Troubleshooting a rounding-up problem

[DaveC426913]

I forgot to mention...
The engine does not appreciably interfere with steering or holding a course.

I never thought so either. The wheel is easy to move, although I need a wheel tamer to take my hand off the wheel, or it will flop hard over. And taking my hand off the wheel is often necessary when single-handing.

I'm still waffling on the quick disconnect. It's a safety issue for me. In the conditions I sail (close to land, restricted waterways, lots of gusting), when I need the motor I need it in a hurry. Not often, but often enough. Better to have it and not need it, than need it and not have it. (I can hear the "real" sailors scoffing and harrumphing at my skillz ).

[DaveC426913]

Tomorrow I will be out sailing with my bro. I will drop a line from the mast head and see where it hits the deck. (And I'll check the levelness od the waterline stripe as well.)

I will also check my shrouds for slackness under sail and my forestay.

Something just occurred to me about levelness. I have heard (and experienced) that moving weight forward in the boat improves perfomance. Sitting forward of the helm, rather than behind, helps.

I think it improves speed and other aspects, but I'm not sure if it helps mitigate rounding up.

[DaveC426913]

There may be a little confusion here between a downhaul and cunningham.

A cunningham attaches to the sail and changes its actual shape to increase performance. A downhaul attaches to the spar and applies a downward force to the boom. You will also find downhaul's on poled spinnakers and jibs.

Yes. It was my aim to harden the luff. If I don't raise the main when it is fully luffed, sometimes there's a little slack, especially in fresh winds. The only way to take up that slack when underway is to go into irons and haul on the halyard - a pain in a fresh breeze. A cunningham would allow me to take up that slack conveniently without having to come to a complete stop.

[Be Free]

...
Why couldn't they all have just said that, like you did!

I can think of a couple of reasons.

• They are getting paid by the word.

• They are trying to impress the audience.

• It is actually necessary in context

Only the last one is not firmly "tongue in cheek".

I've spent a long career dealing with technical subjects and explaining them to non-technical clients. One of the first things I would have to do is determine what "language" the client speaks. If we both shared a common technical background then I could explain the situation in a short time. If we did not share the same "language" it could take many paragraphs to convey the same idea.

I told you in one my my first posts that I was not going to use technical terms and gave a coded request to those who might be tempted do so to not complicate matters by introducing them at that time (thank you to those who refrained ) because I knew that you (and many of the current and future readers) and I did not share that common "language".

See our discussion above. I used 251 words to explain it to you in a way that you would understand. If you had known the terms but did not understand how they were interacting I would have said, "it moves the CE behind the CLR" (7 words).

If we shared a common language I might say, "physics". Translation: "I know that if you just stop and think about it you will realize that you already know how these forces are interacting and you can answer your own question".

[Be Free]

Tomorrow I will be out sailing with my bro. I will drop a line from the mast head and see where it hits the deck. (And I'll check the levelness od the waterline stripe as well.)

I will also check my shrouds for slackness under sail and my forestay.

Something just occurred to me about levelness. I have heard (and experienced) that moving weight forward in the boat improves perfomance. Sitting forward of the helm, rather than behind, helps.

I think it improves speed and other aspects, but I'm not sure if it helps mitigate rounding up.

I don't think you are going to find a serious problem with your mast rake. Remember to check the waterline stripe before you bother to measure the rake angle. If the boat is already noticeable lower in the stern then your mast rake has to be off. Get the boat "sitting on her lines" first.

A boat that is listing noticeably in any direction is like trying to drive a car with the alignment off (or maybe with the steering wheel installed off-center, analogies are tricky). The car I learned to drive in had at least 20 degrees of play in in the steering wheel each direction. With practice you could drive it straight, but it would have been so much easier if it didn't have the play in the first place.

Moving forward of the helm is just compensating for a boat that is already out of balance. Get it to float level and you won't have to play games to get it to handle right.

[Be Free]

Yes. It was my aim to harden the luff. If I don't raise the main when it is fully luffed, sometimes there's a little slack, especially in fresh winds. The only way to take up that slack when underway is to go into irons and haul on the halyard - a pain in a fresh breeze. A cunningham would allow me to take up that slack conveniently without having to come to a complete stop.

You are lifting the boom with your topping lift when you raise the main, right?

[DaveC426913]

If we shared a common language I might say, "physics". Translation: "I know that if you just stop and think about it you will realize that you already know how these forces are interacting and you can answer your own question".

Yeah, I'm a physics guy. Though not formally.
And I'm a math guy, but not so much formulae, I'm visual, so I see it via geometry.

[DaveC426913]

You are lifting the boom with your topping lift when you raise the main, right?

Yes.

What I'm not doing is remembering to dry lube my mast channel every spring beore raising it.
So if I'm not dead up-wind, that last few inches can get onerous. (Espicially since my port winch slips. I took it apart and replaced the pawls and springs but that it didn't fix it.)

