Bimini Advice

I am in the process of extending the bimini on my flybridge. The photos show the existing cover, and a Photoshopped version of how I hope it'll look when the extension is complete. The black line indicates the projected position of the new bow I already have, and the white line will be straps to the aft rail. The approximate length of the extension is 56". My question is this: Do you think I need a short center bow in the extension, like the one in the original cover, or should the single bow be sufficient? Is there a rule of thumb regarding how far a cover like this can extend without center support?

I would think it would depend on how much you're willing to let the fabric sag and how much rainwater you are willing to let puddle up there. And how much you are willing to have the canvas flap in the wind. If it was me I'd probably want the extra bow based on your illustration. But I don't think it would be needed for strength. Just to control sag and flapping.

Art,

I had a separate bimini made for the aft section. 3 bows, and it seems to need the 3rd bow in the middle. In the Spring and Fall we usually have just the forward bimini up, but in the Summer it's scorching hot without the aft one providing shade.

If it's not pretty tight, it will collect rain water. It will also flap in the wind and might damage itself. I would think support every two to three feet would be appropriate.

Are you looking to have it up all the time or just rain/sun protection when at anchor/dock, etc?

I'm going to have an extension to mine for at anchor dock...zip it to the existing bimini, corners to halyards on the mast and a topping lift to a enter strap in the middle to shed water/wind.

Here's how I did it.

For folks going to the Bahamas , any thing that will collect rain water is a plus.

FF said:

For folks going to the Bahamas , any thing that will collect rain water is a plus.

Click to expand...

That, mixed with the bird poop will be great!

On my boat, the rear section zips to the front section but the reat has two bows. There is a bow every two to three feet from front to back when they are both deployed.

If you call in an experienced boat canvas person or shop, they will know what you need. They do this all the time and have to stand behind their work.

Thanks for the inputs. I'm going to add the middle support bow. Ron, the reason I'm forgoing professional advice nad tackling this myself is to hopefully do itt on a budget. I already have about 10 yards of matching blue Sunbrella I picked up on eBay a couple of years ago, so the hardware, seam tape, etc will be my only expense.

I've tackled a few other canvas projects, so I am OK with the challenge. I've learned that if it doesn't look quite right the first time, you can always pull out a seam or two and redo it... or just get used to it!. One of the advantages of working on a nearly 40-year-old boat is that nothing's perfect, and so my home-made efforts blend in well anyway.

Glad you're adding the extra bow for all the reasons stated above.

I'd give serious consideration to using aft support poles in lieu of the straps. The top will be much stronger and they will help resist flexing. They can be hard mounted to the top of your rail on a bracket with clevis pins to allow for easy removal. (see pic below marked "brace kit.")





Bimini Top Advice & Tips

Sunbrella is much easier stuff to work than sailcloth - more like folding thin aluminium. The secret is to use the very sticky seam-tape specially made for acrylic cloths. Sunbrella is so hairy that the ordinary sail-cloth seam-tape doesn't stick very well. An electric or butane hot-knife is worth buying. It cuts cleanly and all your edges are sealed, even though you are going to hem them. Sailrite and Sailmaker's Supply are good sources of everything you'll need. Do you have a sewing machine that can handle 3 or 4 layers of Sunbrella?

Well, it's pretty much done. A few details to work out on tying the corners of the two bimini pieces together, (maybe Velcro, or a couple of snaps?) but overall I am pleased with the result. That old Kenmore sewing machine managed to get thru the max of 3-4 layers of fabric I needed for this project with no problem. One thing I wasn't counting on was that the radius of the bows I added was different from the existing ones.. required a little fiddling to bring it all together.

Nice job! Well done!

Shade is a good thing

Shoalwaters said:

Sunbrella is much easier stuff to work than sailcloth - more like folding thin aluminium. The secret is to use the very sticky seam-tape specially made for acrylic cloths. Sunbrella is so hairy that the ordinary sail-cloth seam-tape doesn't stick very well. An electric or butane hot-knife is worth buying. It cuts cleanly and all your edges are sealed, even though you are going to hem them. Sailrite and Sailmaker's Supply are good sources of everything you'll need. Do you have a sewing machine that can handle 3 or 4 layers of Sunbrella?

Click to expand...

My "cutting knife" is a little 30 watt soldering iron with a fat tip that holds heat but has a sort of knife edge as well. Set a straight-edge against it, and it'll cut a great non-fraying edge thru Sunbrella for a whole lot less$$ than buying a hot knife!. I have found that Walmart "denim needles" in my sewing machine will punch thru a whole lot more Sunbrella than you'd think. It'd be nice to have one of those walking foot machines.. keeps the stitches way straighter... but for my needs, my 40 yr old Sears machine works.

