Mast Rake - How much do you have?

[Warren Nethercote]

Parallel to a Facebook post, what sort of mast rake a are people running? How is it measured: with main halyard as a plumb bob (at what fore and aft trim) or as distance from masthead to transom as done for many one-design boats?

Mast rake is neither here nor there apart from weather helm issues, but it does influence required spinnaker luff length if people are running lots of rake. My first interest is spinnaker luff length specification. Base rake will also affect my mainsail tack angle, because my gooseneck is positioned for near maximum mainsail luff length and I can do without a must-crawl-under-it boom. Absent other information I would guess at 12 to 15 inches of rake, aft of the vertical plane established by frame 89.

[lohwaikin]

21 inches on the Big Bad Wolf!
I'm going to take a photo of the mast-head shadow at noon time to prove that...the shadow lands right on frame F110.
The problem lies with the wooden mast.
It seems to be bending gradually over these 3 years.
The cap-shrouds turn-buckles are at their shortest, the shrouds can now be plucked like guitar strings.
I have been receiving remarks from fellow club members on that extreme "rake".

Still going strong though, but I'm constantly looking out for used masts... (for the past 3 years...).

Cheers,

[micah202]

...don't have any #'s,, but I was continually adding rake aft when I was active racing in the NW,, it certainly didn't hurt.

[monsters inc]

So to revisit this, the boat will tolerate a lot of rake, 20 inches, if need be . Was weather helm an issue ? Warren is saying 12 to 15 inches.

[Warren Nethercote]

Conventional wisdom has a boat with moderate weather helm for safety and additionally with enough weather helm for a degree or two of rudder angle so the rudder provides some steady-state lift rather than being just a source of drag. We typically have BIG rudders for control, so we need to shift the centre of effort farther aft than it would be with a smaller rudder. We get there with mast rake, as Carbon Offset suggests. It is interesting that Leon, in South Africa, built PhatAss with the keel forward of Frame 110 and did not complain about weather helm.

That is my story, based on no experience whatsoever with an i550 to date.

[monsters inc]

I have stood the mast up on my hull, now, and have lashed the shrouds that came with my mast to the chain plates. I only have outer shrouds and the forestay, and needed to measure the "adaptor shroud length", and the inner shroud length . It became apparent that a hinged mast foot system is going to be needed, and that the halyard turning blocks could be incorporated into the mast base at the same time. The rake on the mast is already visible with only light pressure on the shrouds, so I don't think that it is necessary to pull the liner on Viper aluminum masts. I have a turn buckle for the forestay to adjust rake / forestay tension , and I am hopefull the adjustment will be enough to find a good groove for the helm. For now , it's back to the shed to come up with some new ideas. Warren, I feel like a bit of weather helm may help if the driver were to go man overboard. Or if you are trying to pick some one out of the water. Either way, I still have a ways to go before getting on the water...thanks for all the advice here. Mike

[Warren Nethercote]

The other thing about weather helm is that it makes the boat easy to sail, in moderation (the 1 to 2 degree steady helm angle). If you have ever sailed a J24 you will know about the reverse: 24s carry neutral helm at best when sailed flat and many tend to lee helm. A forestay limitation prohibits dialing in more rake to fix the issue. I admire people who sail them well because it is tough to find the 'groove' on a boat with little or no helm. It is like pushing an egg around a frying pan - it moves, but there is no feedback.