| Re: mast question
[Re: mitch]
#144731 06/03/08 09:45 PM 06/03/08 09:45 PM |
Joined: Sep 2007 Posts: 224 Cincinnati, Ohio Tri_X_Troll
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Posts: 224 Cincinnati, Ohio | I don't know much about the ones that cleat at the base of the mast, but the ones that cleat at the top usually have a second slug for reefing. At least the older H16's did when they still had reef points.
I know I wouldn't trust the cleat at the base of the mast on my 16. It just seems very flimsy.
Ryan - H16
I prefer to go sailing because baseball, football, tennis, and golf only require 1 ball!
| | | Re: mast question
[Re: DennisMe]
#144734 06/04/08 02:17 AM 06/04/08 02:17 AM |
Joined: Jul 2001 Posts: 1,200 Vancouver, BC Tornado
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Posts: 1,200 Vancouver, BC | On a mast with the sail hooked at the top, the halyard line is unloaded during sailing...so the main luff is the only force making compression on the mast...and most of that is from the downhaul force.
Now if you run a base cleat instead of the top hook, now you've got two forces acting to make mast compression...the loaded halyard and still the sail luff. Input force is still primarily the the downhaul, but you get 2:1 purchase (halyard + luff) compressing the mast.
The extrusion can easily take this, assuming you've got reasonable diamonds and don't get crazy with >16:1 downhaul purchase. Biggest concern will be the top sheave & it's mount pin...not usually designed for these kind of loads.
The base cleat needs to handle at least as much force as you can put on the downhaul line..plus some margin for gusts, etc.
Mike.
Mike Dobbs Tornado CAN 99 "Full Tilt"
| | | Re: mast question
[Re: mitch]
#144735 06/04/08 06:55 AM 06/04/08 06:55 AM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | somebody with some tech knowledge please illuminate: how much does a main halyard that goes over the top and cleats at the mast base cause compression, how much of a problem is this, can it or will it break the stick? Locking the halyard at the top is tough on some boats, reefing is a problem etc. the Hobie 21sc just cleats at the base... with new nonstretch line is the simple halyard cleat at the base a viable option? thanks for input It doubles. If you pull 100 pounds on the luff of a sail that is hooked at the top, you get 100 pounds of compression on the mast. If you pull 100 pounds on the luff of a sail where the halyard freewheels at the top and is cleated at the base, you get 100 pounds of compression from the sail luff and from the halyard = 200 lb of compression no the mast. It still baffles me how the monohull world has yet to catch up to this novel concept (except for the America's Cup boats).
Jake Kohl | | | Re: mast question
[Re: Jake]
#144738 06/04/08 03:44 PM 06/04/08 03:44 PM |
Joined: Oct 2002 Posts: 1,226 Atlanta bvining
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Posts: 1,226 Atlanta | It still baffles me how the monohull world has yet to catch up to this novel concept How would you propose to hook and unhook a fixed (non rotating) monohull mast? I suppose you could rig some sort of a trip line, to a mechanical catch at the top of the mast, but that seems more complex than a halyard to hold the sail up. Bill | | | Re: mast question
[Re: bvining]
#144739 06/04/08 03:57 PM 06/04/08 03:57 PM | Anonymous
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Unregistered | you could utilize a claw and bead system similar to the hobie16... | | | Re: mast question
[Re: bvining]
#144740 06/04/08 04:09 PM 06/04/08 04:09 PM |
Joined: Jul 2001 Posts: 1,200 Vancouver, BC Tornado
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Posts: 1,200 Vancouver, BC | There is s solution for hooking a mainsail without requiring rotation. The simple cable with stopper system used on a lot of dinghy jib setups could be beefed up to hold the main. These use a catch fitting that the stopper engages in. The problem is how do you un-catch it when needing to drop sail? Well, we use a locking box with an interesting geometry on Afterburner...the halyard is pulled through the box until a swaged on stainless slug passes into the box...then drops into a notch & locks in place. To disengage, we apply more tension to the halyard, pulling the slug further through the box until it clears the notch. It is now unable to re-engage in the notch as we release the halyard. This exact same design lock fittng is downsized and used on Marstrom Tornado forstays for jib halyards. It still baffles me how the monohull world has yet to catch up to this novel concept How would you propose to hook and unhook a fixed (non rotating) monohull mast? I suppose you could rig some sort of a trip line, to a mechanical catch at the top of the mast, but that seems more complex than a halyard to hold the sail up. Bill
Mike Dobbs Tornado CAN 99 "Full Tilt"
| | | Re: mast question
[Re: ]
#144742 06/04/08 06:12 PM 06/04/08 06:12 PM |
Joined: Sep 2007 Posts: 224 Cincinnati, Ohio Tri_X_Troll
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Posts: 224 Cincinnati, Ohio | If I recall, the C-Scow uses a system similar to that of the hobie 16
Ryan - H16
I prefer to go sailing because baseball, football, tennis, and golf only require 1 ball!
| | | Re: mast question
[Re: bvining]
#144743 06/04/08 06:27 PM 06/04/08 06:27 PM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | It still baffles me how the monohull world has yet to catch up to this novel concept How would you propose to hook and unhook a fixed (non rotating) monohull mast? I suppose you could rig some sort of a trip line, to a mechanical catch at the top of the mast, but that seems more complex than a halyard to hold the sail up. Bill Who said the mast shouldn't rotate?
Jake Kohl | | | Re: mast question
[Re: Jake]
#144744 06/05/08 06:55 AM 06/05/08 06:55 AM |
Joined: Oct 2002 Posts: 1,226 Atlanta bvining
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Posts: 1,226 Atlanta | Who said the mast shouldn't rotate? I'm not saying they shouldnt, I'm saying they usually dont. | | | Re: mast question
[Re: Tornado]
#165073 01/15/09 07:02 PM 01/15/09 07:02 PM |
Joined: Dec 2005 Posts: 55 Los Angeles, CA chrisun
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Posts: 55 Los Angeles, CA | Well, we use a locking box with an interesting geometry on Afterburner...the halyard is pulled through the box until a swaged on stainless slug passes into the box...then drops into a notch & locks in place. To disengage, we apply more tension to the halyard, pulling the slug further through the box until it clears the notch. It is now unable to re-engage in the notch as we release the halyard.
I like this system. Works well. Easy to engage and disengage. However, there was an interesting point made about compression on the sheave. Unfortunately this system does not unload the sheave when it is engaged. The halyard still carries the load over the halyard sheave.
Last edited by chrisun; 01/15/09 07:05 PM.
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