Modifying a Bimini for Height and the Backstay.

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taylormade
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Modifying a Bimini for Height and the Backstay.

Post by taylormade »

Howdy folks! I was gifted this big honkin' bimini from a friend who put a tower on his center console and no longer needed it. I chopped about a foot off the C poles and I feel it looks good and performs good but when I fold it up pole A doesn't come close to lining up. I'd like to be able to use the "sock" when it's not deployed but I'm not sure what I need to do in order to cut the poles but still maintain enough pressure on the fabric to keep it taught.

Second up, for those X owners who've run the back stay through the bimini, did you run a grommet or sew a slit or another option that I'm not even aware of yet? Thanks in advance!

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K9Kampers
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Re: Modifying a Bimini for Height and the Backstay.

Post by K9Kampers »

My bimini is MacGregor original (AFAIK) and attaches to the gunnel about a foot ahead of where yours does, folds up so all bows align, and sets up forward of the backstay without touching it.

You'd have to shorten bow A to match bow C, then cut or reposition bow B according ly. Ultimately, the fabric would need to be shortened and restitched for bow A.
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Jimmyt
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Re: Modifying a Bimini for Height and the Backstay.

Post by Jimmyt »

Wow - that's a nice Bimini.

The attachment point between A and C has to slide downward as the Bimini is folded back. You may have cut too much off of C to allow the two shapes to match up, but that is what it looks like needs to happen. There should be pins in C to stop the hinge point from sliding up past where it is now; but the hinge point should slide freely down C as you fold it up. You will probably need to add pins or clips below the hinge point to hold it up when deployed.

As K9 points out above, shortening A to match it up, if you can't get there with a sliding hinge, will result in a stitching job.

You might be able to shorten A slightly and move the hinge point of B forward on A. This will raise the height of the center, but should tighten up some slack from the shorter A. You would need to get the boom in position and take several measurements to work it out on paper. Otherwise, you'll be in an iterative cut and check situation. If you aren't up to it, I'd advise mounting the boom and posting measurements to get more specific advice.

After looking at Tom's rig, you could shorten A and mount the hinge point of A on the boat rather than to C. If you mount the hinge point forward of C's hinge point, A gets "shorter" as it folds back. Again, lots of dimensions required to work this out. I would not want to have to move the boom if possible while deploying the Bimini. It may not be a practical constraint, but I would look at that first while working it out.
Last edited by Jimmyt on Mon Oct 01, 2018 8:05 am, edited 4 times in total.
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Tomfoolery
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Re: Modifying a Bimini for Height and the Backstay.

Post by Tomfoolery »

taylormade wrote:Second up, for those X owners who've run the back stay through the bimini, did you run a grommet or sew a slit or another option that I'm not even aware of yet? Thanks in advance!
My Dowsar bimini has a zippered slit with a 'sock' of sorts that sticks out of the top with a draw string around the backstay.

This is the only pic that even remotely shows what I have. You can see the collapsed 'sock' on the starboard side, near the back of the bimini, and you can see the zipper line to the aft edge. That canvas is part of the full enclosure, by the way.

Image

That zipper is a bit of a waste, though, as I have to fold up the bimini hoops to drop the mast, and that means disconnecting the backstay first, so it just pulls through the opening in the bimini without using the zipper. I suppose I could coordinate folding the hoops with the mast half down, but I'd rather not work under a suspended load, so I just disconnect the backstay and move on.
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rsvpasap
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Re: Modifying a Bimini for Height and the Backstay.

Post by rsvpasap »

If you are never using more than a single headsail at once (jib, genoa or spinnaker variation), is there a compelling safety reason you can't just remove the backstay on a 26X?

98% of the time, the only headsail I use is the furling jib. I'm more likely to reef or even drop the main before reefing the jib because I feel like I keep better boat control that way in rowdy weather, (plus there's no chance of getting hit in the head by an accidental jib of the boom).

Since learning 26Ms generally don't have backstays, and since the backstay was rubbing a hole in my bimini, I haven't used it all summer despite repeatedly sailing in 25-30 mph gusts and a squall or two that was probably more than that.

Ignoring the issue of adjusting mast rake to tune sail shape, is there a compelling safety reason I really need to have a backstay on a 26x?
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Re: Modifying a Bimini for Height and the Backstay.

Post by Highlander »

I believe ur :macx: has 36" spreaders & the chain plates r further forward to the bow thus the backstay

The :macm: has 44" spreaders & the chain plates r further aft thus no need for a backstay

I,d say u r playing with fire & could end up with an expensive rigging failure

I know some guy,s have put the taller :macm: mast on their :macx: but I,m assuming they also went with the longer spreaders & moved their chain plates further aft if they done away with their backstays I,d guss they would have to chum in ?

J 8)
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taylormade
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Re: Modifying a Bimini for Height and the Backstay.

Post by taylormade »

Ok, thanks for the advice and feedback. I'd rather not change the size of the bimini as I like how much it covers. I'll just deal with the goofiness of it when not in use. As for not using the backstay, I'd never raise a sail without the back stay. It'd put way too much pressure on the side stays to trust them alone IMO.
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Re: Modifying a Bimini for Height and the Backstay.

