Crab claw Sail

In December 2010 I completed round two of sea-trials on a conversion of my rig from Bermuda to crab-claw. I have posted two videos.


http://www.youtube.com/watch?v=XAVFh2heetA
http://www.youtube.com/watch?v=4JSH1s6aGEQ

To help control weather helm I have an adjustable tack. I physically move the tack forward when going down wind by pulling it forward using the windlass. Additionally, it is important to lift the boom high using a spilling line and allow the wind to pull the sail forward and high up. Both of these factors adjust the center of effort for the rig forward.

I'm very excited that I demonstrated a rather small crab claw sail could pull my big rig into the wind. While lI do say small, I believe I currently have the two largest crab claw sails in the world. My small one stands over 4 stories tall!

I have more detailed posts on a thread about aft-mast rigs. The reason is my boat also has an aft-mast.

http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-24.html

Philip Maise
Owner Hot Buoys Trimaran

 

What is the design objective for this sail ? Looks to me to be small, poorly trimed , with many lines and a boomed foot. Is it a sun awning ?

 

Thats no crab claw sail ! Its just a jib with a solid forstay and a boom. The fact its all supported by a vertical mast means its just a butchered bermuda rig IMHO.

 

Size and Shape

The video shows the smaller of the two sails and the scale of my boat makes it look small. In feet it is roughly 45 feet tall with a 30 foot boom. I built this smaller sail for initial testing and for high winds. The larger sail is roughly 61 feet tall with a foot about 37 feet long. The attached photo shows the small sail in production. The area of my sails is larger then the total area of a typical Lagoon 500.

The overall purpose is as demonstrated in the videos. It is an easy to operate self-tacking sail with lift. A Bermuda head sail drives the boat both forward and DOWN. The crab claw drives it forward and UP.

Regarding the trim...the sail is not what you are used to looking at as you are used to seeing a sail curved in the vertical not horizontal plane.

Regarding the comment that it looks like a Bermuda rig..I suggest you review this link to learn what a Bermuda rig is.
http://en.wikipedia.org/wiki/Bermuda_rig

My rig has no main sail and doesn't split the sail plan with a mast in the middle interrupting air flow.

There is some debate among other designers whether my sail is better described as being a lateen or lanteen sail. I prefer to call it semi-crab claw since I have eliminated the upper spar by using the bolt rope instead.

Thanks for checking in.

Philip Maise
Hot Buoys Trimaran

 

Crab claw sail yards are supported by the short mast ~1/3 from front end, not hanged at the ends from huge mast.

Sure, this arrangement have it's virtues.

But it is not a crab claw sail, it is a jib with battens along luff and foot.


Sorry, if it sound negative.

 

Pmaise, you may be completely assured that Rwatson knows what a Bermuda rig is without the slightest reference to wiki or any other net source.

Aside from that, your rig is most interesting and none can deny that you have put your money where your mouth is. The videos attest to the fact that the rig indeed operates as a propulsion system. Keep us posted.