If someone has a preventer geared up for a Hunter 420, can they send provide pictures or a sketch?
I want to get on set up for this season.
I want to get on set up for this season.
Preventer for a Hunter 420
- Thread starter Stephen M
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,296
Hello Steven.
You asked for a Hunter owner. I am not.
The idea of a Preventer is a universal sailing concept.
I rig my preventer by attaching a Dacron or Polyester line to the end of the boom, running it up to a block that I attach to a bow cleat, and then running the line back on the deck along side the cabin to the cockpit, where I tie it off to a cleat.
The next step is rather simple. I adjust the main sheet to pull the boom toward me, and the preventer line to pull the boom outwards.
You'll want to pull the preventer till the boom is just off the aft shroud.
Some ask, why not just run a line from the boom to the side of the boat. While it feels ok, it ignores the extreme force should the boom dip into the water.
The long line acts as a buffer, stretching to relieve the pressure on the boom.
You asked for a Hunter owner. I am not.
The idea of a Preventer is a universal sailing concept.
I rig my preventer by attaching a Dacron or Polyester line to the end of the boom, running it up to a block that I attach to a bow cleat, and then running the line back on the deck along side the cabin to the cockpit, where I tie it off to a cleat.
The next step is rather simple. I adjust the main sheet to pull the boom toward me, and the preventer line to pull the boom outwards.
You'll want to pull the preventer till the boom is just off the aft shroud.
Some ask, why not just run a line from the boom to the side of the boat. While it feels ok, it ignores the extreme force should the boom dip into the water.
The long line acts as a buffer, stretching to relieve the pressure on the boom.
Roy, could you send me a sketch on how you run your lines, I would like to have them set up for easy deploy.
Regards
Stephen
Regards
Stephen
Stephen, my preventer photos are below. Presently the connection at the boom is on the old vang loop. I would prefer to have that connection closer to the boom center. In the past I ran a line between the vang loop and the mainsheet loop with the preventer attached near the center but have done away with that this season. We will see.
Hi Roy, recommend that you consider moving the preventer attach point further aft on the boom. If in a wind jibe, the stress at that point might cause the boom to collapse. Just MHO.
I left our vang on because of the need for down wind sailing, but use a boom connect point further aft for our preventer where stress levels are lower..
I left our vang on because of the need for down wind sailing, but use a boom connect point further aft for our preventer where stress levels are lower..
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,296
Terry is spot on.
Booms are not designed to take the high force stresses in the middle. When you attach the preventer to the center of the boom you are putting the boom under a single point of stress. The sail then acts upon both ends of the boom around that single point with all the force that the wind is using to move the boat. The booms are not designed to handle the forces applied laterally.
You have a short line from the rail to the boom. You will want to use a nylon line that will stretch to absorb some of the shock involved in a sudden gybe, which the preventer is intended to "prevent".
All of this is dependent on the sailing conditions. On a mild day, cruising downwind in less than 10 knots, the rail preventer can help to stop the boom from wildly swinging across the deck sweeping crew into the water.
When the winds blow 15 plus, as in an open water passage, and you have a swell involved (which can cause the boom to sweep across the deck) the preventer run to the bow from the end of the boom can provide the safety you seek. A danger not often considered in open water swells is the boom dipping to the swell.
A properly rigged preventer can help the boom to come back out of the water in one piece.
What can happen when you accidentally gybe....
One post of interest:
Booms are not designed to take the high force stresses in the middle. When you attach the preventer to the center of the boom you are putting the boom under a single point of stress. The sail then acts upon both ends of the boom around that single point with all the force that the wind is using to move the boat. The booms are not designed to handle the forces applied laterally.
You have a short line from the rail to the boom. You will want to use a nylon line that will stretch to absorb some of the shock involved in a sudden gybe, which the preventer is intended to "prevent".
All of this is dependent on the sailing conditions. On a mild day, cruising downwind in less than 10 knots, the rail preventer can help to stop the boom from wildly swinging across the deck sweeping crew into the water.
When the winds blow 15 plus, as in an open water passage, and you have a swell involved (which can cause the boom to sweep across the deck) the preventer run to the bow from the end of the boom can provide the safety you seek. A danger not often considered in open water swells is the boom dipping to the swell.
A properly rigged preventer can help the boom to come back out of the water in one piece.
What can happen when you accidentally gybe....
One post of interest:
Rigging preventer lines H260
Anyone have experience running preventer lines on a H260, and how did you set them up?
forums.sailboatowners.com
My boom only has the two bails, one for the preventer and one for the mainsheet. In prior seasons to get an attachment for the preventer closer to the center of the boom I have tried two other arrangements. One was a line run between the two bails with a connection loop for the preventer near the center. This spread the load over the entire boom but was messy. The other was simpler and consisted of a line run from the mainsheet bail, along the boom to about the center and then a wrap around the boom followed by the preventer attachment. That worked well. This season I am trying just using the original vang bail. The vang is no longer needed as the preventer performs that duty pretty well. We will see. As for shock loads, once the preventer is rigged and tensioned shock loads are minimized. Without a preventer shock loads on the mainsheet are a real threat with a surprise jibe. BTW, I am unlikely to be sailing in wild seas like those shown above and be worried about my boom striking the water.
