Twin sheet mainsail(A frame style) - anyone with experience?

[chowdan]

Im looking at having a custom arch welded up that will be the basis of my main sheet system/semi hard dodger, and for convenience sake I was thinking of switching to an A frame/twin sheet main setup. This frame structure will be bolted to the deck aswell as the dodger coamings.

The reason I'm looking at doing this is mainly because my companion way is a hole in the deck with a sliding hatch. Moving the mainsheet to be above the dodger would allow me to have an easier access to the hatch, would also give me a nice structure to base my hard dodger design off and in turn, allow me to be able to sit under in the event of bad weather(our cockpit is very exposed). It also would give me a structure to run a canvas out to the radar arch for shade.

I'm currently in Canada so internet is limited but have been sketching some ideas up that I think will maybe be better at explaining the idea. I'll try to upload photos of the existing layout and also some photos of my drawings

In general does anyone have experience with A frame mainsheeting for a cruising boat?

[wingssail]

Originally Posted by chowdan

Im looking at having a custom arch welded up that will be the basis of my main sheet system/semi hard dodger, and for convenience sake I was thinking of switching to an A frame/twin sheet main setup. This frame structure will be bolted to the deck aswell as the dodger coamings.

The reason I'm looking at doing this is mainly because my companion way is a hole in the deck with a sliding hatch. Moving the mainsheet to be above the dodger would allow me to have an easier access to the hatch, would also give me a nice structure to base my hard dodger design off and in turn, allow me to be able to sit under in the event of bad weather(our cockpit is very exposed). It also would give me a structure to run a canvas out to the radar arch for shade.

I'm currently in Canada so internet is limited but have been sketching some ideas up that I think will maybe be better at explaining the idea. I'll try to upload photos of the existing layout and also some photos of my drawings

In general does anyone have experience with A frame mainsheeting for a cruising boat?

Better send a drawing

[Matt Johnson]

I converted from a traveler to a twin block and tackle mainsheet A-frame on my last boat. It did have full sail control - you could set the boom anywhere and with any tension - but it was very hard to finely adjust and we'd often just do gross adjustments for ease of use. It was a game of trigonometry with each tack.

As soon as you start letting the windward sheet out, the boom lifts and the leeward sheet then has to be brought in to pull the boom back down. The opposite of course for centering the boom. Vanging does help if you have an oversized one.

Personally, I'd try my hardest to install a traveller on the arch instead of an A-frame.

[chowdan]

Originally Posted by Matt Johnson

I converted from a traveler to a twin block and tackle mainsheet A-frame on my last boat. It did have full sail control - you could set the boom anywhere and with any tension - but it was very hard to finely adjust and we'd often just do gross adjustments for ease of use. It was a game of trigonometry with each tack.

As soon as you start letting the windward sheet out, the boom lifts and the leeward sheet then has to be brought in to pull the boom back down. The opposite of course for centering the boom. Vanging does help if you have an oversized one.

Personally, I'd try my hardest to install a traveller on the arch instead of an A-frame.

This is great to know! Exactly what I was looking for. I'll have to reach out to Garhauer to see if they can build a track that would work for me and what sort of space that would take.

Originally Posted by wingssail

Better send a drawing

Will send them as soon as I have better service, possibly tonight, probably tomorrow.

[Franziska]

We have an A frame doublé mainsheet. Works great, you can trim very well and is a lot cheaper than a traveler too.
The leeward sheet is an effective preventer as well.

Drawback, a tad slower than adjusting a single sheet, we have difficulty to set up a Bimini due to this arrangement.

[Ferrity]

Originally Posted by Matt Johnson

As soon as you start letting the windward sheet out, the boom lifts and the leeward sheet then has to be brought in to pull the boom back down. The opposite of course for centering the boom. Vanging does help if you have an oversized one.

Personally, I'd try my hardest to install a traveller on the arch instead of an A-frame.

I have a similar experience with my twin mainsheet system. Singlehanding my cutter with twin mainsheets means handling six sheets when tacking. Short-tacking up a channel is a lot of work.

[Cyrus Safdari]

I am considering a similar "inverted V" or A arrangement but for end-boom sheeting rather than midboom having removed the traveler
There are a number of ways of arranging the lines, including using a bridle, but it takes some fine tuning A rigid vang helps

[thomm225]

Originally Posted by Cyrus Safdari

I am considering a similar "inverted V" or A arrangement but for end-boom sheeting rather than midboom having removed the traveler
There are a number of ways of arranging the lines, including using a bridle, but it takes some fine tuning A rigid vang helps

Something like this original Bristol 27 setup?

