Do bobstays need turnbuckles?

[JohnV]

I'm planning a standing rigging replacement. The boat is a 33' Alajuela, a heavy cruiser. The bow platform is on a tubular aluminum frame and extends 29".
The bobstay is 3/8" 1x19 with the original (I think) 35 yr-old Navtec 500 turnbuckle. Can't say its length offhand but obviously not so long that I'd expect stretch to be much of a factor. The jibstay and backstay are adjustable.
Seems to me that a bobstay turnbuckle is redundant. The different forces acting on the bowsprit must vary a lot. I'd think that would make minute changes in the geometry of the triangle of which the bobstay is one leg. So, if true, the bobstay length must change minutely regardless of the original turnbuckle tension.
There seems to be some variety of opinion on this, and I'd appreciate feedback from this forum.
Thanks in advance.
John V.

[Brion Toss]

Hello,
You are right; because elasticity is not a factor, and because the jibstay will tension the bobstay, there is no need for a turnbuckle. This assumes, of course, that you make the bobstay exactly the right length. It also assumes that there is enough flex in the bowsprit that you can bend it down (with the jibstay slack) to connect a fixed-length bobstay.
If those two variables can't be met, you could use a turnbuckle, but it would be the heaviest, most expensive piece of hardware in the rig, so how about using a Spectra lashing instead? You can easily get far more strength than with a turnbuckle, and far less weight, so less pitching moment. Cheap, too.
Fair leads,
Brion Toss

[JohnV]

Brion, Re: flexing the bowsprit down--for that kind of savings, I'll find a way. Probably set 50-100 lbs on it just to bottom out any flex, then be real careful of the measurements when I assemble the swageless end fittings.
If I used a spectra lashing, I gather I'd mount deadeyes somehow?
I liked the idea of replacing the whole rig with covered dynex dux but it got pretty expensive given the wire size I have. Even then, I'd assumed that anything but a steel bobstay would be vulnerable to damage from anchor, rode, mooring gear, etc etc, wouldn't it?
Thanks for responding to this--I don't like to second-guess the original builders but I'm not comfortable blindly copying them, either.
John V.

[Ian McColgin]

I took the turnbuckle out of the bobstay on two of my schooners when I happened to be replacing the stay anyway. I stove the sprits down a bit by hanging my 200#+ off the end and adding a bit more weight as needed. To protect the sprit against any risk of over bending, I kept the jib stay rigged and eased that turnbuckle a bit at a time till I could get the pin in.

[JohnV]

Ian, thanks for the response. I like the idea of using the jib stay to tweak it down.
John

[keithasully]

I would like to know more about how to use Spectra lashing on the bobstay. I need to replace mine and not sure what to do.