Custom tower canopy - don't do what I did

[tinkertinker]

As a way to give back to this community, I'll share some mistakes I made building my own aluminum canopy / tower.

I wanted a strong frame to support my tarp in snowy NY winters (no garage) and also provide lots of attachment points for overhead rod storage and side rod holders.

I ordered 1" schedule 80 aluminum pipe from onlinemetals.com and cool tinker-toy like Kee Lite fittings from Simplified Building Concepts. Lots of measuring, easy cutting, and a bit of filing the sharp pipe edges. Just an allen wrench and some threadlock to assemble. So far so good.

The bad:

I made the tower too tall, without cross-bracing, and it wobbled horribly underway. It got it's own rhythm going. It is better now that it is shorter, but I'll have to think about more bracing without making it look more stupid.

Using 1.32" sched 80 pipe was overkill. And the holders and gizmos that fit 1.32" OD pipe are EXPENSIVE. The bases for this size pipe are large and have big bolt holes.

I didn't think about the attachment points. The front legs are basically just riding on the bow skin. I cringe when I watch it flex.

The rear legs, which attach to the top of the gunwales, go straight up vertically, so at the dock, if the boat rocks a bit, I have a seriously strong pipe leaning toward the dock, threatening to catch anything that sticks out on the dock as I pull in or back away. I should have mounted them further inboard.

A really square structure just looks inelegant. A slight S bend in both aft legs would look much better. But I'd need a good jig to bend them both identically.

http://picasaweb.google.com/lh/photo/cg63lPP38RjArA8USD-brQ?feat=directlink

http://picasaweb.google.com/lh/photo/zf8MjrEHj1GYu8yHhJYRPA?feat=directlink

Hope this helps someone and/or gives some folks ideas.

 

[Lightnig]

Re: Custom tower canopy - don't do what I did

doesn't look too bad to me, a bit of tweaking more than anything I think - Shorten up the top pieces to give it more of an A-frame look (when viewed from the front or back), and a couple of angle braces between the uprights on each side and you should be good to go.

Oh, and if you figure the attachment points are too flimsy, do you have room to add a set of backup plates underneath the skin?

 

[Rickairmedic]

Re: Custom tower canopy - don't do what I did

Tinker thanks for a good post . I dont fish and fortunately the ( average snow load ) here in Louisville isnt quite as bad as you guys have up there . I plan to make some support braces for my cover out of 1" Schedule 40 PVC as I figure that should be overkill for our snowloads . Usually 3" or less at a time except for the once in 100 years freak ice storm LOL. We just did that one this year so I dont figure I will have to worry about it for a while LOL.


Rick

 

[Bifflefan]

Re: Custom tower canopy - don't do what I did

I looks good,
If i may add a thought. Instead of the 90 deg corners on the top, if you went with say 60 deg ones, it would eliminate the wobble that you are getting. The closer you get to a triangle the more strudy it will be. When the legs are angled in a bit its makes a huge difference.

 

[Bob_VT]

Re: Custom tower canopy - don't do what I did

Based on the height I would add a brace on each back leg or even move them towards the rear more (I see you are limited by the front windshield.

Since it sounds like it is ALL aluminum..... I might have the connections welded which will also stiffen it up.

 

[jonesg]

Re: Custom tower canopy - don't do what I did

Since it sounds like it is ALL aluminum..... I might have the connections welded which will also stiffen it up.

Yep ,thats it,

slip fittings held by allen screws aren't good for a moving fixture.

Thats why I veered away from compression fittings on mine and welded everything instead, much more sturdy.

 

[henrye718]

Re: Custom tower canopy - don't do what I did

I think those connection fittings and elbows you have there are some kinda of cast alloy, prolly not weldable.

I think I would drill through the fitting and the pipe and put a bolt in with a lock nut at least on the fittings that secure the cage to the boat.

Those allen things may come lose while underway and hurt someone or lose the the whole kit over board at the very least if that were to happen.

 

[Marcq]

Re: Custom tower canopy - don't do what I did

I looks good,
If i may add a thought. Instead of the 90 deg corners on the top, if you went with say 60 deg ones, it would eliminate the wobble that you are getting. The closer you get to a triangle the more strudy it will be. When the legs are angled in a bit its makes a huge difference.

I agree, in doing so, you'll have to rotate the base fitting also.The hole thing wont look so boxy , It will look a lot nicer

Marc..

 

[tinkertinker]

Re: Custom tower canopy - don't do what I did

Welding... a good thought. Now that I've actually had a chance to test the functionality, angles, and appearance, making a permanent setup (by getting someone to do some welding) might be a good idea.

Maybe I'll start by just having the feet and non-90 angles welded and figuring out a better front base. I just have them backed with plastic cutting board chunks right now. I like the idea of leaning the 4 legs inboard, too.

To be clear, now that I've shortened the tower, the wobble is barely noticeable, except when the rhythm of the boat's motion is just right (or just wrong), and then a sort of tight, harmonic wobbling happens. And I can see that part of the problem is the front skin flexing.

I love these Kee Lite fittings anyway... for those of us who can't weld (esp aluminum) they have some interesting possibilities. They are incredibly strong, stay put, and don't have any perceivable play, except where I am mis-using the swivel base.

I might even use them for a sort of minimalist, maintenance-free seat frame or as a removable fishing console (rod holders, etc) setup in the stern.

 

[NoKlu]

Re: Custom tower canopy - don't do what I did

Glass some 1/2" plywood up under the front legs for a larger area to spread the load of the front legs. oops! and I have been doing a few wake towers and all 4 attaching points have to be reinforced with plywood behind and some very large washers or plates to run the bolts through. It won't take long and will stiffen things up.