Converting to A frame mainsheet from a traveller

[chowdan]

Hey all

I've been pondering this idea about building a hard dodger for my unique companion way (think swan style but worse).

The hard dodger would be either where I put the traveller or an A frame sheeting system. My thought would be to build an aluminum structure that would bolt to the deck and my dodger coamings(fiberglass structure), and the top is where the A frame structure would be attached. I have an aluminum radar arch on the back of the boat made by Atlantic Towers, and the idea I was thinking was essentially the same design.

I'm thinking aluminum because the cost would be far less and much lighter(?), Opinions?

Anyone have opinions of A frame sheeting? I'm thinking this as it'd allow me to raise my dodger up a few more inches and I'd be able to have sitting room under it

I also was thinking the hard dodger would be hard on top, either a fiberglass foam/ply core or even aluminum sheet and canvas sides as this would mean less labor involved in terms of tabbing the structure in. I could just have twist snaps for the canvas.

I am currently cruising in Canada and have limited cell service so I can't upload photos of my existing companion way/dodger or my drawings of my idea so I'm limited to what I can describe.

I'm hoping some of you can give some inputs as to what I've said to start?

 

[bajansailor]

What is the usual clearance of the boom above the dodger under full mainsail?
I am not too sure what you mean by an A frame - I am wondering if you could have a gantry arrangement, similar in concept to your radar arch, which helps to support the dodger, and can also be used as an attachment point for the mainsheet?
Re how you currently have a traveller, is the mainsheet controlled from the block on the traveller in the cockpit, or does it lead forward and down at the gooseneck, to run aft to a winch by the companionway?

 

[chowdan]

What is the usual clearance of the boom above the dodger under full mainsail?
I am not too sure what you mean by an A frame - I am wondering if you could have a gantry arrangement, similar in concept to your radar arch, which helps to support the dodger, and can also be used as an attachment point for the mainsheet?
Re how you currently have a traveller, is the mainsheet controlled from the block on the traveller in the cockpit, or does it lead forward and down at the gooseneck, to run aft to a winch by the companionway?

Just got back in service so apologies for the delay.

As for existing setup, we have a track on deck, boom is mid sheeting with 3 single blocks that go to a 3 block setup on the traveler. It comes down off the block on the boom to a block on deck and to a winch and cleat. As for distance I've got maybe 2ft of clearance. Need to dig up my old tape measure since the new one went to the ocean to get better numbers.

The a frame setup I was thinking was basically a block on either side of the arch, each independently controlled.


I'll try to post a few photos in the next post

 

[gonzo]

The double sheet system works well. However, it will require that the structure of the arch be about the same as if you install a traveler on top of it. If you change the sheeting to the end of the boom, the force will be half.

 

[chowdan]

I do want to mention, by end of this year I'll have finally finished making my stack pack, so the sail will be sitting above the boom rather than on the side/below.

The arch I am thinking of installing will be located pretty much in line where the traveller currently is and would be horizontally inline with the winches on the mast

 

[chowdan]

The double sheet system works well. However, it will require that the structure of the arch be about the same as if you install a traveler on top of it. If you change the sheeting to the end of the boom, the force will be half.

Hrm, that's an idea. I wonder if I could do a boom gallow/traveler setup which would also allow me to reduce clutter up front as the main sheeting winch could be closer to the helm for single handing

Excuse the crap laying around. I've not see end boom sheeting on booms like mine(bottom open), I assume it's still possible?

 

[bajansailor]

I think that I would be inclined to have a gallows for the boom on top of the gantry supporting the hard dodger.
And re the mainsheet, would it be feasible to have two simple block and tackles on the end of the boom, going down to the port and starboard sides, with the rope tails going aft to the helm?
If the tackles are at the end of the boom, then less effort will be required to sheet in, and you could maybe do it by hand?
And the advantage of having two sheeting systems like this (cats often have them) is that you can then use the windward tackle to pull the boom 'up' (ie to windward) if required, and perhaps put some twist in the sail?

 

[jehardiman]

Not sure it is really "mid-boom" given the size of the vang. Could probably go to end boom like Gonzo says without too much change.

 

[chowdan]

Well I've changed my sheeting around abit. It's more German sheeting style now, going to a block next to the kicker and back down and to the cabin top. Kind of an experiment to see how she does with this setup. I am not concerned about busting a boom as I believe the load haven't really changed at all.

One thing I'm still thinking is the design of the arch/gantry. Easiest solution(ie least amount of work) is putting it where the traveller is.

Trying to determine what sort of loads this would see in worst case so I can spec out aluminum and stainless - do I trust harkens calculator? Anyone have any opinions?

 

[gonzo]

If you have a vang taking the vertical forces, the load should not be that great.

 

[CT249]

When I've tried "A frame" sheeting I hated it. If you had to dump the windward sheet, the main could not ease very far before the leeward sheet restricted it. Maybe OK if you don't want to dump sheet quickly, but dreadful if you do.

 

[chowdan]

When I've tried "A frame" sheeting I hated it. If you had to dump the windward sheet, the main could not ease very far before the leeward sheet restricted it. Maybe OK if you don't want to dump sheet quickly, but dreadful if you do.

Thanks for that.

I've re-ran my lines to be a German sheet setup, runs along the boom to a soft shackle on the gooseneck with a block attached then back to the cabin top(had a unused deck block) where it runs through a clutch and to a winch. Previous owners used this winch for reefing, so now my reefing is done at the mast - with the halyard.

I think I'll move the main sheet line all the way aft to the jib sheet winches and do a double end so that I can use the windward winch as my main winch.

I'm still uncertain on placement of the gantry still, I've got a couple different spots that I'll need to play with when we are back in Seattle. I'm not 100% sold on the location where the traveller currently is due to it might be in the way, the next spot is in front of the big winches, just aft of the cabin top, so it'd be a end boom sheet. Need to make sure winch handles can still spin and it's not in the way too much.

I'm thinking of using 6061 aluminum, 2" tubing(thick walled) as the primary structure. Some cruising friends of mine are going to be back in October and if I haven't already, they said they would run numbers to double check strength

 

[RMA]

To get the traveller out of the cockpit and build a hard dodger, I designed and built a structural mainsheet arch. The sheeting is managed by two swivel blocks currently run as a single line to a cabin-top winch, but the setup could easily be converted to German sheeting. I haven't found that I miss the windward adjustment ability on the traveller. The dodger is way nicer than the extra 0.3 kts.

Keep in mind, the forces end up vectored more horizontally than vertically anytime you are sailing off the wind. The vang and preventer become a lot more important here.

Not sure about aluminum, but you can message me about how I built my arch and dodger in cored composites. I even built the carbon grab rails.

 

[bajansailor]

@RMA, your new dodger is beautiful, a real work of art, built to a high standard - and it looks extremely functional as well.
Can you perhaps post a side profile photo of it as well please?

Not sure about aluminum, but you can message me about how I built my arch and dodger in cored composites. I even built the carbon grab rails.

Could you perhaps tell the Forum a bit more about how you built the arch, the dodger and the grab rails please?
I am sure that many folk on here would be interested.

 

[RMA]

@RMA, your new dodger is beautiful, a real work of art, built to a high standard - and it looks extremely functional as well.
Can you perhaps post a side profile photo of it as well please?



Could you perhaps tell the Forum a bit more about how you built the arch, the dodger and the grab rails please?
I am sure that many folk on here would be interested.

Thanks for the complements! I am working on a post right now. It will be a new thread. Cheers.