You need to move the toe rail block forward.... well past the mast.... or move the boom attachment point farther back.. at least to mid point. What you have now may work as a vang... but it is not an adequate preventer. Why? because the preventer function is to eliminate the risk of an accidental jibe, not to maintain tension on the mainsail leech. The preventer works with the mainsheet to keep the stabilize the boom's lateral motion in unfavorable conditions. Your present arrangement's geometry won't handle a violent shock because the angle between boom and deck is so acute. It's almost vertical. That's why you think it's working as a vang. As an experiment, stand along side your boat at a dock and swing the boom out. Now with your "preventer" on, grab the end of the boom and see how much you can move it. Be as violent as you can... because that's the way nature will behave. If it's moving more than a few inches it's not going to perform the job you want it to.....
As far as a vang substitute, the question here is: can you swing the boom from side to side with your device in "vang" mode. If not then it's not really a working vang... I'm going to ask you the obvious question... What are you doing and why?
Joe, will try your dockside test soon. Good idea. However, for the present, there is no way that I can see that it will not work as a preventer. My preventer line (short as you point out) will not permit the boom to cross the deck. In order for the boom to cross the deck the preventer line must be lengthened (a lot) or severed. Works well as a vang also. Admit that it needs to be reset after a jibe to function as a vang. Why am I doing this? My wife and I, when sailing downwind, secure the appropriate side preventer line and it prevents a surprise jibe. Due to the connection point on the toe rail practically under the boom it also works as a vang by holding the boom down. When the time comes to perform a controlled jibe I handle the preventer line and my wife handles the mainsheet. We bring the boom back across the boat totally under control by keeping tension on the preventer as I let it out. Have done this hundreds of times. After the boom crosses over we set the preventer/vang on the other side. Hope that answers your "obvious question" about what and why. Further, It is my observation that preventers rigged far forward near the bow are always in the way even when not required to be deployed. Most sailors will only rig such a preventer when they need it and will remove it soon after because it is in the way (especially when, say, anchoring). Or, they will wing it without bothering to set it up. My wife and I never remove our preventer because it is not really in the way. When we tie up we set the preventer to hold the boom to one side and keep it quiet over night.
You do not need a Boom swing preventer on the Hunter 420.
Simple preventer is using the Traveler on your arch.
That Traveler setting prevents your Main Sail from major rubbing against your Spreaders.
Jim...
Simple preventer is using the Traveler on your arch.
That Traveler setting prevents your Main Sail from major rubbing against your Spreaders.
Jim...
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,296
With the mainsheet attached to the arch unless you are really tall the boom is not likely to swing across the boat and wipe someone out.
Of Course the preventer is not just about protecting the heads of the crew in an uncontrolled gybe. The preventer stops the sail and rig from being damaged as the sail and boom are back winded and swing across the boat without controls.
The simplest rigging is to tie a nylon double braided line to the end of the boom, run the line up to the bow (outside of all stays and in a manner that it does not conflict with the jib sheets). Attach a block to a hard point at the bow. I use a soft shackle through the block and attached to a bow cleat. The line is then returned to the cockpit where it is secured. You can use a cleat or a cam cleat also works.
Adjustment of the preventer is to pull it so the boom moves out and forward. The mainsheet is used to balance this forward movement. WIth both lines tought, the boom is captured in a single place and will stay there till you trim it differently.
To gybe, you release the preventer and pull in the main. Note you will need to switch the preventer to the opposite side of the boat on the new tack in the same way you set it before. The preventer pulls the boom forward and the main sheet pulls it aft.
Good luck In strong winds I use the preventer all the time on a beam reach and as the wind moves aft. The boom stays in control. Due to the work needed to set it I prefer to use the preventer when the wind will be on a certain tack for a while.
Of Course the preventer is not just about protecting the heads of the crew in an uncontrolled gybe. The preventer stops the sail and rig from being damaged as the sail and boom are back winded and swing across the boat without controls.
The simplest rigging is to tie a nylon double braided line to the end of the boom, run the line up to the bow (outside of all stays and in a manner that it does not conflict with the jib sheets). Attach a block to a hard point at the bow. I use a soft shackle through the block and attached to a bow cleat. The line is then returned to the cockpit where it is secured. You can use a cleat or a cam cleat also works.
Adjustment of the preventer is to pull it so the boom moves out and forward. The mainsheet is used to balance this forward movement. WIth both lines tought, the boom is captured in a single place and will stay there till you trim it differently.
To gybe, you release the preventer and pull in the main. Note you will need to switch the preventer to the opposite side of the boat on the new tack in the same way you set it before. The preventer pulls the boom forward and the main sheet pulls it aft.
Good luck In strong winds I use the preventer all the time on a beam reach and as the wind moves aft. The boom stays in control. Due to the work needed to set it I prefer to use the preventer when the wind will be on a certain tack for a while.