I bring the boom down lower when sailing. Gooseneck is floating also so boom can actually come down another 18" or so.....if needed

[Matt Johnson]

Another option If you're not too concerned with perfect sail shape is a bridle with a 2:1 mainsheet. It allows you to get the boom almost on the centerline of the boat and works pretty works well if you have a good vang and strong mainsheet winch.

Basically, it's two dyneema legs going down to the corners of the arch. They connect in the middle just below the lowest height you want the boom. On the end of this bridle is a block. You deadend the mainsheet on the boom, through the bridle's block, back to the boom and forward to the gooseneck. The mainsheet then goes down the mast, mast step block, and back to a winch.

The negative is the block on the bridle swinging around when the boom is outboard.

You can also do a German Mainsheet with this setup.

The other option is just to say screw it to sail shape and put two blocks on each corner of the arch. One mainsheet then runs a 4:1 through this, along the boom and back to the cockpit. With this set-up, you'll struggle with getting the boom towards the centerline and also too much tension when upwind in lightair. But it's easy and pretty inexpensive.

[chowdan]

Finally got some service that I can upload photos.

There might be space to actually have a traveller setup on the arch with side by side blocks and maybe switching to a German sheeting setup(existing setup struggles getting the boom sheeted in to center but that's solved by moving the traveller up to windward

[chowdan]

The arch I'm looking at adding would also construct the aft leading edge of my dodger while the forward leading edge would be supported by two posts bolted to the deck on the inside of the coamings. Strata glass and sunbrella or stamoid would make up the front/sides of the dodger and would run all the way to the dodger coamings that are currently exposed behind the existing traveller

[sean9c]

Wow, whoever designed that deck didn't do anyone any favors. Inconvenient access to the interior made even more difficult by the traveller placement. Those double mainsheets do nothing well. It makes sail trimming more difficult, you now have to have 2 long mainsheets to deal with and, I guess, you now need 2 winches in order to trim. With your idea of attaching the mainsheets to a fabricated arch, the design of the arch would take some pretty good thinking in order to ensure that it's strong enough to take the mainsheet loads. It's hard to tell from the pictures but I wondered if there was a possibility to move the traveller aft and maybe sheet from the end of the boom. There'd likely be a trade off between a more cluttered cockpit and better companionway access. but it might be something to think about.

[chowdan]

Originally Posted by sean9c

Wow, whoever designed that deck didn't do anyone any favors. Inconvenient access to the interior made even more difficult by the traveller placement. Those double mainsheets do nothing well. It makes sail trimming more difficult, you now have to have 2 long mainsheets to deal with and, I guess, you now need 2 winches in order to trim. With your idea of attaching the mainsheets to a fabricated arch, the design of the arch would take some pretty good thinking in order to ensure that it's strong enough to take the mainsheet loads. It's hard to tell from the pictures but I wondered if there was a possibility to move the traveller aft and maybe sheet from the end of the boom. There'd likely be a trade off between a more cluttered cockpit and better companionway access. but it might be something to think about.

I have been pondering an end of boom sheeting with an arch in the cockpit...it'd be similar to hunters and now the newer Catalina's. I'm not a racer and don't intend on racing so loosing performance of perfect sail shape should be acceptable. End boom sheeting also reduces the loads in half so the design wouldnt need to be as strong. Eventually I am going to convert the hatch behind the existing traveller into a companion way. Its quite low on the list right now though and I'd rather build out an arch and dodger that fits better for getting in/out of existing space.

As for designer, we can thank Crealock for it, a design that never made it past 3 boats(I've been told they made 15 from another owner).

[chowdan]

Okay well I've reconfigured the sheeting to be more German sheeting which leads forward then back to the cockpit. Surprisingly after routing it through the unused blocks on deck my wife and I both said 'its almost like it was supposed to be routed this way'.

I'm going to hopefully get a sail with it setup this way soon so I can see how I like the style, but I'm thinking this would be perfect if it was mounted on top of a gantry. Sure more friction but boy would it clean up my companion way.

[Cyrus Safdari]

Originally Posted by thomm225

Something like this original Bristol 27 setup?

I bring the boom down lower when sailing. Gooseneck is floating also so boom can actually come down another 18" or so.....if needed

Yup this is one possible arrangement.

I'd add: blocks on the stern sides placed on swiveling cam cleat bases so you can adjust the boom bridle aka boom sheet by yanking on it from anywhere in the cockpit (I have a rudder so will be moving about the cockpit)

I also want to split the back stay - goal is to open access to the stern under the solar arch as much as possible

Not sure if it helps to use ratcheting blocks for this purpose either