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AlaskaMC 05-06-2014 05:00 PM

Topping lift loads?
 
Hi everyone. As our boat nears splash day, one of our last projects is the topping lift. Could anyone tell me if the loads on a topping lift are ever significant? I am buying the blocks for it and my mind tells me the loads are essentially lifting the boom, but is there ever a time where there are more? Light wind you could use the lift while sailing for additional draft but the stresses would be very light no?

Any thoughts? Thanks again. You have all made this maintenance/update season much easier. I owe you all a beverage! :D

EDIT: Oh yeah, that would be on a Mac 25.

CaptainForce 05-06-2014 05:08 PM

Re: Topping lift loads?
 
I can only think of a few cases when the load would be greater than the weight of the boom and folded mainsail. I do sometimes stand on the main boom close and foreward, near the gooseneck when I first lifting myself for a trip up the bosun's chair to the masthead. There are also times when I tighten the main sheet with the sail down in order to keep my main boom stil in a chop at the dock or motoring. If the main is not snug with the sheet the shock load on the topping lift as the boom swings with a rock can be significant.

I must confess that I adjust my topping lifts on my main and mizzen booms with a half Duncan Yo-Yo passed through a loop. My half plastic yo-yo disc is likely my weakest link, but I haven't had them fail....
http://i305.photobucket.com/albums/n...thya/005-3.jpg
http://i305.photobucket.com/albums/n...thya/002-6.jpg
.... I replace them every five years due to UV damage.

AlaskaMC 05-06-2014 05:15 PM

Re: Topping lift loads?
 
Great points! No issue here on going up the mast as it is a trailer sailer and I wouldn't trust my weight up that mast. Instead I would just crank it down with the mast raising system I built. I also tension the main sheet when at anchor or dock for the same reasons at times, but never anything that would put too much on a block or rivet to strain it.

Faster 05-06-2014 06:05 PM

Re: Topping lift loads?
 
The biggest load you'll see on your TL is when you forget to ease it and haul on the mainsheet.... ;)

AlaskaMC 05-06-2014 06:09 PM

Re: Topping lift loads?
 
Quote:

Originally Posted by Faster (Post 1812578)
The biggest load you'll see on your TL is when you forget to ease it and haul on the mainsheet.... ;)

Uh, how did you know that? :o You must be a psychic!

Multihullgirl 05-06-2014 06:21 PM

Re: Topping lift loads?
 
You might possibly need it as an emergency halyard, so you might size it accordingly

ReefMagnet 05-06-2014 07:17 PM

Re: Topping lift loads?
 
The topping lift needs to be able to survive hauling down hard on the mainsheet.

On a trailer sailer maybe not so important, but I use spectra to keep the diameter small but load capacity high so I can also use the boom as a makeshift crane, including MOB recovery, if needed. Also for mast climbing the topping lift is often used as an additional safety line.

Alex W 05-06-2014 07:46 PM

Re: Topping lift loads?
 
1/8" amsteel has a breaking strength of 2300lbs and makes a great topping lift. The small Harken carbo block is good for hundreds of pounds, which has been enough for my topping lift.

7/64" is more than strong enough too, but it's a bit harder to splice when it gets that small.

My main sheet is left adjusted so that it is slightly longer than the leech of my sail, and so it is slack when you are out sailing.

IStream 05-06-2014 08:39 PM

Re: Topping lift loads?
 
Quote:

Originally Posted by Alex W (Post 1812874)
My main sheet is left adjusted so that it is slightly longer than the leech of my sail, and so it is slack when you are out sailing.

Alex, I assume you meant to say that your topping lift is left adjusted slightly longer than the leech, not your main sheet, correct? If not, could you clarify?

SailingJackson 05-06-2014 08:57 PM

Re: Topping lift loads?
 
I recall times when I or someone else happened to be up on the cabin while flaking the main while the mainsheet was eased, just when some power boat wake comes by and rolls the boat. Loosing balance grabbing the boom, and sometimes swinging almost over the rail. Full weight of one crew member on the little topping lift.

That stress is still less than someone hardening down on the mainsheet while the topping lift is not eased. Keeping with a line that can take 1000+ lbs of load would be a good bet.

If you use the boat hard and want to get through heavy weather without incidents, oversize everything.


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