Aluminum top to replace a canvas top

1/8 or 3/16". no way 3/8" would be needed. way overkill. even 3/16 is prob a bit overkill as well if it isn't going to pack any weight and it's only function is to keep off the sun and rain.There is a lot of strength in aluminum. You see alot of shallow freeboard boats over in florida with quite complicated and large bimini assemblies, some with platforms to support a person at height for spotting, etc. Although the boats are probably designed and engineered for the structures in some way. My concern would be that the wind could put quite a bit of force on the roof structure, especially if caught sideways on a large rolling wave. although the wind would do the same whether the top was canvas or aluminum so I would think it wouldn't make a lot of difference in the big picture. Would rather have an aluminum top myself. So tired of having to replace canvas and plastic windows on earlier boats I've owned.
 
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Aircraft wings are skinned with as light as .o25"

But with a fair amount of under structure support at close centers I would think. With 1/8" formed or bent in a curved radius, you could prob get away with no under structure support (except maybe a tube support or something similar around the edges), ie, less weight (possibly), less work, less materials, simplicity of design. Wouldn't be suprised if you could go lighter than 1/8" though to a lighter gauge with no problems. I just have a habit of building things a bit more on the HD side, rather than on the light duty side. Prob comes from working in industry and seeing how engineers often design things as light as they think they can get away with and us having to come in and beef things up quite often after they fail... hehe.
 
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and the 1/8 will prob stand up to those golf ball size hail stones that come around every so often... hehe
been there, done that,
roof on the f'th wheel didn't come out of it very well....
 
Bloodbath

Thinking you are mid island, PM me if you want, you can come look at my DE if your in Vic. I have taken the water jetting, wind flapping and finally leaking soft tops of off 3 DE and replaced with aluminum hardtops. I purchased the metal (last from Courtenay shop) bent, cut and fitted then had a welder weld, (also Courtenay). I used the thinnest I could, 1/8 I think, you will need some sort of understructure as support. I made mine to carry our kayaks for quiet sneaking up to beaches, or prawn/crab traps. A lesson I did learn, after cutting out the windows metal and installing windows the wind vibrated the metal. I had to weld in extra tube bracing, this worked.

Go for it, don't look back. Hardtop works better for my boating style.

HM
 
I built this for my boat, best modification so far, the top is 1/8, you need to use at least that to be able to weld it. I haven't notice any stability issues since putting it on, catches a bit more wind from the side, but nothing major. Go for it, you won't regret it !!!
 

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Bloodbath

Took a couple pics in the white this morning. I am no fabricator (sculpin is) but this is my handiwork. Works awesome for what I want, never felt any change in stability, maneuverability or changes when up and running. Bit more surface for the wind to catch when drifting but barely noticeable. Hope pics work.

HM
 

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One other thing, think I will add slider opening windows to the top, above the brace next. On those rare still hot days it is hot under the top. I do troll from the back so not really an issue for me but guests get hot. Notice the cross member above the window, these were added after window to stop flex that I spoke about above. As for weight, top was on boat for tack welding then taken of for full weld, I picked up in my truck, then lifted and placed on boat alone. Then waterproof sealed, bolted, riveted while in final spot. Maybe 100-150lb as a guess.

HM
 
Hi bloodbath. Your boat's vertical center of gravity is about where the actual waterline is when sitting still in the water. Both the weight of, and distance of the weight from this COG matter. Similar issues to these is probably what caused the whale watching boat to capsize off of Tofino. IMO for someone to make a blanket statement that "it will be fine" or "I didn't notice anything" is very irresponsible; boat specific issues such as initial & dynamic stability matter. You may not notice anything either til you loose power and are taking large waves on the beam (side). Remember, there are bold boaters & there are old boaters, but there are no old bold boaters.
That rogue wave had nothing to do with the capsizing.
I was on that boat at least 12 times in all sea conditions and never felt like it was unsafe.
 
That rogue wave had nothing to do with the capsizing.
I was on that boat at least 12 times in all sea conditions and never felt like it was unsafe.

Are you saying the Transportation Safety Board erred in its findings of the Leviathan II capsize?
It may not have been a 'rogue' wave, but it was found to be a large wave.
http://www.tsb.gc.ca/eng/enquetes-investigations/marine/2015/m15p0347/m15p0347.asp

I think you want to determine the change to static stability and not dynamic.
I am usually worried about my boat's ability to return upright.

And to the thread, I think that thin skin aluminum top on bentley's boat looks very nice.
 
Any extra weight above will affect the center of gravity - and hence the righting lever. The question is: is that weight sufficient enough to make the vessel inherently unstable - esp. at larger angles of heel where the effects of the righting lever is truncated. I rather doubt if a thin aluminum top would do that - even for a smaller boat. Add numerous people on top of that - standing on one side - a large wave - the rest is speculation, I guess wrt the Leviathan.
 
1/8 or 3/16". no way 3/8" would be needed. way overkill. even 3/16 is prob a bit overkill as well if it isn't going to pack any weight and it's only function is to keep off the sun and rain.There is a lot of strength in aluminum. You see alot of shallow freeboard boats over in florida with quite complicated and large bimini assemblies, some with platforms to support a person at height for spotting, etc. Although the boats are probably designed and engineered for the structures in some way. My concern would be that the wind could put quite a bit of force on the roof structure, especially if caught sideways on a large rolling wave. although the wind would do the same whether the top was canvas or aluminum so I would think it wouldn't make a lot of difference in the big picture. Would rather have an aluminum top myself. So tired of having to replace canvas and plastic windows on earlier boats I've owned.
3/8 is overkill. 1/8 is all I would use. The weight also is going to be nothing to worry about. You really doing nothing different than all the other boats that size with rod/holder tower tec. Look at all the Gradys with all the add-on.
 
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Hi,

I have an older Campion 21 foot Fishing Machine boat with a canvas top and sides.

I am looking for someone in the Nanaimo to Courtney area that could give me a quote on replacing the canvas top with an aluminum top and possibly rocketlaunchers.

Would then replace the side and back curtains as well.

Would possibly look at replacing all the internal support poles.

Thanks

If you do want to build one you can always ask Len at Brady's Powder coating. He is an awesome welder and fabricator. There shop in the Cedar area.
 
Great post Gong Show. A rogue wave is defined as any wave that is 2x the size of average waves as I recall. The wave buoys also advertise that waves 2x the size of average SHOULD be planned upon by the prudent boater.

Fishtofino says he never felt unsafe after being on the boat 12 times in all sea conditions (except the conditions that capsized it.) READ THE REPORT!! I say to those who state "I never noticed anything/nothing to worry about" you are DEAD wrong - go ahead & trash me; I am used to it but I had my lesson out on Swiftsure Bank in plus 20ft seas over 30 years ago, learned from it & am still alive.
 
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