Advice on raising backstay split on a Mark I please

[Jeff Tancock]

I know this topic has been covered several times in the past, but I'm looking for some follow up on those of you who have raised your split on a Mark I to ease the movement through the split in the backstay. How high did you go up and was it enough or was it too much? It has always irritated us ducking and squeezing through the split.
I have pulled my mast for the first time ever and thought that it was an opportune time to raise the split and do a few other things. The local rigger suggested putting  turnbuckles at the bottom of each side and going up about 10'. He wasn't really sure how high to go. Any thoughts? I did rig a backstay tensioner years ago but am willing to leave it off to get better passage.
Thanks!

[Stu Jackson]

Jeff,

See photos, it's about 8 feet up to the triangle plate.  The higher you go the less inward pull you get on the adjuster.  The sketch is from Dave Davis.  I agree that two turnbuckles at the transom is the way to go.  I only have one at the top of the triangle and it's a bear to access - needs a four foot ladder and a tall helper!  Our gear is a Garhauer splitter with a Garhauer vang adjuster.  I added BIG D shackles at the transom as well to handle the rode from the vang.

While you're at it, add toggles at the transom too, since the chainplates aren't in the same plane as the backstay.

[Jeff Tancock]

Thanks for the copmments Stu. I did see Dave's diagram and read it as 90"(blurry), but some of the accompanying text said 9'. My problem is I don't know where I started as far as the distance before verses after. Do you have significantly better passage afterwards at 8'?

[Ken Juul]

It will be a while before I get to the boat and look at my owners manual.  At some point around 89-90 they raised the split in the backstay.  The 1988 owners manual on the wiki lists the backstay at about 41.5'.  The MkII manual has the backstay at 32.5'.  Using that as a reference you can have your rigger raise the split about a foot.  I don't know how high mine is, but I have to stand on the stern rails to reach it, so I think it is higher than Stu's 8 ft.

[Jeff Tancock]

Thanks Ken. I looked at the manuals to confirm the measurements you mentioned because I didn't quite get that difference between 41.5' and 32.5' is one foot. I am guessing that the 41.5 is without a split? In the Mark II it also mentions the backstay bridle as 15'. Would that be the measure of each of the lower split sections from the triangle splitter to the transom?

[Stu Jackson]

Do you have significantly better passage afterwards at 8'?

Absolutely.  No problem getting through when coming up from the dinghy.

However, the best part is standing at the helm - no more head knockers.

As far as distance is concerned, you could copy the pictures, print them out, and then scale them using the C34 brochure sections.  If you know the height of the transom, you can find out how high my backstay split is.

[waterdog]

I raised mine considerably higher.   The goal was to fit a solar panel of a particular width between the backstays at a particular height off cockpit floor.   Don't remember any of the measurements.   So I have something like 2.5 feet between them at head height.   Beautiful for clearance.   The trick was the methodology - I was trying to remember triginometry and drawing diagrams.   The rigger wouldn't even let me start before he did a full scale layout on his floor.  All you need is the old backstay and the measurement between the attachment points and height from you cockpit floor.  You can lay it out the new one full size (if you have the space), lay down on it and see how you like the spacing.  The rigger needs to nail the pin to pin measurements any way so will probably want to do a full scale layout.  Two turnbuckles at the base means you don't have to worry about the how high the split is.    The legs on my backstay have to be somewhere between 10 and 15 feet.  I'll see if I can find a picture and give a better approximation. 

I added stern seats on the rail.  The combination of the new backstay position and bimini frame run off the pushpit rail makes for a fantastically secure seat in all sea conditions - with a great view. 

[Ken Juul]

So much for doing math after a couple beers and shoveling the driveway.  That should be about 9' shorter, which raises it quite a bit.
The 41.5 & 32.5 are the length of the backstay, top of mast to split.  The 15' bridle seems about right for the higher (shorter) backstay.

[Ken Juul]

Becalmed on a July afternoon, but you can see how high the backstay split is.

[Jeff Tancock]

Thanks for that Ken. I just need a number to give the rigger. I am guessing that the length of the split stays around 15'.

[Stu Jackson]

Becalmed on a July afternoon, but you can see how high the backstay split is.

Becalmed?!?  Look at what a great light air boat that is!!!  Just look at the wake and bow.  WOW!   

[hump180]

Jeff, have your rigger look at the angle of the backstay chainplates. Ron has mentioned this before - catalina angled the backstay chainplates to the angle of the standing rigging. Changing the height - changes the angle of pull on these chainplates. I would also like to heighten mine (non-walk thru) but I am not sure about changing the pull on the chainplates. Steve/waterdog is the only one on the MB that has a closed transom and a raised backstay so he could be a good resource in this modification.

[Stu Jackson]

1.  Jeff, have your rigger look at the angle of the backstay chainplates. Ron has mentioned this before - catalina angled the backstay chainplates to the angle of the standing rigging.

2.   Changing the height - changes the angle of pull on these chainplates. I would also like to heighten mine (non-walk thru) but I am not sure about changing the pull on the chainplates.

3.  Steve/waterdog is the only one on the MB that has a closed transom and a raised backstay so he could be a good resource in this modification.

Bill

1.  Mentioned in Reply #1, Catalina did not angle them - they MIS-angled them in the plane of backstay-to-masthead; they may have angled them inwards a bit, but it's a single pin anyway.
2.  Not that much - the recommended toggles take care of it
3.  Not quite - see my pictures in Reply #1 - I, too, qualify for that remark!

[waterdog]

I'm not the only one.   I was aware of it as a concern though, and brought it up with my rigger.    He more or less laughed at me because he regards them as being pretty overbuilt as all the rigging on the Catalina is.   Standard cruising doctrine is that you upsize your rigging to the next size when you are replacing your standing rigging and going on an extended cruise.  He also dismissed that as unnecessary on a c34 - "You're already one size bigger."   

I've put 5000 mainly open ocean miles on since I moved the split.  Chainplates show no evidence of any problems.   Doesn't mean its not a problem - it just hasn't been for me.  I don't test it with uncontrolled gybes

[Ron Hill]

Guys : I don't believe that the angle of the chain plates into the transom is as important as I once thought it was.  There are a couple of things happening here :
1. The angle was set by Catalina (in the transom) is based on NOT having a compression back stay adjuster that changes the upper angle of that triangle formed by the split backstay.  The pull at the split was calculated to be a constant angle.
2.  As Stu mentioned, after you heighten the top junction, you have to pull the adjuster down a bit as that angle (compared to the original) is much shallower.
3.  I'll guess that after tightening the back stay adjuster (from looking at Stu's transom picture in reply 1) the top angle will be nearly the same as it was when the boat left the factory!

Myself, I'm 5'8" (and shrinking) so I and my shorter 1st Mate have no trouble getting up the boarding ladder into the cockpit with the height of the factory split!!

My canvas is made for the factory split and I no intention of changing.

A few thoughts