Mast angle

Topics primarily or specifically about the DS1. Many topics are of general interest, so please use forum sections on Rigging, Sails, etc. where appropriate.

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Mast angle

Postby Paddyt » Thu Jun 06, 2019 10:15 pm

Hi everyone,

I acquired a ‘66 DS1 last month and have been fixing her up to get ready to sail. One of the things I had to do was make a new mast stub as the PO has cut the original so it was just flush with the deck when the mast jack was all the way up. Anyway, thanks to this forum I knew where to go to get the parts I needed. What a great resource this forum is.

So I attached the new tabernacle onto the new mast stub and slid it into the deck and onto the mast jack. What I see is the mast is at an angle and does not sit flush on the jack. Is this normal? The picture shows how the mast is angle back to get through the hole in the deck.

Lastly, I have a question about searching on the forum. Understandably the search omits words that are very common. How do I get the common word to be included in the search? Adding a + before the word does not work. ie searching “mast angle” ignores the word ‘mast’.

Thanks
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Paddyt
 
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Re: Mast angle

Postby GreenLake » Thu Jun 06, 2019 11:23 pm

Welcome to the forum.

For search tips, please check the "How to use this forum" part of this forum.

The angle for the mast (called mast rake) is given by the placement of the mast partners (=deck opening) and the mast step.

Your mast is supposed to be raked back somewhat. You can check for correct mast rake by tying a tape measure to the main halyard and using it to measure the distance from mast head to transom.

The expected number is something like 25' and couple of inches. (Locate a North Sails tuning guide for a more accurate number).

(The measurement assumes that the top of the mast track is at 22' 6" above the deck.)

Assuming that nobody messed with the location of the mast step, it should be in the correct position, and then the angle should be the correct one. I have a mast-jack like that, but don't see this effect. However, my mast jack can "wobble" a little bit, presumably that's how it makes the adjustment, so there's no wedge shaped gap between mast foot and the circular nut.
~ green ~ lake ~ ~
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Re: Mast angle

Postby Paddyt » Fri Jun 07, 2019 11:36 am

Thanks for the reply.

What you say makes sense. As I apply downward pressure on the mast, the jack will rock to meet the rake of the mast.

One more question about this setup; there is a slot under the mast step on either side of the keel. It looks like it lines up with the hole in the jack. Am I missing a pin that keeps the jack in place?
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Paddyt
 
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Re: Mast angle

Postby GreenLake » Sat Jun 08, 2019 2:25 am

Can't get to my boat immediately, but it makes sense for the mast step to be fixed in the fore/aft position.

Your mast jack looks brand new, shiny copper colored and all.

The fore/aft position of the mast step controls the mast rake (angle). If your mast step is free to move, then you need to measure your mast rake (using the North Sails tuning guide for the DS). After you have the correct rake, you need to fix the step so it can't move out of position. Could be that a simple bolt would be enough.

Would love to confirm from my boat, but not able to, immediately.
~ green ~ lake ~ ~
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Re: Mast angle

Postby Paddyt » Sat Jun 08, 2019 12:14 pm

It’s all coming together now, sometimes it takes a while to sink into my brain. Thanks for your help. I’ll put together a bolt and washer setup to hold it in place.

The jack had been painted over in some spots so I used the wire wheel on my bench grinder to take it off then decided to do the whole thing so it can acquire a nice even patina. The threaded part looks brass and the rest looks like it is made of bronze.
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Re: Mast angle

Postby GreenLake » Sat Jun 08, 2019 2:57 pm

Make sure to lube it well. The threads are under some pressure when you raise it.

Was just able to check mine, and I do have the bolt, but in a single hole, not a slot.

Looks like the slot was some previous owner's attempt to make the mast rake adjustable. The mast rake affects your boat's balance and you do want to set it to the correct angle.

The North Sails Daysailer Tuning Guide tells you that the distance between the top of the mast and the top of the transom at the very back of the boat should be between 24'11" and 25'1". You measure it with a tape measure pulled aloft by the main halyard.

The result should be that sailing in 8-10 knots of breeze, going upwind, there's not a very strong force on the rudder, so the boat is balanced. If you need to pull hard on the tiller in those conditions, your boat would be imbalanced with too much "weather helm", which is like sailing with the parking brake on.

So, raise the mast, adjust the mast rake until you get the target numbers (read tuning guide for details of how to measure). Then, fix the mast step, go sailing and see whether your boat is balanced. If too much weather helm, you can let the mast come forward a bit, if lee-helm (you need to push the tiller upwind) you can let the mast come back a bit.

Once you have a setup that's correct, mark it, and secure permanently.
~ green ~ lake ~ ~
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