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post #1 of 11 Old 10-07-2008 Thread Starter
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Mast Placement ?

Hey , Im new to this site, and have a question.
Ive got a 1972 Venture 17 that was a complete wreck when I got it. I have rebuilt it and sailed it for a couple of years now. I have recently been trying to figure out how well it sails compared to other boats. I don't like the way it will blow the bow around ( rounds up I think ), and won't respond to the rudder in certain conditions.
My question is whether the placement of the mast would have any affect on this. I have discovered through looking at pictures of other Venture 17s that my mast has been moved aft, by about 6 to 8 inches.
In my logic that seems like it would help, not hurt the problem, but I don't know.
Any help or opinions would be useful to me. Thanks
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post #2 of 11 Old 10-07-2008
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Joevacs,

I'm not familiar with your boat. But I can say that moving a mast aft will usually increase weather helm, or in other words cause it to to round-up into the wind more readily.

If you are certain that yours is stepped further aft, then it probably would be worthwhile to experiment by shifting the mast further forward. Maybe not to it's original position -- a previous owner may have shifted it aft to compensate for lee-helm. Try splitting the difference.

A little weather helm is usually better than lee-helm.


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post #3 of 11 Old 10-07-2008
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Little trailer sailors often have moveable steps, and they also have very bendy masts to begin with. Mast rake, and bend can play a huge part in the weather helm issue. I see questions like this posted a lot where owners want to change a major part of their boat to correct an issue likely can be corrected much more easily by other means. There was one not to long ago where someone wanted to add a bulb to their centerboard... A lot of work goes into designing most boats, so unless there is an obvious change that was done I wouldn't touch it until you have gone through all other options. Tighten your fore stay and slacken your shrouds should relieve some of the weather helm. If your jib is designed to take the load of the forestay make sure you are getting it really tight. Add a loop in the halyard when the jib is at full hoist and then feed the halyard back through. Put the bight of the loop around the clear and pull the bitter end taught. This gives a little purchase power to the jib halyard to ensure you take out all the slack. Also give the main a really good tug. Flatter sails will result in less weather helm. If you sails are really old and baggy there may be no adjustment that makes much of a difference. There are a ton of little books referencing sail trim for boats this size. The same things that work for the FJ's, 420s etc will work for your boat. But by all means don't be afraid to play around.

Last edited by sailboy21; 10-07-2008 at 05:07 PM.
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post #4 of 11 Old 10-07-2008 Thread Starter
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Thankyou both. That is good information. I appreciate your input. I am sure that the mast was moved because the companionway hatch doesn't open all the way and the nonskid that's molded into the deck is cut away forward of where the step is now.It's not a moveable one, without fiberglass work. I will tighten the fore stay and lengthen the shrouds to see the difference before I relocate the mast back to it's original location. It does have quite a bit of rake as it is now too.
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before you go to the trouble (and structural risk?) of moving the mast step, try reducing the mast rake. You said it's raked quite a bit, so ease off on the backstay, take up on the headstay, and see if that changes the balance and gives you less weather helm.

One other thought. How big is your jib? Maybe if you got a slightly larger one with roughly the same hoist measurement, you could pull the center of effort (of sails) forward a little. You'd still have to move the jibsheet leads, though maybe not. If you could borrow such a jib, you could find out the answer for free.

Weather or lee helm is dependent on where the center of sail effort (CE) is in comparison to the hull's center of lateral resistance (CLR), or pivot-point. When both sails are trimmed properly upwind, you want a slight weather helm.
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Looks like a pretty neat boat. A lot like my old American 16. I had more fun in a boat that size than I ever thought possible. Even cruising on Lake Superior

There were a lot of day sailors in this era of similar design. Their rudders are horribly inefficient. One thing I did for my A16 was to replace the rudder (after it was lost in a broach) with a new high aspect ratio blade with a real foil profile, not just a sheet of plywood. That might be another option for you in a boat like this if you want to trick it out a little.. ala Turbo-V-17. Might even get into the 4th mode
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post #7 of 11 Old 10-08-2008 Thread Starter
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Quote:
Originally Posted by nolatom View Post
before you go to the trouble (and structural risk?) of moving the mast step, try reducing the mast rake. You said it's raked quite a bit, so ease off on the backstay, take up on the headstay, and see if that changes the balance and gives you less weather helm.

One other thought. How big is your jib? Maybe if you got a slightly larger one with roughly the same hoist measurement, you could pull the center of effort (of sails) forward a little. You'd still have to move the jibsheet leads, though maybe not. If you could borrow such a jib, you could find out the answer for free.

Weather or lee helm is dependent on where the center of sail effort (CE) is in comparison to the hull's center of lateral resistance (CLR), or pivot-point. When both sails are trimmed properly upwind, you want a slight weather helm.
I plan to reduce the rake, but what your saying about the jib is what's perplexing to me. I bought a new main sail and a 130 percent genoa after I rebuilt the boat. I am using the 100 jib all the time , because every time I have tried using the genoa, I have no way to steer. It just blows me in circles. That's why I was wondering about this whole thing to begin with. I don't think the boat is balanced correctly.
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Quote:
Originally Posted by Joevacs View Post
I plan to reduce the rake, but what your saying about the jib is what's perplexing to me. I bought a new main sail and a 130 percent genoa after I rebuilt the boat. I am using the 100 jib all the time , because every time I have tried using the genoa, I have no way to steer. It just blows me in circles. That's why I was wondering about this whole thing to begin with. I don't think the boat is balanced correctly.
A head sail can induce weather helm too, especially sailing close to the wind. Is you boat like the one in the line drawing I posted? If it is as fractional as that you would probably benefit from just using the 130 for off the wind and use the 100 for everything else.
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Quote:
Originally Posted by sailboy21 View Post
A head sail can induce weather helm too, especially sailing close to the wind. Is you boat like the one in the line drawing I posted? If it is as fractional as that you would probably benefit from just using the 130 for off the wind and use the 100 for everything else.
Yes, its the boat in the picture. And yes, that's what I have found to work best, I just don't understand why it works that way, unless the mast being moved was a bad choice.
Also, something I haven't mentioned, The guy I bought the boat from had patched it up in a very crude way. He had salvaged it from it's previous owner, to clean up and sell. It was basically abandoned and full of rainwater. The bow, from where the fore stay connects had been torn from the boat, and I suspect the boat was dismasted. I don't know if he placed the mast step where it is now, not knowing any better, Or if the previous owner had moved it for a real reason. I am inclined to think it's the former, not the latter. That's why I'm thinking the boat would be better balanced if I put it back to the original placement.
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I used to sail a MacGregor 25, and any little change in the set-up affected the balance. I would put the mast back in it's original place. I experienced the lack of control you mention, at times when I was overpowered. To regain control, I let out the mainsheet a little. Your rudder can also have a big effect on balance. Make sure it is all the way down when sailing. Also be sure your keel is all the way down when going upwind.

Do you have a post, inside the cabin, under the mast? If you move the mast, you will have to move the post back to the original place also. After you move the mast forward, you might want to start with the mast basicly straight up, and rake it back as needed to reduce lee helm.
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