Preventer Attachment point

[jimp1234]

I've owned my boat for only a few months and I'm heading out on a short coastal passage and I'd like to rig preventers for the mainsail. I plan on using something like a 1/2 inch 3 strand line run from the the end of the boom up to the bow then back to the cockpit. The problem is this boat doesn't have deck cleats forward, or padeyes on the foredeck (on my list to install eventually), just a single bollard (see photo) for an attachment point. So would a dyneema strop with a snatch block, or an antal ring around the bollard work? Not sure about the loads (~ 500 sq ft. main) nor do I have much experience splicing so good idea or not? Other ideas or alternatives? TIA

-Jim

[GILow]

Originally Posted by jimp1234

I've owned my boat for only a few months and I'm heading out on a short coastal passage and I'd like to rig preventers for the mainsail. I plan on using something like a 1/2 inch 3 strand line run from the the end of the boom up to the bow then back to the cockpit. The problem is this boat doesn't have deck cleats forward, or padeyes on the foredeck (on my list to install eventually), just a single bollard (see photo) for an attachment point. So would a dyneema strop with a snatch block, or an antal ring around the bollard work? Not sure about the loads (~ 500 sq ft. main) nor do I have much experience splicing so good idea or not? Other ideas or alternatives? TIA

-Jim

Sorry if this seems an obvious question, but any way you can attach a block to something like the toe rail?

The problem I anticipate with the bollard is that it is too far inboard to get the sort of angle you want on a preventer.

[Paul L]

A dyneema strop and a low friction ring should work fine. I'd use a double braid line, not 3 strand.

[Jim Cate]

I agree with Paul: three strand of that length will stretch quite a lot, and you don't want that in a preventer. You might post a pic of your whole foredeck and we'll see if any cool ideas pop up.

Jim

[jimp1234]

Thanks guys.


Here's a wider angle of the bollard location and the best shot I have of the foredeck. Not sure you can see but the boat has a wide caprail, with no attachment points currently. This was a custom built boat and the builder did a good job on most things, but IMHO he did not add enough attachment points on deck particularly up forward. I'm out on the boat later in the week, and I can can take a better pic then.



-Jim

[Cheechako]

Do you have a mid boat hawse possibly? That and a nylon strop ....
no tracks for the headsail? I always used my 4 part boom vang with cam release and snap shackle as a preventer. Easy to quick release. But I see you have the rigid vang. Never liked or wanted a rigid vang on a cruiser.

[wingssail]

Originally Posted by jimp1234

Thanks guys.

Here's a wider angle of the bollard location and the best shot I have of the foredeck. Not sure you can see but the boat has a wide caprail, with no attachment points currently. This was a custom built boat and the builder did a good job on most things, but IMHO he did not add enough attachment points on deck particularly up forward. I'm out on the boat later in the week, and I can can take a better pic then.

-Jim

We run a line (3/8 Dacron) from the end of the boom to a stanchion base then back to a winch or cleat in the cockpit. A block attached to the stanchion bases with a light line might be appropriate in your situation. When not in use the single preventer line is lead to the boom near the gooseneck and coiled there. When jibing we uncleat the preventer, jibe the boom then lead the preventer to the other side.

When close reaching and we want a preventer to stabilize the boom we lead the preventer to a stanchion farther aft, to keep a better angle.

It is important to have this preventer where it can be quickly released, a winch is better than a cleat. I've learned that the hard way, being pinned down by a backwinded mainsail and unable to release the preventer.

[jt11791]

A bit of stretch in a preventer line is a good thing IMHO. There is little to no load on the line unless you get gybed, in which case stretch will soften the impact.



I use a length of three strand from a bow cleat aft to a point just short of where my prop is, so if the line goes in the water it can't foul the prop. There is a second double braid line that runs from the cockpit through the boom and out the end, to be connected to the three-strand line when the preventer is needed.

[DefinitelyMe]

Agree that stretch is a good thing in a preventer. The more shock-absorption the better. Leading the line forward to the foredeck is great but if you have to go forward every time you want to trim the main, the system will lose its appeal fast. What about a block through a mid-ship hawse-hole? Or do you have a spare jib car that you can put on the track just behind the working one and go through that up to the boom and back to a winch, or a cockpit cleat? Not as strong as going forward, but much more convenient.

Agree that end-of-boom attachment (or as close to the clew of the sail as possible) is good. Mid-boom attachment points lead to broken booms in my experience, especially if a low-stretch line is used.

[Jim Cate]

I won't get into a stretch vs low stretch argument, but it looks like it would be easy to put a strop through your forward fairleads for hanging your turning blocks. Plenty of strength there and no new holes in the deck/

FWIW, I've used mid boom preventers (two or three part tackles) lead to strong points near the shroud chainplates and then aft to a cockpit winch on my last three boats (30,36 and now 46 foot sloops). They are permanently rigged, and we employ them every time the wind is aft of the beam. They act both as preventers and as very powerful vangs, with much lower goose neck loads that a conventional vang imposes.

Between those three boats, we've logged over 150,000 miles. Yes, we did break the poom on this boat once, and it happened at the attachment point. But, investigation showed that the primary issue was vertical loads imposed when we had tightened the sheet too hard against a rigid vang when the mainsail was down, not loads from the preventers.

I'm still happy with the system, and would install the same on any other boat in the unlikely event that we should change mounts again.

Jim

[Rich_M]

Could you simply run your preventer line from the boom through the outside of a forward fairlead (port or starboard as appropriate) and then back to the cockpit?

This is how ours is rigged except our fairlead is the central hole in our froward cleats.

[Paul L]

A bit of stretch in the preventer is a good thing. You will get this with appropriate sized double braid (non techy line) run to the bow and back. 3 strand is not going to run through the low friction rings well and probably has too much stretch.

No need to have mechanical advantage on the preventer; block and tackle or winch. Just let the boom out a few extra inches, hand tighten and secure the preventer. Then bring boom back in where you want it.