Sunbrella stretch

[Capt.Don]

Hi, I'm starting to sew new Sunbrella toerail covers to replace our 10+ year old covers. Using the old covers as a guide (boat is in Mexico) the finished length is about 35'. I recall from Sailrite (handrail covers video) that I should add 1" per 10' when sewing Sunbrella -- does it make sense to add 3" to the overall length?

In general, how much extra should I allow when sewing Sunbrella for shrinkage?

Thanks--Don

[JPA Cate]

Following with interest. I've never made toerail covers, our last two boats have aluminum perforated toerails. I never added fabric to allow for shrinkage, but have occasionally had Sunbrella shorten from having the bobbin tension too tight. AFAIK, acrylic canvas doesn't "shrink," per se. But I could be wrong about that. If cut on the bias, it will stretch a lot, compared to cutting it on the straight grain of the fabric.

If you're concerned about it, do a pre-fit before you completely finish one end, to check it, rather than having to worry about it, and add the length as Sailright suggests. It is only a small addition, and they should be right about something like that.

Ann

[Capt.Don]

Hi Ann,

Thanks for the reply. I just read a post on Canvas Boat Cover Advisor that mentions +/- 1%. That's consistent with Sailrite's 1"/10' (e.g., 35' + 3 1/2"). I'd rather have the covers long - either to shorten at the end (easy) or have 3"-4" of slop over 35'.

I'm thinking about taking the Pfaff 130 down to Mexico to finish the cutouts for cleats, toerail hardware, and leather trim. It might be fun to have the sewing machine on the boat!

On a side note, when we first bought the boat, the original toerail covers used 1" Sunbrella straps with twist-n-lock snaps to hold the cover to the stanchions. Since the covers were old when we bought the boat, these didn't hold up and I replaced with 1/8" line. I thought the line worked well and I may do the same thing on the new covers. Also thinking about sewing in a bunch of soft-shackles!

Don

[Painted Skies]

I have done sets of toerail/rubstrake covers from regular Sunbrella for our original Tartan 37 and our current Tartan 412 - and both of them have shortened over time due to shrinkage. In fact, our handhold covers on deck have all ended up being too short with age, even though I added a couple extra inches to each of them to compensate for this issue. Part of the shrinkage also comes from any binding and facing along the edges, and like Ann mentions - the thread tension used for the stitching.

I would go with Sailrite's recommendation of adding 1" for every 10 feet of length - that seems about right, even if it ends up being a bit long to start - it will 'shrink to fit' in a couple of years.

[JPA Cate]

@Painted Skies,

Thanks for the input. I've had marineTex shrink quite a lot as the plasticizers evaporate out, but never had it with Sunbrella. That's great to know, as I think I might be making Sunbrella chaps for our dinghy.

@Capt.Don,

You don't really need the strength of the soft shackles, and I'd think the 1/8" line would hold up pretty well. It is not very expensive. Seems like a good choice to me.


Ann

[donradcliffe]

From my experience with sail covers, sunbrella shrinks a lot!

[thinwater]

It shrinks a few percent. With dodgers this is usually a good thing, because it makes them snug. But I've made covers that certainly shrunk over time, in addition to shrinkage from sewing. About 3% in my experience.


Another reason people have different figures. If the cloth is held in place with snaps (dodger) while it dries, it does not shrink. If it is not tensioned (rail cover that might be stowed in a locker wet) it does.