[DaveC426913]

I don't think you are going to find a serious problem with your mast rake.

See pic 1 below. (My tape measure went missing, but those pieces of paper are 11" each.) so my mast rake is about 25.5".
That's from the masthead halyard block, which stands at least 2-3 inches proud of the masthead itself. (I don't know if one includes or excludes those 2 or so inches. If I subtract it out, my rake is only 23.5" or less.)

Remember to check the waterline stripe before you bother to measure the rake angle. If the boat is already noticeable lower in the stern then your mast rake has to be off. Get the boat "sitting on her lines" first.
A boat that is listing noticeably in any direction is like trying to drive a car with the alignment off (or maybe with the steering wheel installed off-center, analogies are tricky).

Yep. I checked. There's 3" of stripe at the bow and 2" at the stern. If I leveled it perfectly, that would actually reduce the rake (by maybe 2").

Moving forward of the helm is just compensating for a boat that is already out of balance. Get it to float level and you won't have to play games to get it to handle right.

I suppose I could move some gear forward to get it to balance a little better. Or move some gear off the boat.

I think, though, the wisdom is that a boat with 200 pounds of skipper and gear aft of the helm will unbalance an otherwise balanced boat. Moving meat toward centre makes for a happier boat.

I tested this. I put my first mate at the helm but it only moved my plumb line another half inch inches aft. (see pic 2) Two of us would move it an inch.


Pic 1: (no meat at helm)


Pic 2: (one meat at helm)

[Be Free]

You are lifting the boom with your topping lift when you raise the main, right?

Yes.

What I'm not doing is remembering to dry lube my mast channel every spring beore raising it.
So if I'm not dead up-wind, that last few inches can get onerous. (Espicially since my port winch slips. I took it apart and replaced the pawls and springs but that it didn't fix it.)

See if you can find what is binding in those last few inches. You should not have to use a winch to raise the main on a MacGregor.

[Be Free]

Everyone: Please check my math.

The 26X is 276" at the waterline. You have a difference of 1" between the bow and the stern. That comes out to .2 degrees (inv sin (1/276))
The 26X mast is 336". You measured 25.5" from the mast base to the plumb line. That comes out to 85.6 degrees ( inv cos (25.5/336))

Your current mast rake is 90-85.6 = 4.4 degees
If the boat were floating level you would remove .2 degrees and be at 4.2 degrees.

Neither configuration should introduce significant weather helm but moving some gear around to remove that .2 degrees is easy and certainly won't hurt.

[DaveC426913]

See if you can find what is binding in those last few inches. You should not have to use a winch to raise the main on a MacGregor.

Nono. What's binding is raising the main in a 10 knot wind and I'm not fully head-to-wind. It's not a gear/rigging fail, it's a crew fail.

[DaveC426913]

Everyone: Please check my math.

The 26X is 276" at the waterline. You have a difference of 1" between the bow and the stern. That comes out to .2 degrees (inv sin (1/276))
The 26X mast is 336". You measured 25.5" from the mast base to the plumb line. That comes out to 85.6 degrees ( inv cos (25.5/336))

Your current mast rake is 90-85.6 = 4.4 degees
If the boat were floating level you would remove .2 degrees and be at 4.2 degrees.

Neither configuration should introduce significant weather helm but moving some gear around to remove that .2 degrees is easy and certainly won't hurt.

I was doing it without the trig or angles, just geometry.

I've roughed down the dimensions to the mast being as tall off the deck as the waterline is long (see below).

Generally, if the bow and stern (each X long) each rotate by Y,
then the mast (which is 2X long) will rotate by 2Y.



All without math.


In my specific case Y is 1/2 inch therefore mast rake will be altered by 2Y, or one inch.


If you're a stickler for accuracy, use better numbers for mast-height and LWL ratio, and multiply the result by that.
So, for a height to LWL ratio of 28/23, the mast rake is mitigated by 1.2 inches instead of 1 inch. :shrug:

[DaveC426913]

Ultimately, I guess we agree that mitigating my mast rake is more effort than it's worth. I'm not even sure how I would change it. It's hardware attached at both ends, with little options for adjustment. I'd probably have to replace the forestay itself because it would need to be re-swaged. Or I could move the forestay attachment point up the mast.

On a positive note, I was out on Sunday in a 4-5 knot breeze on a close reach and went several minutes without touching the wheel. So balance is at least theoretically achievable in a light wind.



But I tested the shrouds and they are loose IMO. Leeward shrouds could easily move 2 inches when knocked by a boathook. Windward shrouds could move an inch with similar light pressure.

[Be Free]

You don't have anything to mitigate. Your mast is at most .4 degrees too far aft. That's not enough to worry about.