Author Topic: C33 Mast Rake  (Read 1141 times)

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ptsparr

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C33 Mast Rake
« on: 13 June, 2013, 04:44:00 »
Hello,

This is my first post.  I recently purchased a Contest 33 mk I.  I am about to replace the standing rigging, and would like to know what the appropriate mast rake is for this design.  I measured the current mast rake by hanging a weight from the main halyard, and found it to be raked aft by 16 inches (40 cm).  To me this seems excessive.  I will need to shorten the forestay and lengthen the backstays by a few inches to reduce it, so I am interested if any C33 owners have comments on what amount of rake has provided the best sail balance in their experience.  Any help is greatly appreciated.  Thanks.

Philip

Valentine

  • Guest
Re: C33 Mast Rake
« Reply #1 on: 13 June, 2013, 10:59:21 »
Hi Phillipp.

yep, 40 cm seems pretty much. Independently from C33 it should be around 3°. Knowing the length of the mast, Cosinus can help to calculate the appropriate distance from mastfoot to the weight on the main halyard. (f*#* long time ago...)

Apart from that, if you consinder new standing rigging, why not think about a way bring some more tension on your backstays if needed? C33 has two backstays and as far as I know there is one more chainplate in the middle of the stern. Attach some sort of mainsheet there and pull down two sheets of stainless with two rolls running outside of each backstay.

Best regards

Alex

JF

  • Guest
Re: C33 Mast Rake
« Reply #2 on: 13 June, 2013, 13:15:29 »
On my 33 i started out with about 1 or 2 degrees, wich is about 20cm i think. But it's really about balance/handling and the quality and size of your sails. I finally ended up with 0 degree to get the best balance with my (then) new sails. The backstay's on our 33 are adjustible by pulling them together with a sheet, but that's only to get more tension on the forestay when sailing.

And congrats with your purchase, the 33's are great boats!!

ptsparr

  • Guest
Re: C33 Mast Rake
« Reply #3 on: 13 June, 2013, 23:57:14 »
Thanks for the quick replies.

I did the math, and 40cm over the length of the mast is close to 2 degrees, so maybe it's not as excessive as I thought.  Another C33 owner told me that the mast should have no rake, so I'm starting to think this model typically sails best with little or no rake.  I will at least change the stay lengths so that I can adjust it to zero rake, which is not possible with the current rigging.

I only sailed the boat a couple of times before having it hauled, so I wasn't able to thoroughly evaluate the balance, but the previous owner took me sailing on a windy day, ~ 20 knts, gusting to 28 kts, and I noticed the boat did develop extreme weather helm when overpowered in the gusts. When a gust would hit, the boat would heel to ~45 degrees and try strongly to round up. Several times the boat rounded up into the wind against my will.  I think this is normal for most designs to some extent, but it felt excessive.  I'm not sure if this was caused by poor sail trim and/or mast rake, or if the hull design creates a large turning force when heeled far over.  I'm wondering to what extent this is something I can change, and to what extent it is a characteristic of the boat.  Again, any comments are greatly appreciated.

Philip

Offline AndyT

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Re: C33 Mast Rake
« Reply #4 on: 14 June, 2013, 11:47:31 »
Sounds like new rigging to at least allow the mast to stand with no rake is a good idea - you can at least start afresh with setting up the rig.

With regards to the rounding up it could be a number of reasons but certainly mast rake is a potential cause but with the current set up it sounds like it cannot be corrected.

Where about are you based with the boat?

ptsparr

  • Guest
Re: C33 Mast Rake
« Reply #5 on: 14 June, 2013, 16:17:47 »
Yes, the forestay is toggled directly to the stemhead fitting, so there's no way to shorten without cutting it.  There are two toggles on each backstay, which makes me think the mast was raked even farther aft in the past. 

The boat is currently in Boston, Massachusetts in the U.S., however I hope to reduce my latitude next year.

Valentine

  • Guest
Re: C33 Mast Rake
« Reply #6 on: 16 June, 2013, 18:00:15 »
Sailing a 33 thwo weeks ago in some 6-7 bft up wind, we fingured out that does an sensitive side when it comes to trimming. The usual stuff, traveller to lee, more tension on the backstay, Genoasheets back etc. You will know that. But what delivered an astonishing impact was to finally reduce the mainsail to reef 1. We did not loose any speed, the angle of the ruder in the water became smaler, so less breaking by that. And she didn´t heel over that much. Now, thats no breaking news, but for some owners of heavy old ships it seems to be an issue of quality to not have to reef. C33 can have a lot, but if reefing helps, why not.

Do you have MK I or II model? What is the hullnumber?

Best regards

Alex

ptsparr

  • Guest
Re: C33 Mast Rake
« Reply #7 on: 20 June, 2013, 14:29:23 »
Alex,

During the test sail we had one, then two reefs in the main, and a partially furled 135.  I'm sure the boat could always be reefed or trimmed to balance nicely in steady wind, but the problem is in gusty conditions.  When a gust would hit, and it heeled past a certain point, the weather helm increased dramatically until you could not prevent it from rounding up.  I'm comparing this to my last boat, which was an Alberg 30.  They are known for heeling a lot, and having a lot of weather helm, but you could always control the boat, even at large heel angles.

My boat is a Mk I, hull number 34.  I know that the keel and rudder are slightly different between the MK I and MK II, but I don't know if the changes were to improve the balance, or were because of other considerations.

Philip

 


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