hardtop tubing support help needed

[mcgyver]

Finished up the fab and mig'ing of the aluminum supports for the hardtop but I'm getting far too much side to side movement for my comfort. thought it would have been stiffer with the side 45's and the front 30's. Fore/aft there is no movement. I'm thinking that i need to connect the tubing that is from side to side and runs along the bottom of the hardtop..... can anyone else see an area that I have missed that can stiffen this thing up. 2" tubing and 1.5" tubing 6061 used. thanks....I'm kinda out of ideas

 

[Trooper82]

Re: hardtop tubing support help needed

I agree with you...."I'm thinking that i need to connect the tubing that is from side to side and runs along the bottom of the hardtop...."

Looks like the two pieces you have angled out on the bow are preventing the movement for/aft. If you tied across side to side that ought to take care of it I would think.

 

[Grandad]

Re: hardtop tubing support help needed

Hi McGyver, Could you add a short stub where I've shown in red to stiffen the forward vertical? The aft verticals would be stiffer if the tubes extended through the deck to secure at a second attachment point. Also, if the tubing itself is actually bending, perhaps it could be lined with a second tube inside. In the end, maybe you'll have to live with a little bit of flex. - Grandad

 

[Shife]

Re: hardtop tubing support help needed

Standoffs will help, but the tubing at the top should have interconnected to form a loop. You have the right idea with the bracing you put in, but that hardtop isn't stiff enough to replace the lost integrity of the upper hoop tying the legs together. Connecting the upper sections and adding a couple standoffs as illustrated by Grandad would be ideal. You could reinforce the glass top to add stiffness, but you would pay a large weight penalty in an area where you really don't want to add weight.

I just built something rather similar but with a canvas top for my tin dual console. It's on the last page of the rebuild link in my sig.

 

[Scott Danforth]

Re: hardtop tubing support help needed

criss-cross braces in the front or add hoops. with a screen name like Mcgyver, that should have been second nature.

 

[mcgyver]

Re: hardtop tubing support help needed

Thanks, do you think that welding in connecters like i have drawn in red will do enough to stiffen it or should i also look at modding like "grandpa" suggested?I think I underestimated the strength of the actual hardtop and notice that some movement occurs at the 45 degree cut ends of the cross pieces with lateral flexion. Hoping that by beefing that up it solidifies the top much more.... and further thoughts?
thanks

 

[Scott Danforth]

Re: hardtop tubing support help needed

that will help.

 

[kmarine]

Re: hardtop tubing support help needed

Definately. the reason for movement is tha the fiberglass will flex . when you tie the tubing togetherwith the fiberglass they will work in conjunction with each other. Both the tubing and the fiberglass together make them exponentially stronger.

 

[Shife]

Re: hardtop tubing support help needed

I'd rotate the rear uprights 90 degrees and connect fore, aft, port, and stbd to form a loop, tying the whole piece together. The standoffs shown by Grandad would then add significant resistance to side/side movement. You're very close, you just need a bit more.

 

[mcgyver]

Re: hardtop tubing support help needed

Thanks, I'm concerned my powdercoater wouldn't be able to do the whole piece if welded together to form a ring......

 

[kmarine]

Re: hardtop tubing support help needed

You can always see if you can make couplings by placing tubing inside. You can then drill and pin them together. Some wakeboard towers are made this way for shipping purposes.

 

[mcgyver]

Re: hardtop tubing support help needed

Like the coupling idea....

 

[kmarine]

Re: hardtop tubing support help needed

Yes, the nice thing is that if you decide later to use it on a different boat, all you need to doo is widen the center tube. I build some of my bimini tops this way. kind of a one design fits many boats idea.

 

[chriscraft254]

Re: hardtop tubing support help needed

Imo, you want the top to be one piece, all tubing connected. Basically the tubing should be a roll cage and the top itsself is just to keep the rain and sun off of you.

The more connection points you have to the hull, the better and make sure you have large backing plates anywhere that it is connected to the hull.

Angle forward and aft and side to side act like trusses and will keep it solid as a rock if you have enough connecting points and the top is solid one peice. I have a total of ten connecting points to the hull structure on mine and mine is a simple design.

Here are some pics of the top on my Chris Craft. I can tell you, there are alot of newer tops that looks estetically much better, but this one you could probably stand the boat upside down on the top. No flex, no rocking, shaking etc. Its an entrical part of the boat.

also keep in mind, if you are going to make canvas for an inclosure, having a solid one peice going around the top will allow you to mount canvas alot easier than what you have now. Good luck

Hope the pics help.

 

[mcgyver]

Re: hardtop tubing support help needed

Chris, beautiful boat...... have the aluminum tubing and am going to mig in the bottom of the HT supports this weekend...will let yoou know if it "stiffens" up....I'm hoping so!

 

[chriscraft254]

Re: hardtop tubing support help needed

Chris, beautiful boat...... have the aluminum tubing and am going to mig in the bottom of the HT supports this weekend...will let yoou know if it "stiffens" up....I'm hoping so!

Thanks man, just thought the pics might help with a design/stiffening. Looks like you got a good start on it. good luck