How to compromise junk to trimaran?

You're right, Tom compared 3 rigs on the same hull and it was a sharpie. The book is at my Hobart home and I'm in Sydney ATM. And yes, no great difference except off the wind where I think the Chinese lug rig walked away.

Does this apply to any other hull shape? No, but it seems to be the only actual test done.

People have budgets. If I set a budget of $10k for a rig and sails, buy or make yourself, your choice, but it has to be new materials, will a marconi rig still out-perform a Chinese lug rig?

PDW

 

I think it depends on your definition of perform?

 

Chinese rig can be bigger than marconi for lower mast height, has more square footage so maybe will perform better, maybe, if you can work around the extra weight and its penalty on stability. Like in V8 engines, there's no substitute for cubic inches, same can be said of square feet of sail area, so if your boat can hold it up, a bigger sail of any kind will make you go better. Chinese sail is most controllable option.
On trimaran possibly a heavily roached battened marconi main is another.

 

Good point. How about for the marconi rig vs Chinese lug rig at the specified price:

1. Same or less time point to point sailing over periods of a week ie passage from port to port.

2. Same or better sail longevity, with actual sailing time say 90 days per annum.

3. Same requirement for sail changing or less while sailing, wind conditions as below.

4. Same or smaller requirement for crew to efficiently handle the rig.

Wind conditions typical of 42 south; anywhere from none to 40+ knots.

I'm interested as to what peoples' opinions are, and why, given that I'll be building or buying a rig this year and I have plans from the designer for 4 different ones, my choice.

PDW

 

pdwiley: the marconi would be cheaper if it is a cruising type. You can contact any rigging company and everything for a marconi is standard equipment.

 

see my reply in red above

 

Are you saying that I can source all the materials I need, new, for a marconi rig for a 12m ketch for less than $10,000 AUD?

I use that figure because it's my 'back of the envelope' calculation for a junk rig for the same vessel. I'm willing to bet that I won't be more than 15% out.

There are a number of issues.

First, the cost of the rig in absolute dollar terms.

Second, the efficiency of the rig in moving the vessel on all points of sail. This efficiency being: (a) a function of wind force translated into vessel motion on the one hand, and (b) demands on crew on the other.

Third, longevity of the rig as a function of days of use.

Just about everything I've read comparing rigs concentrates pretty exclusively on my point 2(a) and ignores the others.

PDW

 

Thanks, Tad. That is in line with my thoughts. It's always nice when that happens, especially so as it's rare....

Yes, if I had to go to windward and I wasn't making the progress I desired or wanted to point higher, I'd fire up the engine and motor-sail. Just like (nearly) everyone else.

Junk sails made from Top Gun, Sunbrella or other low stretch synthetic canvas don't need sail covers as their material is what sail covers are made of. Chafe is an issue I'd assume (having never had a rig) but seems manageable from the experience of people who have such rigs.

PDW

 

Sunbrella and other acrylic boat cover fabrics are very easily chafed, stretch badly and make poor sails. Duradon and Oceanus work well for junk sails. BERTIE's main is Duradon with dacron headsails and mizzen and the last set was used for 25 years. The sun will break down even resistant cloth like Duradon and covers are a necessity. I went through 4 mainsail covers the last set of sails.
Try to make the junk rig as large and light as possible consistent with adequate strength, as most of your sailing will be in moderate conditions. Sail cloth for junk can be quite light and BERTIE's mainsail is a little too heavy (I wish I'd used the next lighter fabric).

 

Cambered junk sails


There is a world of difference in performance between a flat junk sail and a modern cambered one. The battens are rigid and you actually have individual shaped sails between each pair of battens. The draft of each panel can be carefully controlled and upper panels have a flatter shape than the lower ones.
Because reefing is ten second job, you can have a larger than normal sailplan and perform well in light airs. Having sheetlets led to most of the leech of the sail gives unprecedented twist control without resorting to massive vangs.
Not only that but you could take several cannon balls through the sail without reducing much of its effectiveness. Nelson was lucky that the Chinese never came visiting.
I have noticed no reduction in windward performance over the other rigs I have used.

 

Lovely, lovely....

 

Gary,

It is great to see you reply to this post with pics of your boat. I am nearly finished with the hull of my own Wa'Apa, built from your plans, and am planning a Junk rigs as well. I am glad to hear you have had success with it.