Automatic Mainsail Foot Tightening

[Craic]

I made a small mod using the mainsail foot outhaul under the boom to hook my mainsheet to, and Bingo! now the mainsail foot is tightened automatically when I haul the sheet tight. Incredibly simple and works like a dream.
Described with photo at http://www.swallowboats.co.uk/component/option,com_smf/Itemid,52/expv,0/topic,262.new#new
The question came up if this system has been used before, and if not why not.
C.

[Thorne]

I suspect that the reason most similar systems connect to the boom is that otherwise you can get the sail tighter/ further down the mast than the boom.

Todd Bradshaw has an illustration of this method, and I used a variation of it on my dory skiff. The boom has to have gaff jaws or otherwise be adjustable on the mast, so that pulling in the mainsheet also pulls the boom (and sail) down the mast.

http://www.luckhardt.com/boomrigged2.jpg

http://www.luckhardt.com/elk29.jpg

[gert]

Craic's http://farm4.static.flickr.com/3165/3501687182_72af118960.jpg

[Hwyl]

No, I've never seen anything like that, you do need to modify it to keep the clew down on the boom, otherwise your clew outhaul als o acts like a sheet.


Hwyl Gareth

[Craic]

Thorne,
this is a spritboom.
C.

[Todd Bradshaw]

It's always dangerous to think that nobody else has ever tried something before, but that's one I haven't seen yet and it's pretty clever on a sprit-boomed sail. As long as you have some means of limiting the adjustment at either end (which you seem to have by the nature of how much slack you allow on the "traveler line") I like it!

[Figment]

Does that have the potential to overtension (damage) the foot?

[John B]

You'd need a good stop eh.
I messed with a variation on this a bit on my gaff at one stage . I was trying to make the peak span give me head tension as I hauled more peak halyard tension on. I didn't persevere with it because it was wrong LOL. Then I tried to make it work when I pulled throat tension on and at least that was the right way of thinking. Problem with that was there was already a great deal of power there and I felt it was just adding to the stresses. Main was 600 ft and quite hard work to get set properly. I gave up on that too, but its probably worth playing with, perhaps on a smaller sail.

[Todd Bradshaw]

"Does that have the potential to overtension (damage) the foot?"

Yes, it does. There needs to be some sort of stopper built into the system at each end of the available travel. The floating block reaching the boom should do it in terms of limiting tension increase and the amount of slack in the bridle under the boom should limit tension decrease. What you don't want is some sort of unlimited system where increased mainsheet tension just makes the outhaul tighter and tighter until the foot stretches out of shape or tears, or one that slacks off past a reasonable point as mainsheet tension is eased, off the wind.

[Craic]

Does that have the potential to overtension (damage) the foot?

Enigmatic question. On sailing boats ANYTHING has THE POTENTIAL to give.

The only relevant question is what will give FIRST.
If a sail foot should get damaged by tensioning it, it is in the first place a poorly crafted sail, period.

No need to worry or abstain. The shown setup has an automatic force limiting effect. As the foot is tensioned, the angle of the horizontal outhaul rope under the boom gets less effective and the setup looses purchase. By just adjusting the length of the rope you can increase or decrease the foot tension any way you like.
And of course if you are anxious you can knot a stopper in, but I wouldn't, it works perfectly with the in-built limiting.

[Todd Bradshaw]

"If a sail foot should get damaged by tensioning it, it is in the first place a poorly crafted sail, period."

This is simply not true, and for anyone who knows much about sails it should be pretty obvious. I've been building sails and repairing other builder's sails for 29 years now, and I haven't seen a single one yet that that ignorant statement would apply to. Who would have guessed that they were all poorly made until some expert came along to set the record straight?