outhaul routing - why?

[Birdseye]

Posting on here where I know there is a lot of sail setting expertise.

Issue is this. I attempted to remove the outhaul rope in my boom yesterday by pulling on the wire at the boom end. What I didnt know was that the outhaul goes round two in boom blocks which means a 3:1 mechanival advantage and yes, you guessed , I hadnt put a mouse line or stropper knot on the mast end of the outhaul because I had expected that the outfaul tail from mast foot to companionway winch to be more than enough.Mea culpa.

But why on a 29ft bilgie would they give the outhaul such extra strength when the main halyard is a simple up the mast and back to the winch job? Why would I ever need so much tension in the foot of the mai? Anmd more to the point, is there any reason why I cant just abandon the blocks and route the outhaul direct?

 

[Poignard]

Posting on here where I know there is a lot of sail setting expertise.

Issue is this. I attempted to remove the outhaul rope in my boom yesterday by pulling on the wire at the boom end. What I didnt know was that the outhaul goes round two in boom blocks which means a 3:1 mechanival advantage and yes, you guessed , I hadnt put a mouse line or stropper knot on the mast end of the outhaul because I had expected that the outfaul tail from mast foot to companionway winch to be more than enough.Mea culpa.

But why on a 29ft bilgie would they give the outhaul such extra strength when the main halyard is a simple up the mast and back to the winch job? Why would I ever need so much tension in the foot of the mai? Anmd more to the point, is there any reason why I cant just abandon the blocks and route the outhaul direct?

I had the same arrangement in my original boom.

I fitted a new boom after the original one broke in two, and it has no blocks inside.

The outhaul leads aft from the clew over a sheave at the end of the boom. Then internally to a sheave at the forward end and down through a jammer.

To tension the foot of the sail I simply haul downwards. I don't have a reefing winch. The mainsail on the Twister is quite small and I haven't felt the need for one.

 

[Praxinoscope]

I thought the same when I decided to replace the cord on the Kemp boom on my Sadler 25, it seems to be overkill and over complicated for a small yacht.
As the wire has started to part at the thimble exposing nasty little sharp bits (there are enough bits on a boat for to to injure myself on with this addition) and the cord was on its last legs I hadn’t to replace both, mousing didn’t work the mousing line seemed to jam on something so had to take off the gooseneck assembly and fish the out the internal assembly, having gone to this extent I kept the outhaul system and just replaced the wire and cord, but maybe I should have simplified it,

 

[Birdseye]

My suspicion is that the boom is designed for the outhaul tail to end at the mast as it did on my last boat - they werent expecting it to be lead aft to a winch

 

[Thistle]

When I sailed an Enterprise we had a wire cascade system inside the boom with tensioning lines led to both sides between the helm and crew. Either of us could heap on the tension to really flatten the foot of the main in windier conditions.

 

[Bobc]

My suspicion is that the boom is designed for the outhaul tail to end at the mast as it did on my last boat - they werent expecting it to be lead aft to a winch

Correct. If you are leading it back to a winch, you do not need the purchase.

 

[Neeves]

I don't visit this section of the Forum - I'm a bit late but......

Our outhaul was a mix of rope and wire, the wire failed (it snapped at a sheave). It was a block system in the boom (but I forget the detail). Tension was applied by a winch on the mast with a clutch in the boom, Selden system. We replaced the whole lot with a dyneema outhaul.

What I do recall was that the boom fittings were secured with a security variant of a simple Alan bolt - and we did not have the matching key (and had to bodge) to get the end piece off. This all happened off the east coast of Tasmania and, we could have done worse, returned to Wineglass Bay to effect the repairs/upgrade.

We were grudgingly given the correct tool to work on the mast in future (and we have had no problems since ).

Jonathan

 

[Laser310]

i think it's pretty unusual to lead an outhaul to a winch on a 29ft boat.

probably it was rigged to be trimmed by hand.

and, i wouldn't be surprised to learn that your 3:1 is inside a cascade giving 6:1.

Cascades are very common on outhauls.

