Mast prebend and rake 35.5

Apr 30, 2013
2
Hunter 35.5 Otterbay
Hi all,
This is an old topic but I would like more information if possible.
I am presently setting up the mast rake on my 35.5. I have check all the threads and I am getting different setting by different people. First I want to set the mast up for proper prebend. I had "Gene" say to set the mast at 10" measured along the boom and using the main halyard with a weight as a plumb bob. Is this correct??
Then once this is achieved I would introduce 4" of prebend with the back stay.
That would be a total of 14"

In another post I see that "Alan" has 17" of rake. How did you achieve this? Is that the total rake with the prebend?

I am running 155 Genoa 3DL an a Norlam radial cut main, all racing sails. Who has the best setting for this set up?

When the boat is in the water, is that the level plane, that we would use for the measurement along the boom with the main halyard line (plumb bob)? For the 10"?

"Gene" then also says to take the main halyard on a tight line down to the boom at the mast and there should be 4" of prebend at the 25' level. Is that correct? This is only done once we have induced the 4" of rake by the backstay.

Alan, what prebend did you start with, before adding the backstay rake?

I have presently set the rig as per "Gene" recommendation's, but it looks to far forward. Might be ok?? I have set all the shroud tensions to about 20%, That looks good.
 
May 16, 2007
1,509
Boatless ! 26 Ottawa, Ontario
I'm not an expert on this. I'm sure the experts will give you some good advice.

This is how I've done it.

I lay the sail out on the grass to see how the luff is cut. By running a string down the luff I can see if it has say 6" of sail in front of the string. I then know I want at least 6" of pretend, a bit more if I sail in higher winds a bit less if I sail in less winds. The pretend is measured with the halyard tight down the aft side of mast.

The rake is set with a weight on the main halyard. I think the pretend and rake should be adjusted with minimal tension on back stay, the back stay can not effect rake. The rake is only set by the forestay.

The rake I set by the weather helm, if the boat has too much weather helm I'll reduce the amount of rake. The rake must be measured on the water in normal trim.

Once you get some experience with your boat and how it sails you can fine tune the amount of each.

If you racing sails it probably will not help you much to copy what someone else did with stock sails.

Bob
 
Jun 27, 2004
113
Hunter 34 New Bern, NC
Does your 35.5 have the B&R rig? I doubt very much that you can induce mast pre-bend using the backstay. On a B&R rig the backstay is mostly ornamental. Newer Hunters do not even have a backstay!
Prebend can be induced by adjusting the side stays, and the diamond stays. With respect to rake, this is controlled by forestay length. If the boat has weather helm then you should reduce the rake, or even lean the mast forward a bit.