Spiv
Ancient Mariner
- Joined
- Jun 23, 2007
- Messages
- 221
- Reaction score
- 17
- Location
- The Big Wide Blue Brother
Hi everyone,
I mentioned a few times that I was working on a new(ish) design for a cruising rig, a rig that I though off since I built a 12.5m cat in 2002.
Basically my cat cannot be sailed with the main only; now, I know that others can, however this is not the only point, what got me thinking is:
1.Mains can only be reefed upwind (where there is more wind), this can also be dangerous if you were running and left too much canvas up too late and, is never a one man job.
2.The boom is a real nonsense, jibing more complicated than headsails.
3.Even with lazyjacks, it is not that easy to get rid of the main.
4.But the most significant thing is that the mast turbulence affects the first part of the sail: the most important part as far as efficiency is concerned (see C. A. Marchaj).
Another thing I want to do with my next boat is go up rivers and visit cities, this is when you need to go under bridges, powerlines and other obstructions. A properly engineered tabernacle a winch and a couple of poles will let you lower the mast, but it is a precarious situation, power boats going by can cause havoc, even injuries or damage.
So, my first thought lead me towards an “A” frame mast with a furler in the middle for the main and one or two up front for the jib and the screecher. That way I can reduce sail downwind and the mast is not in the way.
The two masts only work in compression, so do not need to be so strong as the normal mast that is not only compressed, but also wildly twisted by the main.
No need for shrouds, chainplates etc.
The hull needs to be engineered differently as now there is tension in the middle rather than compression, the rest is as any other cat.
This was my line of thought until I bumped on Brian Eiland “Mast-Aft” rig: a mizzen sail on a wishbone boom! What a great idea!
For all the many benefits of such a rig, please read Brian’s article on his design here.
Some points to consider:
5.If the mast is stepped aft and inclined forward, it will protrude less from the bow when lowered.
6.Also the main (jibsail) can be self tacking.
7.Not too far back as the backstays need some angle, perhaps they could be on a targa bar.
8.The boat is a 13m cruising cat on 15~16m long hulls. Composite vac-bagged sandwich, 7~8 ton + 3ton gear.
9.The sails could be 70, 50 and 50sqm or thereabout, that will give a lot of canvas for light winds.
Forgive the crude drawing, I draw it in MS Word.... I downloaded Freeship and was going to design this rig myself with the final touch by the Naval Architect whom will also design the hull, but it will take time to learn Freeship, so since I discovered this forum and realized the talent that is behind all you guys, maybe we can design this all together and if it performs well we might make a change in the way the world goes sailing…. Or at least the cruising world.
I mentioned a few times that I was working on a new(ish) design for a cruising rig, a rig that I though off since I built a 12.5m cat in 2002.
Basically my cat cannot be sailed with the main only; now, I know that others can, however this is not the only point, what got me thinking is:
1.Mains can only be reefed upwind (where there is more wind), this can also be dangerous if you were running and left too much canvas up too late and, is never a one man job.
2.The boom is a real nonsense, jibing more complicated than headsails.
3.Even with lazyjacks, it is not that easy to get rid of the main.
4.But the most significant thing is that the mast turbulence affects the first part of the sail: the most important part as far as efficiency is concerned (see C. A. Marchaj).
Another thing I want to do with my next boat is go up rivers and visit cities, this is when you need to go under bridges, powerlines and other obstructions. A properly engineered tabernacle a winch and a couple of poles will let you lower the mast, but it is a precarious situation, power boats going by can cause havoc, even injuries or damage.
So, my first thought lead me towards an “A” frame mast with a furler in the middle for the main and one or two up front for the jib and the screecher. That way I can reduce sail downwind and the mast is not in the way.
The two masts only work in compression, so do not need to be so strong as the normal mast that is not only compressed, but also wildly twisted by the main.
No need for shrouds, chainplates etc.
The hull needs to be engineered differently as now there is tension in the middle rather than compression, the rest is as any other cat.
This was my line of thought until I bumped on Brian Eiland “Mast-Aft” rig: a mizzen sail on a wishbone boom! What a great idea!
For all the many benefits of such a rig, please read Brian’s article on his design here.
Some points to consider:
5.If the mast is stepped aft and inclined forward, it will protrude less from the bow when lowered.
6.Also the main (jibsail) can be self tacking.
7.Not too far back as the backstays need some angle, perhaps they could be on a targa bar.
8.The boat is a 13m cruising cat on 15~16m long hulls. Composite vac-bagged sandwich, 7~8 ton + 3ton gear.
9.The sails could be 70, 50 and 50sqm or thereabout, that will give a lot of canvas for light winds.
Forgive the crude drawing, I draw it in MS Word.... I downloaded Freeship and was going to design this rig myself with the final touch by the Naval Architect whom will also design the hull, but it will take time to learn Freeship, so since I discovered this forum and realized the talent that is behind all you guys, maybe we can design this all together and if it performs well we might make a change in the way the world goes sailing…. Or at least the cruising world.
