Boom Preventer

[capnsensible]

I've discovered that on long distance sailing with modern swept back spreaders and a prevented main, you can cause a lot of friction wear in the sail.

 

[flaming]

I've discovered that on long distance sailing with modern swept back spreaders and a prevented main, you can cause a lot of friction wear in the sail.

Stick on spreader patches are cheap and easy. Just replace as necessary.

 

[Refueler]

Stick on spreader patches are cheap and easy. Just replace as necessary.

I have 3D printed 'sail wheels' clipped onto shroud .. it sits on top of spreader and can revolve

 

[doug748]

"...............However another though occurred, could I use the spinnaker pole down haul attached to the permanently installed lines? Would it be sufficiently strong (AWB bolted through the deck but behind a head lining)....... jamimb


I do a similar thing. Rigged a second long downhaul as well so the lines go from near the end of the boom forward to the foredeck and back to winches/jammers by the companionway. They can be clipped on easily, as my boom is pretty short, and I can sail with both ready to use. Most of the time, when not in use I just pull the snap shackles to the blocks on the foredeck.

I am sure some might feel they are a bit feeble but I am happy with them for the sailing I do.

.

 

[Kelpie]

So... anybody got an example of a preventer leading to rig damage?

 

[Laser310]

think this is genuinely a conversation worth having.
My preventer is not intended to break. I'm going entirely on intuition but I think I'd prefer a backed mainsail to a crash gybe.

I agree.

I experienced a backed prevented main several times on the ocean, and it was not that big a deal - it can take a while to undo.., but the loads are not that great, because the boat spins - Ease/roll the jib, and eventually you can get everything sorted.

The first few times can be kind of scary though...

that was on an oyster 485 - a difficult boat to hand steer dead down wind in quartering seas.

I think the biggest loads happen just while sailing along, if the boat rolls and the boom end goes in the water - you need to watch this.

depending on the main sheet setup, some boats can use a single line along the boom, as it can be moved under the boom to use on the opposite side, but some require two lines on the boom, because the line will foul on the blocks or sheet if it is moved.

as others have noted, the best setup is to have the line or lines just reach the mast, where they can be secured when not being used. This makes gybing easy, as nobody has to go to the leeward side to reconnect the preventer.

be careful of attaching a preventer mid-boom as it can break the boom.

usually a (strong) turning block all the way forward is best.., with a line that can be taken to a winch in the cockpit. A clutch is fine, but make sure you have a free winch. I prefer to just leave it on the winch. If you are adjusting the main a lot, then you need to be able to adjust the preventer too.

Offshore races often require that a preventer is at least available these days.

 

[Laser310]

So... anybody got an example of a preventer leading to rig damage?

I've seen booms broken from preventers attached mid-boom.

in at least one case, the preventer was led to the rail amidships, not forward.., but I think the big problem was the mid-boom attachment on a boom which sheeted to the end.

Also, i think it's okay to use a somewhat stretchy line for the part that goes from the mast forward and back to the cockpit. Typically the part along the boom is dyneema. having a somewhat stretchy line, and the length of a lne that goes forward allows the syetm to yield a bit, and makes it easier to trim the preventer tight so that it doesn't bang around

 

[Kelpie]

I agree.

I experienced a backed prevented main several times on the ocean, and it was not that big a deal - it can take a while to undo.., but the loads are not that great, because the boat spins - Ease/roll the jib, and eventually you can get everything sorted.

The first few times can be kind of scary though...

that was on an oyster 485 - a difficult boat to hand steer dead down wind in quartering seas.

I think the biggest loads happen just while sailing along, if the boat rolls and the boom end goes in the water - you need to watch this.

depending on the main sheet setup, some boats can use a single line along the boom, as it can be moved under the boom to use on the opposite side, but some require two lines on the boom, because the line will foul on the blocks or sheet if it is moved.

as others have noted, the best setup is to have the line or lines just reach the mast, where they can be secured when not being used. This makes gybing easy, as nobody has to go to the leeward side to reconnect the preventer.

be careful of attaching a preventer mid-boom as it can break the boom.

usually a (strong) turning block all the way forward is best.., with a line that can be taken to a winch in the cockpit. A clutch is fine, but make sure you have a free winch. I prefer to just leave it on the winch. If you are adjusting the main a lot, then you need to be able to adjust the preventer too.

Offshore races often require that a preventer is at least available these days.

I thought about a wire strop mounted under the boom, but had visions of it sawing through the shrouds. So I've got 10mm line with dyneema core instead.
I just have a bowline at the forward end, but I should really have a spliced eye. I tie the extension line on, rather than using a clip- again, I don't want to be dragging bits of metal past the shrouds.

 

[flaming]

So... anybody got an example of a preventer leading to rig damage?

Like I said, we've snapped a boom... Does that count?

 

[Kelpie]

I've seen booms broken from preventers attached mid-boom.

in at least one case, the preventer was led to the rail amidships, not forward.., but I think the big problem was the mid-boom attachment on a boom which sheeted to the end.

Also, i think it's okay to use a somewhat stretchy line for the part that goes from the mast forward and back to the cockpit. Typically the part along the boom is dyneema. having a somewhat stretchy line, and the length of a lne that goes forward allows the syetm to yield a bit, and makes it easier to trim the preventer tight so that it doesn't bang around

The YouTubers 'Sailing Florence' broke their boom by using a mid point preventer. But that's not because the preventer was too strong, it was attached in the wrong place.

