DIY Bimini/Canopy Made From Alumimium, Hardtop/Softtop Idea

[gazza2006au]

Hey guys looking for advice on a hard top/soft top bimini/canopy for my tinny, looking to do a DIY need advice on what size and shape aluminium i should chose?

i was thinking of doing the vertical post from round tube in 3mm and the top square frame from rectangle 3mm material, do u think this thickness would be sufficient?

[gazza2006au]

I should be picking up the material this week, haven't decided weather to go with 25x3mm or 32x3mm round tubing, i have done a couple edits in paint i am happy with either design below more so the second one, if the canopy works out i will try my hand at making some clears although i have never stitched!

the roof might be really thin .8mm aluminium to keep the top light or i could build it from some soft bimini material and buttoned on

just got the ESAB welder sorted last night added a spool gun for welding the aluminium frame, stay tuned!

[gazza2006au]

I need to do some tack welding does anyone know if u have to remove the motor to weld on the hull? nothing is welded yet it has just been cut and taped together to get an idea of size and angles, i purchased a Hafco pipe notcher to make the final cuts

tomorrow if i have time i need to weld on the bottom 4 legs round feet as the canopy will be bolted to the hull, I'm not confident in welding new to old aluminium

[catshark]

hey Gazza, Do you intend to weld the pipe flush fit onto the gunnel of you boat? or would you weld onto flat plate and thru bolt that onto the boat. lm thinking the height you have set will catch the wind more so than standard bimimis, what can happen is you build it to with stand the wind load when youre in a forward direction and then that energy transfers into lateral movement, when your towing you will see your bimimi rocking sideways and eventually cracks will occur at the most vunerable points so stiffner plates and angles are needed to strengthing those joints as well as alloy welds ive heard can become brittle then the parent metal.

[gazza2006au]

Hey CatShark Thanks for bringing that up, My original thought was to put some sort of hinges on the rear legs and pin locks on the front legs so while under tow i could fold the canopy back into the boat by biggest worry is doing 90 down the highway and it sails off into the sunset but i havent yet designed a hinge or locking pin yet but i drew one below, i was just focusing on the canopy and than the whole hinge and lock got away from me and i thought i would just bolt it down but i think the canopy is quiet high, the height came to mind while i was thinking about 4 of us fishing on a rainy day if it starts to hail than all of us will need to stand under the canopy

this is what i had thought about for the front legs and just drew it up i hope u can make out what I'm thinking of

[shakey55]

I totally agree with Catshark. Your idea of having it hinged is also good, BUT when you lay it back for travelling, from what I understand the roof is going to be solid so the wind on the roof section while travelling will be a huge force.

Good on you for having a go, but I think more thought required before final construction.


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[gazza2006au]

shakey, The aerodynamics of towing a boat hits the windscreen and goes right over the boat than sucks back in around the motor so there should only be forward draft on the canopy while towing, the canopy doesn't stick much higher than the windscreen once folded

[ric]

I need to do some tack welding does anyone know if u have to remove the motor to weld on the hull? nothing is welded yet it has just been cut and taped together to get an idea of size and angles, i purchased a Hafco pipe notcher to make the final cuts

tomorrow if i have time i need to weld on the bottom 4 legs round feet as the canopy will be bolted to the hull, I'm not confident in welding new to old aluminium

For what your doing, the age of the alloy doesn't matter. What matters most is proper cleaning of your hull before welding. Use a stainless steel brush to clean your existing surface back from its oxidised layer and you won't have any problems.
You need lateral support for that structure otherwise it won't even make it to the ramp for its first sea trial.
I would be welding the structure to base plates with gussets, and then bolting with backing plates to the hull. Welding that section straight to the hull won't hold.
Fore/aft strength also needs beefing up bit that's alot easier to make it look pretty.
Base plate/backing min 4mm, gussets 4mm, tube structure 3mm, 8mm bolts in sst with nyloc nuts and nylon washers.

Hope this helps mate.

[gazza2006au]

Thanks Ric, i was back at it this evening but i burnt out the drill and relised the pipe notcher is to big to fit into my bench drill, I'll grab another drill in the next few days and give it another go

[gazza2006au]

The last design took a change i just could not work out the multi combonation cuts or mitre cuts its not just a simple angle cut but it just became to technical so i took a simpler approach and made it like this pictured

there were a couple teething problems with the Chinese spool gun on the ESAB mig, the Chinese didn't make a normal size spool for the wire so i had to jerry rig a ordinary .5kg alloy spool of wire to the gun either that or sit there for 3 hours rewinding the Chinese spool with wire

so far i have both sides completed i just need to cut and notch the top front and top rear than get it all square and weld away

once i have the canopy sorted i will move on to buttoning on the fabric roof and creating the canopy clears for the front and sides i cant wait to do this bit

forgot i will add some 45 degree bracing before its finished

[gazza2006au]

Got the frame welded now i need to fabricate some bases for the legs, i may still cut the canopy down but its perfect height for me standing upAttachment 115895