Wednesday, January20, 2021
Privacy Policy

8:1 and 20:1 Cascaded Boom Vang

8:1 Cascade Vang System

Cheaper than using two fiddle blocks, lighter, and stronger. What is not to like? You just run the control line back to the cockpit where you put a cam cleat. You will likely need a turning block on deck but then you have the vang where you want it when it needs to be released quickly before you round up.

An intriguing variation is to use $5 repel rings from REI and Amsteel. It takes about 15 pounds pull to get 10 pounds on the other side of the ring. But that is giving you 25 pounds pull on the ring instead of 30 so the loss isn't as great as you might think. For every ring you use instead of a block, multiply the theoretical purchase by 80% to account for the frictional loss. This 8:1 system would be 6.5:1 with a ring instead of the top block. Even lighter, almost as much leverage, and very strong as those rings are rated at 5,000 pounds.

You could use 2 rings and have a 5:1 system, more than the typical 4:1 that so many people have, at a fraction of the cost. The remain two blocks are now only taking a fraction of the load so they can be very small and light.

If using all blocks, each block down the line needs to take 1/2 the load of the one above it, except both blocks with the red line have the same load. You cannot use rings for the red line as that can't be Amsteel because you can't lock it in a cleat and anything that locks in a cleat has just way too much friction through a ring.

As a final note, you can use two fiddle blocks and get a 16:1 if you want a lot of purchase. The upper two single blocks stay the same. For a 16:1 system, the math would be 2 x 2 x 4 = 16.


20:1 Cascade Vang System on Papoose

The vang system on Papoose is arranged to give even vang tension with boom position even though the primary padeye is aft of the pivot point of the boom. Before I did this system, the vang tension would increase by itself as the boom was let out. This was caused by the geometry of the layout with the pivot point of the boom forward of the padeye that was as far forward as it would go and still be on the cabin top. The solution is shown where there are two stand up blocks on the cabin top that are forward of the boom pivot point. The net is that the forward blocks exactly compensate for the aft padeye location so that there is no increase in vang tension as the boom is let out. The red line starts at one of the beckets of the two blocks on the boom, goes through these one of the stand up blocks, thought the first boom mounted single block, through the second stand up block, through the second boom mounted block, and terminates at a 4:1 pair of fiddle blocks. The red line system has 5 parts so the total purchase is 4 times 5 or 20:1.


16 More Vang Systems

Follow THIS LINK for more vang systems.

Cookie Policy:
This website uses cookies to save your settings. No personal information is saved. I do not collect statistics on your visit. You can disable cookies in your browser if you like but it is not recommended for this site. I do not sell cookies. Go to a bakery for that. In fact I do not sell anything. To disable cookies from, please refer to the Help button in your browser.
Privacy Policy:
I do not sell or share any user data or anything else for that matter. The only personal information I save is in the site log which has a line for each page view which includes the IP address your browser sends in the header as well as which page you requested. I use this to block hackers and other bad actors. I do not use this raw data to create profiles on users. I periodically delete the log files. Google supplies the ads on this site. Because I do not track who you are, I cannot customize how these ads are served. They may be personalized to improve the ad experience. If you do not want personalized ads, please adjust the settings on the Google site HERE. NOTE: The best I can determine, this site is not subject to CCPA but I am doing my best to comply anyway.
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.