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-   -   Mast Rake for Cape Dory 30 (http://www.sailnet.com/forums/general-discussion-sailing-related/1598-mast-rake-cape-dory-30-a.html)

Bob Ohler 06-27-2001 03:11 PM

Mast Rake for Cape Dory 30
 
I am the proud new owner of a Cape Dory 30 Cutter. I believe that the main sail is blown out, but I also have a feeling that the mast is raked too far aft.
The present conditions are as follows:
1. The boom appears to be hanging too low... head high to the helmsman. The boom is so low in fact that the bimini cannot be up while the sail is up.
2. The main does not appear to be devloping enough drive and the boat has lee helm.

tiz_1 07-13-2001 11:44 AM

Mast Rake for Cape Dory 30
 
If you have lee helm the mast may be too far FORWARD. I sailed on an Island Packet cutter that often had lee helm and it too had fairly old sails.

1) is the main going all the way up the sail track?

2) Is the main sail from another boat (recut)?

3) have you measured the rig dimensions, i.e. the I,P,E measurements? I=mast height to the deck (not cabin top); P=boom to top of mast OR mainsail luff**; E=mainsail foot length. Are they equal to the specs for the CD30 as advertised?

If the mainsail luff is too long** the boom would set too low. Also if the mainsail foot or leech were too long it would droop.

4) call a local sailmaker to see if they will sail the boat with you to establish a) what is wrong b)if anything can be done with the current sails c) recommend new sails necessary to put the boat right. They will mostly do this for free but may be somewhat aggressive about selling you new sails.

--Kevin

dhartdallas 07-30-2001 09:59 PM

Mast Rake for Cape Dory 30
 
Ahoy, Bob Ohler. Regarding your 7-13 on mast
rake, may I comment. Kevin is right about your mast rake. If your mast is raked aft and
you still have lee helm, you do have a problem.
Visualize with me a moment. Think of your
boat as a wind vane. The point on your hull where you could push your boat and it would move straight side ways with out falling off at either the bow or stern is the center of
lateral resistance of your hull. Let me call
it the pivot point for sake of visualization.
Now, take a piece of paper and a pencil and draw two triangles representing the foresail and main. Draw a straight line from the point of the clew to the midpoint of the
luff and from the point of the tack to the midpoint of the leach. Do that in both triangles. Where those lines cross is the geometric center of the sail. Now connect the
point in the jib to the point in the main with a straight line. Finally, assume for reference sake that the fore sail is 60% of the total sail area and the main is 40%. Start at the center point in the jib and move
toward the center point in the main 60% of that line connecting the two. Put a point there. That point is the center of effort of
your sails (it is the geometric center of your total sail area).
If now that point is directly over the pivot point, your boat is in balance and will
not fall off by either the bow or stern.
Now visualize that you rake your mast forward. You move more sail onto the jib side of the point that was your center of effort, creating a new center of effort in front of the pivot point and your boat will now weathervane by the bow, spinning around the pivot point. You will then have to put your tiller down to compensate, thus lee helm. Though it isn''t the kosher way to do it, you can relieve lee helm by raking your mast aft, and relieve weather helm by raking it forward.
I suspect, though, with Kevin, that it is
your sails. You have too much canvas in your
foretriange. Masts on cutters, as you know, are stepped in the center or very near the center of the boat so there will be more room
forward to carry two sails.
I suggest you try this. With your mast straight up, get sailing with your full suit of sails. Now drop the staysail and check your helm. Then hoist your staysail and drop your jib and check your helm. That will show
you the amount of shift in your balance with
different sail configurations and should point to the culprit if it is in fact your foresails
I suspect, though, that it is your main.
I would say call the manufacturer and ask them for the measurements Kevin was talking about, the I.P.E. of all three sails as they were designed to be. Measure your sails and
compare to the designed measurements. You probably do not have the suit of sails that boat was designed to carry.
Finally, I''m a purist and a traditionalist
where boats are concerned. Possibly because I
am a bit of a romantic. I love gaffers and cutters. And, too, maybe it is because I use to sail with a buddy who had a cutter and we spent so much time short tacking up rivers.
Didn''t mean to insult your intelligence or
to take so long. It''s easier when you can draw pictures. Drawing them with words is tough sometimes. A sailing boat is just a resolution of forces. Track the bad guy down.
Good luck.
DHD

newuser 08-08-2001 10:03 AM

Mast Rake for Cape Dory 30
 
I think those guys answered your question on the lee helm issue. I''d like to know the name of the boat. My dad used to have a Cape Dory 30 and I''ve always wondered what happened to it. (Skymark was the name of my dad''s)


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