Designing a Soft Top for My Tower

Hi Guys. I'm trying to design a new canvas top for my old 21' Starcraft Holiday. I like the looks of the support ribs when they run fore and aft rather than the traditional athwartship. I'd like your comments on the looks and practicality of this design. In particular, I'd like to know how a professionally built top such as a T-top would have Sunbrella wrapped around the perimeter edge and what hardware secures it. I'm concerned about wrinkles where the canvas wraps around and fastens to the inside of a curved support tube. Will Sunbrella (or another product) stretch sufficiently at the corners to eliminate the wrinkles?

Pictured below is the tower in progress that will provide most of the support for the frame.



Below is how I envision the frame for the canvas to be shaped. Not all structural support is shown. At this point, I'm confident that I can make the structure adequately strong, but the canvas worries me some.
Thanks for your help - Grandad

Re: Designing a Soft Top for My Tower

Hey guys, the silence is deafening. Maybe the thread's in the wrong forum. No-one has a T-top? - Grandad

Re: Designing a Soft Top for My Tower

How you gonna get a sun tan hiding under that t-top Pops?

I have nothing to add about the fabrication, but sensed you were lonely in here all by yourself.

Re: Designing a Soft Top for My Tower

I'm sure someone will be along that knows what they are talking about,......

If your doing the fabricating why not just use aluminum sheet for the top??

Re: Designing a Soft Top for My Tower

The design is perfect and typical of you. Well thought out and something you probably will enjoy making. I admire your skills and accomplishments.

OK enough of the smooze.

I do not have your skills or mindset yet have had some success by finding the correct people that do have answers, experience and a desire to share that info. Specifically, you need to find the Grandad of canvas if they arent in Iboats.

My past work neighbor was a skilled boatyard with a variety of old salts. They were very helpfull in sharing knowledge so when it came time for my canvas work they pointed me to the correct person.

I know you have a wide choice of full service marinas and I bet a wide choice of canvas vendors but among those sources is a Grandad imho.

I will be interested to see what you come up with but cant imagine any other fastener to keep it taught than following:


canvas snaps and fasteners - Bing Images

I hope that comes out OK. In general it is just the standard "turn snap button fastener" for canvas.

Looks like the Canuckistanians are going to be able to enjoy Hockey Night in Canada after all, eh.

Re: Designing a Soft Top for My Tower

G'day,

Very well done illustration. Although I get the feeling that you want to make something similar to
Aerial Freeride Tower Bimini - Stainless Steel (1 of 2)

If that is the case you could probably use the info on that to make one to suit your application.

Cheers mate
Evo

Re: Designing a Soft Top for My Tower

Thanks Jig, my personal solar panel tends to overcharge me. I never go out without a top up.

Thanks Teamster. Ya, I've been considering adding a thin aluminum sheet and then perhaps covering that with Sunbrella, but I'm concerned about the added weight. The top will be about 8' long by just under 6' wide. As I recall my calculations from a few months back, just the aluminum sheet would add another 35 lbs, or so. I'm trying to make the whole assembly fold with the tower as in the thread linked in my signature.

The tower mechanism would carry some of the weight of course as it folds, but this senior is getting more awkward at duck-walking under things while carrying overhead weight. I think the folding process will be to tip the tower back toward the stern first, locking into vertical support posts with the top still rigidly attached.



This would point the top up about 40 degrees into the air. Step 2 would fold the top down onto supports added at the corners of the windshield. I would then strap the top down for trailering. - Grandad

Re: Designing a Soft Top for My Tower

Thanks Streetgang. I'm maybe overthinking the problem of wrapping the canvas around the perimeter. I'd like to know if the fabric will take kindly to the compound roll around the curves at the "corners" of the top. If there is a limit to what I can get away with, I could modify the frame to suit. In the end, I think you're right; just some turn buttons inside might do it. It may need a stiffener of sorts in a canvas pocket on the periphery to provide a uniform pull/stretch on the fabric. I haven't sewn at all, so this will be another new challenge.

Thanks evolution1985. I checked that link. WOW. If that top was a uniform 70" wide, I'd order it and make it work somehow. My plan for the top is about 70" x 100". That is some tower and top and accessories. Alas, I'm part of the 99%, not the 1%. My whole rig including trailer is probably worth less than that tower package. - Grandad

Re: Designing a Soft Top for My Tower

canvas will wrap the corners fine if you pattern it properly, you will have a seam along the top perimeter then a band around the bar, if it is purely fir shade and easy break down, you might consider just making a a flat panel of canvas with grommets lining the perimeter then use a tie to keep it in place, a lot like hammock furniture...

a lot like how these chairs are tied on...would make for an easy DIY job since patterning canvas can be tricky to keep it tight
Deluxe Zero Gravity Outdoor Folding Recliner | Overstock.com

Re: Designing a Soft Top for My Tower

JDA1975 said:

canvas will wrap the corners fine if you pattern it properly, you will have a seam along the top perimeter then a band around the bar, if it is purely fir shade and easy break down, you might consider just making a a flat panel of canvas with grommets lining the perimeter then use a tie to keep it in place, a lot like hammock furniture...

Click to expand...

Thanks Judge. When I started with this tower and top plan, I wanted ultimately to be able to close in the cockpit and use it for a poor man's overnight cruises. I do like the simplicity of a shade top held in place with grommets and ties for fair weather day trips that we usually do most times, but I haven't given up (yet) on full enclosure side curtains. I have some health issues to overcome in the next few months that may influence what I end up doing (2 MRI's scheduled for this week). Gotta keep smiling and dreaming. - Grandad

Re: Designing a Soft Top for My Tower

Ok, I should update just to finish this thread. The top is finished. I revised my design for something more conventional. This top does fold for those that want sun and will be a little easier to trailer folded. The first design would require folding the tower to protect the canvas from highway speed winds and would be a pain to gain access to the cockpit when folded. I used 7/8" stainless for the bows and Sunbrella in "Toast" for the top. Anyway, there's more details in the restoration thread linked in my signature below. So, thanks for the suggestions. - Grandad