boom preventer

[CapnGL]

I have a block and tackle attached to the middle of my boom with a large U bolt attached and that attaches to the base of the mast where my Gin pole attaches. Is this my preventer? I'm thinkin yes as per my research....just want some verification. BTW the help here has been tremendous and I can't thank everyone enough.

thanks
Greg

 

[Justin_NSA]

Sounds like your boom vang to me. I have read where vangs are use as preventers. Only practical on long tacks IMO

 

[CapnGL]

yep Boom Vang it is! Thanks Justin! I have a traveller across the cabin entrance for the Boom....would that act as a preventer as the boom couldn't swing much if it's tight to one side? If not I should look into rigging one?

cheers
Greg

 

[alexco38]

Think technically: What is a preventer?

Why: It prevent (or slow down) the boom from coming across the cockpit during accidental gybe.
What: If there is a way to hold the boom to the side and let it cross the cockpit slowly.
How: some people tie the mast end of the vang to the side of the boat. some use a slowing down device to release the boom slowly.
Hook the vang to the side is the easiest but not very safe as it could broach the boat. Use a friction device is the best as it allow the boom to come across slowly.

Mountain climber use descender. I copied the idea:
https://www.amazon.ca/FUSION-FP-814...UTF8&qid=1474915231&sr=8-7&keywords=descender

I ran a line from one side of the boat thru a descender on the middle of the boom to the other side of the boat. The tension can be adjusted from the cockpit. Also use mountain climbing rope as they stretches to provide some spring action. When going down wind, all crew knows to tighten the preventer line. Safety first.

 

[alexco38]

The traveller won't help if you are going down wind with the traveller and boom are all the way to one side.
The boom will come across the cockpit as much as the main sheet allows it.

 

[BudGates]

I've tried many different methods of preventers but the figure-8 decender, as alexco38 mentioned, works the best for me. Sailboat supply places sell more robust "boom-breaks" but for boats like ours the climbing gear is plenty strong for a lot less money.

 

[CapnGL]

Great info...I'll go that direction. Do you need two? or is one all you need?
thanks
Greg

 

[Gunni]

One, like this (attached to your boom):

 

[Jackdaw]

You can rig one, but I really can't image anyone needing a preventor on a 26 foot boat and a 10 foot boom. Work on good technique, instead of hardware and rigging to make up for that.

 

[CapnGL]

OK.....thanks, that's perfect!

 

[alexco38]

Try not to sail dead downwind. It's slow and good chance to accidental gybe. At most go within 120 apparent wind. You should remember to center the boom before doing a gybe.
I race and sometimes single/short handed. A preventor is a great safety device when auto pilot decided to do a gybe on me.
Yes, only need one figure-8 descender for a 30 foot boat.

 

[thinwater]

One, like this (attached to your boom):

So with the rescue wrap there is enough friction for a 40' boat? In how much wind?

 

[thinwater]

Perhaps the best use for a preventer is when sailing wing-and-wing DDW. It is the only time I use one. A boom brake is not enough, neither is a vang to leeward. You need a line way forward, from the mid-point of the boom or from the end. Contrary to popular belief, in many boats and in many conditions, it is the fastest VMG down wind. It is on my boat, and she aint' slow on a reach. But you've got to stabilize the boom, since you often sail slightly by the lee.

 

[alexco38]

typical polar chart:

 

[Tally Ho]

I have a 4:1 tackle that I use to hold my boom to the side and to prevent it from swinging while at anchor or dock. When sailing down wind, I will use it as a preventer, moving the lower connection point forward on my toe rail.

I have also practiced a controlled jibe, so I can jibe, even if I the boom extended, when necessary.

I have an O'Day 322. Not sure of the boom length.

Greg

 

[thinwater]

typical polar chart:
View attachment 128554

I'm going to bet that that polar does not include wing-and-wing. This one does. There would have to be a bump. The deeper you head you go slower and slower... until you jibe the genoa over and catch air on the opposite side. There logically has to be a bump.

This speed polar has 2 distinct differences from the prior example. This boat has more of a reaching bulge (catamaran), and it has a bump for wing-and-wing. The result is that wing and wing is not the fastest course, but that it makes sense as soon as the course is too low for good reaching.

