Mast chock replacement device?

[Philip Kwasinski]

I am sailing on Hull 99.
Instead of mast chocks it has a line that runs forward of the mast that we believe takes the place of mast chocks, is this correct?
Also on the APS site under picture there is a picture with mast chocks and then a line that runs aft of the mast to prevent it from moving aft, we do not have any setup for this.  Should we rig something to prevent the mast from moving aft? We can only limit the masts forward movement.

[Drew Harper]

It takes a LOT of purchase to actually affect prebend on chocking.

Need more than that simple line.

I've tried it but never really had much effect.

[Tim Carter]

I think the real question is the line aft around the mast as a preventer essential in big breeze for rig saftey??

I have seen a couple of carbon rig boats without this feature..

[Lee Shuckerow]

The line and hardware that come on the new boat like ours (119) is designed to pull the mast aft. It works to a point but is hard to control and takes a lot of work to get the mast pulled back. We use chocks that we made but I would buy the APS chocks for 105$ it's pretty inexpensive when you add in the time and effort it takes to make them. We only chock at most 2" back.
I checked the APS site and yes the system that it shows is to pull the mast forward. Why? Not sure. 

[Tim Carter]

So the new system pulls it aft so you can shove a couple of more shims in??

[Dave Nickerson]

The new system was intended to pull the mast back at the partners, I believe, as a substitute for mast chocks.  It can also easily be rigged to hold the mast forward.  Don't have pics but I could take one this weekend.  What several boats are doing is using solid mast chocks and then holding the mast forward against those chocks.  I think of it as a safety thing - may not really do anything, but seems like additional insurance to help prevent mast inversion in breeze.  It's certainly no substitue for a tight gnav and tight uppers though.

We've had some sucess in light air (no one really hiking) by removing about 3/4" of mast chocks in front of the mast and then pushing/pulling the mast forward the same 3/4"s.  Someone pushes the mast forward while the mast puller line is tightened.  It helps bend the mast (and makes the main flatter - removing some cord depth that you don't need in light air) and at the same time puts a little sag in the headstay (giving you a nice fuller, more powerful jib).  It's an easy between-races adjustment.

[Jeff Jones]

I believe the line that comes on the new Rondars is a mast puller.   

Chock back as the breeze comes on to help with your forestay tension.   Pull the mast forward in light air to induce mast bend, flattening the main w/o putting on excessive forestay tension via Mainsheet. 

The 505's he builds have a mast ram... two controls, ram up to induce pre-bend and ram down to push back.    I dont think the line has any safety implications.

but.. i could be off base  I took mine off and used it for the cunningham.

[Paul Zimmerman]

The line is intended to replace solid blocks period.  It is not a safety device at all.  People never really started pulling mast forward until the flatter mainsails came out.  Realistically you can sail without any blocks ever and not worry about the mast. However chocking aft with blocks or the line works well in breeze and chop.
People have taken the system supplied by the builder and use it to hold the mast forward.  This is allowable per class rules as long as no additional hardware, ie blocks or pulleys are used in doing so.

The builders theory is if no mast chocks are supplied the mast is allowed to bend naturally as it was designed to do.
I have seen some people wrongly over block aft causing inversion down low, which is not a good thing.

[Drew Harper]

I use the Ronstans

http://www.ronstan.us/marine5/range.asp?RnID=108A

Cheap $25 and effective. They are slightly too narrow for the partners but it doesn't matter.

I'm with Lee, we block less than 2"

[Somers Kempe]

Sailing in Miami we had the line setup, pulling the mast aft at the partners.  The jib guy would crank it on at the leeward mark and let it go at the top.  The only issue was the line got a bit chewed up by the end of the week.