Hunter 30T 1993 fractional rigging: What is an appropriate rake. I've seen posts anywhere from 1 to 3 degrees or 10 to 30 inches on a 45' mast. We cruise on Lake Ontario and cross the lake.
Mast Rake or PreBend
- Thread starter Rleiby
- Start date
Well, I’m a new sailor with limited knowledge but I would like to try and answer. I just tuned my B&R rig. I set my mast to the same 1-3 degrees using the halyard as a plumb. My knowledge now says sail the vessel and fine tune from there. Too much weather helm, lots of strength required on the tiller to pull towards the wind, to much aft rake. Always trying to move away from the wind, Lee-helm, mast too far forward.
Somewhere in there is a fairly balanced feel to keep the vessel going straight.
Somewhere in there is a fairly balanced feel to keep the vessel going straight.
It would be different if you have in mast furling. With in mast furling the pre-bend would be little or none. If no in mast furling the prebend could be up to 6". This is not rake.
Prebend is the amount the mast bends in the mid section looking from masthead to deck. The masthead and mast step remain in whatever their position is. It is considered safe to have some prebend to stabilize the mast for sailing in gusty conditions or waves. The luff sail cut and the mast should be in harmony i.e. match in regard to the bend. . So if the sail is cut to whatever the pre-bend, the only opportunity to change the prebend is to change the mast bend and re-cut or buy a new sail cut for the new prebend. Or the mast can be tuned to fit the sail you have or possibly a new sail.
Rake is different. It is the lean of the mast. It is set by the forestay length - nothing else. It does affect the helm balance with regard to weather or lee helm. You want an approximately 3 degree weather helm - just a comfortable tug on your arm if you have a tiller. Too much weather helm and the rudder becomes a brake - which is slow. Lee helm can make the boat hard to hold into the wind and is considered a bit dangerous. Maybe for an ocean cruising boat that sails primarily downwind it wouldn't be so bad but others with more ocean experience might comment on that.
Rake and Pre-bent - different.
Prebend is the amount the mast bends in the mid section looking from masthead to deck. The masthead and mast step remain in whatever their position is. It is considered safe to have some prebend to stabilize the mast for sailing in gusty conditions or waves. The luff sail cut and the mast should be in harmony i.e. match in regard to the bend. . So if the sail is cut to whatever the pre-bend, the only opportunity to change the prebend is to change the mast bend and re-cut or buy a new sail cut for the new prebend. Or the mast can be tuned to fit the sail you have or possibly a new sail.
Rake is different. It is the lean of the mast. It is set by the forestay length - nothing else. It does affect the helm balance with regard to weather or lee helm. You want an approximately 3 degree weather helm - just a comfortable tug on your arm if you have a tiller. Too much weather helm and the rudder becomes a brake - which is slow. Lee helm can make the boat hard to hold into the wind and is considered a bit dangerous. Maybe for an ocean cruising boat that sails primarily downwind it wouldn't be so bad but others with more ocean experience might comment on that.
Rake and Pre-bent - different.
@shemandr has it right - rake and prebend are two different things. A deck stepped mast usually has the mast step shimmed to the correct rake angle for the boat. Otherwise, the mast would be loaded on the aft edge if it was raked. Some mast bottoms have a curved plug in them that accommodates rake more independent of the mast step.
Is your mast step angled? If so, the mast bottom should sit plumb on it, and then you will have the rake designed for the boat.
Mark
Is your mast step angled? If so, the mast bottom should sit plumb on it, and then you will have the rake designed for the boat.
Mark
I was wondering why you brought up pre-bend then I seen it in his title. Pre-bend a sail trim component. Used for taking advantage of lower wind speeds not so much how the boat feels/handles?
I'm adjusting the backstays on the mast. I seem to be always guessing how tight to have them adjusted. Adjusting the backstay tension to where I thing it should be, the top of the mast appears to have too much aft bend in it. With the backstays too loose, I'm concerned my head sail furler may over bend and get a knick in the aluminum when wind gusts give it a snap. I use a Loos tool for the side shrouds, but the tension guide recommendation doesn't really make sense for the backstays.
No. Prebend is to prevent the mast from inverting. If the mast is perfectly straight the middle can bend forward or aft. Prebend prevents this by inducing a slight bend in the mast so that the middle of the mast is bent forward.
Rake induced both by tuning the rig and by the mast step. The mast step is not flat, it is either mounted at an angle or built with a slant on the base.
You mention plural backstays - do you have a split backstay with a tensioner on it? If so, then they should be adjusted at rest without additional tension (or with 25% of the tensioner) so that the forestay has the tension needed for normal sailing conditions. Then the backstay tensioner is used dynamically to adjust the shape of the main as needed.
Mark
Thank you all for the clarification of terminology, definitions, and expertise. I truly appreciate it. At times I really feel like a Gilligan. Appreciate you all on the forum and willingness to help. FYI my backstay splits 3/4 down to port and starboard turnbuckles. In the past I didn't have enough tension on the backstay and somehow, with a gusty conditions I presume, created a bend in the furler which I had to have repaired. I don't want a repeat of that issue. Thank you all.
It would take a very loose forestay to bend a furler extrusion. So loose that I'd expect the mast to jump off. Taking furlers on and off from a raised mast to dock usually involve it bending in large arcs with no issues, and they often get put on the ground where they take a large arc from the fitting up on the stands to ground.
Are you sure that was the reason for the bend?
Mark
Thanks Dave
I’m learning more and more all the time. I thought I would have a fair bit to offer on this one, sorry guys.