Post by Highlander »

I guess u could also go with an inverted Y backstay install a back stay cable on both aft corners then bring it up high enough to b above the Bimini on both sides plus the width of the boat stern add a alum spreader bar wider than the bimini & use ur main halyard for a backstay this would work for powering & could b made from good halyard line an a strong alum paint pole & if it worked ok I guess u could make a permanent one & use it for sailing

but ur topping lift & boom can b used as a backstay in the center position while powering also if it doe,s not interfere with ur bimin

J 8)
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Re: Modifying a Bimini for Height and the Backstay.

Post by Jimmyt »

Maybe a picture would clarify the rambling response.

Image

Bimini Up

Image

Bimini Down

Tom does much better, but maybe this will give you the essence of it. "A" gets shorter and pivot point moves to deck. "B" and "C" stay same size, but pivot point of "B" moves upward on "A".

Scaled from your photo, so not highly accurate; but looks like the concept would work.

Now all you need is a Highlander arch to handle the backstay and you're golden. :D
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taylormade
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Re: Modifying a Bimini for Height and the Backstay.

Post by taylormade »

Thanks for the advice Highlander and the pics Jimmy! As for the inverted Y backstay, I think the only way I'd do that is with the addition of a radar arch to hold solar panels. That's not in the cards anytime soon though, so I think a simple cut in the bimini with some super glue carefully applied to try to seal it might be the ticket.

Jimmy, the pictures definitely help, but I think a concern still would be that the fabric would have to be shortened, no? Perhaps not but I'd think that the pivot point of A would have to move forward a fair amount. I actually have an old bimini so I might chop it up and see what it looks like. Thanks again!
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Re: Modifying a Bimini for Height and the Backstay.

Post by Jimmyt »

Shouldn't have to modify the cloth at all if it's done correctly. You have to measure everything accurately, draw a scale model of the top as-is, and then design the modified support to fit the top. During this process you have to rotate the members through their range to make sure everything works for your top-up condition as well as your constraint of fitting in the storage sleeve when down. I didn't know what your stored position was, so further adjustments to the concept may be necessary. Remember, I was scale modeling from a photograph, so this is conceptual only!

If you have a spare set of bows, you could leave your top up and experiment with spare bows and duct tape, or masking tape, etc. - if you are more comfortable with reality than scale modeling.

If you look closely at the crude concept model, I used pins at the pivot points to allow me to move the members through their range.

Again, I would want to put the boom up and work with that constraint- if it was my boat, but, your boat - your choice.

Good luck with it. It's a really nice top.
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Re: Modifying a Bimini for Height and the Backstay.

Post by taylormade »

Thanks again Jimmy, really appreciate the advice and the efforts you went through! I'll post an update once there is one. Cheers!
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Re: Modifying a Bimini for Height and the Backstay.

Post by Tomfoolery »

If it were me, I'd remove the bimini, leaving the hoops in place and using temporary straps to keep the hoops (especially the rear hoop) where it will be in use. Put the backstay in place, then measure the location where it passes through the fabric, using the rear hoop for a reference. That's where strapping the hoops is important, so they stay in place. A strap on each side of the backstay path between the rear and middle hoop will make sure the elevation is correct, then measure off the rear hoop, and a reference mark on each hoop in the center that matches a reference on each hoop. That gives a lateral location.

Or is that not what you were looking for suggestions on? :|
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Re: Modifying a Bimini for Height and the Backstay.

Post by Jimmyt »

OP part 2: "Second up, for those X owners who've run the back stay through the bimini, did you run a grommet or sew a slit or another option that I'm not even aware of yet? Thanks in advance! "

Appears he was interested in HOW to penetrate the top, not where.

OP part 1: "I chopped about a foot off the C poles and I feel it looks good and performs good but when I fold it up pole A doesn't come close to lining up. I'd like to be able to use the "sock" when it's not deployed but I'm not sure what I need to do in order to cut the poles but still maintain enough pressure on the fabric to keep it taught."

Since I'm not an X owner and, therefore, excluded from part 2, all I could work on was part 1. I assumed he stowed it behind the cockpit as I do. I probably missed his question, but thought he just wanted to rework the supports so they all stowed tight and he could put the zipper sock over it - without altering the top fabric.

I'm sure that I missed the point. Story of my life. I used to think everybody else was crazy until my wife said it was me... :?
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Re: Modifying a Bimini for Height and the Backstay.

Post by taylormade »

Tomfoolery wrote: Or is that not what you were looking for suggestions on? :|
Absolutely I was looking for that Tom and it's a great idea! As I stated in another post, I actually have another bimini frame laying around already. I can cut it down to size to mimic the "real" one and know precisely where the opening should go. Much better than guessing and ending up with a 10" hole, ha.
Brilliant!
Jimmyt wrote: I'm sure that I missed the point. Story of my life. I used to think everybody else was crazy until my wife said it was me... :?
Not at all! You thoroughly answered part one of my two part question and I thank you for that! I put the boom on yesterday to get a feel for what kind of room I had and how much more I was going to need to trim off the base (c) poles. I'll have to wait for a less windy day (it's been blowing 6mph constant lately here!) to put the main up at dock, but I can already tell it's going to be another 4-6" or so. Kind of a bummer because I raised the gooseneck up 9" to 36" from the deck and, at 6'1", I'm able to stand under the bimini currently.
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