Also note that like many cats with swept back shrouds and no backstay, we can't ease the boom all the way. This limits deep reaching unless we are wing-and-wing (which we can do without a wisker pole) or carrying a chute.

I think you will find most non-spinakar boats race down wind wing-and-wing.

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n2P9s8PhMTU6aqw9QsAnJ1i5sy42EZSsuTHUrfiy3Y9Q9uMPOH6UCTSMmNchsfofBeef7yz4XeEarcY/8A1Ke4FtPD0spBHWcamZptugQVxOfw7uCcXHZO1eTOb6aRznAfdiOWo5/zmsvZ2Mq0H9LQc5jxIzMNyCLgXhVnENH/AIwRBmGCT6keZRhqtMiADyFMAxzaSuqyXqsN2fCNWrUc5znAEkkkGCSTck8SdVOST2LcmmPMqbWNgCY/KN/G1gp1ejDrPAOhs0i/P6KUNbUwbK7muewujQTAPMNfMrPIp025Q1saAEkRyLqkqX9SIIylw45Bbdoo0cYw2NNwg7w1pP6Wwq+E3tfzy1rfTN2TtnEYYuGGIp54zAHNOWY7TzGpWFVxFQnrUqV9TN5J11TfUYTGsje3TkQ4eip6bKYLQWjflF+d/wCcVEwku4i52zVWtad2WPAg8bhyGu4lgA4XPkDZRzzByCNBBbE8dPqpUcG0nrOceNrD8Op/wrqrHN4Rp4/8tVRnff7MCO86cpVlTDsECwncJvyEX81VVp0xMPc06FuUxPiHAWSkMVnR1msncJ3qGJ6Qs6gY2Lw4TIGsahWk0xEPc4d1zyiIQ2nTBNnd4iPHU7u5RYmXS/2Zxr6eLpHEFgpdbPlaDLS02hov1o81le1u1G1q80RLAxrWi4Np9AtfVa0g5S5pPxQY8xICx6eEeBcvN7m48BNln7UmXkv7luPikHWHVvw3/uk7MJJpieGvnI4KT8O0++0xN5Mti9zJBSdQD75raR12/X6LVmGEmAWwZGsCPESkWkEiNdLmOWiqq4ZuuaGyLtAHrMyrehGaDTk3gkiTwsd3moSdOk4e609zcunceKi6lBuO+4HzTe2GwTE7gDl5HqqwZoFyQBdpLwPONfBShQ2q3Md54WvyOisDh4d+X9k6hdENJHMFw89E6gcYbmHPKWnzUJGZty4mw93LM7pJEekrGqY18R0ryLQJFgN2isq4Fzh22xBBM3jumfRYVLYxcY6QgfiA+YVMv50vj/G0jWdFqj+WZ37r1f8A0w2ex2zpqMDukq1C7MJkNhl55FeW0diCb1Kgj+4X8m2XS7M2tVwlJtKniqzWNJgZqRBzOLj7ut+5cvNjllNSN+KyXdrZ+3+yKeGe00m9Wo4uyi8Ea6nTQ/4XKtpW7A7zb6ErdbWx1PEwazqji0Wc6wvqAGiNwWDR2dSNMuY52mkgXG8mDH+FrxZ3HGTKVTkw8stxrzSAFpJ5AeGqfRkRLCCf7R6XgqdTC1Bo8uEng7zM3PkgYfKRJi0gEAOPJubTuutvNl4kKJmDSsd+UDv46pVKMW6M+WbvubwoNoVOzGUX1AE8zqFCpXe0dV9QxbiI8jPorSq2LXUyP/GYPcP3uoMOY2pTG4iPnKj/AFjiIh821I0P84KVV7y0CSJ0Nj87SpFmUjRhA46/zRYRwdPV2HbJ7hffOqnS6XMPtI1MGRMTuaQTvU3vffrEnQ9rfu60qNb/AAmWxNtTc1g4WbPy3Kp7zMGkT+V3rqgVX9kyfy6ab4AUKNCBLSZOodJ8teAUjKey0E/rD4jnYfJWMpEC1xpAiLixAJuoMYaZgPABI1F5jSR9AE6mHe4SAKkycs7uMuUqjI0jrTI3gGb2iBbyUH0pMlzw3gWE+EG7gq5AiaZBtYFu/dJBsp1dlVHOBiBv60erd/goqVvQgj7N9tOwIt3XIUjUBIAJA4kCOZvpyCwzgYeR1wQIMVTbxypUtlEGQ0unear587FDpkGmD