...and yes, I use that seam tape from Sailrite. . Never could have done the project without it.

Looks really great, ARoss. I'm saving pics of this for when I am motivated to extend my FB bimini. If I do it, it'll be in retirement when I have the time and inclination to learn how to sew and build it. What a great skill set to have as a boat owner!!

Just out of curiosity what type of thread did you use to sew it all together? The seams are generally the first thing to let go on a boat's canvas and once they go unless they are repaired immediately the canvas itself will start to come apart with the flapping. There is thread made specifically to prevent this sort of thing from happening.

Marin, I used this stuff from Sailrite. Not only is it "sunproof" but it really slides thru my old machine.
Thread V-69 Derby Navy Polyester UV 4oz (1400 Yds) (1400 Yds)

Not a commercial, I hope, but anyone who isn't familiar with Sailrite should visit their site if you are thinking of doing canvas work. Loads of interesting instructional videos... and all the stuff you will need for any project.

ARoss said:

Marin, I used this stuff from Sailrite. Not only is it "sunproof" but it really slides thru my old machine.
Thread V-69 Derby Navy Polyester UV 4oz (1400 Yds) (1400 Yds)

Click to expand...

On the advice of our canvas shop my wife uses Gore Tenara thread on the canvas on our boat. From what we've been told it's the best thread on the planet for outdoor use. But..... it is staggeringly expensive. The best price we found on-line for it several years ago was $125 for a spool. Tenara spool prices at that time were ranging from that on up to almost $400 for the same size spool. She first started using it some six or seven years ago I think and the seams she did then look like she did them yesterday. It's a little tricky to use, however as it requires a specific type of needle and the tension on the machine has to be set specifically for it.

Other than the canvas pieces she has made since we acquired the boat, the bulk of the boat's canvas came with the boat. Some of it was old when we bought the boat 14 years ago. I've been amazed at how this stuff has held up but it's only because my wife is diligent about replacing any deteriorating seams or weakening spots in the canvas. Considering we've gotten estimates as high as $10,000 to replace all the canvas currently on the boat her efforts are well worth it.

ARoss said:

Well, it's pretty much done. A few details to work out on tying the corners of the two bimini pieces together, (maybe Velcro, or a couple of snaps?).

Click to expand...

A zipper will work the best. And if you have a flap over the zipper, it will keep water from leaking between the two pieces. The flap should be sewn to the front piece and lay over the back when they are zipped together.

Marin said:

On the advice of our canvas shop my wife uses Gore Tenara thread on the canvas on our boat. From what we've been told it's the best thread on the planet for outdoor use. But..... it is staggeringly expensive.

Click to expand...

And IMHO, it's a staggering waste of money. Why use thread rated for longer life than the fabric it holds together? Sailrite's standard thread is rated for ten years. Does anyone really need a lifetime thread? Moreover, there are some differences in technique and machine setup you need to be aware of to use Tanera.

Bess is doing some canvas work as a hobby with a few professional gigs on the side and I can't understand the public's fascination with Tenara thread. Standard thread will work for 99% of applications. It's like killing a fly with a bazooka.

GonzoF1 said:

And IMHO, it's a staggering waste of money. Why use thread rated for longer life than the fabric it holds together? Sailrite's standard thread is rated for ten years. Does anyone really need a lifetime thread? Moreover, there are some differences in technique and machine setup you need to be aware of to use Tanera.

Bess is doing some canvas work as a hobby with a few professional gigs on the side and I can't understand the public's fascination with Tenara thread. Standard thread will work for 99% of applications. It's like killing a fly with a bazooka.

Click to expand...

We had a bimini made in January 2008. We restitched it earlier this year and it looks it. We are having a new cockpit cover made. I asked the 2 bidders what they are using for thread and the one that said Tenara got the job. He was also low bid. That's my story.

Available at Sailrite -

Tenara Lifetime Thread - UV Stable Rot Resistant Outdoor Thread - Tenara

GonzoF1 said:

Bess is doing some canvas work as a hobby with a few professional gigs on the side and I can't understand the public's fascination with Tenara thread. Standard thread will work for 99% of applications. It's like killing a fly with a bazooka.

Click to expand...

But Bess will also gladly use Tanera if the project's customer wants it. It just raises their cost for whatever the project is. So far, no one has asked.

And Al, if you need any snaps or grommets, we'll be at the Seafood Festival next weekend, and my toolkit is on the boat.

