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post #1 of 8 Old 2 Weeks Ago Thread Starter
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Mast Plumb

The Challengers and probably the reg 24's have/had plumb masts, per original design. I am in the throes of installing a new carbon fiber mast and have installed a new base plate and puck of very similar design and size to the original, for receiving the butt of the new stick. After setting the replacement plate I took a reading with a spirit level and athwartship it is level BUT fore and aft, the new base plate, as did the original, evidently, takes a dive down to the bow to the tune of approx 3/8 inch in just the length of the plate. I don't have the old mast piece anymore so cannot gauge if the original mast was square cut at the bottom as I didn't think to check before it went to the recycler. I can't trust the boot line for level, necessarily. I know about setting up a plumb bob and using halyards for checking equi-distance, etc...here is what I am trying to preclude- after my marina mates have helped walk this thin into place I don't wan't, if I can help it, to take away their light beers and make them un-step, grind the end and then reset the thing, if I can help it.

It seems to me that if I set the butt, as is, currently square cut, and if I tension the stays/shrouds equally
using lengths to make the right triangles that I used to figure the new standing rigging, the the mast rake will be a bunch forward, fore and aft as the boat currently sits in the water.... It also seems to me that, most likely, the original aluminum mast was square cut and even if the new mast seems to rake forward, that while underway it may be in column as the bow comes up a bit while on the wind (unless of course I am running down wind and then the mast will be even further raked forward(!).

I am even tempted to grind a "rocker" (as in rocking chair) shape to the bottom and be done with it.

Thots?

Thanks, all.

As of now the mast is wired and with halyards, and sundry sheaves, lights etc...near ready to install save for the lack of standing rigging I await from a local shop.

Huff
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post #2 of 8 Old 2 Weeks Ago
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Re: Mast Plumb

I'm not exactly sure how you use a level on a boat. I'd think it would be near impossible to get a boat perfectly level on the land and certainly impossible to do so on the water.
Perhaps there is a less landlubber sort of way to do that job. Carpentry is not boat building. They are two distinctly different skills.

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Re: Mast Plumb

Id beg borrow and steal info from other owners of that same boat.
Beat up rhe internet....
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Re: Mast Plumb

The rake of the mast is independent from how the boat sits on its lines in the water or underway.

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Re: Mast Plumb

The boats in the water so it is level fore and aft if you want to make it level as sailed then add the weight of two or three people to the cockpit. then use a halyard plumb bob and rig the mast to the correct rake. then do what ever is needed to the mast step so it sits stable. shims or cut the base. this will get you to a good starting point but to set the mast rake for sailing you will need to sail the boat and adjust the rake to balance the helm while sailing to weather. Columbia 24 always has a bit to much weather helm when the wind is up.

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post #6 of 8 Old 2 Weeks Ago Thread Starter
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Re: Mast Plumb

Athwartships I am not worried about as I can pickup easily create equi-distance of measuring points from port & stbd from the chain plates as I set the mast base in the middle. Besides, if it isn't exact it will be close enough that once I get the fore & aft roughly level/plumb, I can then dial in, once in "the realm". I disagree about the boat being automatically level, fore & aft, and adding passenger weight to the cockpit to compensate/adjust, even if the boat is cleared out, otherwise, which it isn't, in my case, since the galley and other stuff, like the battery, skew the/that level. If, in fact, the mast is to be set plumb, when boat is "static"(?- dry dock and reference factory datum points established or re-used) which I am starting to wonder about (I did find the original "pick point" eyelet, down below that was balanced for hoisting for moving the hull around the yard), I can take my recent hull/chain plate measurements and apply them in a real way using right triangle geometry to gauge plumb by plugging in the measured distance from the stem (inclusive of the "drop" slope which is approx 4.5 inches downhill from the bottom of the mast), a known/set distance up and figure the hypotenuse (a tape measure from the stem, intersecting a level at a certain height). Not unlike if one wants to find a 90 degree angle in *ahem* carpentry, do a layout of tape measures at 3 ft 4 ft and the intersecting 5 ft length and there it is, the right angle, thank you Pythagoras.

More later, once theory hits the dock. Huff
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Re: Mast Plumb

you can also get close by using the cockpit floor it will be near level with a slight slop to drain. the other way would be to stand back a 100 ft and just eyeball it. when it looks good nail it and go sailing

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post #8 of 8 Old 2 Weeks Ago Thread Starter
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Re: Mast Plumb

Just put a right angle triangle/protractor to one of the original(?) Challenger spec/factory drawings and it looks as though the mast is actually raked aft by about 1 degree, not dead plumb. Huff
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