2a4ZMaOIBj5JUWte3rV2kzoHTMcRAgqp+DYbvDzFvvHn0LrpOr9AM1MdXf0jnON+Ak929BbiSRq94BuCHMg8IBJ+e9OjTkD7R4A+J2u/QELDpbTbvsZ0F5vGoAhW0Hs6zmNLY1zAR3dkmbp0Mlz2z1qzLfEZdyEOlOrWp+7UEcSHEd8j/ta2tUDhmOQsk3HSNcJ1uB9PJZFDJNg28a53CNZExdQaXvosfBFVoZrOVovzzX8VaMOGkZH5/OL7wASAsd20KU5A5gNweq68WmcttNFk0m9G2RUPIN8YElShiYinJguIPMuIEzEBtuUpPpUjALpd/LDfKeOxbxdr4aeqSYnkWhqjRw1aPvwBqTlJ+RFvBQlfhcEGiQ3X+9wPkTw8EVcMZJMRERMn9RBWJnYAc78ztJaH6nSQ4qnE0aLHDOCM2oaymI5kX+aDINEgkv626CXgX3QAJKyS4AANLe5pzAj1nXesKnjqECm2S2/akRGkWJ4qAxrQ6GAEgHqwb98yL8wm4arYvoVTfLEaOD3ExwmCfKFMUyAZqGZm4JiBwN1hMpGfuspOpGSd0RqPNZlXBjWoDobOMgxqYFj4hShTSryQGmo6ZOYAmButu/wio64bm3WJuZ7w4zKpfWouGam6SNzWQZO+XQArRiBUb2yY5AgjUHqkFQkm5J7V4PWDSZ5uiPJXmo0Nk3jcDUcB4R9FE7MzNzENaBcZbm/fAjyVdDDtfmhxJHuiWW5hSbWsxA4lvm6OQsfRJtamSW9JcWzOa8xxAgXPhxSbhiwSC4SRYvc7S2s/RXV21GtgQ4TMOgC/Ai6jRtdmpEA5wd09UR5iR4pTbrVWxJOsWGnZaOCroYbPGZx4xJIjUTJ+itxuFsAyrl/LadY10TSdqnUswL+ngbtQ0d13aqllJoP3lQ2ktAzFw56x4Kh9OoRLHtO6SzNPdcg2U6uHxR6sthw1hrfDV3yUfAmMJTLjlYAIuQIPKXEIYxjGDK9rG8SQ6fEaJf0jnCbNOhIzOMjd2mgcwp1MEWiTvOuYmTyMwrILMDLmdcadsRzAOvO6m0FxHVbEe9UdI/KsToHvzddwy7hpB5uUGl4BzODm3OU6nnIhBeyoQe3R39mR65SQVBmPBd1spiR1TUid0kiEhSEHqC4nUnz0lYwYwvkO7MZruzX3Dqwo7T02HTvEnMCDuJce6MuZRNf+0TxBYOFiSDPmsauGkA5CcxsC626TJmD4KoUajex0Y3HNncb31ET5KR//9k=

 

[Joe]

You guys a cracking me up.... our newbie barely understands the basic parts of a boat and your start throwing polar charts at the poor guy.

 

[BudGates]

You guys a cracking me up.... our newbie barely understands the basic parts of a boat and your start throwing polar charts at the poor guy.

lol... I think the polar charts are for us old guys who still try to glean a little information here and there. I, for one, can learn a lot more from reading a few charts than I can from an entire book. It's like they say "A picture is worth a thousand words."

 

[alexco38]

I was a newbie at one time until someone throw me a polar chart and tried to understand it all. Over time, you'll get it if curious enough.
Like I just learned the "Bump" today.

 

[SFS]

The 70's dance, or the action that moves a forum thread back to the top of the "to-be-read" pile?