Angle of mast and shroud tension

[seandwyer]

Hi guys,

A couple months ago I noticed that my mast (stub end) was not perfectly level and sitting flat on its end - on top of the casting screwed to the hull floor. I've been putting it off, but last weekend I relocated the castings position by pulling it back about an inch to an inch and a half, allowing the mast stub to be perfectly flat on its end as it raises through the center of the hole in the cuddy. Now I find the small amount of movement aft has caused the top of the mast to move a lot in the forward direction - so much so that the forestay can't possibly be tightened up enough to accommodate for the slack.

I'm at a real loss here. I'm willing to bet that the reason the mast was mounted cocked at an angle was to make up for the slack in the forestay, but I can't believe that it should be resting all of its weight on just one bottom edge as opposed to the entire bottom of the mast. Do I need to just go buy a new shorter forestay - or was the mast where it should have been in the first place? I worry that this means my shrouds are stretched and longer than when original - and therefore not so reliable. I may need to buy new turnbuckles no matter what, because they seem to have locked in place once I started tightening them up - I don't know why, but the turn buckle on the forestay is absolutely frozen now.

So - what to do - budget minded of course - to fix this in a hurry, all the while being safe and proper.

Thanks!

[K.C. Walker]

Hi Sean,

You might want to look at this North Sail tuning guide. http://www.northsailsod.com/class/daysa ... uning.html It talks about setting up your mast rake. It may be a little more technical than you are looking for but it does give you some ideas and measurements. This tuning guide is, of course, for higher performance sailing.

I'm thinking that you have been sailing for a while with the mast raked backwards, as before you moved it. The question is how did it sail? If the boat felt balanced, that is, with no or little weather helm it was probably in the right place. Moving the mast forward gives more lee helm which is undesirable and can be dangerous. Because I am not racing I set my mast rake by feel. I tune my rig forward or aft until I have a very slight weather helm. In doing this we are only moving the mast head forward and aft a small amount.

The turnbuckles are adjusters not tensioners. If you are adjusting the turnbuckles under tension you will likely damage them. If you suspect that the turnbuckles are damaged I would definitely replace them. On the 1st sail in my boat that I purchased last year one of the turnbuckles broke and the mast went over. It was not the kind of excitement I was looking for.

You could also measure your forestay and call Rudy at D & R and see if you have the right length.

Fair winds!

KC

[seandwyer]

Hi KC - you know, I'd never even thought about mast rake.....probably because I don't really know what it means or can do for a boat. I'm also not sure about what whether or lee helm refers to. I guess I have some reading to do.

I guess based on your turn buckle story I had better replace them. None of them are the same having been replaced individually over the years I guess. Perhaps I should go ahead and replace them. I had been planning to replace all the standing rigging in the fall once sailing was over for the year, so that's why I was trying to go cheap for now.

I went ahead and pulled the mast back to where it was because it just didn't feel right at all - but the turn buckle is frozen. It wasn't under tension when I was adjusting it either - in fact, it wasn't even attached to the front of the boat - but some how it froze up while I was turning it - as if the threads ground into each other or something between them caused everything to bind up. I really don't know - it looks clean and in perfect working order, but will not budge! I really wish I could just find someone near by with the same boat, set up properly so I could get things right and put my fears to rest.

[K.C. Walker]

If you are planning on replacing your turnbuckles and had planned replacing all of your standing rigging in the fall, I think I would go ahead and do the rigging now rather than replace the turnbuckles and then replace them again with the rigging.

Moving to the mast forward or back affects how the boat steers (the helm) because it moves the center of effort forward or back. In the case of a windsurfer you steer the boat (board) by moving the mast forward and back, there is no rudder on a windsurfer.

Yeah, you probably have some reading ahead of you. It's all fun!

KC

[GreenLake]

I'm also not sure about what whether or lee helm refers to.

Weather helm means your boat likes to turn into the wind unless you pull your tiller, lee helm is the opposite. Neutral helm means your boat is balanced - you could let go of the tiller and keep sailing.

A small amount of weather helm is usually considered ideal. You don't want a large deflection of the rudder, because that would be like leaving on the parking brake. But with a bit of weather helm, the boat would turn into the wind and stop if you let go of the rudder for any reason.

As K.C. already explained, mast rake (and sail trim) determine the balance of the boat - weather/lee helm are the result.