GonzoF1 said:

And IMHO, it's a staggering waste of money. Why use thread rated for longer life than the fabric it holds together?

Click to expand...

Wrongo dude. A lot of the canvas on our boat is now entering at least it's 18th year. Fourteen since we've owned the boat and it was on the boat at least four years prior to that by the photos we were given. And from everything we can tell and have learned from some of the previous owners the boat has lived in the weather its whole life.

There are people we know in our marina with Sunbrella sail covers that are over 20 years old and still doing fine. But they've needed restitching periodically.

Sunbrella lasts a whole lot longer than most people seem to think--- IF--- it's kept clean and the seams don't start coming apart.

Tenara is amazing stuff. In addition to being longer lasting and stronger than other threads it is more chemical resistant, bird poo resistant, UV resistant, dirt and soot resistant, salt resistant, mildew resistant, rot resistant, etc. It is the thread of choice by the majority of quality canvas shops today, not only just marine but residential and buisiness (awnings and stuff). It's used to stitch together the side curtains on fabric-sided semi-trailers.

Marin said:

Sunbrella lasts a whole lot longer than most people seem to think--- IF--- it's kept clean and the seams don't start coming apart.

Click to expand...

Marin any tips on keeping it clean?

I am impressed you have kept yours maintained well enough to have it last so long. Great job!

Our previous bimini was about 20 years old and it was a piece of ****. Looked like a planetarium underneath it. It looks like the seams did fail, but it was equal parts thread and fabric failure. The best thread can't prevent the fabric around the needle holes from failure (stretching to larger than thread hole). So I will only submit that in your case, I believe that it was your care and feeding of the entire bimini that had as much to do (if not more) with the longevity of the seams than the thread itself. If you take that good of a care to a '72 Pinto, you could tell the same story. But hey... what do I know

Besides, I'd be bored with the color after 10 years and want to change it anyway. I think Bess will replace ours next year (or over the winter) just for the practice of doing one for the first time.

We wash our canvas periodically using a cleaner my wife gets from the canvas company she uses. And before you ask, fabrics is not my thing so the product name of the cleaner she uses is not something I've ever bothered to learn. I do know it's important to wash it twice and rinse it very thoroughly. She also treats it twice with 303 and even that application has a wet-dry process she learned from the canvas company.

So I'm not being of much help, but periodic cleaning-- however you do it--- makes a big difference to the longevity of the Sunbrella. But--- the seams have to be in really good shape because if you wash it and the seams are even just iffy, they will come apart like you wouldn't believe. Hence her switch to Tenara as well as redoing any seams that even start looking suspicious.

Between keeping it clean and redoing the old seems with Tenara I can't believe how long some of this stuff is lasting.

GonzoF1 said:

So I will only submit that in your case, I believe that it was your care and feeding of the entire bimini...

Click to expand...

I'm not talking about the bimini alone. I am talking about all the canvas that came with the boat. So bimini and bimini cover, huge, two-part full flying bridge cover, flying bridge siderail panels, full length handrail, caprail, and grabrail covers, transom cover, sailing dinghy cover, aft hatch cover, and covers for every opening window.

The two-part flying bridge cover is the oldest canvas on the boat and I would not be surprised to learn it was over twenty years old now. My wife has replaced virtually every seam in the two sections.

The cost to replace all this canvas has been quoted to us by a couple of shops as being in the neighborhood of $10,000.

Since aquiring the boat my wife has made a number of other covers--- windlass, flying bridge name boards, dinghy motor, a cover for the crate that holds the stern anchor rode, the barbecue, covers for the non-opening windows and other odds and ends. These were made with Tenara from the outset as well as new fabric of course, and they are in great shape today.

rwidman said:

A zipper will work the best. And if you have a flap over the zipper, it will keep water from leaking between the two pieces. The flap should be sewn to the front piece and lay over the back when they are zipped together.

Click to expand...

Tying the two sections together with a zipper was a non-starter since the forward section, which has been on the boat for quite a while, is virtually impossible to remove, and there was NO WAY I was going to try to hand-stitch a zipper to it! Somehow, the bows were installed in stitched pockets, and to get the fabric off would require total dis-assembly. The two sections are actually free-standing, and abut one another with the flap on the fwd section lying over the the top, and now a couple of pieces of velcro on each side to keep it in place.

Tom/Bess, thanks for the hardware offer; I think I have a pretty good supply of stuff. My next project will be a bridge cover; I still have 4 yards of 64" Sunbrella to use up. We will be at MC Yacht Basin Fri/Sat night of the Seafood Festival; maybe we will catch up with you.