http://dreamgreen.org/products/boat-parts/176-boom-brakes he mentiones installing it on a Bristol 32 which has a sail area of 246 square feet. Here is the video https://www.youtube.com/watch?v=yCkFUGl12xw
I knew I had seen a similar piece of hardware somewhere and realized it was similar to the window washers I see hanging off the 12 story condo building we are living in temporarily.
|This is a Black Diamond Belay and Rappel Device that cost about $16 at REI|
A little more research yielded the Wichard Gyb'easy Boom Brake:
|The current price for this piece is $199 on Defender.com|
Since our Mainsail on our 42 is about 420 sq. Ft. the Wichard just might do the trick, I have no data on a climbers belay and rappel device but a lot of people trust their very lives on the device, and "The Capt. Don Boom Brake has a yield strength calculated to be 9800 pounds before elongation so you can use them for other applications. Remember that the mast and boom absorb most of the sail loading so this boom brake can be used on a sail with a loading far in excess of the yield strength of the boom brake." But I do not know how to translate 9800 pounds to sail area?
We currently use a Boom Preventer when offshore but I learned that my preventer is really a Boom Tackle since it resembles a boom vang. It requires crew to go leave the cockpit to either adjust or gybe the mainsail. When you are offshore these are well planned events usually and carefully controlled. We sailed from St. Petersburg Fl. To Port Aransas TX. in 7 days on one Broad reach Tack, The winds only changed in velocity except during one short 2 hour storm. Our Boom Tackle was deployed the whole time to the end boom and a hard point just forward of the cockpit.
I feel fortunate to have end boom sheeting especially after reading several accounts of injury to crew just from the mainsheet whipping about in the cockpit on accidental jibes.I googled "Boom Preventer Design" and came up with several very interesting articles that have me determined to solve this puzzle before heading offshore again. The accounts of injury and Booms breaking have me really question the use of a Preventer: see http://archive.sailingscuttlebutt.com/news/08/preventer/ A boom brake seems a much better solution especially for a short handed cruising crew when there is often just One person in the cockpit on watch. The crazy stuff always seems to happen at night when you can't always see it coming and being able to manage alone is very difficult, help from below can't come quick enough. Another good read on preventers is http://www.morganscloud.com/2014/03/02/rigging-a-proper-preventer-part-1/ and part 2. Also see http://bermudarace.com/wp-content/uploads/2014/01/Permanently-rigged-preventer-CCA-website-2014-version.pdf
Mechanical Boom brakes like the Dutchman pictured above at about $340 on Defender http://www.defender.com/product.jsp?path=-1|118|2358532|2358536&id=216 are pricey but may be worth the investment and the additional effort to install the required hardware to run the line to the cockpit. The Passive devices just require a port and starboard hard connection point that can take the loads of the mainsail in a hard jib. The case for the passive brake devices are low maintenance and ease on installation. Also since the main is not prevented from jibbing you do not risk the possibility of broaching and/or breaking the boom or other rigging
This is a much more serious concern than I thought before especially after reading of those accounts where things definitely did not work out as planned or thought. One solution cannot be right for all types of vessels nor all crews. I assure you that it is worth whatever expense in time and money to get it right. I have another friend who owned a Catalina 40 with mid boom sheeting and twice he had a crash jib offshore that bent his boom right at the mid boom mainsheet connection. pretty costly both times. Of course it happened at night with short handed crew. He did not have any type of preventer or brake. Even with insurance think of the hassle in replacing your boom twice!
One more thing I have learned in reading all of these accounts is that you need to be very careful of what you add to the boom and where you add it. getting hit with a flat surface is one thing but getting smacked in the head with any type of extruding part like a cleat or other piece of hardware could make a headache turn into serious brain damage. The goal of the device is to keep the crew safe from injury first and second the vessel in seaworthy condition.
If you have a solution that you use and trust or have tested in real conditions that proved to be satisfactory please leave a comment. Or if you have any other pertinent comment please do so and I will edit this post to include your experience to help all of us be better prepared for the unexpected Jib, Crash Jib, or Chinese Jib whichever you name it!