I actually run the preventer forward to a point on the toerail, about four feet back from the bow, because it gives a better angle to the boom, and less friction on the line leading to the cockpit. If my boat was sharper at the pointy end running it right forwards would make more sense.

 

[Laser310]

I thought about a wire strop mounted under the boom, but had visions of it sawing through the shrouds. So I've got 10mm line with dyneema core instead.
I just have a bowline at the forward end, but I should really have a spliced eye. I tie the extension line on, rather than using a clip- again, I don't want to be dragging bits of metal past the shrouds.

Dyneema is the way to go for the part on the boom

The lead inside or outside of the shrouds will occasionally have to be changed.

I'm currently using a splice and a soft shackle, but it can be a bit fiddly...

 

[Laser310]

The YouTubers 'Sailing Florence' broke their boom by using a mid point preventer. But that's not because the preventer was too strong, it was attached in the wrong place.

if the boat has end-boom sheeting, the preventer must be attached at the end.

I did a long delivery on a big-ish Swan owned by a friend with a huge carbon Park Avenue style boom - the kind with a triangular section.

this boat had the main sheet led from about 1/2 to 2/3 along the boom to a bridle arrangement above the companionway.

we attached the preventer there, and I think it was probably okay, but I would have preferred it at the boom end. I think there was nothing secure enough back there.

 

[Dantp]

We broke our rigged preventer as we accidentally jibed. 10mm double braid in a 35 ft boat. It snapped at the bowline used to tie it onto the boom end.
This should give an idea of the forces involved. It did reduce the speed of the boom coming across but I'd always rather it didn't snap at all.
One thing I've always struggled with is if you run the preventer outside everything. If the mainsail backs it can put a lot of load in the guard wires and stanchions.

 

[flaming]

if the boat has end-boom sheeting, the preventer must be attached at the end.

I did a long delivery on a big-ish Swan owned by a friend with a huge carbon Park Avenue style boom - the kind with a triangular section.

this boat had the main sheet led from about 1/2 to 2/3 along the boom to a bridle arrangement above the companionway.

we attached the preventer there, and I think it was probably okay, but I would have preferred it at the boom end. I think there was nothing secure enough back there.

A dynema loop spliced through the clew of the sail and round the boom is a good option. You then clip the preventer to that.

 

[RupertW]

I think this is genuinely a conversation worth having.
My preventer is not intended to break. I'm going entirely on intuition but I think I'd prefer a backed mainsail to a crash gybe.
Our boat is centre cockpit, with the mainsheet aft. An uncontrolled gybe has the potential to injure people in the cockpit, or to sweep them overboard. Not to mention the rig damage from the boom potentially slamming in to the shrouds.
In contrast, wouldn't a backed mainsail simply spin the boat around until you ended up hove to? Even dipping the end of the boom in a wave crest might not be that bad, it would just slow you down.

The times when our preventer has earned its keep, it's always been rather undramatic- mainsail backs, boat starts to slow and turn, I reach for the wheel and get us back on course.

Does anybody have examples of accidental gybes in really strong conditions, where a preventer led to rig damage?

I haven’t seen it personally but I have seen pics of snapped booms where the preventer was attached in the middle rather than where it should be at the end.

 

[Supertramp]

Might be two different situations here.

I can see the risks from crash gybes on a dead run and the evidence from others about breakages. An effective boom brake would be a good solution as a line forwards will come under huge load. Breakable bits of running rigging whiplashing about in a gybe don't appeal to me. Because I have in mast reefing, and often part reef for handling ease, I can safely attach part way down the boom where the clew is attached. This makes it easier to attach to the toerail and cleat midships. I have gybed, nothing broke, but not in extreme conditions.

I often find a preventer is needed on a reach or broad reach in quartering seas when the sail can crash about and a tight preventer to the toerail and midships cleat prevents any boom lift. I keep it set up on passages and use soft shackles to attach it.

 

[capnsensible]

Stick on spreader patches are cheap and easy. Just replace as necessary.

Wonder how many one would get through on a transatlantic?

I was getting a problem on a Jenneau45.2 that I used to sail a lot. I got some pipe lagging ( note, this is a difficult find in Tenerife) and masking taped that around the spreaders. Was still there many years later and helped a lot. Also rolling in a bit of mainsail now and then to change the rubbed area.

It's surprising how much wear an ocean passage puts on sails and all the running rigging.

 

[flaming]

Wonder how many one would get through on a transatlantic?

I was getting a problem on a Jenneau45.2 that I used to sail a lot. I got some pipe lagging ( note, this is a difficult find in Tenerife) and masking taped that around the spreaders. Was still there many years later and helped a lot. Also rolling in a bit of mainsail now and then to change the rubbed area.

It's surprising how much wear an ocean passage puts on sails and all the running rigging.

I would honestly be surprised if you needed to replace the patches after only 1 crossing. They're very tough...

Certainly I don't think the guys who raced a sistership of my boat in the RORC transatlantic did any specific anti chafe on the spreaders as you describe, pretty sure just put the patches on.

Here they are at the start of the race

 

[Stemar]

Dyneema is the way to go for the part on the boom

The lead inside or outside of the shrouds will occasionally have to be changed.

I'm currently using a splice and a soft shackle, but it can be a bit fiddly...

Dyneema has no elasticity. I think I'd favour a more elastic line to reduce shock loads. I know there shouldn't be any, but...

 

[Kelpie]

Dyneema has no elasticity. I think I'd favour a more elastic line to reduce shock loads. I know there shouldn't be any, but...

I disagree. If there's no room for movement, there's no shock loads.

Which part of the rig do people think will be damaged by use of a tight and strong preventer?