Can I Downsize My Forestay?

[redhead]

As some of you know we are in a major overhaul of an old neglected boat.

We are attempting to install Harken MarkIV Unit 2 roller furling for our jib.
Our forestay is currently 7/16" 1x19 316 grade stainless wire rope.
In order to fit Harken's equipment we need to go down to 3/8" 1x19 316 grade stainless wire rope.

The difference in the breaking strength is 5,200 lbs. It seems a lot, but we also know that almost everything on this boat is oversized. So now, we either get a new smaller diameter stay or try to find some other roller furler that will cost the earth. (PS we ordered the Unit2 based on the recommendation from the vendor, our downfall was that we did not check his recommendation. I know, I know....)

Any helpful suggestions are, as always, gratefully appreciated.

[Bean Counter]

Can you not return the Mark IV, then get a Harken ESP unit 2 (for cruising boats) that will take 7/16 you would then get a refund.
https://www.harken.com/productdetail...776&taxid=3541

[JPA Cate]

redhead,

You might consider compact strand wire in the 3/8 size, BUT CHECK THE STRENGTH FIRST to be sure it is as strong as the current wire.

NO, do not go smaller than designed strength for a forestay that will have a furler on it. The stay gets heavy point loading, will work harden and be vulnerable to breaking under load.

I would get the compact strand wire at the designed size or go one up, myself. (Having had a forestay with a furler break once was enough).

That means you would wind up following Bean Counter's advice, and go up one furler size in order to have the compatibility you need.

Ann

[barnakiel]

There is only one correct way to do this:


- size the wire to the displacement,
- size the roller to the wire.


If the wire comes to fat, try Dyform wire. If Dyform is still to fat - get a bigger Harken unit.


b.

[Jim Cate]

To amplify what Ann said above, 10 mm Dyform or Hamma Pro compact strand 1x19 316 wire (which should fit in your furler) is significantly stronger than 7/16 (11 mm) standard 1x19 316 wire. In addition, it will stretch less under load and is in general a more desirable wire.

Should work just fine... we've been using such for years now.

Jim

[Benz]

There also rod, if none of the wires will fit. It has the highest load-to-diameter ratio.

[redhead]

Originally Posted by Bean Counter

Can you not return the Mark IV, then get a Harken ESP unit 2 (for cruising boats) that will take 7/16 you would then get a refund.
https://www.harken.com/productdetail...776&taxid=3541

We spoke to "the vendor" this morning. They are standing behind their 30 day return policy which is long gone (spent most of this summer battling a new diabetes diagnosis) and also we opened the box in such a way that it can't be "returned in original box in condition to be sold to another customer". Oh well. We bought 2 roller furlers (the Unit 1 fits our staysail just fine) and 4 winches along with this Unit 2.

I'm not thrilled, but we should have checked the salesman's sizing, which we didn't....our fault in the end.

[redhead]

Originally Posted by Jim Cate

To amplify what Ann said above, 10 mm Dyform or Hamma Pro compact strand 1x19 316 wire (which should fit in your furler) is significantly stronger than 7/16 (11 mm) standard 1x19 316 wire. In addition, it will stretch less under load and is in general a more desirable wire.

Should work just fine... we've been using such for years now.

Jim

Thanks Jim and Ann - we checked out the Dyform and this is the answer. We are ordering now. Very much appreciate the input!