrade the suspension (springs / axle / tires) to accommodate the extra load.

The chief advantage of a true double-stack trailer is that it relieves the lower boat from the weight of the upper boat.

The upper racks need to be removable (especially the rear one) to facilitate loading / unloading. The upper racks should bear against the trailer frame and not the lower racks. Some trailer's frames aren't conducive to double stacking because of the way the lower boat is positioned on the trailer. Take a look at your boat when it's loaded on the trailer and see where you can locate the vertical supports without interfering with the boat.

based on Matt's comments, make darn sure your trailer can handle the weight of two boats.

many years ago we loaded two H16 onto a steel trailer, using 2x4's between the boats. on the way home at 11:00pm on the BQE expressway in NYC the rear supports on the trailer bent under the load and bouncing on the highway, dragging on the pavement. an hour later and with much retying of lines, the 2x4's became the new lower supports and the booms were inserted between the boats. fortunately there was minimal scratching to the hulls.

you do not want that to happen to you.

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Chris
'88 H18SE Arís

This is a thought that has crossed my mind. If you do this please post progress updates.

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_________________
Catamaran Racing Association of Michigan - Marketing Officer
USF18 - Social Media Manager

2010 NACRA Infusion
2004 F18 Hobie Tiger - SOLD
Hobie 16 - BREAKPOINT - SOLD

Just to reiterate what has already been said above, you need to make sure your trailer is up to the task of carrying two boats (and all the associated gear that go along with them). All Hobie trailers are not built the same. Check the name plate on the trailer (if there is one) for max load capacity, or if there is a P/N contact the trailer manufacturer. The springs, axle, hubs, and wheels also all need to be able to support the extra load. I wouldn't even consider adding a double stack to a trailer that doesn't have either a fully boxed or a heavy C-channel frame. Some trailers (like my old Highlander) are only stamped channel frame and have already cracked under the load of just one Hobie.

Beyond that, what you're describing is pretty much the general design. An elevated, fixed crossbar at the front position and a removable rear crossbar. Be sure to provide adequate lateral support (gussets or cross bracing) as well as fore/aft bracing. Most of the double stacks that I've seen are built using 1-1/2" (give or take) steel square tubing. Make it strong - broken trailers do not make for fun travel experiences.

sm

My dad and I did this to set a H14 on top of an H18. It's made from 2x4s, plywood, some pipe, and pipe fittings. I'll get some pictures soon but there is a structure at the front and rear of the H18 tramp with sockets that point up, but are short enough that the dolphin striker will clear. Once the H18 is on the trailer, two upper structures slide down into the sockets and provide support for the hulls of the H14. These upper structures are like a beam with two pipes sticking down, one at the front and one at the back. The H14 is lifted by 2-4 people up onto the upper structure and tied down. The back structure has a threaded pipe flange bolted to it, and a rear mast support is threaded into it once the H14 is in position. The rear mast support is forked to hold each mast, and the front mast support has a matching fork pattern. There are 2 sail tubes under the H18. Tie everything off and off you go! The trick is needing 2-4 people to lift and lower the H14 from the top position.

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Matt Miller in Colorado
'82 H14 Turbo #38674 Red/Gold
'85 H18 #13222 Nationals White (Prism)

Unfortunately I don't have a plate to figure out what I'm rated for, but I have a fully box square tube frame. My springs are stock, but I have upgraded my trailer with a 2000lb axel and Highway grade 15in rim tires.

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_________________
Catamaran Racing Association of Michigan - Marketing Officer
USF18 - Social Media Manager

2010 NACRA Infusion
2004 F18 Hobie Tiger - SOLD
Hobie 16 - BREAKPOINT - SOLD

Cleaned the boats up and got them ready for the water this weekend. Excuse how dirty they were, but here you can see pics of how our double stack works:

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Matt Miller in Colorado
'82 H14 Turbo #38674 Red/Gold
'85 H18 #13222 Nationals White (Prism)

Thats some serious custom, but it looks like you have a much stronger trailer to being with.

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_________________
Catamaran Racing Association of Michigan - Marketing Officer
USF18 - Social Media Manager

2010 NACRA Infusion
2004 F18 Hobie Tiger - SOLD
Hobie 16 - BREAKPOINT - SOLD

I have a custom built steel galvanized trailer to carry two 21Se's, but not too sure pictures would be much use for your purpose. I made two different front and rear mast carriers. One pair carries a single mast, and the other carries two. It carried 21's all over the country for a few years.

The trailer frame has steel tubes about a foot high that holds the second layer racks. The second layer comes apart in pieces so one person can handle them. The second level rack is assembled with bolts and nuts, so it's not exactly a quick process, but not as bad as it might seem.

The whole thing is fairly heavy, and has tandem axles.+