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Old 29-09-2015, 09:26   #31
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Re: Hobby horsing

Full Definition of INERTIA
1
a : a property of matter by which it remains at rest or in uniform motion in the same straight line unless acted upon by some external force

Hobby horsing is movement around a rotational axis (the center of buoyancy) induced by wave motion. If you want to minimize movement you need a force to resist it.

In the case of a lead mine this force for resistance is provided by the boat’s righting moment which is a combination of hull form and center of gravity.

You can’t change the hull form but by changing how you load the boat you can affect the ballast to displacement ratio and in turn the center of gravity.

One of the reasons people run pipe for their chain out of the bow and down into an anchor locker as close to the center of gravity as possible is to minimize the negative effect of reducing the ballast to displacement ratio resultant from adding weight and increasing the displacement and thereby changing the center of gravity

Where inertia comes into play is that it affects the “feel” of the boat. A boat with weight in the ends will “feel” smoother in it’s motion. But, because of it’s lower ballast to displacement ratio and raised center of gravity it will move more.

Much like a racing boat with extreme deep draft and a bulb keel, the dismasted boat will “feel” like it has violent or jerky motion due to the enhanced stability curve and loss of inertia resultant from it not having a mast because it will be much quicker to react to the forces of the sea acting against it.

Likewise a boat with weight in the ends will be more likely to bury her bow because inertia will make it want to dive down when a wave is trying to lift it up. The other reason to keep weight out of the ends.
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Old 29-09-2015, 10:17   #32
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Re: Hobby horsing

Shorter waterlines, longer overhangs, weight is in the ends regardless of what you add to it your self. With the right wave spacing etc, then these boats hobby horse. Not a big deal on most, but can be obnoxious at times. (don't ask how I know!)
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Old 29-09-2015, 10:35   #33
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Re: Hobby horsing

"I really appreciated the fact that they went without the masthead unit because I saw a lot of techno wennies in that fleet who would spend all their time and effort focused on their laptops and data instead of paying attention to what was happening on the racecourse and to the wind and sea state.

Suffice it to say these guys consistently beat a lot of very excellent sailors. Not having a masthead unit was one of the reasons." Delancey


Priceless!!!
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Old 29-09-2015, 11:23   #34
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Re: Hobby horsing

Is this Hobby Horsing?
https://www.facebook.com/eventinglb/...69537/?fref=nf
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Old 29-09-2015, 12:12   #35
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Re: Hobby horsing

You have to choose slamming OR hobby horsing !
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Old 29-09-2015, 12:15   #36
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Re: Hobby horsing

Quote:
Originally Posted by Cheechako View Post
That happens every time i go out! That's it, I'm taking the 20lb anchor off the bow!
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Old 30-09-2015, 00:13   #37
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Re: Hobby horsing

Quote:
Originally Posted by Cheechako View Post
a little extra time spent trimming the boat would help alleviate that. Shouldn't hobby horse in those small seas
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Old 30-09-2015, 13:43   #38
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Re: Hobby horsing

My boat is one of those with a rep for hobby horsing, I haven't noticed it or been bothered by it yet. One thing to remember is that with narrow beam, long overhang, boats, yes they do seem primed for hobby horsing, and probably will if loaded heavily in the ends (think of a see-saw, not hobby horse), but often we are sailing at a heel angle of 20 degrees or so, so that changes the math a bit. Most boats now seem to be designed for folks who don't want to lean over.
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Old 30-09-2015, 14:43   #39
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Re: Hobby horsing

Is "hobby horsing" just another term for pitching, or are the two somehow different?
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Old 30-09-2015, 16:11   #40
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Re: Hobby horsing

Well my understanding of it, and I could be wrong, a boat with too much weight fore and aft will develop a kind of pitching that is in a kind of harmonic resonance with the wave lengths and rock back and forth and will slow down as a result, or the pitching will be intermittent but exaggerated due to the see-saw of the bow and stern weights rocking back and forth. Imagine, in the extreme, a boat with a deep heavy keel, wide beam and narrow bow and stern with overhangs. Then imagine loading the ends with lots of weight. Not hard to see how that set-up will make a person sea-sick, and a boat slow.
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Old 30-09-2015, 16:13   #41
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Re: Hobby horsing

I think pitching is secondary to large waves. I have hobby-horsed on small waves, it just seems to be second nature in some boats.
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