 

[BabaYaga]

But why on a 29ft bilgie would they give the outhaul such extra strength when the main halyard is a simple up the mast and back to the winch job? Why would I ever need so much tension in the foot of the mai? Anmd more to the point, is there any reason why I cant just abandon the blocks and route the outhaul direct?

i think it's pretty unusual to lead an outhaul to a winch on a 29ft boat.

probably it was rigged to be trimmed by hand.

I also have a 29ft boat, built in 1980 with a Seldén rig. Like in the case of the OP, the outhaul line inside the boom has a 3 (or possibly) 4:1 purchase and the tail exiting at the forward end can be lead to the reefing winch on the aft side of the mast.
As long as my mainsail had a bolt rope along the foot (creating a lot of friction) I found that the winch was very useful for tightening while sailing. Now, with a loose footed mainsail, the need of the winch has diminished, but it can still be convenient.
If you decide to keep the blocks, it is well worth the effort to open the boom to give them a little maintenance, so that they roll smoothly.

 

[Ardenfour]

I think you'd struggle to get a decent flat, reefed sail without a winch or block cascade on the outhaul.

 

[tr11olar1v6]

The reason why the outhaul is designed with a mechanical advantage is to provide increased control over the sail shape. By having a 3:1 mechanical advantage, you can apply greater tension to the sail foot with less effort, allowing you to fine-tune the shape of the sail to suit the conditions. This can be especially important in high wind conditions, where small adjustments to the sail can have a big impact on boat speed and handling.
However, if you prefer to route the outhaul direct and without the blocks, you can certainly do so. You will lose the mechanical advantage, which means you'll need to use more effort to apply the same tension to the sail foot, but this may not be a big issue depending on the conditions you sail in and your personal preferences.
In terms of why the main halyard is a simple up the mast and back to the winch job, it's likely because the tension required on the main halyard is not as high as the tension required on the outhaul. The main halyard primarily needs to support the weight of the sail, while the outhaul needs to apply tension to the foot of the sail to control its shape.

 

[sarabande]

Your post doesn't make sense. The main halyard tension plays a crucial role in the shape of the main, along with the cunningham.

 

[Chiara’s slave]

The reason for a 3:1 or even better a cascade is twofold. Obviously it's mechanical advantage, but it also reduces compression loads at the gooseneck. The outhaul loads can be quite high, the gooseneck may not be up to the job of it being winched directly.

 

[flaming]

it's likely because the tension required on the main halyard is not as high as the tension required on the outhaul. The main halyard primarily needs to support the weight of the sail, while the outhaul needs to apply tension to the foot of the sail to control its shape.

Er... no...

Main halyard tension is significantly higher than outhaul tension. At least if you're actually tuning the sail correctly.

 

[Chiara’s slave]

Might depend on whether you have a loose footed sail too. The load in my outhaul is considerable.

 

[flaming]

Might depend on whether you have a loose footed sail too. The load in my outhaul is considerable.

Outhaul loads aren't low, but halyard loads are significantly higher... Or should be anyway.

 

[Birdseye]

The reason for a 3:1 or even better a cascade is twofold. Obviously it's mechanical advantage, but it also reduces compression loads at the gooseneck. The outhaul loads can be quite high, the gooseneck may not be up to the job of it being winched directly.

The load on the gooseneck is the same whatever the system inside the boom for a given tension in the foot of the main.

 

[Chiara’s slave]

The load on the gooseneck is the same whatever the system inside the boom for a given tension in the foot of the main.

Not if all the mechanical advantage is on the boom its not. The load in the control line is reduced

 

[Birdseye]

I disagree. One end of the sail foot is attached to the part of the gooseneck attached to the mast - the other end is attached to the end of the boom with the reqired level of tension. Any outhaul blocks are fastened to the inside of the boom and the outhall string doesnt go near the fixed gooseneck .

 

[Chiara’s slave]

I disagree. One end of the sail foot is attached to the part of the gooseneck attached to the mast - the other end is attached to the end of the boom with the reqired level of tension. Any outhaul blocks are fastened to the inside of the boom and the outhall string doesnt go near the fixed gooseneck .

Feel free to disagree. I have a cascade outhaul on my boom. It is rigged in that way to reduce thrust at the gooseneck. A straight 1:1 outhaul doubles the load created by the sail. a cascade, with the front block fixed to the boom reduces that. The control line applies less load. Part of it is carried by compression in the boom itself.