Easily adjustable downhaul position on a balanced lug?

[laukejas]

A suggestion to help reduce wear and tear on the mast. The pivot of the boom is to the side of the mast so the downhaul can be fitted to the deck on the side of the mast. This gives more equal tension when the sail is eased out on a run on both port and starboard.

A bunch of downhaul images from the Goat Island Skiff Facebook group. If wanting a closer look visit the group and check MEDIA > ALBUMS

Note that while many are similar some lead back to the centrecase. For racing the Oz Geeese in the Philippines fleet we can't afford or access any cool fittings - so we just lash it.

Yes, thank you, that was indeed a mistake on my original boat. On the new one I'm definitely adding the downhaul attachment on the side, regardless of whether it will be on the mast or on the mast partner!

I made up this from an old sheet track, to allow for the adjustments I wanted.

Having one of these at each end of an endless loop, would also work for adjustment, when it is within hand reach.

Nice! Yes, that is basically what I envisioned, but with the rope and Prusik knot instead of a track. What you showed here, with that clamcleat should definitely work, but I was wondering if the position adjustment line could work without a cleat, utilizing the friction of the Prusik. Here is a pic from a few posts ago to clarify:

The idea was that the adjustment line (green) would wrap around the track line (blue) with a small bowline loop on both ends of the Prusik, so that tugging on either end of the adjustment line would slide the Prusik forward or back, and once the downhaul is tensioned, the friction would take care of the rest. The downside of this system, compared to yours, is that one would need to de-tension the downhaul in order to make adjustments, otherwise the Prusik wouldn't slide. I haven't tested this though, I don't know if it would really work, it is entirely possible that the green line would only jam the Prusik and it wouldn't slide at all.

 

[skaraborgcraft]

Even with a track, letting off on the downhaul tension would make life a bit easier. This was set up as a lines-to-cockpit controlled system.

I see no reason why your system wont work, but you will need a way to lock or tie off your green traveller line, as the boom is free to slide within the range of the downhaul between the blocks, unless that knot has exceptional grip? It might be possible given enough downhaul, and perhaps slack-angle in the travller, to prevent easy boom movement for n aft. Fixed pad eye blocks on the underside of boom with enough angle might create enough friction.

 

[laukejas]

unless that knot has exceptional grip

It does That's the whole point of Prusik knot. When tension is applied to it, it locks down and will not slide. Take a look at seasquirt's post where he tested this idea (minus the green adjustment line).

 

[skaraborgcraft]

My other thought on this was some kind of saddle that goes over the boom, with enough surface area to have enough friction to not require for n aft position sheets. But i came back to a double looped strop is adequate for the job when in hands reach, for boom adjustment.

 

[skaraborgcraft]

Yeah, I can see how that will work, and yes can see why tension would have to be released to set it, and why that might be an issue.

 

[skaraborgcraft]

You may have seen this. The blocks can get expensive.

 

[skaraborgcraft]

I do believe the algorithm is spying......

 

[seasquirt]

Hi guys, the photo displayed is of a doubled prusik knot, where I wrapped it around the red rope twice, before threading through the loop, but just wrapping once works well, doesn't slip, and is much easier to loosen in the frenzy of changing sail position. I got rid of the blue piece of cord, and now just use the thin red dyneema cord for the single prusik, on the thick red rope. It still works fine. The double downhaul in a V configuration works well, but involves extra work to adjust and cleat 2 ropes. I think a single lever clamp for the downhaul on the mast or deck, after a pulley system, would be quick and beneficial. All good ideas there, and cam cleats will grip well, but may chafe the rope eventually; and plastic ones can have their sharp ridges dulled by sliding usage, plus getting whacked in the head by one or two wouldn't be nice. Keep it simple. Yes, computers and phones are always listening to you, 'siri, can you get lost' ? Ha Ha.

 

[laukejas]

You may have seen this. The blocks can get expensive.

Yeah, I've seen this one! Aside from additional hardware, it's a neat system. I don't mind additional hardware; I make my own ball bearing rope blocks for $2 each, but the real issue is that each of these downhauls controls two things at once (downward tension and boom fore-aft position). So if you want to adjust the tension without shifting the boom, you need to manage two lines at once... Not ideal.

But in any case, you guys suggested lots of good ideas in this topic. I think I'll be able to test many of them once the boat is built, it's not like it impacts the design at this stage.