Mainsheets - to travel or not to travel...

Well almost anyway.

I've seen on a lot of boats that they dont use main travellers, even on performance boats with genoas, instead they use the boom kicker to keep the boom at the correct level when sheeting out to be able to contol the twist.

What are your thougts on the pros or cons about setups like that?
And while you're at it include your pros and cons for traveller as well

Erik

 

It depends on how big the boat is, and how powerful your kicker is. My Merlin Rocket, with its mast stepped on the sole, had a hoop that raised the mainsheet blocks so the sheet ran horizontally to the boom with no twist effect at all. The kicker ran all the way to the mast step and well back on the boom, and had a powerful purchase. But my M-16 scow, with its rotating deck-stepped mast and low boom, had a ridiculously short vertical distance for the kicker, and depended greatly on the traveler spanning its wide hull. On my F-24 trimaran, I seem to use the traveler as much for windward sheeting as I do for easing it down to control twist. The main is generally sheeted in so much, even off the wind, that often the issue is feeding aditional twist into the main, rather than taking it out. So it's very much a horses for courses issue.

I'd say the advantage of using a kicker over a traveler for twist control is it's more effective for large boom movements, and it completely decouples twist control from angle of attack control. The downside is the loads are very high and it takes a high mechanical advantage to be able to play it properly. Also, there's a large thrust on the gooseneck, so this can affect mast bend - for good or bad.

The advantange of a traveler is you can bring the boom up to the centerline, and the relationship between sheet and twist is somewhat automatic - sheet out a little and it mostly goes into twist, sheet out a lot and the boom moves to leeward, too. If you have the right purchase on the traveler, you can play it instead of the sheet. This gives the pure angle of attack control of the kicker-only option. Downside of the traveler is it needs a wide beam to work effectively - otherwise you quickly run out of traveler authority. Traveler can also be heavier than an kicker and needs substantial structure to tie it to. And with a traveler, everything you do with the sheet affects both twist and angle of attack, so you have to make coordinated use of both sheet and traveler when trimming for performance.

 

As you mentioned, the traveller and its foundations are heavy. There may be a boat in the Vendee Globe that has opted for 2 mainsheets (one to starboard and one to port?) instead of a traveller. Both would interact to control the boom. I would never know which string to pull for more/less twist, etc. However, the chances of an accidental gybe could be eliminated.

 

Well my design in progress is a racing cruiser 8.5 m spirit boat design.
I can already hear what you are thinking "Oh no, not another R/C".
Well it won't be, and I'll show you why when I get there

One idea is that to get more people into racing is (among other things) to simplify on the technology side and get tactics and actual sailing into the first room. And not having to fiddle with two mainsheet controls all the time on a boat that is intended to be raced by a small crew sounds good to me, instead using one to control twist and the other to control the angle. Also it gives less clutter in the cockpit and that is a good thing on a small boat as well.

Any more opinions?

 

I don't know how much time you have spent racing on boats with sprit sails (by which I am assuming that you mean a leg of mutton sail with a sprit, rather than a quadralateral sail with a sprit) but the snotter takes the place of the traveler or boom vang in controlling twist. If you are racing a boat with a sprit sail, (especially if the boat is as big as 8.5 meters) you adjust the snotter almost as often as you would have adjusted the traveler only it is a much harder adjustment to make and it also changes mast bend adversely (pulling bend out of the mast just when you need more mast bend to depower). Also as you ease the sail onto a reach the snotter needs to be loosened because the snotter tightens as it twists around the mast, flattening the sail when you would normally like to power it up.

There are other issues with sprits such as the chafe on the sails, and the ability to sail faster on one tack vs the other which adds an artificial tactical decision to the race. Reefing is more difficult. All and all sprits make sense for small non-performance oriented boats or low performance trainers like an Opti but are not very suitable for bigger race boats.

Respectfully,
Jeff

 

Jeff! LFMAO

Maybe I'm using the wrong word... isn't it called a spirit that you use on sportboats with an assymetric these days?

[Edit] Ok a bow sprit then , dang this english language can be hard to master at times, but it does create som amusing discussions

Erik

 

That is a funny mistake on my part. I am sorry about that. Because of the mainsail/traveler context I thought that you were considering a sprit rigged mainsail and not a bowsprit for an assymetrical.

With regards to your question about travelers, I would suggest that an important part of racing is leaning about sail trim. When you talk about racing an 8.5 meter boat, tools like the traveler, vang and adjustable backstay are easy to learn and really add a lot to the sailing experience. If you create a boat without these tools, you are creating a boat that the neophyte will outgrow pretty quickly. I teach a lot of people to sail and race, and within a half a dozen sails or so, most are ready to start learning more advanced sail trim techniques such as controlling mainsail twist with the traveler, sheet, vang, and backstay, or jib twist with the sheet lead. These skills are important to develop even for simple daysailing as they allow very easy, on the fly, powering up and down to reduce weather helm and heeling through a much wider wind range without having to reduce sail area.

Respectfully
Jeff

 

A wishbone boom controls twist well without much attention. And there's nothing below the foot to interefere with the crew, as there is with either a kicker or center sheeting to a traveler.

 

Wishbone

Wishbone is a possible solution, but it might scare away potential buyers as it won't look like they are used to...
Has it been done on medium size boats?

 

Wishbone booms have been used on comparably large catboats such as the Nonesuch. In that application, it meant increased construction complexity, expense and if you are trying to get performance out of the boat, the wishbone simply exchanged adjusting the snotter and outhaul (since they are coupled) instead of adjusting a vang or a traveler.

Jeff

 

Worth looking at the latest project Schooner Creek Boatworks is working on - Tom Wylies' take on a cat rig with wishbone boom:

http://www.schoonercreek.com/new_const/Wylie_wildcat/concept_features.htm

Chris Krumm

 

wishbone

Hello, just surfing and saw the notes on wishbones. My 38 ft 4000kg cat has a composite wishbone that I absolutely love. As an ex dinghy racer I liked vang sheeting and the loads on a cat worried me so when i built the boat I used a wishbone. It is a very good option for those who don't want to constantly adjust leech tension although you could lead the snotter to the cockpit if you wanted. It is fab for a cruising cat and is much cheaper and simpler than the usual set up. I would unhesitatingly recommend it for the cruiser but maybe not the racer who wants to adjust leech and foot tensions. Use composites to make the wishbone and it is easy to get a good result.

cheers

Phil Thompson
Kankama

Phil Thompson