Details of a canting rig

[bruceb]

Self-righting would be nice, but I am mostly interested in the performance gain and what issues I would have to deal with. Finding block and line sizes, rigging details, and handing and setting the rig are still most of my interest. B

[bad dog]

The Firebird uses Tornado mainsheet line and blocks for the canting - pretty beefy! Catapult uses 6mm line with equivalent sized Ronstan triple blocks. Make sure you get the line centre of effort centred in the blocks or they won't pull straight, but I reckon you'd have guessed that!

When the mast is centred vertical, the blocks were 450mm apart even. When canted to max 8° windward, the windward side would be a tad under 300mm apart.

I tried to find the characteristics of the curve for canting angle. Got wet more than once when I went beyond the limit - like 15° canting on a shy reach flying a hull in 8 kn of breeze - startling speed and balance, but no latitude at all - as soon as there was the slightest puff, the rig stood up into it more, loaded more, but then the platform and its hapless crew were at 45° to horizontal and well beyond any powerful righting moment. And in less than a moment - we were in! ...yep, 5° is good - 8° is really the limit.

[farjoe]

Any thoughts about how to build the bearing underneath the mast?

My own is a simple thing which allows the mast to rotate aft on a simple hinge and around its own axis on a seperate pin. This is ok for mast rotation and raising the mast but no good if you want to cant it to windward.

[bruceb]

Thank you BD for the details, that helps a lot. Farjoe, what size boat/mast do you have? I have a 36' Al spar on a 2" delrin? ball with a matching cast al mast base. Simple but seems strong and reliable. If I set the mast up to cant, I will have to fit some sort of retainer on the base, as is, it just sits there and is retained by fore and side stay tension. Most beach cats have a similar arrangement. Not a very good pic, but I can take some more soon if you are interested. I saw a recent post describing an all composite step for a wing mast. I also have at least four different beach cat mast/step examples in my yard I have too many boat parts. B

[farjoe]

I have a cat with a 33ft al spar. the "bearing" is a standard bottom fitting to which a 10mm thick round plate has been welded. this has a central 12mm hole drilled and is connected to a square 10mm thick, 100mmx100mm plate with a recessed bolt and nut. in turn the square plate fits inside another C shaped plate together forming a simple hinge.

i would love to see a close photo of your system.

Originally Posted by bruceb

Thank you BD for the details, that helps a lot. Farjoe, what size boat/mast do you have? I have a 36' Al spar on a 2" delrin? ball with a matching cast al mast base. Simple but seems strong and reliable. If I set the mast up to cant, I will have to fit some sort of retainer on the base, as is, it just sits there and is retained by fore and side stay tension. Most beach cats have a similar arrangement. Not a very good pic, but I can take some more soon if you are interested. I saw a recent post describing an all composite step for a wing mast. I also have at least four different beach cat mast/step examples in my yard I have too many boat parts. B

[bruceb]

I will post a pic later this week. B

[bad dog]

I reckon the ball and socket is the simplest and strongest. Each part is easily machined & fabricated to suit existing beam and bast profiles.